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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> | |
8658d16d PA |
37 | #define HAVE_SOCKETS 1 |
38 | #elif defined HAVE_SYS_SOCKET_H | |
5d71132c TT |
39 | #include <sys/socket.h> |
40 | /* Define HAVE_F_GETFD if we plan to use F_GETFD. */ | |
41 | #define HAVE_F_GETFD F_GETFD | |
8658d16d | 42 | #define HAVE_SOCKETS 1 |
5d71132c TT |
43 | #endif |
44 | ||
614c279d TT |
45 | #ifdef HAVE_SYS_RESOURCE_H |
46 | #include <sys/resource.h> | |
47 | #endif /* HAVE_SYS_RESOURCE_H */ | |
48 | ||
49 | #ifndef O_CLOEXEC | |
50 | #define O_CLOEXEC 0 | |
51 | #endif | |
52 | ||
53 | #ifndef SOCK_CLOEXEC | |
54 | #define SOCK_CLOEXEC 0 | |
55 | #endif | |
56 | ||
57 | \f | |
58 | ||
59 | #ifndef HAVE_FDWALK | |
60 | ||
01da98f9 | 61 | #include "gdb_dirent.h" |
614c279d TT |
62 | |
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 | |
68 | finished. */ | |
69 | ||
70 | static int | |
71 | fdwalk (int (*func) (void *, int), void *arg) | |
72 | { | |
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 | |
75 | configure. */ | |
76 | #ifdef __linux__ | |
77 | DIR *dir; | |
78 | ||
79 | dir = opendir ("/proc/self/fd"); | |
80 | if (dir != NULL) | |
81 | { | |
82 | struct dirent *entry; | |
83 | int result = 0; | |
84 | ||
85 | for (entry = readdir (dir); entry != NULL; entry = readdir (dir)) | |
86 | { | |
87 | long fd; | |
88 | char *tail; | |
89 | int result; | |
90 | ||
91 | errno = 0; | |
92 | fd = strtol (entry->d_name, &tail, 10); | |
93 | if (*tail != '\0' || errno != 0) | |
94 | continue; | |
95 | if ((int) fd != fd) | |
96 | { | |
97 | /* What can we do here really? */ | |
98 | continue; | |
99 | } | |
100 | ||
101 | if (fd == dirfd (dir)) | |
102 | continue; | |
103 | ||
104 | result = func (arg, fd); | |
105 | if (result != 0) | |
106 | break; | |
107 | } | |
108 | ||
109 | closedir (dir); | |
110 | return result; | |
111 | } | |
112 | /* We may fall through to the next case. */ | |
113 | #endif | |
114 | ||
115 | { | |
116 | int max, fd; | |
117 | ||
118 | #ifdef HAVE_GETRLIMIT | |
119 | struct rlimit rlim; | |
120 | ||
121 | if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY) | |
122 | max = rlim.rlim_max; | |
123 | else | |
124 | #endif | |
125 | { | |
126 | #ifdef _SC_OPEN_MAX | |
127 | max = sysconf (_SC_OPEN_MAX); | |
128 | #else | |
129 | /* Whoops. */ | |
130 | return 0; | |
131 | #endif /* _SC_OPEN_MAX */ | |
132 | } | |
133 | ||
134 | for (fd = 0; fd < max; ++fd) | |
135 | { | |
136 | struct stat sb; | |
137 | int result; | |
138 | ||
139 | /* Only call FUNC for open fds. */ | |
140 | if (fstat (fd, &sb) == -1) | |
141 | continue; | |
142 | ||
143 | result = func (arg, fd); | |
144 | if (result != 0) | |
145 | return result; | |
146 | } | |
147 | ||
148 | return 0; | |
149 | } | |
150 | } | |
151 | ||
152 | #endif /* HAVE_FDWALK */ | |
153 | ||
154 | \f | |
155 | ||
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. */ | |
159 | ||
160 | DEF_VEC_I (int); | |
161 | ||
162 | static VEC (int) *open_fds; | |
163 | ||
164 | /* An fdwalk callback function used by notice_open_fds. It puts the | |
