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614c279d TT |
1 | /* Low-level file-handling. |
2 | Copyright (C) 2012, 2013 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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/>. */ | |
18 | ||
19 | #ifdef GDBSERVER | |
20 | #include "server.h" | |
21 | #else | |
22 | #include "defs.h" | |
23 | #include "gdb_string.h" | |
24 | #endif | |
25 | #include "filestuff.h" | |
26 | #include "gdb_vecs.h" | |
27 | ||
28 | #include <string.h> | |
29 | #include <fcntl.h> | |
30 | #include <unistd.h> | |
614c279d | 31 | #include <sys/types.h> |
366c6766 | 32 | #include "gdb_stat.h" |
614c279d | 33 | |
5d71132c TT |
34 | #ifdef USE_WIN32API |
35 | #include <winsock2.h> | |
36 | #include <windows.h> | |
37 | #else | |
38 | #include <sys/socket.h> | |
39 | /* Define HAVE_F_GETFD if we plan to use F_GETFD. */ | |
40 | #define HAVE_F_GETFD F_GETFD | |
41 | #endif | |
42 | ||
614c279d TT |
43 | #ifdef HAVE_SYS_RESOURCE_H |
44 | #include <sys/resource.h> | |
45 | #endif /* HAVE_SYS_RESOURCE_H */ | |
46 | ||
47 | #ifndef O_CLOEXEC | |
48 | #define O_CLOEXEC 0 | |
49 | #endif | |
50 | ||
51 | #ifndef SOCK_CLOEXEC | |
52 | #define SOCK_CLOEXEC 0 | |
53 | #endif | |
54 | ||
55 | \f | |
56 | ||
57 | #ifndef HAVE_FDWALK | |
58 | ||
59 | #include <dirent.h> | |
60 | ||
61 | /* Replacement for fdwalk, if the system doesn't define it. Walks all | |
62 | open file descriptors (though this implementation may walk closed | |
63 | ones as well, depending on the host platform's capabilities) and | |
64 | call FUNC with ARG. If FUNC returns non-zero, stops immediately | |
65 | and returns the same value. Otherwise, returns zero when | |
66 | finished. */ | |
67 | ||
68 | static int | |
69 | fdwalk (int (*func) (void *, int), void *arg) | |
70 | { | |
71 | /* Checking __linux__ isn't great but it isn't clear what would be | |
72 | better. There doesn't seem to be a good way to check for this in | |
73 | configure. */ | |
74 | #ifdef __linux__ | |
75 | DIR *dir; | |
76 | ||
77 | dir = opendir ("/proc/self/fd"); | |
78 | if (dir != NULL) | |
79 | { | |
80 | struct dirent *entry; | |
81 | int result = 0; | |
82 | ||
83 | for (entry = readdir (dir); entry != NULL; entry = readdir (dir)) | |
84 | { | |
85 | long fd; | |
86 | char *tail; | |
87 | int result; | |
88 | ||
89 | errno = 0; | |
90 | fd = strtol (entry->d_name, &tail, 10); | |
91 | if (*tail != '\0' || errno != 0) | |
92 | continue; | |
93 | if ((int) fd != fd) | |
94 | { | |
95 | /* What can we do here really? */ | |
96 | continue; | |
97 | } | |
98 | ||
99 | if (fd == dirfd (dir)) | |
100 | continue; | |
101 | ||
102 | result = func (arg, fd); | |
103 | if (result != 0) | |
104 | break; | |
105 | } | |
106 | ||
107 | closedir (dir); | |
108 | return result; | |
109 | } | |
110 | /* We may fall through to the next case. */ | |
111 | #endif | |
112 | ||
113 | { | |
114 | int max, fd; | |
115 | ||
116 | #ifdef HAVE_GETRLIMIT | |
117 | struct rlimit rlim; | |
118 | ||
119 | if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY) | |
120 | max = rlim.rlim_max; | |
121 | else | |
122 | #endif | |
123 | { | |
124 | #ifdef _SC_OPEN_MAX | |
125 | max = sysconf (_SC_OPEN_MAX); | |
126 | #else | |
127 | /* Whoops. */ | |
128 | return 0; | |
129 | #endif /* _SC_OPEN_MAX */ | |
