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glibc/malloc/malloc.c

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/* Malloc implementation for multiple threads without lock contention.
Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>
and Doug Lea <dl@cs.oswego.edu>, 1996.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* V2.6.4-pt3 Thu Feb 20 1997
This work is mainly derived from malloc-2.6.4 by Doug Lea
<dl@cs.oswego.edu>, which is available from:
ftp://g.oswego.edu/pub/misc/malloc.c
Most of the original comments are reproduced in the code below.
* Why use this malloc?
This is not the fastest, most space-conserving, most portable, or
most tunable malloc ever written. However it is among the fastest
while also being among the most space-conserving, portable and tunable.
Consistent balance across these factors results in a good general-purpose
allocator. For a high-level description, see
http://g.oswego.edu/dl/html/malloc.html
On many systems, the standard malloc implementation is by itself not
thread-safe, and therefore wrapped with a single global lock around
all malloc-related functions. In some applications, especially with
multiple available processors, this can lead to contention problems
and bad performance. This malloc version was designed with the goal
to avoid waiting for locks as much as possible. Statistics indicate
that this goal is achieved in many cases.
* Synopsis of public routines
(Much fuller descriptions are contained in the program documentation below.)
ptmalloc_init();
Initialize global configuration. When compiled for multiple threads,
this function must be called once before any other function in the
package. It is not required otherwise. It is called automatically
in the Linux/GNU C libray or when compiling with MALLOC_HOOKS.
malloc(size_t n);
Return a pointer to a newly allocated chunk of at least n bytes, or null
if no space is available.
free(Void_t* p);
Release the chunk of memory pointed to by p, or no effect if p is null.
realloc(Void_t* p, size_t n);
Return a pointer to a chunk of size n that contains the same data
as does chunk p up to the minimum of (n, p's size) bytes, or null
if no space is available. The returned pointer may or may not be
the same as p. If p is null, equivalent to malloc. Unless the
#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
memalign(size_t alignment, size_t n);
Return a pointer to a newly allocated chunk of n bytes, aligned
in accord with the alignment argument, which must be a power of
two.
valloc(size_t n);
Equivalent to memalign(pagesize, n), where pagesize is the page
size of the system (or as near to this as can be figured out from
all the includes/defines below.)
pvalloc(size_t n);
Equivalent to valloc(minimum-page-that-holds(n)), that is,
round up n to nearest pagesize.
calloc(size_t unit, size_t quantity);
Returns a pointer to quantity * unit bytes, with all locations
set to zero.
cfree(Void_t* p);
Equivalent to free(p).
malloc_trim(size_t pad);
Release all but pad bytes of freed top-most memory back
to the system. Return 1 if successful, else 0.
malloc_usable_size(Void_t* p);
Report the number usable allocated bytes associated with allocated
chunk p. This may or may not report more bytes than were requested,
due to alignment and minimum size constraints.
malloc_stats();
Prints brief summary statistics on stderr.
mallinfo()
Returns (by copy) a struct containing various summary statistics.
mallopt(int parameter_number, int parameter_value)
Changes one of the tunable parameters described below. Returns
1 if successful in changing the parameter, else 0.
* Vital statistics:
Alignment: 8-byte
8 byte alignment is currently hardwired into the design. This
seems to suffice for all current machines and C compilers.
Assumed pointer representation: 4 or 8 bytes
Code for 8-byte pointers is untested by me but has worked
reliably by Wolfram Gloger, who contributed most of the
changes supporting this.
Assumed size_t representation: 4 or 8 bytes
Note that size_t is allowed to be 4 bytes even if pointers are 8.
Minimum overhead per allocated chunk: 4 or 8 bytes
Each malloced chunk has a hidden overhead of 4 bytes holding size
and status information.
Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
needed; 4 (8) for a trailing size field
and 8 (16) bytes for free list pointers. Thus, the minimum
allocatable size is 16/24/32 bytes.
Even a request for zero bytes (i.e., malloc(0)) returns a
pointer to something of the minimum allocatable size.
Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
8-byte size_t: 2^63 - 16 bytes
It is assumed that (possibly signed) size_t bit values suffice to
represent chunk sizes. `Possibly signed' is due to the fact
that `size_t' may be defined on a system as either a signed or
an unsigned type. To be conservative, values that would appear
as negative numbers are avoided.
Requests for sizes with a negative sign bit will return a
minimum-sized chunk.
Maximum overhead wastage per allocated chunk: normally 15 bytes
Alignment demands, plus the minimum allocatable size restriction
make the normal worst-case wastage 15 bytes (i.e., up to 15
more bytes will be allocated than were requested in malloc), with
two exceptions:
1. Because requests for zero bytes allocate non-zero space,
the worst case wastage for a request of zero bytes is 24 bytes.
2. For requests >= mmap_threshold that are serviced via
mmap(), the worst case wastage is 8 bytes plus the remainder
from a system page (the minimal mmap unit); typically 4096 bytes.
* Limitations
Here are some features that are NOT currently supported
* No automated mechanism for fully checking that all accesses
to malloced memory stay within their bounds.
* No support for compaction.
* Synopsis of compile-time options:
People have reported using previous versions of this malloc on all
versions of Unix, sometimes by tweaking some of the defines
below. It has been tested most extensively on Solaris and
Linux. People have also reported adapting this malloc for use in
stand-alone embedded systems.
The implementation is in straight, hand-tuned ANSI C. Among other
consequences, it uses a lot of macros. Because of this, to be at
all usable, this code should be compiled using an optimizing compiler
(for example gcc -O2) that can simplify expressions and control
paths.
__STD_C (default: derived from C compiler defines)
Nonzero if using ANSI-standard C compiler, a C++ compiler, or
a C compiler sufficiently close to ANSI to get away with it.
MALLOC_DEBUG (default: NOT defined)
Define to enable debugging. Adds fairly extensive assertion-based
checking to help track down memory errors, but noticeably slows down
execution.
MALLOC_HOOKS (default: NOT defined)
Define to enable support run-time replacement of the allocation
functions through user-defined `hooks'.
REALLOC_ZERO_BYTES_FREES (default: defined)
Define this if you think that realloc(p, 0) should be equivalent
to free(p). (The C standard requires this behaviour, therefore
it is the default.) Otherwise, since malloc returns a unique
pointer for malloc(0), so does realloc(p, 0).
HAVE_MEMCPY (default: defined)
Define if you are not otherwise using ANSI STD C, but still
have memcpy and memset in your C library and want to use them.
Otherwise, simple internal versions are supplied.
USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
Define as 1 if you want the C library versions of memset and
memcpy called in realloc and calloc (otherwise macro versions are used).
At least on some platforms, the simple macro versions usually
outperform libc versions.
HAVE_MMAP (default: defined as 1)
Define to non-zero to optionally make malloc() use mmap() to
allocate very large blocks.
HAVE_MREMAP (default: defined as 0 unless Linux libc set)
Define to non-zero to optionally make realloc() use mremap() to
reallocate very large blocks.
malloc_getpagesize (default: derived from system #includes)
Either a constant or routine call returning the system page size.
HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
Optionally define if you are on a system with a /usr/include/malloc.h
that declares struct mallinfo. It is not at all necessary to
define this even if you do, but will ensure consistency.
INTERNAL_SIZE_T (default: size_t)
Define to a 32-bit type (probably `unsigned int') if you are on a
64-bit machine, yet do not want or need to allow malloc requests of
greater than 2^31 to be handled. This saves space, especially for
very small chunks.
_LIBC (default: NOT defined)
Defined only when compiled as part of the Linux libc/glibc.
Also note that there is some odd internal name-mangling via defines
(for example, internally, `malloc' is named `mALLOc') needed
when compiling in this case. These look funny but don't otherwise
affect anything.
LACKS_UNISTD_H (default: undefined)
Define this if your system does not have a <unistd.h>.
MORECORE (default: sbrk)
The name of the routine to call to obtain more memory from the system.
MORECORE_FAILURE (default: -1)
The value returned upon failure of MORECORE.
MORECORE_CLEARS (default 1)
True (1) if the routine mapped to MORECORE zeroes out memory (which
holds for sbrk).
DEFAULT_TRIM_THRESHOLD
DEFAULT_TOP_PAD
DEFAULT_MMAP_THRESHOLD
DEFAULT_MMAP_MAX
Default values of tunable parameters (described in detail below)
controlling interaction with host system routines (sbrk, mmap, etc).
These values may also be changed dynamically via mallopt(). The
preset defaults are those that give best performance for typical
programs/systems.
DEFAULT_CHECK_ACTION
When the standard debugging hooks are in place, and a pointer is
detected as corrupt, do nothing (0), print an error message (1),
or call abort() (2).
*/
/*
* Compile-time options for multiple threads:
USE_PTHREADS, USE_THR, USE_SPROC
Define one of these as 1 to select the thread interface:
POSIX threads, Solaris threads or SGI sproc's, respectively.
If none of these is defined as non-zero, you get a `normal'
malloc implementation which is not thread-safe. Support for
multiple threads requires HAVE_MMAP=1. As an exception, when
compiling for GNU libc, i.e. when _LIBC is defined, then none of
the USE_... symbols have to be defined.
HEAP_MIN_SIZE
HEAP_MAX_SIZE
When thread support is enabled, additional `heap's are created
with mmap calls. These are limited in size; HEAP_MIN_SIZE should
be a multiple of the page size, while HEAP_MAX_SIZE must be a power
of two for alignment reasons. HEAP_MAX_SIZE should be at least
twice as large as the mmap threshold.
THREAD_STATS
When this is defined as non-zero, some statistics on mutex locking
are computed.
*/
/* Preliminaries */
#ifndef __STD_C
#if defined (__STDC__)
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/
#ifndef Void_t
#if __STD_C
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/
#if __STD_C
# include <stddef.h> /* for size_t */
# if defined _LIBC || defined MALLOC_HOOKS
# include <stdlib.h> /* for getenv(), abort() */
# endif
#else
# include <sys/types.h>
#endif
/* Macros for handling mutexes and thread-specific data. This is
included early, because some thread-related header files (such as
pthread.h) should be included before any others. */
#include "thread-m.h"
#ifdef __cplusplus
extern "C" {
#endif
#include <errno.h>
#include <stdio.h> /* needed for malloc_stats */
/*
Compile-time options
*/
/*
Debugging:
Because freed chunks may be overwritten with link fields, this
malloc will often die when freed memory is overwritten by user
programs. This can be very effective (albeit in an annoying way)
in helping track down dangling pointers.
If you compile with -DMALLOC_DEBUG, a number of assertion checks are
enabled that will catch more memory errors. You probably won't be
able to make much sense of the actual assertion errors, but they
should help you locate incorrectly overwritten memory. The
checking is fairly extensive, and will slow down execution
noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set will
attempt to check every non-mmapped allocated and free chunk in the
course of computing the summaries. (By nature, mmapped regions
cannot be checked very much automatically.)
Setting MALLOC_DEBUG may also be helpful if you are trying to modify
this code. The assertions in the check routines spell out in more
detail the assumptions and invariants underlying the algorithms.
*/
#if MALLOC_DEBUG
#include <assert.h>
#else
#define assert(x) ((void)0)
#endif
/*
INTERNAL_SIZE_T is the word-size used for internal bookkeeping
of chunk sizes. On a 64-bit machine, you can reduce malloc
overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
at the expense of not being able to handle requests greater than
2^31. This limitation is hardly ever a concern; you are encouraged
to set this. However, the default version is the same as size_t.
*/
#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif
/*
REALLOC_ZERO_BYTES_FREES should be set if a call to realloc with
zero bytes should be the same as a call to free. The C standard
requires this. Otherwise, since this malloc returns a unique pointer
for malloc(0), so does realloc(p, 0).
*/
#define REALLOC_ZERO_BYTES_FREES
/*
HAVE_MEMCPY should be defined if you are not otherwise using
ANSI STD C, but still have memcpy and memset in your C library
and want to use them in calloc and realloc. Otherwise simple
macro versions are defined here.
USE_MEMCPY should be defined as 1 if you actually want to
have memset and memcpy called. People report that the macro
versions are often enough faster than libc versions on many
systems that it is better to use them.
*/
#define HAVE_MEMCPY 1
#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif
#if (__STD_C || defined(HAVE_MEMCPY))
#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
#else
Void_t* memset();
Void_t* memcpy();
#endif
#endif
#if USE_MEMCPY
/* The following macros are only invoked with (2n+1)-multiples of
INTERNAL_SIZE_T units, with a positive integer n. This is exploited
for fast inline execution when n is small. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T mzsz = (nbytes); \
if(mzsz <= 9*sizeof(mzsz)) { \
INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; }}} \
*mz++ = 0; \
*mz++ = 0; \
*mz = 0; \
} else memset((charp), 0, mzsz); \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T mcsz = (nbytes); \
if(mcsz <= 9*sizeof(mcsz)) { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; }}} \
*mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
*mcdst = *mcsrc ; \
} else memcpy(dest, src, mcsz); \
} while(0)
#else /* !USE_MEMCPY */
/* Use Duff's device for good zeroing/copying performance. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mzp++ = 0; \
case 7: *mzp++ = 0; \
case 6: *mzp++ = 0; \
case 5: *mzp++ = 0; \
case 4: *mzp++ = 0; \
case 3: *mzp++ = 0; \
case 2: *mzp++ = 0; \
case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mcdst++ = *mcsrc++; \
case 7: *mcdst++ = *mcsrc++; \
case 6: *mcdst++ = *mcsrc++; \
case 5: *mcdst++ = *mcsrc++; \
case 4: *mcdst++ = *mcsrc++; \
case 3: *mcdst++ = *mcsrc++; \
case 2: *mcdst++ = *mcsrc++; \
case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#endif
#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif
/*
Define HAVE_MMAP to optionally make malloc() use mmap() to
allocate very large blocks. These will be returned to the
operating system immediately after a free().
*/
#ifndef HAVE_MMAP
# ifdef _POSIX_MAPPED_FILES
# define HAVE_MMAP 1
# endif
#endif
/*
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
large blocks. This is currently only possible on Linux with
kernel versions newer than 1.3.77.
*/
#ifndef HAVE_MREMAP
#define HAVE_MREMAP defined(__linux__) && !defined(__arm__)
#endif
#if HAVE_MMAP
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif
#if !defined(MAP_FAILED)
#define MAP_FAILED ((char*)-1)
#endif
#ifndef MAP_NORESERVE
# ifdef MAP_AUTORESRV
# define MAP_NORESERVE MAP_AUTORESRV
# else
# define MAP_NORESERVE 0
# endif
#endif
#endif /* HAVE_MMAP */
/*
Access to system page size. To the extent possible, this malloc
manages memory from the system in page-size units.
The following mechanics for getpagesize were adapted from
bsd/gnu getpagesize.h
*/
#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# include <sys/param.h>
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
#endif
/*
This version of malloc supports the standard SVID/XPG mallinfo
routine that returns a struct containing the same kind of
information you can get from malloc_stats. It should work on
any SVID/XPG compliant system that has a /usr/include/malloc.h
defining struct mallinfo. (If you'd like to install such a thing
yourself, cut out the preliminary declarations as described above
and below and save them in a malloc.h file. But there's no
compelling reason to bother to do this.)
