compat/closefrom.c

   1 /*
   2  * Copyright (c) 2004-2005 Todd C. Miller <Todd.Miller@courtesan.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #ifndef HAVE_CLOSEFROM
  18
  19 #include <sys/types.h>
  20 #include <sys/param.h>
  21 #include <unistd.h>
  22 #include <stdio.h>
  23 #ifdef HAVE_FCNTL_H
  24 # include <fcntl.h>
  25 #endif
  26 #include <limits.h>
  27 #include <stdlib.h>
  28 #include <stddef.h>
  29 #include <string.h>
  30 #include <unistd.h>
  31 #ifdef HAVE_DIRENT_H
  32 # include <dirent.h>
  33 # define NAMLEN(dirent) strlen((dirent)->d_name)
  34 #else
  35 # define dirent direct
  36 # define NAMLEN(dirent) (dirent)->d_namlen
  37 # ifdef HAVE_SYS_NDIR_H
  38 #  include <sys/ndir.h>
  39 # endif
  40 # ifdef HAVE_SYS_DIR_H
  41 #  include <sys/dir.h>
  42 # endif
  43 # ifdef HAVE_NDIR_H
  44 #  include <ndir.h>
  45 # endif
  46 #endif
  47 #if defined(HAVE_LIBPROC_H)
  48 # include <libproc.h>
  49 #endif
  50
  51 #include "compat.h"
  52
  53 #ifndef OPEN_MAX
  54 # define OPEN_MAX       256
  55 #endif
  56
  57 #if 0
  58 __unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
  59 #endif /* lint */
  60
  61 #ifndef HAVE_FCNTL_CLOSEM
  62 /*
  63  * Close all file descriptors greater than or equal to lowfd.
  64  */
  65 static void
  66 closefrom_fallback(int lowfd)
  67 {
  68         long fd, maxfd;
  69
  70         /*
  71          * Fall back on sysconf() or getdtablesize().  We avoid checking
  72          * resource limits since it is possible to open a file descriptor
  73          * and then drop the rlimit such that it is below the open fd.
  74          */
  75 #ifdef HAVE_SYSCONF
  76         maxfd = sysconf(_SC_OPEN_MAX);
  77 #else
  78         maxfd = getdtablesize();
  79 #endif /* HAVE_SYSCONF */
  80         if (maxfd < 0)
  81                 maxfd = OPEN_MAX;
  82
  83         for (fd = lowfd; fd < maxfd; fd++)
  84                 (void) close((int) fd);
  85 }
  86 #endif /* HAVE_FCNTL_CLOSEM */
  87
  88 #ifdef HAVE_FCNTL_CLOSEM
  89 void
  90 closefrom(int lowfd)
  91 {
  92     (void) fcntl(lowfd, F_CLOSEM, 0);
  93 }
  94 #elif defined(HAVE_LIBPROC_H) && defined(HAVE_PROC_PIDINFO)
  95 void
  96 closefrom(int lowfd)
  97 {
  98         int i, r, sz;
  99         pid_t pid = getpid();
 100         struct proc_fdinfo *fdinfo_buf = NULL;
 101
 102         sz = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
 103         if (sz == 0)
 104                 return; /* no fds, really? */
 105         else if (sz == -1)
 106                 goto fallback;
 107         if ((fdinfo_buf = malloc(sz)) == NULL)
 108                 goto fallback;
 109         r = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, fdinfo_buf, sz);
 110         if (r < 0 || r > sz)
 111                 goto fallback;
 112         for (i = 0; i < r / (int)PROC_PIDLISTFD_SIZE; i++) {
 113                 if (fdinfo_buf[i].proc_fd >= lowfd)
 114                         close(fdinfo_buf[i].proc_fd);
 115         }
 116         free(fdinfo_buf);
 117         return;
 118  fallback:
 119         free(fdinfo_buf);
 120         closefrom_fallback(lowfd);
 121         return;
 122 }
 123 #elif defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
 124 void
 125 closefrom(int lowfd)
 126 {
 127     long fd;
 128     char fdpath[PATH_MAX], *endp;
 129     struct dirent *dent;
 130     DIR *dirp;
 131     int len;
 132
 133     /* Check for a /proc/$$/fd directory. */
 134     len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
 135     if (len > 0 && (size_t)len < sizeof(fdpath) && (dirp = opendir(fdpath))) {
 136         while ((dent = readdir(dirp)) != NULL) {
 137             fd = strtol(dent->d_name, &endp, 10);
 138             if (dent->d_name != endp && *endp == '\0' &&
 139                 fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
 140                 (void) close((int) fd);
 141         }
 142         (void) closedir(dirp);
 143         return;
 144     }
 145     /* /proc/$$/fd strategy failed, fall back to brute force closure */
 146     closefrom_fallback(lowfd);
 147 }
 148 #else
 149 void
 150 closefrom(int lowfd)
 151 {
 152         closefrom_fallback(lowfd);
 153 }
 154 #endif /* !HAVE_FCNTL_CLOSEM */
 155 #endif /* HAVE_CLOSEFROM */