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Remove __ASSUME_ATFCTS conditionals in sysdeps/unix/sysv/linux/. 
This patch cleans up for __ASSUME_ATFCTS now always being true for the
supported Linux kernel versions by removing conditional code in
sysdeps/unix/sysv/linux.  Several fchownat.c files that were only
present because of differences in the fallback syscalls used
(depending on the architecture-specific names of chown-related
syscalls for 32-bit uids) are removed.  Files that looks like they
could be replaced by syscalls.list entries have the standard "Consider
moving to syscalls.list." comment (see bug 14138) added.  Conditionals
on the relevant __NR_* syscall numbers being defined are also removed,
since my analysis indicated that the relevant syscalls are always
defined for all relevant kernel versions using any affected file.
Much of the removed fallback code had unbounded stack allocations, so
this reduces the number of cases to consider for anyone reviewing uses
of alloca and VLAs in glibc.

There remain tests of __ASSUME_ATFCTS in io/openat.c (to determine
whether to define __have_atfcts) and sysdeps/posix/getcwd.c (which
also uses __have_atfcts); thus, the definition of __ASSUME_ATFCTS
remains in kernel-features.h.  The logical condition relevant there is
whether openat64_not_cancel_3 is known to work.  Hurd doesn't use this
version of getcwd at all, so the conditionals in getcwd.c are always
true in glibc.  However, this code is also used in gnulib.  So the
best way to deal with the conditionals there may be for gnulib people
to deal with merging all relevant changes in both directions between
the glibc and gnulib versions of this file, at the end of which the
openat conditionals should be in whatever form is best for gnulib, and
hardcoded in the _LIBC case to having openat supported.

Tested by comparing before-and-after disassembly of installed
(stripped) shared libraries, on x86_64 and x86.  On x86 the patch made
no change to the disassembly; on x86_64, the only changes were in
readlinkat, where formerly the return value from the readlinkat
syscall was stored in an int variable before being converted to
ssize_t for the return, and now the return value is returned directly
without truncation to int.  I think it's clearly correct not to
truncate the return value (although I also think the truncation would
not have been a user-visible bug because the kernel would never have
returned a value it could have affected).