The main declaration needed is the mallinfo struct that is returned
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
bunch of fields, most of which are not even meaningful in this
version of malloc. Some of these fields are are instead filled by
mallinfo() with other numbers that might possibly be of interest.
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
/usr/include/malloc.h file that includes a declaration of struct
mallinfo. If so, it is included; else an SVID2/XPG2 compliant
version is declared below. These must be precisely the same for
mallinfo() to work.
*/
/* #define HAVE_USR_INCLUDE_MALLOC_H */
#if HAVE_USR_INCLUDE_MALLOC_H
# include "/usr/include/malloc.h"
#else
# ifdef _LIBC
# include "malloc.h"
# else
# include "ptmalloc.h"
# endif
#endif
#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif
/*
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
to keep before releasing via malloc_trim in free().
Automatic trimming is mainly useful in long-lived programs.
Because trimming via sbrk can be slow on some systems, and can
sometimes be wasteful (in cases where programs immediately
afterward allocate more large chunks) the value should be high
enough so that your overall system performance would improve by
releasing.
The trim threshold and the mmap control parameters (see below)
can be traded off with one another. Trimming and mmapping are
two different ways of releasing unused memory back to the
system. Between these two, it is often possible to keep
system-level demands of a long-lived program down to a bare
minimum. For example, in one test suite of sessions measuring
the XF86 X server on Linux, using a trim threshold of 128K and a
mmap threshold of 192K led to near-minimal long term resource
consumption.
If you are using this malloc in a long-lived program, it should
pay to experiment with these values. As a rough guide, you
might set to a value close to the average size of a process
(program) running on your system. Releasing this much memory
would allow such a process to run in memory. Generally, it's
worth it to tune for trimming rather than memory mapping when a
program undergoes phases where several large chunks are
allocated and released in ways that can reuse each other's
storage, perhaps mixed with phases where there are no such
chunks at all. And in well-behaved long-lived programs,
controlling release of large blocks via trimming versus mapping
is usually faster.
However, in most programs, these parameters serve mainly as
protection against the system-level effects of carrying around
massive amounts of unneeded memory. Since frequent calls to
sbrk, mmap, and munmap otherwise degrade performance, the default
parameters are set to relatively high values that serve only as
safeguards.
The default trim value is high enough to cause trimming only in
fairly extreme (by current memory consumption standards) cases.
It must be greater than page size to have any useful effect. To
disable trimming completely, you can set to (unsigned long)(-1);
*/
#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif
/*
M_TOP_PAD is the amount of extra `padding' space to allocate or
retain whenever sbrk is called. It is used in two ways internally:
* When sbrk is called to extend the top of the arena to satisfy
a new malloc request, this much padding is added to the sbrk
request.
* When malloc_trim is called automatically from free(),
it is used as the `pad' argument.
In both cases, the actual amount of padding is rounded
so that the end of the arena is always a system page boundary.
The main reason for using padding is to avoid calling sbrk so
often. Having even a small pad greatly reduces the likelihood
that nearly every malloc request during program start-up (or
after trimming) will invoke sbrk, which needlessly wastes
time.
Automatic rounding-up to page-size units is normally sufficient
to avoid measurable overhead, so the default is 0. However, in
systems where sbrk is relatively slow, it can pay to increase
this value, at the expense of carrying around more memory than
the program needs.
*/
#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif
/*
M_MMAP_THRESHOLD is the request size threshold for using mmap()
to service a request. Requests of at least this size that cannot
be allocated using already-existing space will be serviced via mmap.
(If enough normal freed space already exists it is used instead.)
Using mmap segregates relatively large chunks of memory so that
they can be individually obtained and released from the host
system. A request serviced through mmap is never reused by any
other request (at least not directly; the system may just so
happen to remap successive requests to the same locations).
Segregating space in this way has the benefit that mmapped space
can ALWAYS be individually released back to the system, which
helps keep the system level memory demands of a long-lived
program low. Mapped memory can never become `locked' between
other chunks, as can happen with normally allocated chunks, which
menas that even trimming via malloc_trim would not release them.
However, it has the disadvantages that:
1. The space cannot be reclaimed, consolidated, and then
used to service later requests, as happens with normal chunks.
2. It can lead to more wastage because of mmap page alignment
requirements
3. It causes malloc performance to be more dependent on host
system memory management support routines which may vary in
implementation quality and may impose arbitrary
limitations. Generally, servicing a request via normal
malloc steps is faster than going through a system's mmap.
All together, these considerations should lead you to use mmap
only for relatively large requests.
*/
#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX (1024)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif
/*
M_MMAP_MAX is the maximum number of requests to simultaneously
service using mmap. This parameter exists because:
1. Some systems have a limited number of internal tables for
use by mmap.
2. In most systems, overreliance on mmap can degrade overall
performance.
3. If a program allocates many large regions, it is probably
better off using normal sbrk-based allocation routines that
can reclaim and reallocate normal heap memory. Using a
small value allows transition into this mode after the
first few allocations.
Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
the default value is 0, and attempts to set it to non-zero values
in mallopt will fail.
*/
#ifndef DEFAULT_CHECK_ACTION
#define DEFAULT_CHECK_ACTION 1
#endif
/* What to do if the standard debugging hooks are in place and a
corrupt pointer is detected: do nothing (0), print an error message
(1), or call abort() (2). */
#define HEAP_MIN_SIZE (32*1024)
#define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */
/* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps
that are dynamically created for multi-threaded programs. The
maximum size must be a power of two, for fast determination of
which heap belongs to a chunk. It should be much larger than
the mmap threshold, so that requests with a size just below that
threshold can be fulfilled without creating too many heaps.
*/
#ifndef THREAD_STATS
#define THREAD_STATS 0
#endif
/* If THREAD_STATS is non-zero, some statistics on mutex locking are
computed. */
/* Macro to set errno. */
#ifndef __set_errno
# define __set_errno(val) errno = (val)
#endif
/* On some platforms we can compile internal, not exported functions better.
Let the environment provide a macro and define it to be empty if it
is not available. */
#ifndef internal_function
# define internal_function
#endif
/*
Special defines for the Linux/GNU C library.
*/
#ifdef _LIBC
#if __STD_C
Void_t * __default_morecore (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore;
#else
Void_t * __default_morecore ();
Void_t *(*__morecore)() = __default_morecore;
#endif
static size_t __libc_pagesize;
#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#define MORECORE_CLEARS 1
#define mmap __mmap
#define munmap __munmap
#define mremap __mremap
#define mprotect __mprotect
#undef malloc_getpagesize
#define malloc_getpagesize __libc_pagesize
#else /* _LIBC */
#if __STD_C
extern Void_t* sbrk(ptrdiff_t);
#else
extern Void_t* sbrk();
#endif
#ifndef MORECORE
#define MORECORE sbrk
#endif
#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif
#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif
#endif /* _LIBC */
#ifdef _LIBC
#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt
#define mALLOC_STATs __malloc_stats
#define mALLOC_USABLE_SIZe __malloc_usable_size
#define mALLOC_TRIm __malloc_trim
#define mALLOC_GET_STATe __malloc_get_state
#define mALLOC_SET_STATe __malloc_set_state
#else
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#define mALLOC_STATs malloc_stats
#define mALLOC_USABLE_SIZe malloc_usable_size
#define mALLOC_TRIm malloc_trim
#define mALLOC_GET_STATe malloc_get_state
#define mALLOC_SET_STATe malloc_set_state
#endif
/* Public routines */
#if __STD_C
#ifndef _LIBC
void ptmalloc_init(void);
#endif
Void_t* mALLOc(size_t);
void fREe(Void_t*);
Void_t* rEALLOc(Void_t*, size_t);
Void_t* mEMALIGn(size_t, size_t);
Void_t* vALLOc(size_t);
Void_t* pvALLOc(size_t);
Void_t* cALLOc(size_t, size_t);
void cfree(Void_t*);
int mALLOC_TRIm(size_t);
size_t mALLOC_USABLE_SIZe(Void_t*);
void mALLOC_STATs(void);
int mALLOPt(int, int);
struct mallinfo mALLINFo(void);
Void_t* mALLOC_GET_STATe(void);
int mALLOC_SET_STATe(Void_t*);
#else /* !__STD_C */
#ifndef _LIBC
void ptmalloc_init();
#endif
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int mALLOC_TRIm();
size_t mALLOC_USABLE_SIZe();
void mALLOC_STATs();
int mALLOPt();
struct mallinfo mALLINFo();
Void_t* mALLOC_GET_STATe();
int mALLOC_SET_STATe();
#endif /* __STD_C */
#ifdef __cplusplus
}; /* end of extern "C" */
#endif
#if !defined(NO_THREADS) && !HAVE_MMAP
"Can't have threads support without mmap"
#endif
/*
Type declarations
*/
struct malloc_chunk
{
INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
struct malloc_chunk* fd; /* double links -- used only if free. */
struct malloc_chunk* bk;
};
typedef struct malloc_chunk* mchunkptr;
/*
malloc_chunk details:
(The following includes lightly edited explanations by Colin Plumb.)
Chunks of memory are maintained using a `boundary tag' method as
described in e.g., Knuth or Standish. (See the paper by Paul
Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
survey of such techniques.) Sizes of free chunks are stored both
in the front of each chunk and at the end. This makes
consolidating fragmented chunks into bigger chunks very fast. The
size fields also hold bits representing whether chunks are free or
in use.
An allocated chunk looks like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk, if allocated | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User data starts here... .
. .
. (malloc_usable_space() bytes) .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where "chunk" is the front of the chunk for the purpose of most of
the malloc code, but "mem" is the pointer that is returned to the
user. "Nextchunk" is the beginning of the next contiguous chunk.
Chunks always begin on even word boundaries, so the mem portion
(which is returned to the user) is also on an even word boundary, and
thus double-word aligned.
Free chunks are stored in circular doubly-linked lists, and look like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`head:' | Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forward pointer to next chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Back pointer to previous chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused space (may be 0 bytes long) .
. .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`foot:' | Size of chunk, in bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The P (PREV_INUSE) bit, stored in the unused low-order bit of the
chunk size (which is always a multiple of two words), is an in-use
bit for the *previous* chunk. If that bit is *clear*, then the
word before the current chunk size contains the previous chunk
size, and can be used to find the front of the previous chunk.
(The very first chunk allocated always has this bit set,
preventing access to non-existent (or non-owned) memory.)
Note that the `foot' of the current chunk is actually represented
as the prev_size of the NEXT chunk. (This makes it easier to
deal with alignments etc).
The two exceptions to all this are
1. The special chunk `top', which doesn't bother using the
trailing size field since there is no
next contiguous chunk that would have to index off it. (After
initialization, `top' is forced to always exist. If it would
become less than MINSIZE bytes long, it is replenished via
malloc_extend_top.)
2. Chunks allocated via mmap, which have the second-lowest-order
bit (IS_MMAPPED) set in their size fields. Because they are
never merged or traversed from any other chunk, they have no
foot size or inuse information.
Available chunks are kept in any of several places (all declared below):
* `av': An array of chunks serving as bin headers for consolidated
chunks. Each bin is doubly linked. The bins are approximately
proportionally (log) spaced. There are a lot of these bins
(128). This may look excessive, but works very well in
practice. All procedures maintain the invariant that no
consolidated chunk physically borders another one. Chunks in
bins are kept in size order, with ties going to the
approximately least recently used chunk.
The chunks in each bin are maintained in decreasing sorted order by
size. This is irrelevant for the small bins, which all contain
the same-sized chunks, but facilitates best-fit allocation for
larger chunks. (These lists are just sequential. Keeping them in
order almost never requires enough traversal to warrant using
fancier ordered data structures.) Chunks of the same size are
linked with the most recently freed at the front, and allocations
are taken from the back. This results in LRU or FIFO allocation
order, which tends to give each chunk an equal opportunity to be
consolidated with adjacent freed chunks, resulting in larger free
chunks and less fragmentation.
* `top': The top-most available chunk (i.e., the one bordering the
end of available memory) is treated specially. It is never
included in any bin, is used only if no other chunk is
available, and is released back to the system if it is very
large (see M_TRIM_THRESHOLD).
* `last_remainder': A bin holding only the remainder of the
most recently split (non-top) chunk. This bin is checked
before other non-fitting chunks, so as to provide better
locality for runs of sequentially allocated chunks.
* Implicitly, through the host system's memory mapping tables.
If supported, requests greater than a threshold are usually
serviced via calls to mmap, and then later released via munmap.
*/
/*
Bins
The bins are an array of pairs of pointers serving as the
heads of (initially empty) doubly-linked lists of chunks, laid out
in a way so that each pair can be treated as if it were in a
malloc_chunk. (This way, the fd/bk offsets for linking bin heads
and chunks are the same).
Bins for sizes < 512 bytes contain chunks of all the same size, spaced
8 bytes apart. Larger bins are approximately logarithmically
spaced. (See the table below.)
Bin layout:
64 bins of size 8
32 bins of size 64
16 bins of size 512
8 bins of size 4096
4 bins of size 32768
2 bins of size 262144
1 bin of size what's left
There is actually a little bit of slop in the numbers in bin_index
for the sake of speed. This makes no difference elsewhere.
The special chunks `top' and `last_remainder' get their own bins,
(this is implemented via yet more trickery with the av array),
although `top' is never properly linked to its bin since it is
always handled specially.
