xref: /freebsd/crypto/openssh/openbsd-compat/bsd-closefrom.c (revision 5ab1c5846ff41be24b1f6beb0317bf8258cd4409)
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 #include "includes.h"
18 
19 #ifndef HAVE_CLOSEFROM
20 
21 #include <sys/types.h>
22 #include <sys/param.h>
23 #include <unistd.h>
24 #include <stdio.h>
25 #ifdef HAVE_FCNTL_H
26 # include <fcntl.h>
27 #endif
28 #include <limits.h>
29 #include <stdlib.h>
30 #include <stddef.h>
31 #include <string.h>
32 #include <unistd.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 #ifndef OPEN_MAX
51 # define OPEN_MAX	256
52 #endif
53 
54 #if 0
55 __unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
56 #endif /* lint */
57 
58 /*
59  * Close all file descriptors greater than or equal to lowfd.
60  */
61 #ifdef HAVE_FCNTL_CLOSEM
62 void
63 closefrom(int lowfd)
64 {
65     (void) fcntl(lowfd, F_CLOSEM, 0);
66 }
67 #else
68 void
69 closefrom(int lowfd)
70 {
71     long fd, maxfd;
72 #if defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
73     char fdpath[PATH_MAX], *endp;
74     struct dirent *dent;
75     DIR *dirp;
76     int len;
77 
78     /* Check for a /proc/$$/fd directory. */
79     len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
80     if (len > 0 && (size_t)len < sizeof(fdpath) && (dirp = opendir(fdpath))) {
81 	while ((dent = readdir(dirp)) != NULL) {
82 	    fd = strtol(dent->d_name, &endp, 10);
83 	    if (dent->d_name != endp && *endp == '\0' &&
84 		fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
85 		(void) close((int) fd);
86 	}
87 	(void) closedir(dirp);
88     } else
89 #endif
90     {
91 	/*
92 	 * Fall back on sysconf() or getdtablesize().  We avoid checking
93 	 * resource limits since it is possible to open a file descriptor
94 	 * and then drop the rlimit such that it is below the open fd.
95 	 */
96 #ifdef HAVE_SYSCONF
97 	maxfd = sysconf(_SC_OPEN_MAX);
98 #else
99 	maxfd = getdtablesize();
100 #endif /* HAVE_SYSCONF */
101 	if (maxfd < 0)
102 	    maxfd = OPEN_MAX;
103 
104 	for (fd = lowfd; fd < maxfd; fd++)
105 	    (void) close((int) fd);
106     }
107 }
108 #endif /* !HAVE_FCNTL_CLOSEM */
109 #endif /* HAVE_CLOSEFROM */
110