kc3-lang/libbsd/src/closefrom.c

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• Hash : 30e328cb
  Author :
  Date : 2014-11-03T00:43:27
  

  Do not close file descriptors while scanning the /proc filesystem Closing file descriptors changes the content of the fd directories in the /proc filesystem, which means readdir() might get very confused. Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=85663

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• src/closefrom.c

• /*
   * Copyright (c) 2004-2005, 2007, 2010, 2012-2014
   *	Todd C. Miller <Todd.Miller@courtesan.com>
   *
   * 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>
  
  #include <sys/types.h>
  #include <unistd.h>
  #include <stdio.h>
  #ifdef STDC_HEADERS
  # include <stdlib.h>
  # include <stddef.h>
  #else
  # ifdef HAVE_STDLIB_H
  #  include <stdlib.h>
  # endif
  #endif /* STDC_HEADERS */
  #include <fcntl.h>
  #include <limits.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
  
  #if defined(HAVE_FCNTL_CLOSEM) && !defined(HAVE_DIRFD)
  # define closefrom	closefrom_fallback
  #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
  }
  
  /*
   * Close all file descriptors greater than or equal to lowfd.
   * This is the expensive (fallback) method.
   */
  void
  closefrom_fallback(int lowfd)
  {
  	long fd, maxfd;
  
  	/*
  	 * Fall back on sysconf() or getdtablesize().  We avoid checking
  	 * resource limits since it is possible to open a file descriptor
  	 * and then drop the rlimit such that it is below the open fd.
  	 */
  #ifdef HAVE_SYSCONF
  	maxfd = sysconf(_SC_OPEN_MAX);
  #else
  	maxfd = getdtablesize();
  #endif /* HAVE_SYSCONF */
  	if (maxfd < 0)
  		maxfd = OPEN_MAX;
  
  	for (fd = lowfd; fd < maxfd; fd++)
  		closefrom_close(fd);
  }
  
  /*
   * Close all file descriptors greater than or equal to lowfd.
   * We try the fast way first, falling back on the slow method.
   */
  #if defined(HAVE_FCNTL_CLOSEM)
  void
  closefrom(int lowfd)
  {
  	if (fcntl(lowfd, F_CLOSEM, 0) == -1)
  		closefrom_fallback(lowfd);
  }
  #elif defined(HAVE_PSTAT_GETPROC)
  void
  closefrom(int lowfd)
  {
  	struct pst_status pstat;
  	int fd;
  
  	if (pstat_getproc(&pstat, sizeof(pstat), 0, getpid()) != -1) {
  		for (fd = lowfd; fd <= pstat.pst_highestfd; fd++)
  			(void)close(fd);
  	} else {
  		closefrom_fallback(lowfd);
  	}
  }
  #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 i;
  
  	/* Use /proc/self/fd (or /dev/fd on FreeBSD) if it exists. */
  # if defined(__FreeBSD__) || defined(__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)
  				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 0;
  }
  
  void
  closefrom(int lowfd)
  {
  	if (closefrom_procfs(lowfd) == 0)
  		return;
  
  	closefrom_fallback(lowfd);
  }
  #endif /* HAVE_FCNTL_CLOSEM */
  

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