*/
#define NAV 128 /* number of bins */
typedef struct malloc_chunk* mbinptr;
/* An arena is a configuration of malloc_chunks together with an array
of bins. With multiple threads, it must be locked via a mutex
before changing its data structures. One or more `heaps' are
associated with each arena, except for the main_arena, which is
associated only with the `main heap', i.e. the conventional free
store obtained with calls to MORECORE() (usually sbrk). The `av'
array is never mentioned directly in the code, but instead used via
bin access macros. */
typedef struct _arena {
mbinptr av[2*NAV + 2];
struct _arena *next;
size_t size;
#if THREAD_STATS
long stat_lock_direct, stat_lock_loop, stat_lock_wait;
#endif
mutex_t mutex;
} arena;
/* A heap is a single contiguous memory region holding (coalesceable)
malloc_chunks. It is allocated with mmap() and always starts at an
address aligned to HEAP_MAX_SIZE. Not used unless compiling for
multiple threads. */
typedef struct _heap_info {
arena *ar_ptr; /* Arena for this heap. */
struct _heap_info *prev; /* Previous heap. */
size_t size; /* Current size in bytes. */
size_t pad; /* Make sure the following data is properly aligned. */
} heap_info;
/*
Static functions (forward declarations)
*/
#if __STD_C
static void chunk_free(arena *ar_ptr, mchunkptr p) internal_function;
static mchunkptr chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T size)
internal_function;
static mchunkptr chunk_realloc(arena *ar_ptr, mchunkptr oldp,
INTERNAL_SIZE_T oldsize, INTERNAL_SIZE_T nb)
internal_function;
static mchunkptr chunk_align(arena *ar_ptr, INTERNAL_SIZE_T nb,
size_t alignment) internal_function;
static int main_trim(size_t pad) internal_function;
#ifndef NO_THREADS
static int heap_trim(heap_info *heap, size_t pad) internal_function;
#endif
#if defined _LIBC || defined MALLOC_HOOKS
static Void_t* malloc_check(size_t sz, const Void_t *caller);
static void free_check(Void_t* mem, const Void_t *caller);
static Void_t* realloc_check(Void_t* oldmem, size_t bytes,
const Void_t *caller);
static Void_t* memalign_check(size_t alignment, size_t bytes,
const Void_t *caller);
#ifndef NO_THREADS
static Void_t* malloc_starter(size_t sz, const Void_t *caller);
static void free_starter(Void_t* mem, const Void_t *caller);
static Void_t* malloc_atfork(size_t sz, const Void_t *caller);
static void free_atfork(Void_t* mem, const Void_t *caller);
#endif
#endif
#else
static void chunk_free();
static mchunkptr chunk_alloc();
static mchunkptr chunk_realloc();
static mchunkptr chunk_align();
static int main_trim();
#ifndef NO_THREADS
static int heap_trim();
#endif
#if defined _LIBC || defined MALLOC_HOOKS
static Void_t* malloc_check();
static void free_check();
static Void_t* realloc_check();
static Void_t* memalign_check();
#ifndef NO_THREADS
static Void_t* malloc_starter();
static void free_starter();
static Void_t* malloc_atfork();
static void free_atfork();
#endif
#endif
#endif
/* sizes, alignments */
#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
#define MINSIZE (sizeof(struct malloc_chunk))
/* conversion from malloc headers to user pointers, and back */
#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
/* pad request bytes into a usable size, return non-zero on overflow */
#define request2size(req, nb) \
((nb = (req) + (SIZE_SZ + MALLOC_ALIGN_MASK)),\
((long)nb <= 0 || nb < (INTERNAL_SIZE_T) (req) \
? (__set_errno (ENOMEM), 1) \
: ((nb < (MINSIZE + MALLOC_ALIGN_MASK) \
? (nb = MINSIZE) : (nb &= ~MALLOC_ALIGN_MASK)), 0)))
/* Check if m has acceptable alignment */
#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
/*
Physical chunk operations
*/
/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
#define PREV_INUSE 0x1
/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
#define IS_MMAPPED 0x2
/* Bits to mask off when extracting size */
#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
/* Ptr to next physical malloc_chunk. */
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
/* Ptr to previous physical malloc_chunk */
#define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
/* Treat space at ptr + offset as a chunk */
#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
/*
Dealing with use bits
*/
/* extract p's inuse bit */
#define inuse(p) \
((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
/* extract inuse bit of previous chunk */
#define prev_inuse(p) ((p)->size & PREV_INUSE)
/* check for mmap()'ed chunk */
#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
/* set/clear chunk as in use without otherwise disturbing */
#define set_inuse(p) \
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
#define clear_inuse(p) \
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
/* check/set/clear inuse bits in known places */
#define inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
#define set_inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
#define clear_inuse_bit_at_offset(p, s)\
(((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
/*
Dealing with size fields
*/
/* Get size, ignoring use bits */
#define chunksize(p) ((p)->size & ~(SIZE_BITS))
/* Set size at head, without disturbing its use bit */
#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
/* Set size/use ignoring previous bits in header */
#define set_head(p, s) ((p)->size = (s))
/* Set size at footer (only when chunk is not in use) */
#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
/* access macros */
#define bin_at(a, i) ((mbinptr)((char*)&(((a)->av)[2*(i) + 2]) - 2*SIZE_SZ))
#define init_bin(a, i) ((a)->av[2*i+2] = (a)->av[2*i+3] = bin_at((a), i))
#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
/*
The first 2 bins are never indexed. The corresponding av cells are instead
used for bookkeeping. This is not to save space, but to simplify
indexing, maintain locality, and avoid some initialization tests.
*/
#define binblocks(a) (bin_at(a,0)->size)/* bitvector of nonempty blocks */
#define top(a) (bin_at(a,0)->fd) /* The topmost chunk */
#define last_remainder(a) (bin_at(a,1)) /* remainder from last split */
/*
Because top initially points to its own bin with initial
zero size, thus forcing extension on the first malloc request,
we avoid having any special code in malloc to check whether
it even exists yet. But we still need to in malloc_extend_top.
*/
#define initial_top(a) ((mchunkptr)bin_at(a, 0))
/* field-extraction macros */
#define first(b) ((b)->fd)
#define last(b) ((b)->bk)
/*
Indexing into bins
*/
#define bin_index(sz) \
(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3):\
((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6):\
((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9):\
((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12):\
((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15):\
((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18):\
126)
/*
bins for chunks < 512 are all spaced 8 bytes apart, and hold
identically sized chunks. This is exploited in malloc.
*/
#define MAX_SMALLBIN 63
#define MAX_SMALLBIN_SIZE 512
#define SMALLBIN_WIDTH 8
#define smallbin_index(sz) (((unsigned long)(sz)) >> 3)
/*
Requests are `small' if both the corresponding and the next bin are small
*/
#define is_small_request(nb) ((nb) < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
/*
To help compensate for the large number of bins, a one-level index
structure is used for bin-by-bin searching. `binblocks' is a
one-word bitvector recording whether groups of BINBLOCKWIDTH bins
have any (possibly) non-empty bins, so they can be skipped over
all at once during during traversals. The bits are NOT always
cleared as soon as all bins in a block are empty, but instead only
when all are noticed to be empty during traversal in malloc.
*/
#define BINBLOCKWIDTH 4 /* bins per block */
/* bin<->block macros */
#define idx2binblock(ix) ((unsigned)1 << ((ix) / BINBLOCKWIDTH))
#define mark_binblock(a, ii) (binblocks(a) |= idx2binblock(ii))
#define clear_binblock(a, ii) (binblocks(a) &= ~(idx2binblock(ii)))
/* Static bookkeeping data */
/* Helper macro to initialize bins */
#define IAV(i) bin_at(&main_arena, i), bin_at(&main_arena, i)
static arena main_arena = {
{
0, 0,
IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
},
&main_arena, /* next */
0, /* size */
#if THREAD_STATS
0, 0, 0, /* stat_lock_direct, stat_lock_loop, stat_lock_wait */
#endif
MUTEX_INITIALIZER /* mutex */
};
#undef IAV
/* Thread specific data */
#ifndef NO_THREADS
static tsd_key_t arena_key;
static mutex_t list_lock = MUTEX_INITIALIZER;
#endif
#if THREAD_STATS
static int stat_n_heaps = 0;
#define THREAD_STAT(x) x
#else
#define THREAD_STAT(x) do ; while(0)
#endif
/* variables holding tunable values */
static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
static unsigned long top_pad = DEFAULT_TOP_PAD;
static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
static int check_action = DEFAULT_CHECK_ACTION;
/* The first value returned from sbrk */
static char* sbrk_base = (char*)(-1);
/* The maximum memory obtained from system via sbrk */
static unsigned long max_sbrked_mem = 0;
/* The maximum via either sbrk or mmap (too difficult to track with threads) */
#ifdef NO_THREADS
static unsigned long max_total_mem = 0;
#endif
/* The total memory obtained from system via sbrk */
#define sbrked_mem (main_arena.size)
/* Tracking mmaps */
static unsigned int n_mmaps = 0;
static unsigned int max_n_mmaps = 0;
static unsigned long mmapped_mem = 0;
static unsigned long max_mmapped_mem = 0;
#ifndef _LIBC
#define weak_variable
#else
/* In GNU libc we want the hook variables to be weak definitions to
avoid a problem with Emacs. */
#define weak_variable weak_function
#endif
/* Already initialized? */
int __malloc_initialized = -1;
#ifndef NO_THREADS
/* The following two functions are registered via thread_atfork() to
make sure that the mutexes remain in a consistent state in the
fork()ed version of a thread. Also adapt the malloc and free hooks
temporarily, because the `atfork' handler mechanism may use
malloc/free internally (e.g. in LinuxThreads). */
#if defined _LIBC || defined MALLOC_HOOKS
static __malloc_ptr_t (*save_malloc_hook) __MALLOC_P ((size_t __size,
const __malloc_ptr_t));
static void (*save_free_hook) __MALLOC_P ((__malloc_ptr_t __ptr,
const __malloc_ptr_t));
static Void_t* save_arena;
#endif
static void
ptmalloc_lock_all __MALLOC_P((void))
{
arena *ar_ptr;
(void)mutex_lock(&list_lock);
for(ar_ptr = &main_arena;;) {
(void)mutex_lock(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
#if defined _LIBC || defined MALLOC_HOOKS
save_malloc_hook = __malloc_hook;
save_free_hook = __free_hook;
__malloc_hook = malloc_atfork;
__free_hook = free_atfork;
/* Only the current thread may perform malloc/free calls now. */
tsd_getspecific(arena_key, save_arena);
tsd_setspecific(arena_key, (Void_t*)0);
#endif
}
static void
ptmalloc_unlock_all __MALLOC_P((void))
{
arena *ar_ptr;
#if defined _LIBC || defined MALLOC_HOOKS
tsd_setspecific(arena_key, save_arena);
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
for(ar_ptr = &main_arena;;) {
(void)mutex_unlock(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
(void)mutex_unlock(&list_lock);
}
static void
ptmalloc_init_all __MALLOC_P((void))
{
arena *ar_ptr;
#if defined _LIBC || defined MALLOC_HOOKS
tsd_setspecific(arena_key, save_arena);
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
for(ar_ptr = &main_arena;;) {
(void)mutex_init(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
(void)mutex_init(&list_lock);
}
#endif /* !defined NO_THREADS */
/* Initialization routine. */
#if defined(_LIBC)
#if 0
static void ptmalloc_init __MALLOC_P ((void)) __attribute__ ((constructor));
#endif
static void
ptmalloc_init __MALLOC_P((void))
#else
void
ptmalloc_init __MALLOC_P((void))
#endif
{
#if defined _LIBC || defined MALLOC_HOOKS
const char* s;
#endif
if(__malloc_initialized >= 0) return;
__malloc_initialized = 0;
#ifndef NO_THREADS
#if defined _LIBC || defined MALLOC_HOOKS
/* With some threads implementations, creating thread-specific data
or initializing a mutex may call malloc() itself. Provide a
simple starter version (realloc() won't work). */
save_malloc_hook = __malloc_hook;
save_free_hook = __free_hook;
__malloc_hook = malloc_starter;
__free_hook = free_starter;
#endif
#ifdef _LIBC
/* Initialize the pthreads interface. */
if (__pthread_initialize != NULL)
__pthread_initialize();
__libc_pagesize = __getpagesize();
#endif
mutex_init(&main_arena.mutex);
mutex_init(&list_lock);
tsd_key_create(&arena_key, NULL);
tsd_setspecific(arena_key, (Void_t *)&main_arena);
thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_init_all);
#endif /* !defined NO_THREADS */
#if defined _LIBC || defined MALLOC_HOOKS
if((s = getenv("MALLOC_TRIM_THRESHOLD_")))
mALLOPt(M_TRIM_THRESHOLD, atoi(s));
if((s = getenv("MALLOC_TOP_PAD_")))
mALLOPt(M_TOP_PAD, atoi(s));
if((s = getenv("MALLOC_MMAP_THRESHOLD_")))
mALLOPt(M_MMAP_THRESHOLD, atoi(s));
if((s = getenv("MALLOC_MMAP_MAX_")))
mALLOPt(M_MMAP_MAX, atoi(s));
s = getenv("MALLOC_CHECK_");
#ifndef NO_THREADS
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
if(s) {
if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
__malloc_check_init();
}
if(__malloc_initialize_hook != NULL)
(*__malloc_initialize_hook)();
#endif
__malloc_initialized = 1;
}
/* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
#ifdef thread_atfork_static
thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \
ptmalloc_init_all)
#endif
#if defined _LIBC || defined MALLOC_HOOKS
/* Hooks for debugging versions. The initial hooks just call the
initialization routine, then do the normal work. */
static Void_t*
#if __STD_C
malloc_hook_ini(size_t sz, const __malloc_ptr_t caller)
#else
malloc_hook_ini(sz, caller)
size_t sz; const __malloc_ptr_t caller;
#endif
{
__malloc_hook = NULL;
ptmalloc_init();
return mALLOc(sz);
}
static Void_t*
#if __STD_C
realloc_hook_ini(Void_t* ptr, size_t sz, const __malloc_ptr_t caller)
#else
realloc_hook_ini(ptr, sz, caller)
Void_t* ptr; size_t sz; const __malloc_ptr_t caller;
#endif
{
__malloc_hook = NULL;
__realloc_hook = NULL;
ptmalloc_init();
return rEALLOc(ptr, sz);
}
static Void_t*
#if __STD_C
memalign_hook_ini(size_t sz, size_t alignment, const __malloc_ptr_t caller)
#else
memalign_hook_ini(sz, alignment, caller)
size_t sz; size_t alignment; const __malloc_ptr_t caller;
#endif
{
__memalign_hook = NULL;
ptmalloc_init();
return mEMALIGn(sz, alignment);
}
void weak_variable (*__malloc_initialize_hook) __MALLOC_P ((void)) = NULL;
void weak_variable (*__free_hook) __MALLOC_P ((__malloc_ptr_t __ptr,
const __malloc_ptr_t)) = NULL;
__malloc_ptr_t weak_variable (*__malloc_hook)
__MALLOC_P ((size_t __size, const __malloc_ptr_t)) = malloc_hook_ini;
__malloc_ptr_t weak_variable (*__realloc_hook)
__MALLOC_P ((__malloc_ptr_t __ptr, size_t __size, const __malloc_ptr_t))
= realloc_hook_ini;
__malloc_ptr_t weak_variable (*__memalign_hook)
__MALLOC_P ((size_t __size, size_t __alignment, const __malloc_ptr_t))
= memalign_hook_ini;
void weak_variable (*__after_morecore_hook) __MALLOC_P ((void)) = NULL;
/* Whether we are using malloc checking. */
static int using_malloc_checking;
/* A flag that is set by malloc_set_state, to signal that malloc checking
must not be enabled on the request from the user (via the MALLOC_CHECK_
environment variable). It is reset by __malloc_check_init to tell
malloc_set_state that the user has requested malloc checking.
The purpose of this flag is to make sure that malloc checking is not
enabled when the heap to be restored was constructed without malloc
checking, and thus does not contain the required magic bytes.
Otherwise the heap would be corrupted by calls to free and realloc. If
it turns out that the heap was created with malloc checking and the
user has requested it malloc_set_state just calls __malloc_check_init
again to enable it. On the other hand, reusing such a heap without
further malloc checking is safe. */
static int disallow_malloc_check;
/* Activate a standard set of debugging hooks. */
void
__malloc_check_init()
{
if (disallow_malloc_check) {
disallow_malloc_check = 0;
return;
}
using_malloc_checking = 1;
__malloc_hook = malloc_check;
__free_hook = free_check;
__realloc_hook = realloc_check;
__memalign_hook = memalign_check;
if(check_action & 1)
fprintf(stderr, "malloc: using debugging hooks\n");
}
#endif
/* Routines dealing with mmap(). */
#if HAVE_MMAP
#ifndef MAP_ANONYMOUS
static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
#define MMAP(addr, size, prot, flags) ((dev_zero_fd < 0) ? \
(dev_zero_fd = open("/dev/zero", O_RDWR), \
mmap((addr), (size), (prot), (flags), dev_zero_fd, 0)) : \
mmap((addr), (size), (prot), (flags), dev_zero_fd, 0))
#else
#define MMAP(addr, size, prot, flags) \
(mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0))
#endif
#if defined __GNUC__ && __GNUC__ >= 2
/* This function is only called from one place, inline it. */
inline
#endif
static mchunkptr
internal_function
#if __STD_C
mmap_chunk(size_t size)
#else
mmap_chunk(size) size_t size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
mchunkptr p;
if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
/* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
* there is no following chunk whose prev_size field could be used.
