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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2004-2005, 2007, 2010, 2012-2015, 2017-2018
* Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#ifdef __linux__
# include <sys/syscall.h>
# if defined(__NR_close_range) && !defined(SYS_close_range)
# define SYS_close_range __NR_close_range
# endif
#endif
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_PSTAT_GETPROC
# include <sys/param.h>
# include <sys/pstat.h>
#else
# ifdef HAVE_DIRENT_H
# include <dirent.h>
# define NAMLEN(dirent) strlen((dirent)->d_name)
# else
# define dirent direct
# define NAMLEN(dirent) (dirent)->d_namlen
# ifdef HAVE_SYS_NDIR_H
# include <sys/ndir.h>
# endif
# ifdef HAVE_SYS_DIR_H
# include <sys/dir.h>
# endif
# ifdef HAVE_NDIR_H
# include <ndir.h>
# endif
# endif
#endif
#ifndef OPEN_MAX
# define OPEN_MAX 256
#endif
static inline void
closefrom_close(int fd)
{
#ifdef __APPLE__
/* Avoid potential libdispatch crash when we close its fds. */
(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
#else
(void)close(fd);
#endif
}
#if defined(__linux__) && defined(SYS_close_range)
static inline int
sys_close_range(unsigned int fd, unsigned int max_fd, unsigned int flags)
{
return syscall(SYS_close_range, fd, max_fd, flags);
}
#endif
/*
* Close all file descriptors greater than or equal to lowfd.
* This is the expensive (fallback) method.
*/
static void
closefrom_fallback(int lowfd)
{
long fd, maxfd;
/*
* Fall back on sysconf(_SC_OPEN_MAX) or getdtablesize(). This is
* equivalent to checking the RLIMIT_NOFILE soft limit. It is
* possible for there to be open file descriptors past this limit
* but there is not much we can do about that since the hard limit
* may be RLIM_INFINITY (LLONG_MAX or ULLONG_MAX on modern systems).
*/
#ifdef HAVE_SYSCONF
maxfd = sysconf(_SC_OPEN_MAX);
#else
maxfd = getdtablesize();
#endif /* HAVE_SYSCONF */
if (maxfd < OPEN_MAX)
maxfd = OPEN_MAX;
/* Make sure we did not get RLIM_INFINITY as the upper limit. */
if (maxfd > INT_MAX)
maxfd = INT_MAX;
for (fd = lowfd; fd < maxfd; fd++)
closefrom_close(fd);
}
#if defined(HAVE_PSTAT_GETPROC)
static int
closefrom_pstat(int lowfd)
{
struct pst_status pst;
int fd;
/*
* EOVERFLOW is not a fatal error for the fields we use.
* See the "EOVERFLOW Error" section of pstat_getvminfo(3).
*/
if (pstat_getproc(&pst, sizeof(pst), 0, getpid()) != -1 ||
errno == EOVERFLOW) {
for (fd = lowfd; fd <= pst.pst_highestfd; fd++)
(void)close(fd);
return 0;
}
return -1;
}
#elif defined(HAVE_DIRFD)
static int
closefrom_procfs(int lowfd)
{
const char *path;
DIR *dirp;
struct dirent *dent;
int *fd_array = NULL;
int fd_array_used = 0;
int fd_array_size = 0;
int ret = 0;
int i;
/* Use /proc/self/fd (or /dev/fd on macOS) if it exists. */
# ifdef __APPLE__
path = "/dev/fd";
# else
path = "/proc/self/fd";
# endif
dirp = opendir(path);
if (dirp == NULL)
return -1;
while ((dent = readdir(dirp)) != NULL) {
const char *errstr;
int fd;
fd = strtonum(dent->d_name, lowfd, INT_MAX, &errstr);
if (errstr != NULL || fd == dirfd(dirp))
continue;
if (fd_array_used >= fd_array_size) {
int *ptr;
if (fd_array_size > 0)
fd_array_size *= 2;
else
fd_array_size = 32;
ptr = reallocarray(fd_array, fd_array_size, sizeof(int));
if (ptr == NULL) {
ret = -1;
break;
}
fd_array = ptr;
}
fd_array[fd_array_used++] = fd;
}
for (i = 0; i < fd_array_used; i++)
closefrom_close(fd_array[i]);
free(fd_array);
(void)closedir(dirp);
return ret;
}
#endif
/*
* Close all file descriptors greater than or equal to lowfd.
* We try the fast way first, falling back on the slow method.
*/
void
closefrom(int lowfd)
{
if (lowfd < 0)
lowfd = 0;
/* Try the fast methods first, if possible. */
#if defined(HAVE_FCNTL_CLOSEM)
if (fcntl(lowfd, F_CLOSEM, 0) != -1)
return;
#endif /* HAVE_FCNTL_CLOSEM */
#if defined(__linux__) && defined(SYS_close_range)
if (sys_close_range(lowfd, UINT_MAX, 0) == 0)
return;
#endif
#if defined(HAVE_PSTAT_GETPROC)
if (closefrom_pstat(lowfd) != -1)
return;
#elif defined(HAVE_DIRFD)
if (closefrom_procfs(lowfd) != -1)
return;
#endif /* HAVE_DIRFD */
/* Do things the slow way. */
closefrom_fallback(lowfd);
}
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