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glibc/hurd/alloc-fd.c
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/* Copyright (C) 1994-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 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 | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <hurd.h> | |
#include <hurd/fd.h> | |
#include <hurd/resource.h> | |
#include <stdlib.h> | |
#include "hurdmalloc.h" /* XXX */ | |
/* Allocate a new file descriptor and return it, locked. The new | |
descriptor number will be no less than FIRST_FD. If the table is full, | |
set errno to EMFILE and return NULL. If FIRST_FD is negative or bigger | |
than the size of the table, set errno to EINVAL and return NULL. */ | |
struct hurd_fd * | |
_hurd_alloc_fd (int *fd, int first_fd) | |
{ | |
int i; | |
void *crit; | |
long int rlimit; | |
if (first_fd < 0) | |
{ | |
errno = EINVAL; | |
return NULL; | |
} | |
crit = _hurd_critical_section_lock (); | |
__mutex_lock (&_hurd_dtable_lock); | |
search: | |
for (i = first_fd; i < _hurd_dtablesize; ++i) | |
{ | |
struct hurd_fd *d = _hurd_dtable[i]; | |
if (d == NULL) | |
{ | |
/* Allocate a new descriptor structure for this slot, | |
initializing its port cells to nil. The test below will catch | |
and return this descriptor cell after locking it. */ | |
d = _hurd_new_fd (MACH_PORT_NULL, MACH_PORT_NULL); | |
if (d == NULL) | |
{ | |
__mutex_unlock (&_hurd_dtable_lock); | |
_hurd_critical_section_unlock (crit); | |
return NULL; | |
} | |
_hurd_dtable[i] = d; | |
} | |
__spin_lock (&d->port.lock); | |
if (d->port.port == MACH_PORT_NULL) | |
{ | |
__mutex_unlock (&_hurd_dtable_lock); | |
_hurd_critical_section_unlock (crit); | |
if (fd != NULL) | |
*fd = i; | |
return d; | |
} | |
else | |
__spin_unlock (&d->port.lock); | |
} | |
__mutex_lock (&_hurd_rlimit_lock); | |
rlimit = _hurd_rlimits[RLIMIT_OFILE].rlim_cur; | |
__mutex_unlock (&_hurd_rlimit_lock); | |
if (first_fd < rlimit) | |
{ | |
/* The descriptor table is full. Check if we have reached the | |
resource limit, or only the allocated size. */ | |
if (_hurd_dtablesize < rlimit) | |
{ | |
/* Enlarge the table. */ | |
int save = errno; | |
struct hurd_fd **new; | |
/* Try to double the table size, but don't exceed the limit, | |
and make sure it exceeds FIRST_FD. */ | |
int size = _hurd_dtablesize * 2; | |
if (size > rlimit) | |
size = rlimit; | |
else if (size <= first_fd) | |
size = first_fd + 1; | |
if (size * sizeof (*_hurd_dtable) < size) | |
{ | |
/* Integer overflow! */ | |
errno = ENOMEM; | |
goto out; | |
} | |
/* If we fail to allocate that, decrement the desired size | |
until we succeed in allocating it. */ | |
do | |
new = realloc (_hurd_dtable, size * sizeof (*_hurd_dtable)); | |
while (new == NULL && size-- > first_fd); | |
if (new != NULL) | |
{ | |
/* We managed to allocate a new table. Now install it. */ | |
errno = save; | |
if (first_fd < _hurd_dtablesize) | |
first_fd = _hurd_dtablesize; | |
/* Initialize the new slots. */ | |
for (i = _hurd_dtablesize; i < size; ++i) | |
new[i] = NULL; | |
_hurd_dtablesize = size; | |
_hurd_dtable = new; | |
/* Go back to the loop to initialize the first new slot. */ | |
goto search; | |
} | |
else | |
errno = ENOMEM; | |
} | |
else | |
errno = EMFILE; | |
} | |
else | |
errno = EINVAL; /* Bogus FIRST_FD value. */ | |
out: | |
__mutex_unlock (&_hurd_dtable_lock); | |
_hurd_critical_section_unlock (crit); | |
return NULL; | |
} |