*/
size = (size + SIZE_SZ + page_mask) & ~page_mask;
p = (mchunkptr)MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE);
if(p == (mchunkptr) MAP_FAILED) return 0;
n_mmaps++;
if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
/* We demand that eight bytes into a page must be 8-byte aligned. */
assert(aligned_OK(chunk2mem(p)));
/* The offset to the start of the mmapped region is stored
* in the prev_size field of the chunk; normally it is zero,
* but that can be changed in memalign().
*/
p->prev_size = 0;
set_head(p, size|IS_MMAPPED);
mmapped_mem += size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
#endif
return p;
}
static void
internal_function
#if __STD_C
munmap_chunk(mchunkptr p)
#else
munmap_chunk(p) mchunkptr p;
#endif
{
INTERNAL_SIZE_T size = chunksize(p);
int ret;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
n_mmaps--;
mmapped_mem -= (size + p->prev_size);
ret = munmap((char *)p - p->prev_size, size + p->prev_size);
/* munmap returns non-zero on failure */
assert(ret == 0);
}
#if HAVE_MREMAP
static mchunkptr
internal_function
#if __STD_C
mremap_chunk(mchunkptr p, size_t new_size)
#else
mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
INTERNAL_SIZE_T offset = p->prev_size;
INTERNAL_SIZE_T size = chunksize(p);
char *cp;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((size + offset) & (malloc_getpagesize-1)) == 0);
/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
cp = (char *)mremap((char *)p - offset, size + offset, new_size,
MREMAP_MAYMOVE);
if (cp == MAP_FAILED) return 0;
p = (mchunkptr)(cp + offset);
assert(aligned_OK(chunk2mem(p)));
assert((p->prev_size == offset));
set_head(p, (new_size - offset)|IS_MMAPPED);
mmapped_mem -= size + offset;
mmapped_mem += new_size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
#endif
return p;
}
#endif /* HAVE_MREMAP */
#endif /* HAVE_MMAP */
/* Managing heaps and arenas (for concurrent threads) */
#ifndef NO_THREADS
/* Create a new heap. size is automatically rounded up to a multiple
of the page size. */
static heap_info *
internal_function
#if __STD_C
new_heap(size_t size)
#else
new_heap(size) size_t size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
char *p1, *p2;
unsigned long ul;
heap_info *h;
if(size+top_pad < HEAP_MIN_SIZE)
size = HEAP_MIN_SIZE;
else if(size+top_pad <= HEAP_MAX_SIZE)
size += top_pad;
else if(size > HEAP_MAX_SIZE)
return 0;
else
size = HEAP_MAX_SIZE;
size = (size + page_mask) & ~page_mask;
/* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
No swap space needs to be reserved for the following large
mapping (on Linux, this is the case for all non-writable mappings
anyway). */
p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
if(p1 == MAP_FAILED)
return 0;
p2 = (char *)(((unsigned long)p1 + HEAP_MAX_SIZE) & ~(HEAP_MAX_SIZE-1));
ul = p2 - p1;
munmap(p1, ul);
munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
if(mprotect(p2, size, PROT_READ|PROT_WRITE) != 0) {
munmap(p2, HEAP_MAX_SIZE);
return 0;
}
h = (heap_info *)p2;
h->size = size;
THREAD_STAT(stat_n_heaps++);
return h;
}
/* Grow or shrink a heap. size is automatically rounded up to a
multiple of the page size if it is positive. */
static int
#if __STD_C
grow_heap(heap_info *h, long diff)
#else
grow_heap(h, diff) heap_info *h; long diff;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
long new_size;
if(diff >= 0) {
diff = (diff + page_mask) & ~page_mask;
new_size = (long)h->size + diff;
if(new_size > HEAP_MAX_SIZE)
return -1;
if(mprotect((char *)h + h->size, diff, PROT_READ|PROT_WRITE) != 0)
return -2;
} else {
new_size = (long)h->size + diff;
if(new_size < (long)sizeof(*h))
return -1;
/* Try to re-map the extra heap space freshly to save memory, and
make it inaccessible. */
if((char *)MMAP((char *)h + new_size, -diff, PROT_NONE,
MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
return -2;
}
h->size = new_size;
return 0;
}
/* Delete a heap. */
#define delete_heap(heap) munmap((char*)(heap), HEAP_MAX_SIZE)
/* arena_get() acquires an arena and locks the corresponding mutex.
First, try the one last locked successfully by this thread. (This
is the common case and handled with a macro for speed.) Then, loop
once over the circularly linked list of arenas. If no arena is
readily available, create a new one. */
#define arena_get(ptr, size) do { \
Void_t *vptr = NULL; \
ptr = (arena *)tsd_getspecific(arena_key, vptr); \
if(ptr && !mutex_trylock(&ptr->mutex)) { \
THREAD_STAT(++(ptr->stat_lock_direct)); \
} else \
ptr = arena_get2(ptr, (size)); \
} while(0)
static arena *
internal_function
#if __STD_C
arena_get2(arena *a_tsd, size_t size)
#else
arena_get2(a_tsd, size) arena *a_tsd; size_t size;
#endif
{
arena *a;
heap_info *h;
char *ptr;
int i;
unsigned long misalign;
if(!a_tsd)
a = a_tsd = &main_arena;
else {
a = a_tsd->next;
if(!a) {
/* This can only happen while initializing the new arena. */
(void)mutex_lock(&main_arena.mutex);
THREAD_STAT(++(main_arena.stat_lock_wait));
return &main_arena;
}
}
/* Check the global, circularly linked list for available arenas. */
repeat:
do {
if(!mutex_trylock(&a->mutex)) {
THREAD_STAT(++(a->stat_lock_loop));
tsd_setspecific(arena_key, (Void_t *)a);
return a;
}
a = a->next;
} while(a != a_tsd);
/* If not even the list_lock can be obtained, try again. This can
happen during `atfork', or for example on systems where thread
creation makes it temporarily impossible to obtain _any_
locks. */
if(mutex_trylock(&list_lock)) {
a = a_tsd;
goto repeat;
}
(void)mutex_unlock(&list_lock);
/* Nothing immediately available, so generate a new arena. */
h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT));
if(!h)
return 0;
a = h->ar_ptr = (arena *)(h+1);
for(i=0; i<NAV; i++)
init_bin(a, i);
a->next = NULL;
a->size = h->size;
tsd_setspecific(arena_key, (Void_t *)a);
mutex_init(&a->mutex);
i = mutex_lock(&a->mutex); /* remember result */
/* Set up the top chunk, with proper alignment. */
ptr = (char *)(a + 1);
misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK;
if (misalign > 0)
ptr += MALLOC_ALIGNMENT - misalign;
top(a) = (mchunkptr)ptr;
set_head(top(a), (((char*)h + h->size) - ptr) | PREV_INUSE);
/* Add the new arena to the list. */
(void)mutex_lock(&list_lock);
a->next = main_arena.next;
main_arena.next = a;
(void)mutex_unlock(&list_lock);
if(i) /* locking failed; keep arena for further attempts later */
return 0;
THREAD_STAT(++(a->stat_lock_loop));
return a;
}
/* find the heap and corresponding arena for a given ptr */
#define heap_for_ptr(ptr) \
((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1)))
#define arena_for_ptr(ptr) \
(((mchunkptr)(ptr) < top(&main_arena) && (char *)(ptr) >= sbrk_base) ? \
&main_arena : heap_for_ptr(ptr)->ar_ptr)
#else /* defined(NO_THREADS) */
/* Without concurrent threads, there is only one arena. */
#define arena_get(ptr, sz) (ptr = &main_arena)
#define arena_for_ptr(ptr) (&main_arena)
#endif /* !defined(NO_THREADS) */
/*
Debugging support
*/
#if MALLOC_DEBUG
/*
These routines make a number of assertions about the states
of data structures that should be true at all times. If any
are not true, it's very likely that a user program has somehow
trashed memory. (It's also possible that there is a coding error
in malloc. In which case, please report it!)
*/
#if __STD_C
static void do_check_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
/* No checkable chunk is mmapped */
assert(!chunk_is_mmapped(p));
#ifndef NO_THREADS
if(ar_ptr != &main_arena) {
heap_info *heap = heap_for_ptr(p);
assert(heap->ar_ptr == ar_ptr);
if(p != top(ar_ptr))
assert((char *)p + sz <= (char *)heap + heap->size);
else
assert((char *)p + sz == (char *)heap + heap->size);
return;
}
#endif
/* Check for legal address ... */
assert((char*)p >= sbrk_base);
if (p != top(ar_ptr))
assert((char*)p + sz <= (char*)top(ar_ptr));
else
assert((char*)p + sz <= sbrk_base + sbrked_mem);
}
#if __STD_C
static void do_check_free_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_free_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
mchunkptr next = chunk_at_offset(p, sz);
do_check_chunk(ar_ptr, p);
/* Check whether it claims to be free ... */
assert(!inuse(p));
/* Must have OK size and fields */
assert((long)sz >= (long)MINSIZE);
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(aligned_OK(chunk2mem(p)));
/* ... matching footer field */
assert(next->prev_size == sz);
/* ... and is fully consolidated */
assert(prev_inuse(p));
assert (next == top(ar_ptr) || inuse(next));
/* ... and has minimally sane links */
assert(p->fd->bk == p);
assert(p->bk->fd == p);
}
#if __STD_C
static void do_check_inuse_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_inuse_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
mchunkptr next = next_chunk(p);
do_check_chunk(ar_ptr, p);
/* Check whether it claims to be in use ... */
assert(inuse(p));
/* ... whether its size is OK (it might be a fencepost) ... */
assert(chunksize(p) >= MINSIZE || next->size == (0|PREV_INUSE));
/* ... and is surrounded by OK chunks.
Since more things can be checked with free chunks than inuse ones,
if an inuse chunk borders them and debug is on, it's worth doing them.
*/
if (!prev_inuse(p))
{
mchunkptr prv = prev_chunk(p);
assert(next_chunk(prv) == p);
do_check_free_chunk(ar_ptr, prv);
}
if (next == top(ar_ptr))
{
assert(prev_inuse(next));
assert(chunksize(next) >= MINSIZE);
}
else if (!inuse(next))
do_check_free_chunk(ar_ptr, next);
}
#if __STD_C
static void do_check_malloced_chunk(arena *ar_ptr,
mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_malloced_chunk(ar_ptr, p, s)
arena *ar_ptr; mchunkptr p; INTERNAL_SIZE_T s;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
long room = sz - s;
do_check_inuse_chunk(ar_ptr, p);
/* Legal size ... */
assert((long)sz >= (long)MINSIZE);
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(room >= 0);
assert(room < (long)MINSIZE);
/* ... and alignment */
assert(aligned_OK(chunk2mem(p)));
/* ... and was allocated at front of an available chunk */
assert(prev_inuse(p));
}
#define check_free_chunk(A,P) do_check_free_chunk(A,P)
#define check_inuse_chunk(A,P) do_check_inuse_chunk(A,P)
#define check_chunk(A,P) do_check_chunk(A,P)
#define check_malloced_chunk(A,P,N) do_check_malloced_chunk(A,P,N)
#else
#define check_free_chunk(A,P)
#define check_inuse_chunk(A,P)
#define check_chunk(A,P)
#define check_malloced_chunk(A,P,N)
#endif
/*
Macro-based internal utilities
*/
/*
Linking chunks in bin lists.
Call these only with variables, not arbitrary expressions, as arguments.
*/
/*
Place chunk p of size s in its bin, in size order,
putting it ahead of others of same size.
*/
#define frontlink(A, P, S, IDX, BK, FD) \
{ \
if (S < MAX_SMALLBIN_SIZE) \
{ \
IDX = smallbin_index(S); \
mark_binblock(A, IDX); \
BK = bin_at(A, IDX); \
FD = BK->fd; \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
else \
{ \
IDX = bin_index(S); \
BK = bin_at(A, IDX); \
FD = BK->fd; \
if (FD == BK) mark_binblock(A, IDX); \
else \
{ \
while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
BK = FD->bk; \
} \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
}
/* take a chunk off a list */
#define unlink(P, BK, FD) \
{ \
BK = P->bk; \
FD = P->fd; \
FD->bk = BK; \
BK->fd = FD; \
} \
/* Place p as the last remainder */
#define link_last_remainder(A, P) \
{ \
last_remainder(A)->fd = last_remainder(A)->bk = P; \
P->fd = P->bk = last_remainder(A); \
}
/* Clear the last_remainder bin */
#define clear_last_remainder(A) \
(last_remainder(A)->fd = last_remainder(A)->bk = last_remainder(A))
/*
Extend the top-most chunk by obtaining memory from system.
Main interface to sbrk (but see also malloc_trim).