	* include/fcntl.h (__atfct_seterrno): Remove prototype.
	(__atfct_seterrno_2): Likewise.
	* sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c: Do not include
	<kernel-features.h>.
	(__ASSUME_ATFCTS): Do not undefine and redefine.
	* sysdeps/unix/sysv/linux/alpha/fxstatat.c [__ASSUME_ATFCTS]
	(__have_atfcts): Remove conditional definition.
	(__fxstatat([__NR_fstatat64]: Make code unconditional.
	(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code and code
	unreachable if [__ASSUME_ATFCTS].
	* sysdeps/unix/sysv/linux/dl-fxstatat64.c (__ASSUME_ATFCTS): Do
	not undefine and redefine.
	* sysdeps/unix/sysv/linux/faccessat.c: Do not include
	<kernel-features.h>.
	(faccessat) [__NR_faccessat]: Make code unconditional.
	(faccessat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/fchmodat.c: Do not include
	<kernel-features.h>.
	(fchmodat) [__NR_fchmodat]: Make code unconditional.
	(fchmodat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/fchownat.c: Do not include
	<kernel-features.h>.
	(fchownat) [__NR_fchownat]: Make code unconditional.
	(fchownat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/futimesat.c: Do not include
	<kernel-features.h>.
	(futimesat) [__NR_futimesat]: Make code unconditional.
	(futimesat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/fxstatat.c: Do not include
	<kernel-features.h>.
	(__fxstatat) [__NR_newfstatat]: Make code unconditional.
	(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/fxstatat64.c: Do not include
	<kernel-features.h>.
	(__fxstatat64) [__NR_fstatat64]: Make code unconditional.
	(__fxstatat64) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/i386/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/i386/fxstatat.c: Do not include
	<kernel-features.h>.
	(__fxstatat) [__NR_fstatat64]: Make code unconditional.
	(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/linkat.c: Do not include
	<kernel-features.h>.
	(linkat) [__NR_linkat]: Make code unconditional.
	(linkat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/m68k/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/mips/mips64/fxstatat64.c: Do not include
	<kernel-features.h>.
	(__fxstatat64) [__NR_newfstatat]: Make code unconditional.
	(__fxstatat64) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/mkdirat.c: Do not include
	<kernel-features.h>.
	(mkdirat) [__NR_mkdirat]: Make code unconditional.
	(mkdirat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/openat.c: Do not include
	<kernel-features.h>.
	[!__ASSUME_ATFCTS] (__atfct_seterrno): Remove function.
	[!__ASSUME_ATFCTS] (__have_atfcts): Remove variable.
	(OPENAT_NOT_CANCEL) [__NR_openat]: Make code unconditional.
	(OPENAT_NOT_CANCEL) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/powerpc/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/readlinkat.c: Do not include
	<kernel-features.h>.
	(readlinkat) [__NR_readlinkat]: Make code unconditional.
	(readlinkat) [!__ASSUME_ATFCTS]: Remove conditional code.  Return
	result of INLINE_SYSCALL directly, not via int variable.
	* sysdeps/unix/sysv/linux/renameat.c: Do not include
	<kernel-features.h>.
	[!__ASSUME_ATFCTS] (__atfct_seterrno_2): Remove function.
	(renameat) [__NR_renameat]: Make code unconditional.
	(renameat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/s390/s390-32/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/sh/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/sparc/sparc32/fchownat.c: Remove file.
	* sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c
	(__ASSUME_ATFCTS): Do not undefine and redefine.
	* sysdeps/unix/sysv/linux/symlinkat.c: Do not include
	<kernel-features.h>.
	(symlinkat) [__NR_symlinkat]: Make code unconditional.
	(symlinkat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/unlinkat.c: Do not include
	<kernel-features.h>.
	(unlinkat) [__NR_unlinkat]: Make code unconditional.
	(unlinkat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c
	(__ASSUME_ATFCTS): Do not undefine and redefine.
	* sysdeps/unix/sysv/linux/wordsize-64/fxstatat.c: Do not include
	<kernel-features.h>.
	(__fxstatat) [__NR_newfstatat]: Make code unconditional.
	(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
	* sysdeps/unix/sysv/linux/xmknodat.c: Do not include
	<kernel-features.h>.
	(__xmknodat) [__NR_mknodat]: Make code unconditional.
	(__xmknodat) [!__ASSUME_ATFCTS]: Remove conditional code.
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Joseph Myers committed Jun 20, 2014
1 parent 224c6c5 commit 809fdf0
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97 changes: 97 additions & 0 deletions ChangeLog
View file
@@ -1,3 +1,100 @@
2014-06-20 Joseph Myers <joseph@codesourcery.com>