165 | given file descriptor into the vec. */ | |
166 | ||
167 | static int | |
168 | do_mark_open_fd (void *ignore, int fd) | |
169 | { | |
170 | VEC_safe_push (int, open_fds, fd); | |
171 | return 0; | |
172 | } | |
173 | ||
174 | /* See filestuff.h. */ | |
175 | ||
176 | void | |
177 | notice_open_fds (void) | |
178 | { | |
179 | fdwalk (do_mark_open_fd, NULL); | |
180 | } | |
181 | ||
21ff4686 TT |
182 | /* See filestuff.h. */ |
183 | ||
184 | void | |
185 | mark_fd_no_cloexec (int fd) | |
186 | { | |
187 | do_mark_open_fd (NULL, fd); | |
188 | } | |
189 | ||
190 | /* See filestuff.h. */ | |
191 | ||
192 | void | |
193 | unmark_fd_no_cloexec (int fd) | |
194 | { | |
195 | int i, val; | |
196 | ||
197 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
198 | { | |
199 | if (fd == val) | |
200 | { | |
201 | VEC_unordered_remove (int, open_fds, i); | |
202 | return; | |
203 | } | |
204 | } | |
205 | ||
206 | gdb_assert_not_reached (_("fd not found in open_fds")); | |
207 | } | |
208 | ||
614c279d TT |
209 | /* Helper function for close_most_fds that closes the file descriptor |
210 | if appropriate. */ | |
211 | ||
212 | static int | |
213 | do_close (void *ignore, int fd) | |
214 | { | |
215 | int i, val; | |
216 | ||
217 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
218 | { | |
219 | if (fd == val) | |
220 | { | |
221 | /* Keep this one open. */ | |
222 | return 0; | |
223 | } | |
224 | } | |
225 | ||
226 | close (fd); | |
227 | return 0; | |
228 | } | |
229 | ||
230 | /* See filestuff.h. */ | |
231 | ||
232 | void | |
233 | close_most_fds (void) | |
234 | { | |
235 | fdwalk (do_close, NULL); | |
236 | } | |
237 | ||
238 | \f | |
239 | ||
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. */ | |
246 | ||
247 | static int trust_o_cloexec; | |
248 | ||
249 | /* Mark FD as close-on-exec, ignoring errors. Update | |
250 | TRUST_O_CLOEXEC. */ | |
251 | ||
252 | static void | |
253 | mark_cloexec (int fd) | |
254 | { | |
5d71132c | 255 | #ifdef HAVE_F_GETFD |
614c279d TT |
256 | int old = fcntl (fd, F_GETFD, 0); |
257 | ||
258 | if (old != -1) | |
259 | { | |
260 | fcntl (fd, F_SETFD, old | FD_CLOEXEC); | |
261 | ||
262 | if (trust_o_cloexec == 0) | |
263 | { | |
264 | if ((old & FD_CLOEXEC) != 0) | |
265 | trust_o_cloexec = 1; | |
266 | else | |
267 | trust_o_cloexec = -1; | |
268 | } | |
269 | } | |
5d71132c | 270 | #endif /* HAVE_F_GETFD */ |
614c279d TT |
271 | } |
272 | ||
273 | /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */ | |
274 | ||
275 | static void | |
276 | maybe_mark_cloexec (int fd) | |
277 | { | |
278 | if (trust_o_cloexec <= 0) | |
279 | mark_cloexec (fd); | |
280 | } | |
281 | ||
8658d16d PA |
282 | #ifdef HAVE_SOCKETS |
283 | ||
614c279d TT |
284 | /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */ |
285 | ||
286 | static void | |
287 | socket_mark_cloexec (int fd) | |
288 | { | |
289 | if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0) | |
290 | mark_cloexec (fd); | |
291 | } | |
292 | ||
8658d16d PA |
293 | #endif |
294 | ||
614c279d TT |
295 | \f |
296 | ||
297 | /* See filestuff.h. */ | |
298 | ||