*/
#if defined __GNUC__ && __GNUC__ >= 2
/* This function is called only from one place, inline it. */
inline
#endif
static void
internal_function
#if __STD_C
malloc_extend_top(arena *ar_ptr, INTERNAL_SIZE_T nb)
#else
malloc_extend_top(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb;
#endif
{
unsigned long pagesz = malloc_getpagesize;
mchunkptr old_top = top(ar_ptr); /* Record state of old top */
INTERNAL_SIZE_T old_top_size = chunksize(old_top);
INTERNAL_SIZE_T top_size; /* new size of top chunk */
#ifndef NO_THREADS
if(ar_ptr == &main_arena) {
#endif
char* brk; /* return value from sbrk */
INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
char* new_brk; /* return of 2nd sbrk call */
char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
/* Pad request with top_pad plus minimal overhead */
INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
/* If not the first time through, round to preserve page boundary */
/* Otherwise, we need to correct to a page size below anyway. */
/* (We also correct below if an intervening foreign sbrk call.) */
if (sbrk_base != (char*)(-1))
sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
brk = (char*)(MORECORE (sbrk_size));
/* Fail if sbrk failed or if a foreign sbrk call killed our space */
if (brk == (char*)(MORECORE_FAILURE) ||
(brk < old_end && old_top != initial_top(&main_arena)))
return;
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
sbrked_mem += sbrk_size;
if (brk == old_end) { /* can just add bytes to current top */
top_size = sbrk_size + old_top_size;
set_head(old_top, top_size | PREV_INUSE);
old_top = 0; /* don't free below */
} else {
if (sbrk_base == (char*)(-1)) /* First time through. Record base */
sbrk_base = brk;
else
/* Someone else called sbrk(). Count those bytes as sbrked_mem. */
sbrked_mem += brk - (char*)old_end;
/* Guarantee alignment of first new chunk made from this space */
front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0) {
correction = (MALLOC_ALIGNMENT) - front_misalign;
brk += correction;
} else
correction = 0;
/* Guarantee the next brk will be at a page boundary */
correction += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1));
/* Allocate correction */
new_brk = (char*)(MORECORE (correction));
if (new_brk == (char*)(MORECORE_FAILURE)) return;
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
sbrked_mem += correction;
top(&main_arena) = (mchunkptr)brk;
top_size = new_brk - brk + correction;
set_head(top(&main_arena), top_size | PREV_INUSE);
if (old_top == initial_top(&main_arena))
old_top = 0; /* don't free below */
}
if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
max_sbrked_mem = sbrked_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + sbrked_mem) >
(unsigned long)max_total_mem)
max_total_mem = mmapped_mem + sbrked_mem;
#endif
#ifndef NO_THREADS
} else { /* ar_ptr != &main_arena */
heap_info *old_heap, *heap;
size_t old_heap_size;
if(old_top_size < MINSIZE) /* this should never happen */
return;
/* First try to extend the current heap. */
if(MINSIZE + nb <= old_top_size)
return;
old_heap = heap_for_ptr(old_top);
old_heap_size = old_heap->size;
if(grow_heap(old_heap, MINSIZE + nb - old_top_size) == 0) {
ar_ptr->size += old_heap->size - old_heap_size;
top_size = ((char *)old_heap + old_heap->size) - (char *)old_top;
set_head(old_top, top_size | PREV_INUSE);
return;
}
/* A new heap must be created. */
heap = new_heap(nb + (MINSIZE + sizeof(*heap)));
if(!heap)
return;
heap->ar_ptr = ar_ptr;
heap->prev = old_heap;
ar_ptr->size += heap->size;
/* Set up the new top, so we can safely use chunk_free() below. */
top(ar_ptr) = chunk_at_offset(heap, sizeof(*heap));
top_size = heap->size - sizeof(*heap);
set_head(top(ar_ptr), top_size | PREV_INUSE);
}
#endif /* !defined(NO_THREADS) */
/* We always land on a page boundary */
assert(((unsigned long)((char*)top(ar_ptr) + top_size) & (pagesz-1)) == 0);
/* Setup fencepost and free the old top chunk. */
if(old_top) {
/* The fencepost takes at least MINSIZE bytes, because it might
become the top chunk again later. Note that a footer is set
up, too, although the chunk is marked in use. */
old_top_size -= MINSIZE;
set_head(chunk_at_offset(old_top, old_top_size + 2*SIZE_SZ), 0|PREV_INUSE);
if(old_top_size >= MINSIZE) {
set_head(chunk_at_offset(old_top, old_top_size), (2*SIZE_SZ)|PREV_INUSE);
set_foot(chunk_at_offset(old_top, old_top_size), (2*SIZE_SZ));
set_head_size(old_top, old_top_size);
chunk_free(ar_ptr, old_top);
} else {
set_head(old_top, (old_top_size + 2*SIZE_SZ)|PREV_INUSE);
set_foot(old_top, (old_top_size + 2*SIZE_SZ));
}
}
}
/* Main public routines */
/*
Malloc Algorithm:
The requested size is first converted into a usable form, `nb'.
This currently means to add 4 bytes overhead plus possibly more to
obtain 8-byte alignment and/or to obtain a size of at least
MINSIZE (currently 16, 24, or 32 bytes), the smallest allocatable
size. (All fits are considered `exact' if they are within MINSIZE
bytes.)
From there, the first successful of the following steps is taken:
1. The bin corresponding to the request size is scanned, and if
a chunk of exactly the right size is found, it is taken.
2. The most recently remaindered chunk is used if it is big
enough. This is a form of (roving) first fit, used only in
the absence of exact fits. Runs of consecutive requests use
the remainder of the chunk used for the previous such request
whenever possible. This limited use of a first-fit style
allocation strategy tends to give contiguous chunks
coextensive lifetimes, which improves locality and can reduce
fragmentation in the long run.
3. Other bins are scanned in increasing size order, using a
chunk big enough to fulfill the request, and splitting off
any remainder. This search is strictly by best-fit; i.e.,
the smallest (with ties going to approximately the least
recently used) chunk that fits is selected.
4. If large enough, the chunk bordering the end of memory
(`top') is split off. (This use of `top' is in accord with
the best-fit search rule. In effect, `top' is treated as
larger (and thus less well fitting) than any other available
chunk since it can be extended to be as large as necessary
(up to system limitations).
5. If the request size meets the mmap threshold and the
system supports mmap, and there are few enough currently
allocated mmapped regions, and a call to mmap succeeds,
the request is allocated via direct memory mapping.
6. Otherwise, the top of memory is extended by
obtaining more space from the system (normally using sbrk,
but definable to anything else via the MORECORE macro).
Memory is gathered from the system (in system page-sized
units) in a way that allows chunks obtained across different
sbrk calls to be consolidated, but does not require
contiguous memory. Thus, it should be safe to intersperse
mallocs with other sbrk calls.
All allocations are made from the `lowest' part of any found
chunk. (The implementation invariant is that prev_inuse is
always true of any allocated chunk; i.e., that each allocated
chunk borders either a previously allocated and still in-use chunk,
or the base of its memory arena.)
*/
#if __STD_C
Void_t* mALLOc(size_t bytes)
#else
Void_t* mALLOc(bytes) size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr victim;
#if defined _LIBC || defined MALLOC_HOOKS
if (__malloc_hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*__malloc_hook)(bytes, __builtin_return_address (0));
#else
result = (*__malloc_hook)(bytes, NULL);
#endif
return result;
}
#endif
if(request2size(bytes, nb))
return 0;
arena_get(ar_ptr, nb);
if(!ar_ptr)
return 0;
victim = chunk_alloc(ar_ptr, nb);
(void)mutex_unlock(&ar_ptr->mutex);
if(!victim) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
victim = chunk_alloc(&main_arena, nb);
(void)mutex_unlock(&main_arena.mutex);
}
if(!victim) return 0;
}
return chunk2mem(victim);
}
static mchunkptr
internal_function
#if __STD_C
chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T nb)
#else
chunk_alloc(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb;
#endif
{
mchunkptr victim; /* inspected/selected chunk */
INTERNAL_SIZE_T victim_size; /* its size */
int idx; /* index for bin traversal */
mbinptr bin; /* associated bin */
mchunkptr remainder; /* remainder from a split */
long remainder_size; /* its size */
int remainder_index; /* its bin index */
unsigned long block; /* block traverser bit */
int startidx; /* first bin of a traversed block */
mchunkptr fwd; /* misc temp for linking */
mchunkptr bck; /* misc temp for linking */
mbinptr q; /* misc temp */
/* Check for exact match in a bin */
if (is_small_request(nb)) /* Faster version for small requests */
{
idx = smallbin_index(nb);
/* No traversal or size check necessary for small bins. */
q = bin_at(ar_ptr, idx);
victim = last(q);
/* Also scan the next one, since it would have a remainder < MINSIZE */
if (victim == q)
{
q = next_bin(q);
victim = last(q);
}
if (victim != q)
{
victim_size = chunksize(victim);
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
}
else
{
idx = bin_index(nb);
bin = bin_at(ar_ptr, idx);
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* too big */
{
--idx; /* adjust to rescan below after checking last remainder */
break;
}
else if (remainder_size >= 0) /* exact fit */
{
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
}
++idx;
}
/* Try to use the last split-off remainder */
if ( (victim = last_remainder(ar_ptr)->fd) != last_remainder(ar_ptr))
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* re-split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
link_last_remainder(ar_ptr, remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
clear_last_remainder(ar_ptr);
if (remainder_size >= 0) /* exhaust */
{
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
/* Else place in bin */
frontlink(ar_ptr, victim, victim_size, remainder_index, bck, fwd);
}
/*
If there are any possibly nonempty big-enough blocks,
search for best fitting chunk by scanning bins in blockwidth units.
*/
if ( (block = idx2binblock(idx)) <= binblocks(ar_ptr))
{
/* Get to the first marked block */
if ( (block & binblocks(ar_ptr)) == 0)
{
/* force to an even block boundary */
idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
block <<= 1;
while ((block & binblocks(ar_ptr)) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
/* For each possibly nonempty block ... */
for (;;)
{
startidx = idx; /* (track incomplete blocks) */
q = bin = bin_at(ar_ptr, idx);
/* For each bin in this block ... */
do
{
/* Find and use first big enough chunk ... */
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
unlink(victim, bck, fwd);
link_last_remainder(ar_ptr, remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
else if (remainder_size >= 0) /* take */
{
set_inuse_bit_at_offset(victim, victim_size);
unlink(victim, bck, fwd);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
}
bin = next_bin(bin);
} while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
/* Clear out the block bit. */
do /* Possibly backtrack to try to clear a partial block */
{
if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
{
binblocks(ar_ptr) &= ~block;
break;
}
--startidx;
q = prev_bin(q);
} while (first(q) == q);
/* Get to the next possibly nonempty block */
if ( (block <<= 1) <= binblocks(ar_ptr) && (block != 0) )
{
while ((block & binblocks(ar_ptr)) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
else
break;
}
}
/* Try to use top chunk */
/* Require that there be a remainder, ensuring top always exists */
if ( (remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE)
{
#if HAVE_MMAP
/* If big and would otherwise need to extend, try to use mmap instead */
if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
(victim = mmap_chunk(nb)) != 0)
return victim;
#endif
/* Try to extend */
malloc_extend_top(ar_ptr, nb);
if ((remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE)
return 0; /* propagate failure */
}
victim = top(ar_ptr);
set_head(victim, nb | PREV_INUSE);
top(ar_ptr) = chunk_at_offset(victim, nb);
set_head(top(ar_ptr), remainder_size | PREV_INUSE);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
/*
free() algorithm :
cases:
1. free(0) has no effect.
2. If the chunk was allocated via mmap, it is released via munmap().
3. If a returned chunk borders the current high end of memory,
it is consolidated into the top, and if the total unused
topmost memory exceeds the trim threshold, malloc_trim is
called.
4. Other chunks are consolidated as they arrive, and
placed in corresponding bins. (This includes the case of
consolidating with the current `last_remainder').
*/
#if __STD_C
void fREe(Void_t* mem)
#else
void fREe(mem) Void_t* mem;
#endif
{
arena *ar_ptr;
mchunkptr p; /* chunk corresponding to mem */
#if defined _LIBC || defined MALLOC_HOOKS
if (__free_hook != NULL) {
#if defined __GNUC__ && __GNUC__ >= 2
(*__free_hook)(mem, __builtin_return_address (0));
#else
(*__free_hook)(mem, NULL);
#endif
return;
}
#endif
if (mem == 0) /* free(0) has no effect */
return;
p = mem2chunk(mem);
#if HAVE_MMAP
if (chunk_is_mmapped(p)) /* release mmapped memory. */
{
munmap_chunk(p);
return;
}
#endif
ar_ptr = arena_for_ptr(p);
#if THREAD_STATS
if(!mutex_trylock(&ar_ptr->mutex))
++(ar_ptr->stat_lock_direct);
else {
(void)mutex_lock(&ar_ptr->mutex);
++(ar_ptr->stat_lock_wait);
}
#else
(void)mutex_lock(&ar_ptr->mutex);
#endif
chunk_free(ar_ptr, p);
(void)mutex_unlock(&ar_ptr->mutex);
}
static void
internal_function
#if __STD_C
chunk_free(arena *ar_ptr, mchunkptr p)
#else
chunk_free(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T hd = p->size; /* its head field */
INTERNAL_SIZE_T sz; /* its size */
int idx; /* its bin index */
mchunkptr next; /* next contiguous chunk */
INTERNAL_SIZE_T nextsz; /* its size */
INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
int islr; /* track whether merging with last_remainder */
check_inuse_chunk(ar_ptr, p);
sz = hd & ~PREV_INUSE;
next = chunk_at_offset(p, sz);
nextsz = chunksize(next);
if (next == top(ar_ptr)) /* merge with top */
{
sz += nextsz;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -prevsz);
sz += prevsz;
unlink(p, bck, fwd);
}
set_head(p, sz | PREV_INUSE);
top(ar_ptr) = p;
#ifndef NO_THREADS
if(ar_ptr == &main_arena) {
#endif
if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
main_trim(top_pad);
#ifndef NO_THREADS
} else {
heap_info *heap = heap_for_ptr(p);
assert(heap->ar_ptr == ar_ptr);
/* Try to get rid of completely empty heaps, if possible. */
if((unsigned long)(sz) >= (unsigned long)trim_threshold ||
p == chunk_at_offset(heap, sizeof(*heap)))
heap_trim(heap, top_pad);
}
#endif
return;
}
islr = 0;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -prevsz);
sz += prevsz;
if (p->fd == last_remainder(ar_ptr)) /* keep as last_remainder */
islr = 1;
else
unlink(p, bck, fwd);
}
if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
{
sz += nextsz;
if (!islr && next->fd == last_remainder(ar_ptr))
/* re-insert last_remainder */
{
islr = 1;
link_last_remainder(ar_ptr, p);
}
else
unlink(next, bck, fwd);
next = chunk_at_offset(p, sz);
}
else
set_head(next, nextsz); /* clear inuse bit */
set_head(p, sz | PREV_INUSE);
next->prev_size = sz;
if (!islr)
frontlink(ar_ptr, p, sz, idx, bck, fwd);
#ifndef NO_THREADS
/* Check whether the heap containing top can go away now. */
if(next->size < MINSIZE &&
(unsigned long)sz > trim_threshold &&
ar_ptr != &main_arena) { /* fencepost */
heap_info *heap = heap_for_ptr(top(ar_ptr));
if(top(ar_ptr) == chunk_at_offset(heap, sizeof(*heap)) &&
heap->prev == heap_for_ptr(p))
heap_trim(heap, top_pad);
}
#endif
}
/*
Realloc algorithm:
Chunks that were obtained via mmap cannot be extended or shrunk
unless HAVE_MREMAP is defined, in which case mremap is used.
Otherwise, if their reallocation is for additional space, they are
copied. If for less, they are just left alone.
Otherwise, if the reallocation is for additional space, and the
chunk can be extended, it is, else a malloc-copy-free sequence is
taken. There are several different ways that a chunk could be
extended. All are tried:
* Extending forward into following adjacent free chunk.
* Shifting backwards, joining preceding adjacent space
* Both shifting backwards and extending forward.
* Extending into newly sbrked space
Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
If the reallocation is for less space, and the new request is for
a `small' (<512 bytes) size, then the newly unused space is lopped
off and freed.
The old unix realloc convention of allowing the last-free'd chunk
to be used as an argument to realloc is no longer supported.
I don't know of any programs still relying on this feature,
and allowing it would also allow too many other incorrect
usages of realloc to be sensible.
