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614c279d | 1 | /* Low-level file-handling. |
42a4f53d | 2 | Copyright (C) 2012-2019 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> |
37269bc9 | 26 | #include <algorithm> |
614c279d | 27 | |
5d71132c TT |
28 | #ifdef USE_WIN32API |
29 | #include <winsock2.h> | |
30 | #include <windows.h> | |
8658d16d PA |
31 | #define HAVE_SOCKETS 1 |
32 | #elif defined HAVE_SYS_SOCKET_H | |
5d71132c TT |
33 | #include <sys/socket.h> |
34 | /* Define HAVE_F_GETFD if we plan to use F_GETFD. */ | |
35 | #define HAVE_F_GETFD F_GETFD | |
8658d16d | 36 | #define HAVE_SOCKETS 1 |
5d71132c TT |
37 | #endif |
38 | ||
93579f6f JB |
39 | #ifdef HAVE_KINFO_GETFILE |
40 | #include <sys/user.h> | |
41 | #include <libutil.h> | |
42 | #endif | |
43 | ||
614c279d TT |
44 | #ifdef HAVE_SYS_RESOURCE_H |
45 | #include <sys/resource.h> | |
46 | #endif /* HAVE_SYS_RESOURCE_H */ | |
47 | ||
48 | #ifndef O_CLOEXEC | |
49 | #define O_CLOEXEC 0 | |
50 | #endif | |
51 | ||
2fa1b319 EZ |
52 | #ifndef O_NOINHERIT |
53 | #define O_NOINHERIT 0 | |
54 | #endif | |
55 | ||
614c279d TT |
56 | #ifndef SOCK_CLOEXEC |
57 | #define SOCK_CLOEXEC 0 | |
58 | #endif | |
59 | ||
60 | \f | |
61 | ||
62 | #ifndef HAVE_FDWALK | |
63 | ||
2978b111 | 64 | #include <dirent.h> |
614c279d TT |
65 | |
66 | /* Replacement for fdwalk, if the system doesn't define it. Walks all | |
67 | open file descriptors (though this implementation may walk closed | |
68 | ones as well, depending on the host platform's capabilities) and | |
69 | call FUNC with ARG. If FUNC returns non-zero, stops immediately | |
70 | and returns the same value. Otherwise, returns zero when | |
71 | finished. */ | |
72 | ||
73 | static int | |
74 | fdwalk (int (*func) (void *, int), void *arg) | |
75 | { | |
76 | /* Checking __linux__ isn't great but it isn't clear what would be | |
77 | better. There doesn't seem to be a good way to check for this in | |
78 | configure. */ | |
79 | #ifdef __linux__ | |
80 | DIR *dir; | |
81 | ||
82 | dir = opendir ("/proc/self/fd"); | |
83 | if (dir != NULL) | |
84 | { | |
85 | struct dirent *entry; | |
86 | int result = 0; | |
87 | ||
88 | for (entry = readdir (dir); entry != NULL; entry = readdir (dir)) | |
89 | { | |
90 | long fd; | |
91 | char *tail; | |
614c279d TT |
92 | |
93 | errno = 0; | |
94 | fd = strtol (entry->d_name, &tail, 10); | |
95 | if (*tail != '\0' || errno != 0) | |
96 | continue; | |
97 | if ((int) fd != fd) | |
98 | { | |
99 | /* What can we do here really? */ | |
100 | continue; | |
101 | } | |
102 | ||
103 | if (fd == dirfd (dir)) | |
104 | continue; | |
105 | ||
106 | result = func (arg, fd); | |
107 | if (result != 0) | |
108 | break; | |
109 | } | |
110 | ||
111 | closedir (dir); | |
112 | return result; | |
113 | } | |
114 | /* We may fall through to the next case. */ | |
115 | #endif | |
93579f6f JB |
116 | #ifdef HAVE_KINFO_GETFILE |
117 | int nfd; | |
118 | gdb::unique_xmalloc_ptr<struct kinfo_file[]> fdtbl | |
119 | (kinfo_getfile (getpid (), &nfd)); | |
120 | if (fdtbl != NULL) | |
121 | { | |
122 | for (int i = 0; i < nfd; i++) | |
123 | { | |
124 | if (fdtbl[i].kf_fd >= 0) | |
125 | { | |
126 | int result = func (arg, fdtbl[i].kf_fd); | |
127 | if (result != 0) | |
128 | return result; | |
129 | } | |
