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614c279d | 1 | /* Low-level file-handling. |
32d0add0 | 2 | Copyright (C) 2012-2015 Free Software Foundation, Inc. |
614c279d TT |
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 | ||
727605ca | 19 | #include "common-defs.h" |
614c279d TT |
20 | #include "filestuff.h" |
21 | #include "gdb_vecs.h" | |
614c279d TT |
22 | #include <fcntl.h> |
23 | #include <unistd.h> | |
614c279d | 24 | #include <sys/types.h> |
53ce3c39 | 25 | #include <sys/stat.h> |
614c279d | 26 | |
5d71132c TT |
27 | #ifdef USE_WIN32API |
28 | #include <winsock2.h> | |
29 | #include <windows.h> | |
8658d16d PA |
30 | #define HAVE_SOCKETS 1 |
31 | #elif defined HAVE_SYS_SOCKET_H | |
5d71132c TT |
32 | #include <sys/socket.h> |
33 | /* Define HAVE_F_GETFD if we plan to use F_GETFD. */ | |
34 | #define HAVE_F_GETFD F_GETFD | |
8658d16d | 35 | #define HAVE_SOCKETS 1 |
5d71132c TT |
36 | #endif |
37 | ||
614c279d TT |
38 | #ifdef HAVE_SYS_RESOURCE_H |
39 | #include <sys/resource.h> | |
40 | #endif /* HAVE_SYS_RESOURCE_H */ | |
41 | ||
42 | #ifndef O_CLOEXEC | |
43 | #define O_CLOEXEC 0 | |
44 | #endif | |
45 | ||
46 | #ifndef SOCK_CLOEXEC | |
47 | #define SOCK_CLOEXEC 0 | |
48 | #endif | |
49 | ||
50 | \f | |
51 | ||
52 | #ifndef HAVE_FDWALK | |
53 | ||
2978b111 | 54 | #include <dirent.h> |
614c279d TT |
55 | |
56 | /* Replacement for fdwalk, if the system doesn't define it. Walks all | |
57 | open file descriptors (though this implementation may walk closed | |
58 | ones as well, depending on the host platform's capabilities) and | |
59 | call FUNC with ARG. If FUNC returns non-zero, stops immediately | |
60 | and returns the same value. Otherwise, returns zero when | |
61 | finished. */ | |
62 | ||
63 | static int | |
64 | fdwalk (int (*func) (void *, int), void *arg) | |
65 | { | |
66 | /* Checking __linux__ isn't great but it isn't clear what would be | |
67 | better. There doesn't seem to be a good way to check for this in | |
68 | configure. */ | |
69 | #ifdef __linux__ | |
70 | DIR *dir; | |
71 | ||
72 | dir = opendir ("/proc/self/fd"); | |
73 | if (dir != NULL) | |
74 | { | |
75 | struct dirent *entry; | |
76 | int result = 0; | |
77 | ||
78 | for (entry = readdir (dir); entry != NULL; entry = readdir (dir)) | |
79 | { | |
80 | long fd; | |
81 | char *tail; | |
82 | int result; | |
83 | ||
84 | errno = 0; | |
85 | fd = strtol (entry->d_name, &tail, 10); | |
86 | if (*tail != '\0' || errno != 0) | |
87 | continue; | |
88 | if ((int) fd != fd) | |
89 | { | |
90 | /* What can we do here really? */ | |
91 | continue; | |
92 | } | |
93 | ||
94 | if (fd == dirfd (dir)) | |
95 | continue; | |
96 | ||
97 | result = func (arg, fd); | |
98 | if (result != 0) | |
99 | break; | |
100 | } | |
101 | ||
102 | closedir (dir); | |
103 | return result; | |
104 | } | |
105 | /* We may fall through to the next case. */ | |
106 | #endif | |
107 | ||
108 | { | |
109 | int max, fd; | |
110 | ||
f9b0da3d | 111 | #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE) |
614c279d TT |
112 | struct rlimit rlim; |
113 | ||
114 | if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY) | |
115 | max = rlim.rlim_max; | |
116 | else | |
117 | #endif | |
118 | { | |
119 | #ifdef _SC_OPEN_MAX | |
120 | max = sysconf (_SC_OPEN_MAX); | |
121 | #else | |
122 | /* Whoops. */ | |
123 | return 0; | |
124 | #endif /* _SC_OPEN_MAX */ | |
125 | } | |
126 | ||
127 | for (fd = 0; fd < max; ++fd) | |
128 | { | |
129 | struct stat sb; | |
130 | int result; | |
131 | ||
132 | /* Only call FUNC for open fds. */ | |
133 | if (fstat (fd, &sb) == -1) | |
134 | continue; | |
135 | ||
136 | result = func (arg, fd); | |
137 | if (result != 0) | |
138 | return result; | |
139 | } | |
140 | ||
141 | return 0; | |
142 | } | |
143 | } | |
144 | ||
145 | #endif /* HAVE_FDWALK */ | |
146 | ||
147 | \f | |
148 | ||
149 | /* A VEC holding all the fds open when notice_open_fds was called. We | |