*/
#if __STD_C
Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
#else
Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr oldp; /* chunk corresponding to oldmem */
INTERNAL_SIZE_T oldsize; /* its size */
mchunkptr newp; /* chunk to return */
#if defined _LIBC || defined MALLOC_HOOKS
if (__realloc_hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*__realloc_hook)(oldmem, bytes, __builtin_return_address (0));
#else
result = (*__realloc_hook)(oldmem, bytes, NULL);
#endif
return result;
}
#endif
#ifdef REALLOC_ZERO_BYTES_FREES
if (bytes == 0 && oldmem != NULL) { fREe(oldmem); return 0; }
#endif
/* realloc of null is supposed to be same as malloc */
if (oldmem == 0) return mALLOc(bytes);
oldp = mem2chunk(oldmem);
oldsize = chunksize(oldp);
if(request2size(bytes, nb))
return 0;
#if HAVE_MMAP
if (chunk_is_mmapped(oldp))
{
Void_t* newmem;
#if HAVE_MREMAP
newp = mremap_chunk(oldp, nb);
if(newp) return chunk2mem(newp);
#endif
/* Note the extra SIZE_SZ overhead. */
if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
/* Must alloc, copy, free. */
newmem = mALLOc(bytes);
if (newmem == 0) return 0; /* propagate failure */
MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
munmap_chunk(oldp);
return newmem;
}
#endif
ar_ptr = arena_for_ptr(oldp);
#if THREAD_STATS
if(!mutex_trylock(&ar_ptr->mutex))
++(ar_ptr->stat_lock_direct);
else {
(void)mutex_lock(&ar_ptr->mutex);
++(ar_ptr->stat_lock_wait);
}
#else
(void)mutex_lock(&ar_ptr->mutex);
#endif
#ifndef NO_THREADS
/* As in malloc(), remember this arena for the next allocation. */
tsd_setspecific(arena_key, (Void_t *)ar_ptr);
#endif
newp = chunk_realloc(ar_ptr, oldp, oldsize, nb);
(void)mutex_unlock(&ar_ptr->mutex);
return newp ? chunk2mem(newp) : NULL;
}
static mchunkptr
internal_function
#if __STD_C
chunk_realloc(arena* ar_ptr, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
INTERNAL_SIZE_T nb)
#else
chunk_realloc(ar_ptr, oldp, oldsize, nb)
arena* ar_ptr; mchunkptr oldp; INTERNAL_SIZE_T oldsize, nb;
#endif
{
mchunkptr newp = oldp; /* chunk to return */
INTERNAL_SIZE_T newsize = oldsize; /* its size */
mchunkptr next; /* next contiguous chunk after oldp */
INTERNAL_SIZE_T nextsize; /* its size */
mchunkptr prev; /* previous contiguous chunk before oldp */
INTERNAL_SIZE_T prevsize; /* its size */
mchunkptr remainder; /* holds split off extra space from newp */
INTERNAL_SIZE_T remainder_size; /* its size */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
check_inuse_chunk(ar_ptr, oldp);
if ((long)(oldsize) < (long)(nb))
{
/* Try expanding forward */
next = chunk_at_offset(oldp, oldsize);
if (next == top(ar_ptr) || !inuse(next))
{
nextsize = chunksize(next);
/* Forward into top only if a remainder */
if (next == top(ar_ptr))
{
if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
{
newsize += nextsize;
top(ar_ptr) = chunk_at_offset(oldp, nb);
set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE);
set_head_size(oldp, nb);
return oldp;
}
}
/* Forward into next chunk */
else if (((long)(nextsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
newsize += nextsize;
goto split;
}
}
else
{
next = 0;
nextsize = 0;
}
/* Try shifting backwards. */
if (!prev_inuse(oldp))
{
prev = prev_chunk(oldp);
prevsize = chunksize(prev);
/* try forward + backward first to save a later consolidation */
if (next != 0)
{
/* into top */
if (next == top(ar_ptr))
{
if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize + nextsize;
MALLOC_COPY(chunk2mem(newp), chunk2mem(oldp), oldsize - SIZE_SZ);
top(ar_ptr) = chunk_at_offset(newp, nb);
set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE);
set_head_size(newp, nb);
return newp;
}
}
/* into next chunk */
else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
unlink(prev, bck, fwd);
newp = prev;
newsize += nextsize + prevsize;
MALLOC_COPY(chunk2mem(newp), chunk2mem(oldp), oldsize - SIZE_SZ);
goto split;
}
}
/* backward only */
if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize;
MALLOC_COPY(chunk2mem(newp), chunk2mem(oldp), oldsize - SIZE_SZ);
goto split;
}
}
/* Must allocate */
newp = chunk_alloc (ar_ptr, nb);
if (newp == 0) {
/* Maybe the failure is due to running out of mmapped areas. */
if (ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
newp = chunk_alloc(&main_arena, nb);
(void)mutex_unlock(&main_arena.mutex);
}
if (newp == 0) /* propagate failure */
return 0;
}
/* Avoid copy if newp is next chunk after oldp. */
/* (This can only happen when new chunk is sbrk'ed.) */
if ( newp == next_chunk(oldp))
{
newsize += chunksize(newp);
newp = oldp;
goto split;
}
/* Otherwise copy, free, and exit */
MALLOC_COPY(chunk2mem(newp), chunk2mem(oldp), oldsize - SIZE_SZ);
chunk_free(ar_ptr, oldp);
return newp;
}
split: /* split off extra room in old or expanded chunk */
if (newsize - nb >= MINSIZE) /* split off remainder */
{
remainder = chunk_at_offset(newp, nb);
remainder_size = newsize - nb;
set_head_size(newp, nb);
set_head(remainder, remainder_size | PREV_INUSE);
set_inuse_bit_at_offset(remainder, remainder_size);
chunk_free(ar_ptr, remainder);
}
else
{
set_head_size(newp, newsize);
set_inuse_bit_at_offset(newp, newsize);
}
check_inuse_chunk(ar_ptr, newp);
return newp;
}
/*
memalign algorithm:
memalign requests more than enough space from malloc, finds a spot
within that chunk that meets the alignment request, and then
possibly frees the leading and trailing space.
The alignment argument must be a power of two. This property is not
checked by memalign, so misuse may result in random runtime errors.
8-byte alignment is guaranteed by normal malloc calls, so don't
bother calling memalign with an argument of 8 or less.
Overreliance on memalign is a sure way to fragment space.
*/
#if __STD_C
Void_t* mEMALIGn(size_t alignment, size_t bytes)
#else
Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr p;
#if defined _LIBC || defined MALLOC_HOOKS
if (__memalign_hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*__memalign_hook)(alignment, bytes,
__builtin_return_address (0));
#else
result = (*__memalign_hook)(alignment, bytes, NULL);
#endif
return result;
}
#endif
/* If need less alignment than we give anyway, just relay to malloc */
if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
/* Otherwise, ensure that it is at least a minimum chunk size */
if (alignment < MINSIZE) alignment = MINSIZE;
if(request2size(bytes, nb))
return 0;
arena_get(ar_ptr, nb + alignment + MINSIZE);
if(!ar_ptr)
return 0;
p = chunk_align(ar_ptr, nb, alignment);
(void)mutex_unlock(&ar_ptr->mutex);
if(!p) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
p = chunk_align(&main_arena, nb, alignment);
(void)mutex_unlock(&main_arena.mutex);
}
if(!p) return 0;
}
return chunk2mem(p);
}
static mchunkptr
internal_function
#if __STD_C
chunk_align(arena* ar_ptr, INTERNAL_SIZE_T nb, size_t alignment)
#else
chunk_align(ar_ptr, nb, alignment)
arena* ar_ptr; INTERNAL_SIZE_T nb; size_t alignment;
#endif
{
char* m; /* memory returned by malloc call */
mchunkptr p; /* corresponding chunk */
char* brk; /* alignment point within p */
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
mchunkptr remainder; /* spare room at end to split off */
long remainder_size; /* its size */
/* Call chunk_alloc with worst case padding to hit alignment. */
p = chunk_alloc(ar_ptr, nb + alignment + MINSIZE);
if (p == 0)
return 0; /* propagate failure */
m = chunk2mem(p);
if ((((unsigned long)(m)) % alignment) == 0) /* aligned */
{
#if HAVE_MMAP
if(chunk_is_mmapped(p)) {
return p; /* nothing more to do */
}
#endif
}
else /* misaligned */
{
/*
Find an aligned spot inside chunk.
Since we need to give back leading space in a chunk of at
least MINSIZE, if the first calculation places us at
a spot with less than MINSIZE leader, we can move to the
next aligned spot -- we've allocated enough total room so that
this is always possible.
*/
brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -alignment);
if ((long)(brk - (char*)(p)) < (long)MINSIZE) brk += alignment;
newp = (mchunkptr)brk;
leadsize = brk - (char*)(p);
newsize = chunksize(p) - leadsize;
#if HAVE_MMAP
if(chunk_is_mmapped(p))
{
newp->prev_size = p->prev_size + leadsize;
set_head(newp, newsize|IS_MMAPPED);
return newp;
}
#endif
/* give back leader, use the rest */
set_head(newp, newsize | PREV_INUSE);
set_inuse_bit_at_offset(newp, newsize);
set_head_size(p, leadsize);
chunk_free(ar_ptr, p);
p = newp;
assert (newsize>=nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
}
/* Also give back spare room at the end */
remainder_size = chunksize(p) - nb;
if (remainder_size >= (long)MINSIZE)
{
remainder = chunk_at_offset(p, nb);
set_head(remainder, remainder_size | PREV_INUSE);
set_head_size(p, nb);
chunk_free(ar_ptr, remainder);
}
check_inuse_chunk(ar_ptr, p);
return p;
}
/*
valloc just invokes memalign with alignment argument equal
to the page size of the system (or as near to this as can
be figured out from all the includes/defines above.)
*/
#if __STD_C
Void_t* vALLOc(size_t bytes)
#else
Void_t* vALLOc(bytes) size_t bytes;
#endif
{
return mEMALIGn (malloc_getpagesize, bytes);
}
/*
pvalloc just invokes valloc for the nearest pagesize
that will accommodate request
*/
#if __STD_C
Void_t* pvALLOc(size_t bytes)
#else
Void_t* pvALLOc(bytes) size_t bytes;
#endif
{
size_t pagesize = malloc_getpagesize;
return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
}
/*
calloc calls chunk_alloc, then zeroes out the allocated chunk.
*/
#if __STD_C
Void_t* cALLOc(size_t n, size_t elem_size)
#else
Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
#endif
{
arena *ar_ptr;
mchunkptr p, oldtop;
INTERNAL_SIZE_T sz, csz, oldtopsize;
Void_t* mem;
#if defined _LIBC || defined MALLOC_HOOKS
if (__malloc_hook != NULL) {
sz = n * elem_size;
#if defined __GNUC__ && __GNUC__ >= 2
mem = (*__malloc_hook)(sz, __builtin_return_address (0));
#else
mem = (*__malloc_hook)(sz, NULL);
#endif
if(mem == 0)
return 0;
#ifdef HAVE_MEMSET
return memset(mem, 0, sz);
#else
while(sz > 0) ((char*)mem)[--sz] = 0; /* rather inefficient */
return mem;
#endif
}
#endif
if(request2size(n * elem_size, sz))
return 0;
arena_get(ar_ptr, sz);
if(!ar_ptr)
return 0;
/* check if expand_top called, in which case don't need to clear */
#if MORECORE_CLEARS
oldtop = top(ar_ptr);
oldtopsize = chunksize(top(ar_ptr));
#endif
p = chunk_alloc (ar_ptr, sz);
/* Only clearing follows, so we can unlock early. */
(void)mutex_unlock(&ar_ptr->mutex);
if (p == 0) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
p = chunk_alloc(&main_arena, sz);
(void)mutex_unlock(&main_arena.mutex);
}
if (p == 0) return 0;
}
mem = chunk2mem(p);
/* Two optional cases in which clearing not necessary */
#if HAVE_MMAP
if (chunk_is_mmapped(p)) return mem;
#endif
csz = chunksize(p);
#if MORECORE_CLEARS
if (p == oldtop && csz > oldtopsize) {
/* clear only the bytes from non-freshly-sbrked memory */
csz = oldtopsize;
}
#endif
MALLOC_ZERO(mem, csz - SIZE_SZ);
return mem;
}
/*
cfree just calls free. It is needed/defined on some systems
that pair it with calloc, presumably for odd historical reasons.
*/
#if !defined(_LIBC)
#if __STD_C
void cfree(Void_t *mem)
#else
void cfree(mem) Void_t *mem;
#endif
{
free(mem);
}
#endif
/*
Malloc_trim gives memory back to the system (via negative
arguments to sbrk) if there is unused memory at the `high' end of
the malloc pool. You can call this after freeing large blocks of
memory to potentially reduce the system-level memory requirements
of a program. However, it cannot guarantee to reduce memory. Under
some allocation patterns, some large free blocks of memory will be
locked between two used chunks, so they cannot be given back to
the system.
The `pad' argument to malloc_trim represents the amount of free
trailing space to leave untrimmed. If this argument is zero,
only the minimum amount of memory to maintain internal data
structures will be left (one page or less). Non-zero arguments
can be supplied to maintain enough trailing space to service
future expected allocations without having to re-obtain memory
from the system.
Malloc_trim returns 1 if it actually released any memory, else 0.
*/
#if __STD_C
int mALLOC_TRIm(size_t pad)
#else
int mALLOC_TRIm(pad) size_t pad;
#endif
{
int res;
(void)mutex_lock(&main_arena.mutex);
res = main_trim(pad);
(void)mutex_unlock(&main_arena.mutex);
return res;
}
/* Trim the main arena. */
static int
internal_function
#if __STD_C
main_trim(size_t pad)
#else
main_trim(pad) size_t pad;
#endif
{
mchunkptr top_chunk; /* The current top chunk */
long top_size; /* Amount of top-most memory */
long extra; /* Amount to release */
char* current_brk; /* address returned by pre-check sbrk call */
char* new_brk; /* address returned by negative sbrk call */
unsigned long pagesz = malloc_getpagesize;
top_chunk = top(&main_arena);
top_size = chunksize(top_chunk);
extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
if (extra < (long)pagesz) /* Not enough memory to release */
return 0;
/* Test to make sure no one else called sbrk */
current_brk = (char*)(MORECORE (0));
if (current_brk != (char*)(top_chunk) + top_size)
return 0; /* Apparently we don't own memory; must fail */
new_brk = (char*)(MORECORE (-extra));
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
if (new_brk == (char*)(MORECORE_FAILURE)) { /* sbrk failed? */
/* Try to figure out what we have */
current_brk = (char*)(MORECORE (0));
top_size = current_brk - (char*)top_chunk;
if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
{
sbrked_mem = current_brk - sbrk_base;
set_head(top_chunk, top_size | PREV_INUSE);
}
check_chunk(&main_arena, top_chunk);
return 0;
}
sbrked_mem -= extra;
/* Success. Adjust top accordingly. */
set_head(top_chunk, (top_size - extra) | PREV_INUSE);
check_chunk(&main_arena, top_chunk);
return 1;
}
#ifndef NO_THREADS
static int
internal_function
#if __STD_C
heap_trim(heap_info *heap, size_t pad)
#else
heap_trim(heap, pad) heap_info *heap; size_t pad;
#endif
{
unsigned long pagesz = malloc_getpagesize;
arena *ar_ptr = heap->ar_ptr;
mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
heap_info *prev_heap;
long new_size, top_size, extra;
/* Can this heap go away completely ? */
while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
prev_heap = heap->prev;
p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
p = prev_chunk(p);
new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
assert(new_size>0 && new_size<(long)(2*MINSIZE));
if(!prev_inuse(p))
new_size += p->prev_size;
assert(new_size>0 && new_size<HEAP_MAX_SIZE);
if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
break;
ar_ptr->size -= heap->size;
delete_heap(heap);
heap = prev_heap;
if(!prev_inuse(p)) { /* consolidate backward */
p = prev_chunk(p);
unlink(p, bck, fwd);
}
assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0);
assert( ((char*)p + new_size) == ((char*)heap + heap->size) );
top(ar_ptr) = top_chunk = p;
set_head(top_chunk, new_size | PREV_INUSE);
check_chunk(ar_ptr, top_chunk);
}
top_size = chunksize(top_chunk);
extra = ((top_size - pad - MINSIZE + (pagesz-1))/pagesz - 1) * pagesz;
if(extra < (long)pagesz)
return 0;
/* Try to shrink. */
if(grow_heap(heap, -extra) != 0)
return 0;
ar_ptr->size -= extra;
/* Success. Adjust top accordingly. */
set_head(top_chunk, (top_size - extra) | PREV_INUSE);
check_chunk(ar_ptr, top_chunk);
return 1;
}
#endif
/*
malloc_usable_size:
This routine tells you how many bytes you can actually use in an
allocated chunk, which may be more than you requested (although
often not). You can use this many bytes without worrying about
overwriting other allocated objects. Not a particularly great
programming practice, but still sometimes useful.
