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    1: /*
    2:  * Copyright (c) 2004-2005, 2007, 2010
    3:  *	Todd C. Miller <Todd.Miller@courtesan.com>
    4:  *
    5:  * Permission to use, copy, modify, and distribute this software for any
    6:  * purpose with or without fee is hereby granted, provided that the above
    7:  * copyright notice and this permission notice appear in all copies.
    8:  *
    9:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   10:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   11:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   12:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   13:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   14:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   15:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   16:  */
   17: 
   18: #include <config.h>
   19: 
   20: #include <sys/types.h>
   21: #include <sys/param.h>
   22: #include <unistd.h>
   23: #include <stdio.h>
   24: #ifdef STDC_HEADERS
   25: # include <stdlib.h>
   26: # include <stddef.h>
   27: #else
   28: # ifdef HAVE_STDLIB_H
   29: #  include <stdlib.h>
   30: # endif
   31: #endif /* STDC_HEADERS */
   32: #include <fcntl.h>
   33: #ifdef HAVE_DIRENT_H
   34: # include <dirent.h>
   35: # define NAMLEN(dirent) strlen((dirent)->d_name)
   36: #else
   37: # define dirent direct
   38: # define NAMLEN(dirent) (dirent)->d_namlen
   39: # ifdef HAVE_SYS_NDIR_H
   40: #  include <sys/ndir.h>
   41: # endif
   42: # ifdef HAVE_SYS_DIR_H
   43: #  include <sys/dir.h>
   44: # endif
   45: # ifdef HAVE_NDIR_H
   46: #  include <ndir.h>
   47: # endif
   48: #endif
   49: 
   50: #include "missing.h"
   51: 
   52: #ifndef HAVE_FCNTL_CLOSEM
   53: # ifndef HAVE_DIRFD
   54: #   define closefrom_fallback	closefrom
   55: # endif
   56: #endif
   57: 
   58: /*
   59:  * Close all file descriptors greater than or equal to lowfd.
   60:  * This is the expensive (ballback) method.
   61:  */
   62: void
   63: closefrom_fallback(int lowfd)
   64: {
   65:     long fd, maxfd;
   66: 
   67:     /*
   68:      * Fall back on sysconf() or getdtablesize().  We avoid checking
   69:      * resource limits since it is possible to open a file descriptor
   70:      * and then drop the rlimit such that it is below the open fd.
   71:      */
   72: #ifdef HAVE_SYSCONF
   73:     maxfd = sysconf(_SC_OPEN_MAX);
   74: #else
   75:     maxfd = getdtablesize();
   76: #endif /* HAVE_SYSCONF */
   77:     if (maxfd < 0)
   78: 	maxfd = OPEN_MAX;
   79: 
   80:     for (fd = lowfd; fd < maxfd; fd++)
   81: 	(void) close((int) fd);
   82: }
   83: 
   84: /*
   85:  * Close all file descriptors greater than or equal to lowfd.
   86:  * We try the fast way first, falling back on the slow method.
   87:  */
   88: #ifdef HAVE_FCNTL_CLOSEM
   89: void
   90: closefrom(int lowfd)
   91: {
   92:     if (fcntl(lowfd, F_CLOSEM, 0) == -1)
   93: 	closefrom_fallback(lowfd);
   94: }
   95: #else
   96: # ifdef HAVE_DIRFD
   97: void
   98: closefrom(int lowfd)
   99: {
  100:     struct dirent *dent;
  101:     DIR *dirp;
  102:     char *endp;
  103:     long fd;
  104: 
  105:     /* Use /proc/self/fd directory if it exists. */
  106:     if ((dirp = opendir("/proc/self/fd")) != NULL) {
  107: 	while ((dent = readdir(dirp)) != NULL) {
  108: 	    fd = strtol(dent->d_name, &endp, 10);
  109: 	    if (dent->d_name != endp && *endp == '\0' &&
  110: 		fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
  111: 		(void) close((int) fd);
  112: 	}
  113: 	(void) closedir(dirp);
  114:     } else
  115: 	closefrom_fallback(lowfd);
  116: }
  117: #endif /* HAVE_DIRFD */
  118: #endif /* HAVE_FCNTL_CLOSEM */