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614c279d | 1 | /* Low-level file-handling. |
ecd75fc8 | 2 | Copyright (C) 2012-2014 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 | ||
19 | #ifdef GDBSERVER | |
20 | #include "server.h" | |
21 | #else | |
22 | #include "defs.h" | |
0e9f083f | 23 | #include <string.h> |
614c279d TT |
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> |
53ce3c39 | 32 | #include <sys/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 | ||
2978b111 | 61 | #include <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 | ||
f9b0da3d | 118 | #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE) |
614c279d TT |
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 | ||
614c279d TT |
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 | ||
21ff4686 TT |
180 | /* See filestuff.h. */ |
181 | ||
182 | void | |
183 | mark_fd_no_cloexec (int fd) | |
184 | { | |
185 | do_mark_open_fd (NULL, fd); | |
186 | } | |
187 | ||
188 | /* See filestuff.h. */ | |
189 | ||
190 | void | |
191 | unmark_fd_no_cloexec (int fd) | |
192 | { | |
193 | int i, val; | |
194 | ||
195 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
196 | { | |
197 | if (fd == val) | |
198 | { | |
199 | VEC_unordered_remove (int, open_fds, i); | |
200 | return; | |
201 | } | |
202 | } | |
203 | ||
204 | gdb_assert_not_reached (_("fd not found in open_fds")); | |
205 | } | |
206 | ||
614c279d TT |
207 | /* Helper function for close_most_fds that closes the file descriptor |
208 | if appropriate. */ | |
209 | ||
210 | static int | |
211 | do_close (void *ignore, int fd) | |
212 | { | |
213 | int i, val; | |
214 | ||
215 | for (i = 0; VEC_iterate (int, open_fds, i, val); ++i) | |
216 | { | |
217 | if (fd == val) | |
218 | { | |
219 | /* Keep this one open. */ | |
220 | return 0; | |
221 | } | |
222 | } | |
223 | ||
224 | close (fd); | |
225 | return 0; | |
226 | } | |
227 | ||
228 | /* See filestuff.h. */ | |
229 | ||
230 | void | |
231 | close_most_fds (void) | |
232 | { | |
233 | fdwalk (do_close, NULL); | |
234 | } | |
235 | ||
236 | \f | |
237 | ||
238 | /* This is a tri-state flag. When zero it means we haven't yet tried | |
239 | O_CLOEXEC. When positive it means that O_CLOEXEC works on this | |
240 | host. When negative, it means that O_CLOEXEC doesn't work. We | |
241 | track this state because, while gdb might have been compiled | |
242 | against a libc that supplies O_CLOEXEC, there is no guarantee that | |
243 | the kernel supports it. */ | |
244 | ||
245 | static int trust_o_cloexec; | |
246 | ||
247 | /* Mark FD as close-on-exec, ignoring errors. Update | |
248 | TRUST_O_CLOEXEC. */ | |
249 | ||
250 | static void | |
251 | mark_cloexec (int fd) | |
252 | { | |
5d71132c | 253 | #ifdef HAVE_F_GETFD |
614c279d TT |
254 | int old = fcntl (fd, F_GETFD, 0); |
255 | ||
256 | if (old != -1) | |
257 | { | |
258 | fcntl (fd, F_SETFD, old | FD_CLOEXEC); | |
259 | ||
260 | if (trust_o_cloexec == 0) | |
261 | { | |
262 | if ((old & FD_CLOEXEC) != 0) | |
263 | trust_o_cloexec = 1; | |
264 | else | |
265 | trust_o_cloexec = -1; | |
266 | } | |
267 | } | |
5d71132c | 268 | #endif /* HAVE_F_GETFD */ |
614c279d TT |
269 | } |
270 | ||
271 | /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */ | |
272 | ||
273 | static void | |
274 | maybe_mark_cloexec (int fd) | |
275 | { | |
276 | if (trust_o_cloexec <= 0) | |
277 | mark_cloexec (fd); | |
278 | } | |
279 | ||
8658d16d PA |
280 | #ifdef HAVE_SOCKETS |
281 | ||
614c279d TT |
282 | /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */ |
283 | ||
284 | static void | |
285 | socket_mark_cloexec (int fd) | |
286 | { | |
287 | if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0) | |
288 | mark_cloexec (fd); | |
289 | } | |
290 | ||
8658d16d PA |
291 | #endif |
292 | ||