*/
#if __STD_C
size_t mALLOC_USABLE_SIZe(Void_t* mem)
#else
size_t mALLOC_USABLE_SIZe(mem) Void_t* mem;
#endif
{
mchunkptr p;
if (mem == 0)
return 0;
else
{
p = mem2chunk(mem);
if(!chunk_is_mmapped(p))
{
if (!inuse(p)) return 0;
check_inuse_chunk(arena_for_ptr(mem), p);
return chunksize(p) - SIZE_SZ;
}
return chunksize(p) - 2*SIZE_SZ;
}
}
/* Utility to update mallinfo for malloc_stats() and mallinfo() */
static void
#if __STD_C
malloc_update_mallinfo(arena *ar_ptr, struct mallinfo *mi)
#else
malloc_update_mallinfo(ar_ptr, mi) arena *ar_ptr; struct mallinfo *mi;
#endif
{
int i, navail;
mbinptr b;
mchunkptr p;
#if MALLOC_DEBUG
mchunkptr q;
#endif
INTERNAL_SIZE_T avail;
(void)mutex_lock(&ar_ptr->mutex);
avail = chunksize(top(ar_ptr));
navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
for (i = 1; i < NAV; ++i)
{
b = bin_at(ar_ptr, i);
for (p = last(b); p != b; p = p->bk)
{
#if MALLOC_DEBUG
check_free_chunk(ar_ptr, p);
for (q = next_chunk(p);
q != top(ar_ptr) && inuse(q) && (long)chunksize(q) > 0;
q = next_chunk(q))
check_inuse_chunk(ar_ptr, q);
#endif
avail += chunksize(p);
navail++;
}
}
mi->arena = ar_ptr->size;
mi->ordblks = navail;
mi->smblks = mi->usmblks = mi->fsmblks = 0; /* clear unused fields */
mi->uordblks = ar_ptr->size - avail;
mi->fordblks = avail;
mi->hblks = n_mmaps;
mi->hblkhd = mmapped_mem;
mi->keepcost = chunksize(top(ar_ptr));
(void)mutex_unlock(&ar_ptr->mutex);
}
#if !defined(NO_THREADS) && MALLOC_DEBUG > 1
/* Print the complete contents of a single heap to stderr. */
static void
#if __STD_C
dump_heap(heap_info *heap)
#else
dump_heap(heap) heap_info *heap;
#endif
{
char *ptr;
mchunkptr p;
fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size);
ptr = (heap->ar_ptr != (arena*)(heap+1)) ?
(char*)(heap + 1) : (char*)(heap + 1) + sizeof(arena);
p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) &
~MALLOC_ALIGN_MASK);
for(;;) {
fprintf(stderr, "chunk %p size %10lx", p, (long)p->size);
if(p == top(heap->ar_ptr)) {
fprintf(stderr, " (top)\n");
break;
} else if(p->size == (0|PREV_INUSE)) {
fprintf(stderr, " (fence)\n");
break;
}
fprintf(stderr, "\n");
p = next_chunk(p);
}
}
#endif
/*
malloc_stats:
For all arenas separately and in total, prints on stderr the
amount of space obtained from the system, and the current number
of bytes allocated via malloc (or realloc, etc) but not yet
freed. (Note that this is the number of bytes allocated, not the
number requested. It will be larger than the number requested
because of alignment and bookkeeping overhead.) When not compiled
for multiple threads, the maximum amount of allocated memory
(which may be more than current if malloc_trim and/or munmap got
called) is also reported. When using mmap(), prints the maximum
number of simultaneous mmap regions used, too.
*/
void mALLOC_STATs()
{
int i;
arena *ar_ptr;
struct mallinfo mi;
unsigned int in_use_b = mmapped_mem, system_b = in_use_b;
#if THREAD_STATS
long stat_lock_direct = 0, stat_lock_loop = 0, stat_lock_wait = 0;
#endif
for(i=0, ar_ptr = &main_arena;; i++) {
malloc_update_mallinfo(ar_ptr, &mi);
fprintf(stderr, "Arena %d:\n", i);
fprintf(stderr, "system bytes = %10u\n", (unsigned int)mi.arena);
fprintf(stderr, "in use bytes = %10u\n", (unsigned int)mi.uordblks);
system_b += mi.arena;
in_use_b += mi.uordblks;
#if THREAD_STATS
stat_lock_direct += ar_ptr->stat_lock_direct;
stat_lock_loop += ar_ptr->stat_lock_loop;
stat_lock_wait += ar_ptr->stat_lock_wait;
#endif
#if !defined(NO_THREADS) && MALLOC_DEBUG > 1
if(ar_ptr != &main_arena) {
heap_info *heap;
(void)mutex_lock(&ar_ptr->mutex);
heap = heap_for_ptr(top(ar_ptr));
while(heap) { dump_heap(heap); heap = heap->prev; }
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
#if HAVE_MMAP
fprintf(stderr, "Total (incl. mmap):\n");
#else
fprintf(stderr, "Total:\n");
#endif
fprintf(stderr, "system bytes = %10u\n", system_b);
fprintf(stderr, "in use bytes = %10u\n", in_use_b);
#ifdef NO_THREADS
fprintf(stderr, "max system bytes = %10u\n", (unsigned int)max_total_mem);
#endif
#if HAVE_MMAP
fprintf(stderr, "max mmap regions = %10u\n", (unsigned int)max_n_mmaps);
fprintf(stderr, "max mmap bytes = %10lu\n", max_mmapped_mem);
#endif
#if THREAD_STATS
fprintf(stderr, "heaps created = %10d\n", stat_n_heaps);
fprintf(stderr, "locked directly = %10ld\n", stat_lock_direct);
fprintf(stderr, "locked in loop = %10ld\n", stat_lock_loop);
fprintf(stderr, "locked waiting = %10ld\n", stat_lock_wait);
fprintf(stderr, "locked total = %10ld\n",
stat_lock_direct + stat_lock_loop + stat_lock_wait);
#endif
}
/*
mallinfo returns a copy of updated current mallinfo.
The information reported is for the arena last used by the thread.
*/
struct mallinfo mALLINFo()
{
struct mallinfo mi;
Void_t *vptr = NULL;
#ifndef NO_THREADS
tsd_getspecific(arena_key, vptr);
#endif
malloc_update_mallinfo((vptr ? (arena*)vptr : &main_arena), &mi);
return mi;
}
/*
mallopt:
mallopt is the general SVID/XPG interface to tunable parameters.
The format is to provide a (parameter-number, parameter-value) pair.
mallopt then sets the corresponding parameter to the argument
value if it can (i.e., so long as the value is meaningful),
and returns 1 if successful else 0.
See descriptions of tunable parameters above.
*/
#if __STD_C
int mALLOPt(int param_number, int value)
#else
int mALLOPt(param_number, value) int param_number; int value;
#endif
{
switch(param_number)
{
case M_TRIM_THRESHOLD:
trim_threshold = value; return 1;
case M_TOP_PAD:
top_pad = value; return 1;
case M_MMAP_THRESHOLD:
#ifndef NO_THREADS
/* Forbid setting the threshold too high. */
if((unsigned long)value > HEAP_MAX_SIZE/2) return 0;
#endif
mmap_threshold = value; return 1;
case M_MMAP_MAX:
#if HAVE_MMAP
n_mmaps_max = value; return 1;
#else
if (value != 0) return 0; else n_mmaps_max = value; return 1;
#endif
case M_CHECK_ACTION:
check_action = value; return 1;
default:
return 0;
}
}
/* Get/set state: malloc_get_state() records the current state of all
malloc variables (_except_ for the actual heap contents and `hook'
function pointers) in a system dependent, opaque data structure.
This data structure is dynamically allocated and can be free()d
after use. malloc_set_state() restores the state of all malloc
variables to the previously obtained state. This is especially
useful when using this malloc as part of a shared library, and when
the heap contents are saved/restored via some other method. The
primary example for this is GNU Emacs with its `dumping' procedure.
`Hook' function pointers are never saved or restored by these
functions, with two exceptions: If malloc checking was in use when
malloc_get_state() was called, then malloc_set_state() calls
__malloc_check_init() if possible; if malloc checking was not in
use in the recorded state but the user requested malloc checking,
then the hooks are reset to 0. */
#define MALLOC_STATE_MAGIC 0x444c4541l
#define MALLOC_STATE_VERSION (0*0x100l + 1l) /* major*0x100 + minor */
struct malloc_state {
long magic;
long version;
mbinptr av[NAV * 2 + 2];
char* sbrk_base;
int sbrked_mem_bytes;
unsigned long trim_threshold;
unsigned long top_pad;
unsigned int n_mmaps_max;
unsigned long mmap_threshold;
int check_action;
unsigned long max_sbrked_mem;
unsigned long max_total_mem;
unsigned int n_mmaps;
unsigned int max_n_mmaps;
unsigned long mmapped_mem;
unsigned long max_mmapped_mem;
int using_malloc_checking;
};
Void_t*
mALLOC_GET_STATe()
{
struct malloc_state* ms;
int i;
mbinptr b;
ms = (struct malloc_state*)mALLOc(sizeof(*ms));
if (!ms)
return 0;
(void)mutex_lock(&main_arena.mutex);
ms->magic = MALLOC_STATE_MAGIC;
ms->version = MALLOC_STATE_VERSION;
ms->av[0] = main_arena.av[0];
ms->av[1] = main_arena.av[1];
for(i=0; i<NAV; i++) {
b = bin_at(&main_arena, i);
if(first(b) == b)
ms->av[2*i+2] = ms->av[2*i+3] = 0; /* empty bin (or initial top) */
else {
ms->av[2*i+2] = first(b);
ms->av[2*i+3] = last(b);
}
}
ms->sbrk_base = sbrk_base;
ms->sbrked_mem_bytes = sbrked_mem;
ms->trim_threshold = trim_threshold;
ms->top_pad = top_pad;
ms->n_mmaps_max = n_mmaps_max;
ms->mmap_threshold = mmap_threshold;
ms->check_action = check_action;
ms->max_sbrked_mem = max_sbrked_mem;
#ifdef NO_THREADS
ms->max_total_mem = max_total_mem;
#else
ms->max_total_mem = 0;
#endif
ms->n_mmaps = n_mmaps;
ms->max_n_mmaps = max_n_mmaps;
ms->mmapped_mem = mmapped_mem;
ms->max_mmapped_mem = max_mmapped_mem;
#if defined _LIBC || defined MALLOC_HOOKS
ms->using_malloc_checking = using_malloc_checking;
#else
ms->using_malloc_checking = 0;
#endif
(void)mutex_unlock(&main_arena.mutex);
return (Void_t*)ms;
}
int
#if __STD_C
mALLOC_SET_STATe(Void_t* msptr)
#else
mALLOC_SET_STATe(msptr) Void_t* msptr;
#endif
{
struct malloc_state* ms = (struct malloc_state*)msptr;
int i;
mbinptr b;
#if defined _LIBC || defined MALLOC_HOOKS
disallow_malloc_check = 1;
#endif
ptmalloc_init();
if(ms->magic != MALLOC_STATE_MAGIC) return -1;
/* Must fail if the major version is too high. */
if((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl)) return -2;
(void)mutex_lock(&main_arena.mutex);
main_arena.av[0] = ms->av[0];
main_arena.av[1] = ms->av[1];
for(i=0; i<NAV; i++) {
b = bin_at(&main_arena, i);
if(ms->av[2*i+2] == 0)
first(b) = last(b) = b;
else {
first(b) = ms->av[2*i+2];
last(b) = ms->av[2*i+3];
if(i > 0) {
/* Make sure the links to the `av'-bins in the heap are correct. */
first(b)->bk = b;
last(b)->fd = b;
}
}
}
sbrk_base = ms->sbrk_base;
sbrked_mem = ms->sbrked_mem_bytes;
trim_threshold = ms->trim_threshold;
top_pad = ms->top_pad;
n_mmaps_max = ms->n_mmaps_max;
mmap_threshold = ms->mmap_threshold;
check_action = ms->check_action;
max_sbrked_mem = ms->max_sbrked_mem;
#ifdef NO_THREADS
max_total_mem = ms->max_total_mem;
#endif
n_mmaps = ms->n_mmaps;
max_n_mmaps = ms->max_n_mmaps;
mmapped_mem = ms->mmapped_mem;
max_mmapped_mem = ms->max_mmapped_mem;
/* add version-dependent code here */
if (ms->version >= 1) {
#if defined _LIBC || defined MALLOC_HOOKS
/* Check whether it is safe to enable malloc checking, or whether
it is necessary to disable it. */
if (ms->using_malloc_checking && !using_malloc_checking &&
!disallow_malloc_check)
__malloc_check_init ();
else if (!ms->using_malloc_checking && using_malloc_checking) {
__malloc_hook = 0;
__free_hook = 0;
__realloc_hook = 0;
__memalign_hook = 0;
using_malloc_checking = 0;
}
#endif
}
(void)mutex_unlock(&main_arena.mutex);
return 0;
}
#if defined _LIBC || defined MALLOC_HOOKS
/* A simple, standard set of debugging hooks. Overhead is `only' one
byte per chunk; still this will catch most cases of double frees or
overruns. The goal here is to avoid obscure crashes due to invalid
usage, unlike in the MALLOC_DEBUG code. */
#define MAGICBYTE(p) ( ( ((size_t)p >> 3) ^ ((size_t)p >> 11)) & 0xFF )
/* Instrument a chunk with overrun detector byte(s) and convert it
into a user pointer with requested size sz. */
static Void_t*
internal_function
#if __STD_C
chunk2mem_check(mchunkptr p, size_t sz)
#else
chunk2mem_check(p, sz) mchunkptr p; size_t sz;
#endif
{
unsigned char* m_ptr = (unsigned char*)chunk2mem(p);
size_t i;
for(i = chunksize(p) - (chunk_is_mmapped(p) ? 2*SIZE_SZ+1 : SIZE_SZ+1);
i > sz;
i -= 0xFF) {
if(i-sz < 0x100) {
m_ptr[i] = (unsigned char)(i-sz);
break;
}
m_ptr[i] = 0xFF;
}
m_ptr[sz] = MAGICBYTE(p);
return (Void_t*)m_ptr;
}
/* Convert a pointer to be free()d or realloc()ed to a valid chunk
pointer. If the provided pointer is not valid, return NULL. */
static mchunkptr
internal_function
#if __STD_C
mem2chunk_check(Void_t* mem)
#else
mem2chunk_check(mem) Void_t* mem;
#endif
{
mchunkptr p;
INTERNAL_SIZE_T sz, c;
unsigned char magic;
p = mem2chunk(mem);
if(!aligned_OK(p)) return NULL;
if( (char*)p>=sbrk_base && (char*)p<(sbrk_base+sbrked_mem) ) {
/* Must be a chunk in conventional heap memory. */
if(chunk_is_mmapped(p) ||
( (sz = chunksize(p)), ((char*)p + sz)>=(sbrk_base+sbrked_mem) ) ||
sz<MINSIZE || sz&MALLOC_ALIGN_MASK || !inuse(p) ||
( !prev_inuse(p) && (p->prev_size&MALLOC_ALIGN_MASK ||
(long)prev_chunk(p)<(long)sbrk_base ||
next_chunk(prev_chunk(p))!=p) ))
return NULL;
magic = MAGICBYTE(p);
for(sz += SIZE_SZ-1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
((unsigned char*)p)[sz] ^= 0xFF;
} else {
unsigned long offset, page_mask = malloc_getpagesize-1;
/* mmap()ed chunks have MALLOC_ALIGNMENT or higher power-of-two
alignment relative to the beginning of a page. Check this
first. */
offset = (unsigned long)mem & page_mask;
if((offset!=MALLOC_ALIGNMENT && offset!=0 && offset!=0x10 &&