130 | } | |
131 | ||
132 | for (fd = 0; fd < max; ++fd) | |
133 | { | |
134 | struct stat sb; | |
135 | int result; | |
136 | ||
137 | /* Only call FUNC for open fds. */ | |
138 | if (fstat (fd, &sb) == -1) | |
139 | continue; | |
140 | ||
141 | result = func (arg, fd); | |
142 | if (result != 0) | |
143 | return result; | |
144 | } | |
145 | ||
146 | return 0; | |
147 | } | |
148 | } | |
149 | ||
150 | #endif /* HAVE_FDWALK */ | |
151 | ||
152 | \f | |
153 | ||
154 | /* A VEC holding all the fds open when notice_open_fds was called. We | |
155 | don't use a hashtab because libiberty isn't linked into gdbserver; | |
156 | and anyway we don't expect there to be many open fds. */ | |
157 | ||
158 | DEF_VEC_I (int); | |
159 | ||
160 | static VEC (int) *open_fds; | |
161 | ||
162 | /* An fdwalk callback function used by notice_open_fds. It puts the | |
163 | given file descriptor into the vec. */ | |
164 | ||
165 | static int | |
166 | do_mark_open_fd (void *ignore, int fd) | |
167 | { | |
168 | VEC_safe_push (int, open_fds, fd); | |
169 | return 0; | |
170 | } | |
171 | ||
172 | /* See filestuff.h. */ | |
173 | ||
174 | void | |
175 | notice_open_fds (void) | |
176 | { | |
177 | fdwalk (do_mark_open_fd, NULL); | |
178 | } | |
179 | ||
180 | /* Helper function for close_most_fds that closes the file descriptor | |
181 | if appropriate. */ | |
182 | ||
183 | static int | |
184 | do_close (void *ignore, int fd) | |
185 | { | |
186 | int i, val; | |
187 | ||
188 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
189 | { | |
190 | if (fd == val) | |
191 | { | |
192 | /* Keep this one open. */ | |
193 | return 0; | |
194 | } | |
195 | } | |
196 | ||
197 | close (fd); | |
198 | return 0; | |
199 | } | |
200 | ||
201 | /* See filestuff.h. */ | |
202 | ||
203 | void | |
204 | close_most_fds (void) | |
205 | { | |
206 | fdwalk (do_close, NULL); | |
207 | } | |
208 | ||
209 | \f | |
210 | ||
211 | /* This is a tri-state flag. When zero it means we haven't yet tried | |
212 | O_CLOEXEC. When positive it means that O_CLOEXEC works on this | |
213 | host. When negative, it means that O_CLOEXEC doesn't work. We | |
214 | track this state because, while gdb might have been compiled | |
215 | against a libc that supplies O_CLOEXEC, there is no guarantee that | |
216 | the kernel supports it. */ | |
217 | ||
218 | static int trust_o_cloexec; | |
219 | ||
220 | /* Mark FD as close-on-exec, ignoring errors. Update | |
221 | TRUST_O_CLOEXEC. */ | |
222 | ||
223 | static void | |
224 | mark_cloexec (int fd) | |
225 | { | |
5d71132c | 226 | #ifdef HAVE_F_GETFD |
614c279d TT |
227 | int old = fcntl (fd, F_GETFD, 0); |
228 | ||
229 | if (old != -1) | |
230 | { | |
231 | fcntl (fd, F_SETFD, old | FD_CLOEXEC); | |
232 | ||
233 | if (trust_o_cloexec == 0) | |
234 | { | |
235 | if ((old & FD_CLOEXEC) != 0) | |
236 | trust_o_cloexec = 1; | |
237 | else | |
238 | trust_o_cloexec = -1; | |
239 | } | |
240 | } | |
5d71132c | 241 | #endif /* HAVE_F_GETFD */ |
614c279d TT |
242 | } |
243 | ||
244 | /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */ | |
245 | ||
246 | static void | |
247 | maybe_mark_cloexec (int fd) | |
248 | { | |
249 | if (trust_o_cloexec <= 0) | |
250 | mark_cloexec (fd); | |
251 | } | |
252 | ||
253 | /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */ | |
