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 
48 #ifndef OPEN_MAX
49 # define OPEN_MAX	256
50 #endif
51 
52 #if 0
53 __unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
54 #endif /* lint */
55 
56 /*
57  * Close all file descriptors greater than or equal to lowfd.
58  */
59 #ifdef HAVE_FCNTL_CLOSEM
60 void
61 closefrom(int lowfd)
62 {
63     (void) fcntl(lowfd, F_CLOSEM, 0);
64 }
65 #else
66 void
67 closefrom(int lowfd)
68 {
69     long fd, maxfd;
70 #if defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
71     char fdpath[PATH_MAX], *endp;
72     struct dirent *dent;
73     DIR *dirp;
74     int len;
75 
76     /* Check for a /proc/$$/fd directory. */
77     len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
78     if (len > 0 && (size_t)len <= sizeof(fdpath) && (dirp = opendir(fdpath))) {
79 	while ((dent = readdir(dirp)) != NULL) {
80 	    fd = strtol(dent->d_name, &endp, 10);
81 	    if (dent->d_name != endp && *endp == '\0' &&
82 		fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
83 		(void) close((int) fd);
84 	}
85 	(void) closedir(dirp);
86     } else
87 #endif
88     {
89 	/*
90 	 * Fall back on sysconf() or getdtablesize().  We avoid checking
91 	 * resource limits since it is possible to open a file descriptor
92 	 * and then drop the rlimit such that it is below the open fd.
93 	 */
94 #ifdef HAVE_SYSCONF
95 	maxfd = sysconf(_SC_OPEN_MAX);
96 #else
97 	maxfd = getdtablesize();
98 #endif /* HAVE_SYSCONF */
99 	if (maxfd < 0)
100 	    maxfd = OPEN_MAX;
101 
102 	for (fd = lowfd; fd < maxfd; fd++)
103 	    (void) close((int) fd);
104     }
105 }
106 #endif /* !HAVE_FCNTL_CLOSEM */
107 #endif /* HAVE_CLOSEFROM */