* include/fcntl.h (__atfct_seterrno): Remove prototype.
(__atfct_seterrno_2): Likewise.
* sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c: Do not include
<kernel-features.h>.
(__ASSUME_ATFCTS): Do not undefine and redefine.
* sysdeps/unix/sysv/linux/alpha/fxstatat.c [__ASSUME_ATFCTS]
(__have_atfcts): Remove conditional definition.
(__fxstatat([__NR_fstatat64]: Make code unconditional.
(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code and code
unreachable if [__ASSUME_ATFCTS].
* sysdeps/unix/sysv/linux/dl-fxstatat64.c (__ASSUME_ATFCTS): Do
not undefine and redefine.
* sysdeps/unix/sysv/linux/faccessat.c: Do not include
<kernel-features.h>.
(faccessat) [__NR_faccessat]: Make code unconditional.
(faccessat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/fchmodat.c: Do not include
<kernel-features.h>.
(fchmodat) [__NR_fchmodat]: Make code unconditional.
(fchmodat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/fchownat.c: Do not include
<kernel-features.h>.
(fchownat) [__NR_fchownat]: Make code unconditional.
(fchownat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/futimesat.c: Do not include
<kernel-features.h>.
(futimesat) [__NR_futimesat]: Make code unconditional.
(futimesat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/fxstatat.c: Do not include
<kernel-features.h>.
(__fxstatat) [__NR_newfstatat]: Make code unconditional.
(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/fxstatat64.c: Do not include
<kernel-features.h>.
(__fxstatat64) [__NR_fstatat64]: Make code unconditional.
(__fxstatat64) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/i386/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/i386/fxstatat.c: Do not include
<kernel-features.h>.
(__fxstatat) [__NR_fstatat64]: Make code unconditional.
(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/linkat.c: Do not include
<kernel-features.h>.
(linkat) [__NR_linkat]: Make code unconditional.
(linkat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/m68k/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/mips/mips64/fxstatat64.c: Do not include
<kernel-features.h>.
(__fxstatat64) [__NR_newfstatat]: Make code unconditional.
(__fxstatat64) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/mkdirat.c: Do not include
<kernel-features.h>.
(mkdirat) [__NR_mkdirat]: Make code unconditional.
(mkdirat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/openat.c: Do not include
<kernel-features.h>.
[!__ASSUME_ATFCTS] (__atfct_seterrno): Remove function.
[!__ASSUME_ATFCTS] (__have_atfcts): Remove variable.
(OPENAT_NOT_CANCEL) [__NR_openat]: Make code unconditional.
(OPENAT_NOT_CANCEL) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/powerpc/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/readlinkat.c: Do not include
<kernel-features.h>.
(readlinkat) [__NR_readlinkat]: Make code unconditional.
(readlinkat) [!__ASSUME_ATFCTS]: Remove conditional code. Return
result of INLINE_SYSCALL directly, not via int variable.
* sysdeps/unix/sysv/linux/renameat.c: Do not include
<kernel-features.h>.
[!__ASSUME_ATFCTS] (__atfct_seterrno_2): Remove function.
(renameat) [__NR_renameat]: Make code unconditional.
(renameat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/s390/s390-32/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/sh/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/sparc/sparc32/fchownat.c: Remove file.
* sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c
(__ASSUME_ATFCTS): Do not undefine and redefine.
* sysdeps/unix/sysv/linux/symlinkat.c: Do not include
<kernel-features.h>.
(symlinkat) [__NR_symlinkat]: Make code unconditional.
(symlinkat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/unlinkat.c: Do not include
<kernel-features.h>.
(unlinkat) [__NR_unlinkat]: Make code unconditional.
(unlinkat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c
(__ASSUME_ATFCTS): Do not undefine and redefine.
* sysdeps/unix/sysv/linux/wordsize-64/fxstatat.c: Do not include
<kernel-features.h>.
(__fxstatat) [__NR_newfstatat]: Make code unconditional.
(__fxstatat) [!__ASSUME_ATFCTS]: Remove conditional code.
* sysdeps/unix/sysv/linux/xmknodat.c: Do not include
<kernel-features.h>.
(__xmknodat) [__NR_mknodat]: Make code unconditional.
(__xmknodat) [!__ASSUME_ATFCTS]: Remove conditional code.

2014-06-20 H.J. Lu <hongjiu.lu@intel.com>

* sysdeps/x86_64/multiarch/rtld-strlen.S: Removed.
Expand Down
8 changes: 0 additions & 8 deletions include/fcntl.h
View file
Expand Up @@ -31,14 +31,6 @@ extern int __openat_2 (int __fd, const char *__path, int __oflag);
extern int __openat64_2 (int __fd, const char *__path, int __oflag);


/* Helper functions for the various *at functions. For Linux. */
extern void __atfct_seterrno (int errval, int fd, const char *buf)
attribute_hidden;
extern void __atfct_seterrno_2 (int errval, int fd1, const char *buf1,
int fd2, const char *buf2)
attribute_hidden;