299 | int | |
5d71132c | 300 | gdb_open_cloexec (const char *filename, int flags, unsigned long mode) |
614c279d TT |
301 | { |
302 | int fd = open (filename, flags | O_CLOEXEC, mode); | |
303 | ||
304 | if (fd >= 0) | |
305 | maybe_mark_cloexec (fd); | |
306 | ||
307 | return fd; | |
308 | } | |
309 | ||
310 | /* See filestuff.h. */ | |
311 | ||
312 | FILE * | |
313 | gdb_fopen_cloexec (const char *filename, const char *opentype) | |
314 | { | |
315 | FILE *result = NULL; | |
316 | static int fopen_e_ever_failed; | |
317 | ||
318 | if (!fopen_e_ever_failed) | |
319 | { | |
320 | char *copy; | |
321 | ||
322 | copy = alloca (strlen (opentype) + 2); | |
323 | strcpy (copy, opentype); | |
324 | /* This is a glibc extension but we try it unconditionally on | |
325 | this path. */ | |
326 | strcat (copy, "e"); | |
327 | result = fopen (filename, copy); | |
328 | } | |
329 | ||
330 | if (result == NULL) | |
331 | { | |
332 | /* Fallback. */ | |
333 | result = fopen (filename, opentype); | |
334 | if (result != NULL) | |
335 | fopen_e_ever_failed = 1; | |
336 | } | |
337 | ||
338 | if (result != NULL) | |
339 | maybe_mark_cloexec (fileno (result)); | |
340 | ||
341 | return result; | |
342 | } | |
343 | ||
8658d16d | 344 | #ifdef HAVE_SOCKETS |
614c279d TT |
345 | /* See filestuff.h. */ |
346 | ||
347 | int | |
348 | gdb_socketpair_cloexec (int namespace, int style, int protocol, int filedes[2]) | |
349 | { | |
5d71132c | 350 | #ifdef HAVE_SOCKETPAIR |
614c279d TT |
351 | int result = socketpair (namespace, style | SOCK_CLOEXEC, protocol, filedes); |
352 | ||
353 | if (result != -1) | |
354 | { | |
355 | socket_mark_cloexec (filedes[0]); | |
356 | socket_mark_cloexec (filedes[1]); | |
357 | } | |
358 | ||
359 | return result; | |
5d71132c TT |
360 | #else |
361 | gdb_assert_not_reached (_("socketpair not available on this host")); | |
362 | #endif | |
614c279d TT |
363 | } |
364 | ||
365 | /* See filestuff.h. */ | |
366 | ||
367 | int | |
368 | gdb_socket_cloexec (int namespace, int style, int protocol) | |
369 | { | |
370 | int result = socket (namespace, style | SOCK_CLOEXEC, protocol); | |
371 | ||
372 | if (result != -1) | |
373 | socket_mark_cloexec (result); | |
374 | ||
375 | return result; | |
376 | } | |
8658d16d | 377 | #endif |
614c279d TT |
378 | |
379 | /* See filestuff.h. */ | |
380 | ||
381 | int | |
382 | gdb_pipe_cloexec (int filedes[2]) | |
383 | { | |
384 | int result; | |
385 | ||
386 | #ifdef HAVE_PIPE2 | |
387 | result = pipe2 (filedes, O_CLOEXEC); | |
388 | if (result != -1) | |
389 | { | |
390 | maybe_mark_cloexec (filedes[0]); | |
391 | maybe_mark_cloexec (filedes[1]); | |
392 | } | |
393 | #else | |
5d71132c | 394 | #ifdef HAVE_PIPE |
614c279d TT |
395 | result = pipe (filedes); |
396 | if (result != -1) | |
397 | { | |
398 | mark_cloexec (filedes[0]); | |
399 | mark_cloexec (filedes[1]); | |
400 | } | |
5d71132c TT |
401 | #else /* HAVE_PIPE */ |
402 | gdb_assert_not_reached (_("pipe not available on this host")); | |
403 | #endif /* HAVE_PIPE */ | |
404 | #endif /* HAVE_PIPE2 */ | |
614c279d TT |
405 | |
406 | return result; | |
407 | } |