1 /* Low-level file-handling.
2 Copyright (C) 2012, 2013 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include "gdb_string.h"
25 #include "filestuff.h"
31 #include <sys/types.h>
37 #define HAVE_SOCKETS 1
38 #elif defined HAVE_SYS_SOCKET_H
39 #include <sys/socket.h>
40 /* Define HAVE_F_GETFD if we plan to use F_GETFD. */
41 #define HAVE_F_GETFD F_GETFD
42 #define HAVE_SOCKETS 1
45 #ifdef HAVE_SYS_RESOURCE_H
46 #include <sys/resource.h>
47 #endif /* HAVE_SYS_RESOURCE_H */
54 #define SOCK_CLOEXEC 0
61 #include "gdb_dirent.h"
63 /* Replacement for fdwalk, if the system doesn't define it. Walks all
64 open file descriptors (though this implementation may walk closed
65 ones as well, depending on the host platform's capabilities) and
66 call FUNC with ARG. If FUNC returns non-zero, stops immediately
67 and returns the same value. Otherwise, returns zero when
71 fdwalk (int (*func) (void *, int), void *arg)
73 /* Checking __linux__ isn't great but it isn't clear what would be
74 better. There doesn't seem to be a good way to check for this in
79 dir = opendir ("/proc/self/fd");
85 for (entry = readdir (dir); entry != NULL; entry = readdir (dir))
92 fd = strtol (entry->d_name, &tail, 10);
93 if (*tail != '\0' || errno != 0)
97 /* What can we do here really? */
101 if (fd == dirfd (dir))
104 result = func (arg, fd);
112 /* We may fall through to the next case. */
118 #ifdef HAVE_GETRLIMIT
121 if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY)
127 max = sysconf (_SC_OPEN_MAX);
131 #endif /* _SC_OPEN_MAX */
134 for (fd = 0; fd < max; ++fd)
139 /* Only call FUNC for open fds. */
140 if (fstat (fd, &sb) == -1)
143 result = func (arg, fd);
152 #endif /* HAVE_FDWALK */
156 /* A VEC holding all the fds open when notice_open_fds was called. We
157 don't use a hashtab because libiberty isn't linked into gdbserver;
158 and anyway we don't expect there to be many open fds. */
162 static VEC (int) *open_fds;
164 /* An fdwalk callback function used by notice_open_fds. It puts the
165 given file descriptor into the vec. */
168 do_mark_open_fd (void *ignore, int fd)
170 VEC_safe_push (int, open_fds, fd);
174 /* See filestuff.h. */
177 notice_open_fds (void)
179 fdwalk (do_mark_open_fd, NULL);
182 /* See filestuff.h. */
185 mark_fd_no_cloexec (int fd)
187 do_mark_open_fd (NULL, fd);
190 /* See filestuff.h. */
193 unmark_fd_no_cloexec (int fd)
197 for (i = 0; VEC_iterate (int, open_fds, i, val); ++i)
201 VEC_unordered_remove (int, open_fds, i);
206 gdb_assert_not_reached (_("fd not found in open_fds"));
209 /* Helper function for close_most_fds that closes the file descriptor
213 do_close (void *ignore, int fd)
217 for (i = 0; VEC_iterate (int, open_fds, i, val); ++i)
221 /* Keep this one open. */
230 /* See filestuff.h. */
233 close_most_fds (void)
235 fdwalk (do_close, NULL);
240 /* This is a tri-state flag. When zero it means we haven't yet tried
241 O_CLOEXEC. When positive it means that O_CLOEXEC works on this
242 host. When negative, it means that O_CLOEXEC doesn't work. We
243 track this state because, while gdb might have been compiled
244 against a libc that supplies O_CLOEXEC, there is no guarantee that
245 the kernel supports it. */
247 static int trust_o_cloexec;
249 /* Mark FD as close-on-exec, ignoring errors. Update
253 mark_cloexec (int fd)
256 int old = fcntl (fd, F_GETFD, 0);
260 fcntl (fd, F_SETFD, old | FD_CLOEXEC);
262 if (trust_o_cloexec == 0)
264 if ((old & FD_CLOEXEC) != 0)
267 trust_o_cloexec = -1;
270 #endif /* HAVE_F_GETFD */
273 /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */
276 maybe_mark_cloexec (int fd)
278 if (trust_o_cloexec <= 0)
284 /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */
287 socket_mark_cloexec (int fd)
289 if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0)
297 /* See filestuff.h. */
300 gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
302 int fd = open (filename, flags | O_CLOEXEC, mode);
305 maybe_mark_cloexec (fd);
310 /* See filestuff.h. */
313 gdb_fopen_cloexec (const char *filename, const char *opentype)
316 static int fopen_e_ever_failed;
318 if (!fopen_e_ever_failed)
322 copy = alloca (strlen (opentype) + 2);
323 strcpy (copy, opentype);
324 /* This is a glibc extension but we try it unconditionally on
327 result = fopen (filename, copy);
333 result = fopen (filename, opentype);
335 fopen_e_ever_failed = 1;
339 maybe_mark_cloexec (fileno (result));
345 /* See filestuff.h. */
348 gdb_socketpair_cloexec (int namespace, int style, int protocol, int filedes[2])
350 #ifdef HAVE_SOCKETPAIR
351 int result = socketpair (namespace, style | SOCK_CLOEXEC, protocol, filedes);
355 socket_mark_cloexec (filedes[0]);
356 socket_mark_cloexec (filedes[1]);
361 gdb_assert_not_reached (_("socketpair not available on this host"));
365 /* See filestuff.h. */
368 gdb_socket_cloexec (int namespace, int style, int protocol)
370 int result = socket (namespace, style | SOCK_CLOEXEC, protocol);
373 socket_mark_cloexec (result);
379 /* See filestuff.h. */
382 gdb_pipe_cloexec (int filedes[2])
387 result = pipe2 (filedes, O_CLOEXEC);
390 maybe_mark_cloexec (filedes[0]);
391 maybe_mark_cloexec (filedes[1]);
395 result = pipe (filedes);
398 mark_cloexec (filedes[0]);
399 mark_cloexec (filedes[1]);
401 #else /* HAVE_PIPE */
402 gdb_assert_not_reached (_("pipe not available on this host"));
403 #endif /* HAVE_PIPE */
404 #endif /* HAVE_PIPE2 */