614c279d TT |
293 | \f |
294 | ||
295 | /* See filestuff.h. */ | |
296 | ||
297 | int | |
5d71132c | 298 | gdb_open_cloexec (const char *filename, int flags, unsigned long mode) |
614c279d TT |
299 | { |
300 | int fd = open (filename, flags | O_CLOEXEC, mode); | |
301 | ||
302 | if (fd >= 0) | |
303 | maybe_mark_cloexec (fd); | |
304 | ||
305 | return fd; | |
306 | } | |
307 | ||
308 | /* See filestuff.h. */ | |
309 | ||
310 | FILE * | |
311 | gdb_fopen_cloexec (const char *filename, const char *opentype) | |
312 | { | |
c74e1ccf | 313 | FILE *result; |
88505fac PM |
314 | /* Probe for "e" support once. But, if we can tell the operating |
315 | system doesn't know about close on exec mode "e" without probing, | |
316 | skip it. E.g., the Windows runtime issues an "Invalid parameter | |
317 | passed to C runtime function" OutputDebugString warning for | |
318 | unknown modes. Assume that if O_CLOEXEC is zero, then "e" isn't | |
319 | supported. */ | |
c74e1ccf | 320 | static int fopen_e_ever_failed_einval = O_CLOEXEC == 0; |
614c279d | 321 | |
c74e1ccf | 322 | if (!fopen_e_ever_failed_einval) |
614c279d TT |
323 | { |
324 | char *copy; | |
325 | ||
326 | copy = alloca (strlen (opentype) + 2); | |
327 | strcpy (copy, opentype); | |
328 | /* This is a glibc extension but we try it unconditionally on | |
329 | this path. */ | |
330 | strcat (copy, "e"); | |
331 | result = fopen (filename, copy); | |
614c279d | 332 | |
c74e1ccf JK |
333 | if (result == NULL && errno == EINVAL) |
334 | { | |
335 | result = fopen (filename, opentype); | |
336 | if (result != NULL) | |
337 | fopen_e_ever_failed_einval = 1; | |
338 | } | |
614c279d | 339 | } |
c74e1ccf JK |
340 | else |
341 | result = fopen (filename, opentype); | |
614c279d TT |
342 | |
343 | if (result != NULL) | |
344 | maybe_mark_cloexec (fileno (result)); | |
345 | ||
346 | return result; | |
347 | } | |
348 | ||
8658d16d | 349 | #ifdef HAVE_SOCKETS |
614c279d TT |
350 | /* See filestuff.h. */ |
351 | ||
352 | int | |
353 | gdb_socketpair_cloexec (int namespace, int style, int protocol, int filedes[2]) | |
354 | { | |
5d71132c | 355 | #ifdef HAVE_SOCKETPAIR |
614c279d TT |
356 | int result = socketpair (namespace, style | SOCK_CLOEXEC, protocol, filedes); |
357 | ||
358 | if (result != -1) | |
359 | { | |
360 | socket_mark_cloexec (filedes[0]); | |
361 | socket_mark_cloexec (filedes[1]); | |
362 | } | |
363 | ||
364 | return result; | |
5d71132c TT |
365 | #else |
366 | gdb_assert_not_reached (_("socketpair not available on this host")); | |
367 | #endif | |
614c279d TT |
368 | } |
369 | ||
370 | /* See filestuff.h. */ | |
371 | ||
372 | int | |
373 | gdb_socket_cloexec (int namespace, int style, int protocol) | |
374 | { | |
375 | int result = socket (namespace, style | SOCK_CLOEXEC, protocol); | |
376 | ||
377 | if (result != -1) | |
378 | socket_mark_cloexec (result); | |
379 | ||
380 | return result; | |
381 | } | |
8658d16d | 382 | #endif |
614c279d TT |
383 | |
384 | /* See filestuff.h. */ | |
385 | ||
386 | int | |
387 | gdb_pipe_cloexec (int filedes[2]) | |
388 | { | |
389 | int result; | |
390 | ||
391 | #ifdef HAVE_PIPE2 | |
392 | result = pipe2 (filedes, O_CLOEXEC); | |
393 | if (result != -1) | |
394 | { | |
395 | maybe_mark_cloexec (filedes[0]); | |
396 | maybe_mark_cloexec (filedes[1]); | |
397 | } | |
398 | #else | |
5d71132c | 399 | #ifdef HAVE_PIPE |
614c279d TT |
400 | result = pipe (filedes); |
401 | if (result != -1) | |
402 | { | |
403 | mark_cloexec (filedes[0]); | |
404 | mark_cloexec (filedes[1]); | |
405 | } | |
5d71132c TT |
406 | #else /* HAVE_PIPE */ |
407 | gdb_assert_not_reached (_("pipe not available on this host")); | |
408 | #endif /* HAVE_PIPE */ | |
409 | #endif /* HAVE_PIPE2 */ | |
614c279d TT |
410 | |
411 | return result; | |
412 | } |