254 | ||
255 | static void | |
256 | socket_mark_cloexec (int fd) | |
257 | { | |
258 | if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0) | |
259 | mark_cloexec (fd); | |
260 | } | |
261 | ||
262 | \f | |
263 | ||
264 | /* See filestuff.h. */ | |
265 | ||
266 | int | |
5d71132c | 267 | gdb_open_cloexec (const char *filename, int flags, unsigned long mode) |
614c279d TT |
268 | { |
269 | int fd = open (filename, flags | O_CLOEXEC, mode); | |
270 | ||
271 | if (fd >= 0) | |
272 | maybe_mark_cloexec (fd); | |
273 | ||
274 | return fd; | |
275 | } | |
276 | ||
277 | /* See filestuff.h. */ | |
278 | ||
279 | FILE * | |
280 | gdb_fopen_cloexec (const char *filename, const char *opentype) | |
281 | { | |
282 | FILE *result = NULL; | |
283 | static int fopen_e_ever_failed; | |
284 | ||
285 | if (!fopen_e_ever_failed) | |
286 | { | |
287 | char *copy; | |
288 | ||
289 | copy = alloca (strlen (opentype) + 2); | |
290 | strcpy (copy, opentype); | |
291 | /* This is a glibc extension but we try it unconditionally on | |
292 | this path. */ | |
293 | strcat (copy, "e"); | |
294 | result = fopen (filename, copy); | |
295 | } | |
296 | ||
297 | if (result == NULL) | |
298 | { | |
299 | /* Fallback. */ | |
300 | result = fopen (filename, opentype); | |
301 | if (result != NULL) | |
302 | fopen_e_ever_failed = 1; | |
303 | } | |
304 | ||
305 | if (result != NULL) | |
306 | maybe_mark_cloexec (fileno (result)); | |
307 | ||
308 | return result; | |
309 | } | |
310 | ||
311 | /* See filestuff.h. */ | |
312 | ||
313 | int | |
314 | gdb_socketpair_cloexec (int namespace, int style, int protocol, int filedes[2]) | |
315 | { | |
5d71132c | 316 | #ifdef HAVE_SOCKETPAIR |
614c279d TT |
317 | int result = socketpair (namespace, style | SOCK_CLOEXEC, protocol, filedes); |
318 | ||
319 | if (result != -1) | |
320 | { | |
321 | socket_mark_cloexec (filedes[0]); | |
322 | socket_mark_cloexec (filedes[1]); | |
323 | } | |
324 | ||
325 | return result; | |
5d71132c TT |
326 | #else |
327 | gdb_assert_not_reached (_("socketpair not available on this host")); | |
328 | #endif | |
614c279d TT |
329 | } |
330 | ||
331 | /* See filestuff.h. */ | |
332 | ||
333 | int | |
334 | gdb_socket_cloexec (int namespace, int style, int protocol) | |
335 | { | |
336 | int result = socket (namespace, style | SOCK_CLOEXEC, protocol); | |
337 | ||
338 | if (result != -1) | |
339 | socket_mark_cloexec (result); | |
340 | ||
341 | return result; | |
342 | } | |
343 | ||
344 | /* See filestuff.h. */ | |
345 | ||
346 | int | |
347 | gdb_pipe_cloexec (int filedes[2]) | |
348 | { | |
349 | int result; | |
350 | ||
351 | #ifdef HAVE_PIPE2 | |
352 | result = pipe2 (filedes, O_CLOEXEC); | |
353 | if (result != -1) | |
354 | { | |
355 | maybe_mark_cloexec (filedes[0]); | |
356 | maybe_mark_cloexec (filedes[1]); | |
357 | } | |
358 | #else | |
5d71132c | 359 | #ifdef HAVE_PIPE |
614c279d TT |
360 | result = pipe (filedes); |
361 | if (result != -1) | |
362 | { | |
363 | mark_cloexec (filedes[0]); | |
364 | mark_cloexec (filedes[1]); | |
365 | } | |
5d71132c TT |
366 | #else /* HAVE_PIPE */ |
367 | gdb_assert_not_reached (_("pipe not available on this host")); | |
368 | #endif /* HAVE_PIPE */ | |
369 | #endif /* HAVE_PIPE2 */ | |
614c279d TT |
370 | |
371 | return result; | |
372 | } |