/* Flag determining whether the *at system calls are available. */
extern int __have_atfcts attribute_hidden;

Expand Down
8 changes: 0 additions & 8 deletions sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
View file
@@ -1,9 +1 @@
/* In this implementation we do not really care whether the call fails
because of missing kernel support since we do not even call the
function in this case. */
/* For Alpha, in <kernel-features.h> we redefine the default definition of
when __ASSUME_ATFCTS is present. The hack must wait until after that. */
#include <kernel-features.h>
#undef __ASSUME_ATFCTS
#define __ASSUME_ATFCTS 1
#include "fxstatat.c"
64 changes: 2 additions & 62 deletions sysdeps/unix/sysv/linux/alpha/fxstatat.c
View file
Expand Up @@ -29,10 +29,6 @@

#undef __fxstatat64

#ifdef __ASSUME_ATFCTS
# define __have_atfcts 1
#endif

/* Get information about the file NAME in BUF. */
int
__fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
Expand All @@ -45,67 +41,11 @@ __fxstatat (int vers, int fd, const char *file, struct stat *st, int flag)
cannot actually check this, lest the compiler not optimize the rest
of the function away. */

#ifdef __NR_fstatat64
if (__have_atfcts >= 0)
{
result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, st, flag);
if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
return result;
errno_out = INTERNAL_SYSCALL_ERRNO (result, err);
#ifndef __ASSUME_ATFCTS
if (errno_out == ENOSYS)
__have_atfcts = -1;
else
#endif
{
__set_errno (errno_out);
return -1;
}
}
#endif /* __NR_fstatat64 */

if (flag & ~AT_SYMLINK_NOFOLLOW)
{
__set_errno (EINVAL);
return -1;
}

char *buf = NULL;

if (fd != AT_FDCWD && file[0] != '/')
{
size_t filelen = strlen (file);
if (__builtin_expect (filelen == 0, 0))
{
__set_errno (ENOENT);
return -1;
}

static const char procfd[] = "/proc/self/fd/%d/%s";
/* Buffer for the path name we are going to use. It consists of
- the string /proc/self/fd/
- the file descriptor number
- the file name provided.
The final NUL is included in the sizeof. A bit of overhead
due to the format elements compensates for possible negative
numbers. */
size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
buf = alloca (buflen);

__snprintf (buf, buflen, procfd, fd, file);
file = buf;
}

if (flag & AT_SYMLINK_NOFOLLOW)
result = INTERNAL_SYSCALL (lstat64, err, 2, file, st);
else
result = INTERNAL_SYSCALL (stat64, err, 2, file, st);
result = INTERNAL_SYSCALL (fstatat64, err, 4, fd, file, st, flag);
if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
return result;

errno_out = INTERNAL_SYSCALL_ERRNO (result, err);
__atfct_seterrno (errno_out, fd, buf);

__set_errno (errno_out);
return -1;
}
libc_hidden_def (__fxstatat)
Expand Down
5 changes: 0 additions & 5 deletions sysdeps/unix/sysv/linux/dl-fxstatat64.c
View file
@@ -1,6 +1 @@
/* In this implementation we do not really care whether the call fails
because of missing kernel support since we do not even call the
function in this case. */
#undef __ASSUME_ATFCTS
#define __ASSUME_ATFCTS 1
#include <fxstatat64.c>
73 changes: 2 additions & 71 deletions sysdeps/unix/sysv/linux/faccessat.c
View file
Expand Up @@ -24,7 +24,6 @@
#include <unistd.h>
#include <sys/types.h>
#include <alloca.h>
#include <kernel-features.h>
#include <sysdep.h>