150 | don't use a hashtab because libiberty isn't linked into gdbserver; | |
151 | and anyway we don't expect there to be many open fds. */ | |
152 | ||
614c279d TT |
153 | static VEC (int) *open_fds; |
154 | ||
155 | /* An fdwalk callback function used by notice_open_fds. It puts the | |
156 | given file descriptor into the vec. */ | |
157 | ||
158 | static int | |
159 | do_mark_open_fd (void *ignore, int fd) | |
160 | { | |
161 | VEC_safe_push (int, open_fds, fd); | |
162 | return 0; | |
163 | } | |
164 | ||
165 | /* See filestuff.h. */ | |
166 | ||
167 | void | |
168 | notice_open_fds (void) | |
169 | { | |
170 | fdwalk (do_mark_open_fd, NULL); | |
171 | } | |
172 | ||
21ff4686 TT |
173 | /* See filestuff.h. */ |
174 | ||
175 | void | |
176 | mark_fd_no_cloexec (int fd) | |
177 | { | |
178 | do_mark_open_fd (NULL, fd); | |
179 | } | |
180 | ||
181 | /* See filestuff.h. */ | |
182 | ||
183 | void | |
184 | unmark_fd_no_cloexec (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 | VEC_unordered_remove (int, open_fds, i); | |
193 | return; | |
194 | } | |
195 | } | |
196 | ||
197 | gdb_assert_not_reached (_("fd not found in open_fds")); | |
198 | } | |
199 | ||
614c279d TT |
200 | /* Helper function for close_most_fds that closes the file descriptor |
201 | if appropriate. */ | |
202 | ||
203 | static int | |
204 | do_close (void *ignore, int fd) | |
205 | { | |
206 | int i, val; | |
207 | ||
208 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
209 | { | |
210 | if (fd == val) | |
211 | { | |
212 | /* Keep this one open. */ | |
213 | return 0; | |
214 | } | |
215 | } | |
216 | ||
217 | close (fd); | |
218 | return 0; | |
219 | } | |
220 | ||
221 | /* See filestuff.h. */ | |
222 | ||
223 | void | |
224 | close_most_fds (void) | |
225 | { | |
226 | fdwalk (do_close, NULL); | |
227 | } | |
228 | ||
229 | \f | |
230 | ||
231 | /* This is a tri-state flag. When zero it means we haven't yet tried | |
232 | O_CLOEXEC. When positive it means that O_CLOEXEC works on this | |
233 | host. When negative, it means that O_CLOEXEC doesn't work. We | |
234 | track this state because, while gdb might have been compiled | |
235 | against a libc that supplies O_CLOEXEC, there is no guarantee that | |
236 | the kernel supports it. */ | |
237 | ||
238 | static int trust_o_cloexec; | |
239 | ||
240 | /* Mark FD as close-on-exec, ignoring errors. Update | |
241 | TRUST_O_CLOEXEC. */ | |
242 | ||
243 | static void | |
244 | mark_cloexec (int fd) | |
245 | { | |
5d71132c | 246 | #ifdef HAVE_F_GETFD |
614c279d TT |
247 | int old = fcntl (fd, F_GETFD, 0); |
248 | ||
249 | if (old != -1) | |
250 | { | |
251 | fcntl (fd, F_SETFD, old | FD_CLOEXEC); | |
252 | ||
253 | if (trust_o_cloexec == 0) | |
254 | { | |
255 | if ((old & FD_CLOEXEC) != 0) | |
256 | trust_o_cloexec = 1; | |
257 | else | |
258 | trust_o_cloexec = -1; | |
259 | } | |
260 | } | |
5d71132c | 261 | #endif /* HAVE_F_GETFD */ |
614c279d TT |
262 | } |
263 | ||
264 | /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */ | |
265 | ||
266 | static void | |
267 | maybe_mark_cloexec (int fd) | |
268 | { | |
269 | if (trust_o_cloexec <= 0) | |
270 | mark_cloexec (fd); | |
271 | } | |
272 | ||
8658d16d PA |
273 | #ifdef HAVE_SOCKETS |
274 | ||
614c279d TT |
275 | /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */ |
276 | ||
277 | static void | |
278 | socket_mark_cloexec (int fd) | |
279 | { | |
280 | if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0) | |
281 | mark_cloexec (fd); | |
282 | } | |
283 | ||
8658d16d PA |
284 | #endif |
285 | ||
614c279d TT |
286 | \f |
287 | ||
288 | /* See filestuff.h. */ | |
289 | ||
290 | int | |
5d71132c | 291 | gdb_open_cloexec (const char *filename, int flags, unsigned long mode) |
614c279d TT |
292 | { |
293 | int fd = open (filename, flags | O_CLOEXEC, mode); | |
294 | ||
295 | if (fd >= 0) | |
296 | maybe_mark_cloexec (fd); | |
297 | ||
298 | return fd; | |
299 | } | |
300 | ||
301 | /* See filestuff.h. */ | |
302 | ||
303 | FILE * | |
