1/*
2 * Copyright (c) 2004-2005, 2007, 2010, 2012-2014
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 <unistd.h>
22#include <stdio.h>
23#ifdef STDC_HEADERS
24# include <stdlib.h>
25# include <stddef.h>
26#else
27# ifdef HAVE_STDLIB_H
28#  include <stdlib.h>
29# endif
30#endif /* STDC_HEADERS */
31#include <fcntl.h>
32#include <limits.h>
33#ifdef HAVE_PSTAT_GETPROC
34# include <sys/param.h>
35# include <sys/pstat.h>
36#else
37# ifdef HAVE_DIRENT_H
38#  include <dirent.h>
39#  define NAMLEN(dirent) strlen((dirent)->d_name)
40# else
41#  define dirent direct
42#  define NAMLEN(dirent) (dirent)->d_namlen
43#  ifdef HAVE_SYS_NDIR_H
44#   include <sys/ndir.h>
45#  endif
46#  ifdef HAVE_SYS_DIR_H
47#   include <sys/dir.h>
48#  endif
49#  ifdef HAVE_NDIR_H
50#   include <ndir.h>
51#  endif
52# endif
53#endif
54
55#ifndef OPEN_MAX
56# define OPEN_MAX 256
57#endif
58
59#if defined(HAVE_FCNTL_CLOSEM) && !defined(HAVE_DIRFD)
60# define closefrom	closefrom_fallback
61#endif
62
63static inline void
64closefrom_close(int fd)
65{
66#ifdef __APPLE__
67	/* Avoid potential libdispatch crash when we close its fds. */
68	(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
69#else
70	(void)close(fd);
71#endif
72}
73
74/*
75 * Close all file descriptors greater than or equal to lowfd.
76 * This is the expensive (fallback) method.
77 */
78void
79closefrom_fallback(int lowfd)
80{
81	long fd, maxfd;
82
83	/*
84	 * Fall back on sysconf() or getdtablesize().  We avoid checking
85	 * resource limits since it is possible to open a file descriptor
86	 * and then drop the rlimit such that it is below the open fd.
87	 */
88#ifdef HAVE_SYSCONF
89	maxfd = sysconf(_SC_OPEN_MAX);
90#else
91	maxfd = getdtablesize();
92#endif /* HAVE_SYSCONF */
93	if (maxfd < 0)
94		maxfd = OPEN_MAX;
95
96	for (fd = lowfd; fd < maxfd; fd++)
97		closefrom_close(fd);
98}
99
100/*
101 * Close all file descriptors greater than or equal to lowfd.
102 * We try the fast way first, falling back on the slow method.
103 */
104#if defined(HAVE_FCNTL_CLOSEM)
105void
106closefrom(int lowfd)
107{
108	if (fcntl(lowfd, F_CLOSEM, 0) == -1)
109		closefrom_fallback(lowfd);
110}
111#elif defined(HAVE_PSTAT_GETPROC)
112void
113closefrom(int lowfd)
114{
115	struct pst_status pstat;
116	int fd;
117
118	if (pstat_getproc(&pstat, sizeof(pstat), 0, getpid()) != -1) {
119		for (fd = lowfd; fd <= pstat.pst_highestfd; fd++)
120			(void)close(fd);
121	} else {
122		closefrom_fallback(lowfd);
123	}
124}
125#elif defined(HAVE_DIRFD)
126static int
127closefrom_procfs(int lowfd)
128{
129	const char *path;
130	DIR *dirp;
131	struct dirent *dent;
132	int *fd_array = NULL;
133	int fd_array_used = 0;
134	int fd_array_size = 0;
135	int ret = 0;
136	int i;
137
138	/* Use /proc/self/fd (or /dev/fd on FreeBSD) if it exists. */
139# if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__APPLE__)
140	path = "/dev/fd";
141# else
142	path = "/proc/self/fd";
143# endif
144	dirp = opendir(path);
145	if (dirp == NULL)
146		return -1;
147
148	while ((dent = readdir(dirp)) != NULL) {
149		const char *errstr;
150		int fd;
151
152		fd = strtonum(dent->d_name, lowfd, INT_MAX, &errstr);
153		if (errstr != NULL || fd == dirfd(dirp))
154			continue;
155
156		if (fd_array_used >= fd_array_size) {
157			int *ptr;
158
159			if (fd_array_size > 0)
160				fd_array_size *= 2;
161			else
162				fd_array_size = 32;
163
164			ptr = reallocarray(fd_array, fd_array_size, sizeof(int));
165			if (ptr == NULL) {
166				ret = -1;
167				break;
168			}
169			fd_array = ptr;
170		}
171
172		fd_array[fd_array_used++] = fd;
173	}
174
175	for (i = 0; i < fd_array_used; i++)
176		closefrom_close(fd_array[i]);
177
178	free(fd_array);
179	(void)closedir(dirp);
180
181	return ret;
182}
183
184void
185closefrom(int lowfd)
186{
187	if (closefrom_procfs(lowfd) == 0)
188		return;
189
190	closefrom_fallback(lowfd);
191}
192#endif /* HAVE_FCNTL_CLOSEM */
193