Expand All @@ -41,76 +40,8 @@ faccessat (fd, file, mode, flag)
return -1;
}

#ifdef __NR_faccessat
if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure))
# ifndef __ASSUME_ATFCTS
&& __have_atfcts >= 0
# endif
)
{
int result = INLINE_SYSCALL (faccessat, 3, fd, file, mode);
# ifndef __ASSUME_ATFCTS
if (result == -1 && errno == ENOSYS)
__have_atfcts = -1;
else
# endif
return result;
}
#endif

#ifndef __ASSUME_ATFCTS
if ((!(flag & AT_EACCESS) || ! __libc_enable_secure)
# ifndef __NR_laccess /* Linux so far has no laccess syscall. */
&& !(flag & AT_SYMLINK_NOFOLLOW)
# endif
)
{
/* If we are not set-uid or set-gid, access does the same. */
char *buf = NULL;

if (fd != AT_FDCWD && file[0] != '/')
{
size_t filelen = strlen (file);
if (__glibc_unlikely (filelen == 0))
{
__set_errno (ENOENT);
return -1;
}

static const char procfd[] = "/proc/self/fd/%d/%s";
/* Buffer for the path name we are going to use. It consists of
- the string /proc/self/fd/
- the file descriptor number
- the file name provided.
The final NUL is included in the sizeof. A bit of overhead
due to the format elements compensates for possible negative
numbers. */
size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
buf = alloca (buflen);

__snprintf (buf, buflen, procfd, fd, file);
file = buf;
}

int result;
INTERNAL_SYSCALL_DECL (err);

# ifdef __NR_laccess
if (flag & AT_SYMLINK_NOFOLLOW)
result = INTERNAL_SYSCALL (laccess, err, 2, file, mode);
else
# endif
result = INTERNAL_SYSCALL (access, err, 2, file, mode);

if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
{
__atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
result = -1;
}

return result;
}
#endif
if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure)))
return INLINE_SYSCALL (faccessat, 3, fd, file, mode);

struct stat64 stats;
if (__fxstatat64 (_STAT_VER, fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW))
Expand Down
63 changes: 1 addition & 62 deletions sysdeps/unix/sysv/linux/fchmodat.c
View file
Expand Up @@ -24,7 +24,6 @@
#include <unistd.h>
#include <sys/types.h>
#include <alloca.h>
#include <kernel-features.h>
#include <sysdep.h>

int
Expand All @@ -47,65 +46,5 @@ fchmodat (fd, file, mode, flag)
}
#endif

int result;

#ifdef __NR_fchmodat
# ifndef __ASSUME_ATFCTS
if (__have_atfcts >= 0)
# endif
{
result = INLINE_SYSCALL (fchmodat, 3, fd, file, mode);
# ifndef __ASSUME_ATFCTS
if (result == -1 && errno == ENOSYS)
__have_atfcts = -1;
else
# endif
return result;
}
#endif

#ifndef __ASSUME_ATFCTS
char *buf = NULL;

if (fd != AT_FDCWD && file[0] != '/')
{
size_t filelen = strlen (file);
if (__glibc_unlikely (filelen == 0))
{
__set_errno (ENOENT);
return -1;
}

static const char procfd[] = "/proc/self/fd/%d/%s";
/* Buffer for the path name we are going to use. It consists of
- the string /proc/self/fd/
- the file descriptor number
- the file name provided.
The final NUL is included in the sizeof. A bit of overhead
due to the format elements compensates for possible negative
numbers. */
size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
buf = alloca (buflen);

__snprintf (buf, buflen, procfd, fd, file);
file = buf;
}

INTERNAL_SYSCALL_DECL (err);

# ifdef __NR_lchmod
if (flag & AT_SYMLINK_NOFOLLOW)
result = INTERNAL_SYSCALL (lchmod, err, 2, file, mode);
else
# endif
result = INTERNAL_SYSCALL (chmod, err, 2, file, mode);

if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
{
__atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
result = -1;
}

return result;
#endif
return INLINE_SYSCALL (fchmodat, 3, fd, file, mode);
}

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