304 | gdb_fopen_cloexec (const char *filename, const char *opentype) | |
305 | { | |
c74e1ccf | 306 | FILE *result; |
88505fac PM |
307 | /* Probe for "e" support once. But, if we can tell the operating |
308 | system doesn't know about close on exec mode "e" without probing, | |
309 | skip it. E.g., the Windows runtime issues an "Invalid parameter | |
310 | passed to C runtime function" OutputDebugString warning for | |
311 | unknown modes. Assume that if O_CLOEXEC is zero, then "e" isn't | |
312 | supported. */ | |
c74e1ccf | 313 | static int fopen_e_ever_failed_einval = O_CLOEXEC == 0; |
614c279d | 314 | |
c74e1ccf | 315 | if (!fopen_e_ever_failed_einval) |
614c279d TT |
316 | { |
317 | char *copy; | |
318 | ||
319 | copy = alloca (strlen (opentype) + 2); | |
320 | strcpy (copy, opentype); | |
321 | /* This is a glibc extension but we try it unconditionally on | |
322 | this path. */ | |
323 | strcat (copy, "e"); | |
324 | result = fopen (filename, copy); | |
614c279d | 325 | |
c74e1ccf JK |
326 | if (result == NULL && errno == EINVAL) |
327 | { | |
328 | result = fopen (filename, opentype); | |
329 | if (result != NULL) | |
330 | fopen_e_ever_failed_einval = 1; | |
331 | } | |
614c279d | 332 | } |
c74e1ccf JK |
333 | else |
334 | result = fopen (filename, opentype); | |
614c279d TT |
335 | |
336 | if (result != NULL) | |
337 | maybe_mark_cloexec (fileno (result)); | |
338 | ||
339 | return result; | |
340 | } | |
341 | ||
8658d16d | 342 | #ifdef HAVE_SOCKETS |
614c279d TT |
343 | /* See filestuff.h. */ |
344 | ||
345 | int | |
fe978cb0 PA |
346 | gdb_socketpair_cloexec (int domain, int style, int protocol, |
347 | int filedes[2]) | |
614c279d | 348 | { |
5d71132c | 349 | #ifdef HAVE_SOCKETPAIR |
fe978cb0 | 350 | int result = socketpair (domain, style | SOCK_CLOEXEC, protocol, filedes); |
614c279d TT |
351 | |
352 | if (result != -1) | |
353 | { | |
354 | socket_mark_cloexec (filedes[0]); | |
355 | socket_mark_cloexec (filedes[1]); | |
356 | } | |
357 | ||
358 | return result; | |
5d71132c TT |
359 | #else |
360 | gdb_assert_not_reached (_("socketpair not available on this host")); | |
361 | #endif | |
614c279d TT |
362 | } |
363 | ||
364 | /* See filestuff.h. */ | |
365 | ||
366 | int | |
fe978cb0 | 367 | gdb_socket_cloexec (int domain, int style, int protocol) |
614c279d | 368 | { |
fe978cb0 | 369 | int result = socket (domain, style | SOCK_CLOEXEC, protocol); |
614c279d TT |
370 | |
371 | if (result != -1) | |
372 | socket_mark_cloexec (result); | |
373 | ||
374 | return result; | |
375 | } | |
8658d16d | 376 | #endif |
614c279d TT |
377 | |
378 | /* See filestuff.h. */ | |
379 | ||
380 | int | |
381 | gdb_pipe_cloexec (int filedes[2]) | |
382 | { | |
383 | int result; | |
384 | ||
385 | #ifdef HAVE_PIPE2 | |
386 | result = pipe2 (filedes, O_CLOEXEC); | |
387 | if (result != -1) | |
388 | { | |
389 | maybe_mark_cloexec (filedes[0]); | |
390 | maybe_mark_cloexec (filedes[1]); | |
391 | } | |
392 | #else | |
5d71132c | 393 | #ifdef HAVE_PIPE |
614c279d TT |
394 | result = pipe (filedes); |
395 | if (result != -1) | |
396 | { | |
397 | mark_cloexec (filedes[0]); | |
398 | mark_cloexec (filedes[1]); | |
399 | } | |
5d71132c TT |
400 | #else /* HAVE_PIPE */ |
401 | gdb_assert_not_reached (_("pipe not available on this host")); | |
402 | #endif /* HAVE_PIPE */ | |
403 | #endif /* HAVE_PIPE2 */ | |
614c279d TT |
404 | |
405 | return result; | |
406 | } | |
ca095836 GB |
407 | |
408 | /* Helper function which does the work for make_cleanup_close. */ | |
409 | ||
410 | static void | |
411 | do_close_cleanup (void *arg) | |
412 | { | |
413 | int *fd = arg; | |
414 | ||
415 | close (*fd); | |
416 | } | |
417 | ||
418 | /* See cleanup-utils.h. */ | |
419 | ||
420 | struct cleanup * | |
421 | make_cleanup_close (int fd) | |
422 | { | |
8d749320 | 423 | int *saved_fd = XNEW (int); |
ca095836 GB |
424 | |
425 | *saved_fd = fd; | |
426 | return make_cleanup_dtor (do_close_cleanup, saved_fd, xfree); | |
427 | } |