offset!=0x20 && offset!=0x40 && offset!=0x80 && offset!=0x100 &&
offset!=0x200 && offset!=0x400 && offset!=0x800 && offset!=0x1000 &&
offset<0x2000) ||
!chunk_is_mmapped(p) || (p->size & PREV_INUSE) ||
( (((unsigned long)p - p->prev_size) & page_mask) != 0 ) ||
( (sz = chunksize(p)), ((p->prev_size + sz) & page_mask) != 0 ) )
return NULL;
magic = MAGICBYTE(p);
for(sz -= 1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
((unsigned char*)p)[sz] ^= 0xFF;
}
return p;
}
/* Check for corruption of the top chunk, and try to recover if
necessary. */
static int
internal_function
#if __STD_C
top_check(void)
#else
top_check()
#endif
{
mchunkptr t = top(&main_arena);
char* brk, * new_brk;
INTERNAL_SIZE_T front_misalign, sbrk_size;
unsigned long pagesz = malloc_getpagesize;
if((char*)t + chunksize(t) == sbrk_base + sbrked_mem ||
t == initial_top(&main_arena)) return 0;
if(check_action & 1)
fprintf(stderr, "malloc: top chunk is corrupt\n");
if(check_action & 2)
abort();
/* Try to set up a new top chunk. */
brk = MORECORE(0);
front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
front_misalign = MALLOC_ALIGNMENT - front_misalign;
sbrk_size = front_misalign + top_pad + MINSIZE;
sbrk_size += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1));
new_brk = (char*)(MORECORE (sbrk_size));
if (new_brk == (char*)(MORECORE_FAILURE)) return -1;
sbrked_mem = (new_brk - sbrk_base) + sbrk_size;
top(&main_arena) = (mchunkptr)(brk + front_misalign);
set_head(top(&main_arena), (sbrk_size - front_misalign) | PREV_INUSE);
return 0;
}
static Void_t*
#if __STD_C
malloc_check(size_t sz, const Void_t *caller)
#else
malloc_check(sz, caller) size_t sz; const Void_t *caller;
#endif
{
mchunkptr victim;
INTERNAL_SIZE_T nb;
if(request2size(sz+1, nb))
return 0;
(void)mutex_lock(&main_arena.mutex);
victim = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL;
(void)mutex_unlock(&main_arena.mutex);
if(!victim) return NULL;
return chunk2mem_check(victim, sz);
}
static void
#if __STD_C
free_check(Void_t* mem, const Void_t *caller)
#else
free_check(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
mchunkptr p;
if(!mem) return;
(void)mutex_lock(&main_arena.mutex);
p = mem2chunk_check(mem);
if(!p) {
(void)mutex_unlock(&main_arena.mutex);
if(check_action & 1)
fprintf(stderr, "free(): invalid pointer %p!\n", mem);
if(check_action & 2)
abort();
return;
}
#if HAVE_MMAP
if (chunk_is_mmapped(p)) {
(void)mutex_unlock(&main_arena.mutex);
munmap_chunk(p);
return;
}
#endif
#if 0 /* Erase freed memory. */
memset(mem, 0, chunksize(p) - (SIZE_SZ+1));
#endif
chunk_free(&main_arena, p);
(void)mutex_unlock(&main_arena.mutex);
}
static Void_t*
#if __STD_C
realloc_check(Void_t* oldmem, size_t bytes, const Void_t *caller)
#else
realloc_check(oldmem, bytes, caller)
Void_t* oldmem; size_t bytes; const Void_t *caller;
#endif
{
mchunkptr oldp, newp;
INTERNAL_SIZE_T nb, oldsize;
if (oldmem == 0) return malloc_check(bytes, NULL);
(void)mutex_lock(&main_arena.mutex);
oldp = mem2chunk_check(oldmem);
if(!oldp) {
(void)mutex_unlock(&main_arena.mutex);
if (check_action & 1)
fprintf(stderr, "realloc(): invalid pointer %p!\n", oldmem);
if (check_action & 2)
abort();
return malloc_check(bytes, NULL);
}
oldsize = chunksize(oldp);
if(request2size(bytes+1, nb)) {
(void)mutex_unlock(&main_arena.mutex);
return 0;
}
#if HAVE_MMAP
if (chunk_is_mmapped(oldp)) {
#if HAVE_MREMAP
newp = mremap_chunk(oldp, nb);
if(!newp) {
#endif
/* Note the extra SIZE_SZ overhead. */
if(oldsize - SIZE_SZ >= nb) newp = oldp; /* do nothing */
else {
/* Must alloc, copy, free. */
newp = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL;
if (newp) {
MALLOC_COPY(chunk2mem(newp), oldmem, oldsize - 2*SIZE_SZ);
munmap_chunk(oldp);
}
}
#if HAVE_MREMAP
}
#endif
} else {
#endif /* HAVE_MMAP */
newp = (top_check() >= 0) ?
chunk_realloc(&main_arena, oldp, oldsize, nb) : NULL;
#if 0 /* Erase freed memory. */
nb = chunksize(newp);
if(oldp<newp || oldp>=chunk_at_offset(newp, nb)) {
memset((char*)oldmem + 2*sizeof(mbinptr), 0,
oldsize - (2*sizeof(mbinptr)+2*SIZE_SZ+1));
} else if(nb > oldsize+SIZE_SZ) {
memset((char*)chunk2mem(newp) + oldsize, 0, nb - (oldsize+SIZE_SZ));
}
#endif
#if HAVE_MMAP
}
#endif
(void)mutex_unlock(&main_arena.mutex);
if(!newp) return NULL;
return chunk2mem_check(newp, bytes);
}
static Void_t*
#if __STD_C
memalign_check(size_t alignment, size_t bytes, const Void_t *caller)
#else
memalign_check(alignment, bytes, caller)
size_t alignment; size_t bytes; const Void_t *caller;
#endif
{
INTERNAL_SIZE_T nb;
mchunkptr p;
if (alignment <= MALLOC_ALIGNMENT) return malloc_check(bytes, NULL);
if (alignment < MINSIZE) alignment = MINSIZE;
if(request2size(bytes+1, nb))
return 0;
(void)mutex_lock(&main_arena.mutex);
p = (top_check() >= 0) ? chunk_align(&main_arena, nb, alignment) : NULL;
(void)mutex_unlock(&main_arena.mutex);
if(!p) return NULL;
return chunk2mem_check(p, bytes);
}
#ifndef NO_THREADS
/* The following hooks are used when the global initialization in
ptmalloc_init() hasn't completed yet. */
static Void_t*
#if __STD_C
malloc_starter(size_t sz, const Void_t *caller)
#else
malloc_starter(sz, caller) size_t sz; const Void_t *caller;
#endif
{
INTERNAL_SIZE_T nb;
mchunkptr victim;
if(request2size(sz, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? chunk2mem(victim) : 0;
}
static void
#if __STD_C
free_starter(Void_t* mem, const Void_t *caller)
#else
free_starter(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
mchunkptr p;
if(!mem) return;
p = mem2chunk(mem);
#if HAVE_MMAP
if (chunk_is_mmapped(p)) {
munmap_chunk(p);
return;
}
#endif
chunk_free(&main_arena, p);
}
/* The following hooks are used while the `atfork' handling mechanism
is active. */
static Void_t*
#if __STD_C
malloc_atfork (size_t sz, const Void_t *caller)
#else
malloc_atfork(sz, caller) size_t sz; const Void_t *caller;
#endif
{
Void_t *vptr = NULL;
INTERNAL_SIZE_T nb;
mchunkptr victim;
tsd_getspecific(arena_key, vptr);
if(!vptr) {
if(save_malloc_hook != malloc_check) {
if(request2size(sz, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? chunk2mem(victim) : 0;
} else {
if(top_check()<0 || request2size(sz+1, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? chunk2mem_check(victim, sz) : 0;
}
} else {
/* Suspend the thread until the `atfork' handlers have completed.
By that time, the hooks will have been reset as well, so that
mALLOc() can be used again. */
(void)mutex_lock(&list_lock);
(void)mutex_unlock(&list_lock);
return mALLOc(sz);
}
}
static void
#if __STD_C
free_atfork(Void_t* mem, const Void_t *caller)
#else
free_atfork(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
Void_t *vptr = NULL;
arena *ar_ptr;
mchunkptr p; /* chunk corresponding to mem */
if (mem == 0) /* free(0) has no effect */
return;
p = mem2chunk(mem); /* do not bother to replicate free_check here */
#if HAVE_MMAP
if (chunk_is_mmapped(p)) /* release mmapped memory. */
{
munmap_chunk(p);
return;
}
#endif
ar_ptr = arena_for_ptr(p);
tsd_getspecific(arena_key, vptr);
if(vptr)
(void)mutex_lock(&ar_ptr->mutex);
chunk_free(ar_ptr, p);
if(vptr)
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif /* !defined NO_THREADS */
#endif /* defined _LIBC || defined MALLOC_HOOKS */
#ifdef _LIBC
weak_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
weak_alias (__libc_free, __cfree) weak_alias (__libc_free, cfree)
weak_alias (__libc_free, __free) weak_alias (__libc_free, free)
weak_alias (__libc_malloc, __malloc) weak_alias (__libc_malloc, malloc)
weak_alias (__libc_memalign, __memalign) weak_alias (__libc_memalign, memalign)
weak_alias (__libc_realloc, __realloc) weak_alias (__libc_realloc, realloc)
weak_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
weak_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
weak_alias (__libc_mallinfo, __mallinfo) weak_alias (__libc_mallinfo, mallinfo)
weak_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_usable_size, malloc_usable_size)
weak_alias (__malloc_trim, malloc_trim)
weak_alias (__malloc_get_state, malloc_get_state)
weak_alias (__malloc_set_state, malloc_set_state)
#endif
/*
History:
V2.6.4-pt3 Thu Feb 20 1997 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
* Added malloc_get/set_state() (mainly for use in GNU emacs),
using interface from Marcus Daniels
* All parameters are now adjustable via environment variables
V2.6.4-pt2 Sat Dec 14 1996 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
* Added debugging hooks
* Fixed possible deadlock in realloc() when out of memory
* Don't pollute namespace in glibc: use __getpagesize, __mmap, etc.
V2.6.4-pt Wed Dec 4 1996 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
* Very minor updates from the released 2.6.4 version.
* Trimmed include file down to exported data structures.
* Changes from H.J. Lu for glibc-2.0.
V2.6.3i-pt Sep 16 1996 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
* Many changes for multiple threads
* Introduced arenas and heaps
V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
* Added pvalloc, as recommended by H.J. Liu
* Added 64bit pointer support mainly from Wolfram Gloger
* Added anonymously donated WIN32 sbrk emulation
* Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
* malloc_extend_top: fix mask error that caused wastage after
foreign sbrks
* Add linux mremap support code from HJ Liu
V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
* Integrated most documentation with the code.
* Add support for mmap, with help from
Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
* Use last_remainder in more cases.
* Pack bins using idea from colin@nyx10.cs.du.edu
* Use ordered bins instead of best-fit threshold
* Eliminate block-local decls to simplify tracing and debugging.
* Support another case of realloc via move into top
* Fix error occurring when initial sbrk_base not word-aligned.
* Rely on page size for units instead of SBRK_UNIT to
avoid surprises about sbrk alignment conventions.
* Add mallinfo, mallopt. Thanks to Raymond Nijssen
(raymond@es.ele.tue.nl) for the suggestion.
* Add `pad' argument to malloc_trim and top_pad mallopt parameter.
* More precautions for cases where other routines call sbrk,
courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
* Added macros etc., allowing use in linux libc from
H.J. Lu (hjl@gnu.ai.mit.edu)
* Inverted this history list
V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
* Re-tuned and fixed to behave more nicely with V2.6.0 changes.
* Removed all preallocation code since under current scheme
the work required to undo bad preallocations exceeds
the work saved in good cases for most test programs.
* No longer use return list or unconsolidated bins since
no scheme using them consistently outperforms those that don't
given above changes.
* Use best fit for very large chunks to prevent some worst-cases.
* Added some support for debugging
V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
* Removed footers when chunks are in use. Thanks to
Paul Wilson (wilson@cs.texas.edu) for the suggestion.
V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
* Added malloc_trim, with help from Wolfram Gloger
(wmglo@Dent.MED.Uni-Muenchen.DE).
V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
* realloc: try to expand in both directions
* malloc: swap order of clean-bin strategy;
* realloc: only conditionally expand backwards
* Try not to scavenge used bins
* Use bin counts as a guide to preallocation
* Occasionally bin return list chunks in first scan
* Add a few optimizations from colin@nyx10.cs.du.edu
V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
* faster bin computation & slightly different binning
* merged all consolidations to one part of malloc proper
(eliminating old malloc_find_space & malloc_clean_bin)
* Scan 2 returns chunks (not just 1)
* Propagate failure in realloc if malloc returns 0
* Add stuff to allow compilation on non-ANSI compilers
from kpv@research.att.com
V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
* removed potential for odd address access in prev_chunk
* removed dependency on getpagesize.h
* misc cosmetics and a bit more internal documentation
* anticosmetics: mangled names in macros to evade debugger strangeness
* tested on sparc, hp-700, dec-mips, rs6000
with gcc & native cc (hp, dec only) allowing
Detlefs & Zorn comparison study (in SIGPLAN Notices.)
Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
* Based loosely on libg++-1.2X malloc. (It retains some of the overall
structure of old version, but most details differ.)
*/