mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-01 17:30:07 +00:00
105 lines
3.3 KiB
C
105 lines
3.3 KiB
C
/* Close a range of file descriptors. Linux version.
|
|
Copyright (C) 2021-2023 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <arch-fd_to_filename.h>
|
|
#include <dirent.h>
|
|
#include <not-cancel.h>
|
|
#include <stdbool.h>
|
|
|
|
#if !__ASSUME_CLOSE_RANGE
|
|
|
|
/* Fallback code: iterates over /proc/self/fd, closing each file descriptor
|
|
that fall on the criteria. If DIRFD_FALLBACK is set, a failure on
|
|
/proc/self/fd open will trigger a fallback that tries to close a file
|
|
descriptor before proceed. */
|
|
_Bool
|
|
__closefrom_fallback (int from, _Bool dirfd_fallback)
|
|
{
|
|
int dirfd = __open_nocancel (FD_TO_FILENAME_PREFIX, O_RDONLY | O_DIRECTORY,
|
|
0);
|
|
if (dirfd == -1)
|
|
{
|
|
/* Return if procfs can not be opened for some reason. */
|
|
if ((errno != EMFILE && errno != ENFILE && errno != ENOMEM)
|
|
|| !dirfd_fallback)
|
|
return false;
|
|
|
|
/* The closefrom should work even when process can't open new files. */
|
|
for (int i = from; i < INT_MAX; i++)
|
|
{
|
|
int r = __close_nocancel (i);
|
|
if (r == 0 || (r == -1 && errno != EBADF))
|
|
break;
|
|
}
|
|
|
|
dirfd = __open_nocancel (FD_TO_FILENAME_PREFIX, O_RDONLY | O_DIRECTORY,
|
|
0);
|
|
if (dirfd == -1)
|
|
return false;
|
|
}
|
|
|
|
char buffer[1024];
|
|
bool ret = false;
|
|
while (true)
|
|
{
|
|
ssize_t ret = __getdents64 (dirfd, buffer, sizeof (buffer));
|
|
if (ret == -1)
|
|
goto err;
|
|
else if (ret == 0)
|
|
break;
|
|
|
|
/* If any file descriptor is closed it resets the /proc/self position
|
|
read again from the start (to obtain any possible kernel update). */
|
|
bool closed = false;
|
|
char *begin = buffer, *end = buffer + ret;
|
|
while (begin != end)
|
|
{
|
|
unsigned short int d_reclen;
|
|
memcpy (&d_reclen, begin + offsetof (struct dirent64, d_reclen),
|
|
sizeof (d_reclen));
|
|
const char *dname = begin + offsetof (struct dirent64, d_name);
|
|
begin += d_reclen;
|
|
|
|
if (dname[0] == '.')
|
|
continue;
|
|
|
|
int fd = 0;
|
|
for (const char *s = dname; (unsigned int) (*s) - '0' < 10; s++)
|
|
fd = 10 * fd + (*s - '0');
|
|
|
|
if (fd == dirfd || fd < from)
|
|
continue;
|
|
|
|
/* We ignore close errors because EBADF, EINTR, and EIO means the
|
|
descriptor has been released. */
|
|
__close_nocancel (fd);
|
|
closed = true;
|
|
}
|
|
|
|
if (closed && __lseek (dirfd, 0, SEEK_SET) < 0)
|
|
goto err;
|
|
}
|
|
|
|
ret = true;
|
|
err:
|
|
__close_nocancel (dirfd);
|
|
return ret;
|
|
}
|
|
|
|
#endif
|