130 | } | |
131 | return 0; | |
132 | } | |
133 | /* We may fall through to the next case. */ | |
134 | #endif | |
614c279d TT |
135 | |
136 | { | |
137 | int max, fd; | |
138 | ||
f9b0da3d | 139 | #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE) |
614c279d TT |
140 | struct rlimit rlim; |
141 | ||
142 | if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY) | |
143 | max = rlim.rlim_max; | |
144 | else | |
145 | #endif | |
146 | { | |
147 | #ifdef _SC_OPEN_MAX | |
148 | max = sysconf (_SC_OPEN_MAX); | |
149 | #else | |
150 | /* Whoops. */ | |
151 | return 0; | |
152 | #endif /* _SC_OPEN_MAX */ | |
153 | } | |
154 | ||
155 | for (fd = 0; fd < max; ++fd) | |
156 | { | |
157 | struct stat sb; | |
158 | int result; | |
159 | ||
160 | /* Only call FUNC for open fds. */ | |
161 | if (fstat (fd, &sb) == -1) | |
162 | continue; | |
163 | ||
164 | result = func (arg, fd); | |
165 | if (result != 0) | |
166 | return result; | |
167 | } | |
168 | ||
169 | return 0; | |
170 | } | |
171 | } | |
172 | ||
173 | #endif /* HAVE_FDWALK */ | |
174 | ||
175 | \f | |
176 | ||
37269bc9 SM |
177 | /* A vector holding all the fds open when notice_open_fds was called. We |
178 | don't use a hashtab because we don't expect there to be many open fds. */ | |
614c279d | 179 | |
37269bc9 | 180 | static std::vector<int> open_fds; |
614c279d TT |
181 | |
182 | /* An fdwalk callback function used by notice_open_fds. It puts the | |
183 | given file descriptor into the vec. */ | |
184 | ||
185 | static int | |
186 | do_mark_open_fd (void *ignore, int fd) | |
187 | { | |
37269bc9 | 188 | open_fds.push_back (fd); |
614c279d TT |
189 | return 0; |
190 | } | |
191 | ||
192 | /* See filestuff.h. */ | |
193 | ||
194 | void | |
195 | notice_open_fds (void) | |
196 | { | |
197 | fdwalk (do_mark_open_fd, NULL); | |
198 | } | |
199 | ||
21ff4686 TT |
200 | /* See filestuff.h. */ |
201 | ||
202 | void | |
203 | mark_fd_no_cloexec (int fd) | |
204 | { | |
205 | do_mark_open_fd (NULL, fd); | |
206 | } | |
207 | ||
208 | /* See filestuff.h. */ | |
209 | ||
210 | void | |
211 | unmark_fd_no_cloexec (int fd) | |
212 | { | |
37269bc9 | 213 | auto it = std::remove (open_fds.begin (), open_fds.end (), fd); |
21ff4686 | 214 | |
37269bc9 SM |
215 | if (it != open_fds.end ()) |
216 | open_fds.erase (it); | |
217 | else | |
218 | gdb_assert_not_reached (_("fd not found in open_fds")); | |
21ff4686 TT |
219 | } |
220 | ||
614c279d TT |
221 | /* Helper function for close_most_fds that closes the file descriptor |
222 | if appropriate. */ | |
223 | ||
224 | static int | |
225 | do_close (void *ignore, int fd) | |
226 | { | |
37269bc9 | 227 | for (int val : open_fds) |
614c279d TT |
228 | { |
229 | if (fd == val) | |
230 | { | |
231 | /* Keep this one open. */ | |
232 | return 0; | |
233 | } | |
234 | } | |
235 | ||
236 | close (fd); | |
237 | return 0; | |
238 | } | |
239 | ||
240 | /* See filestuff.h. */ | |
241 | ||
242 | void | |
243 | close_most_fds (void) | |
244 | { | |
245 | fdwalk (do_close, NULL); | |
246 | } | |
247 | ||
248 | \f | |
249 | ||
250 | /* This is a tri-state flag. When zero it means we haven't yet tried | |
251 | O_CLOEXEC. When positive it means that O_CLOEXEC works on this | |
252 | host. When negative, it means that O_CLOEXEC doesn't work. We | |
253 | track this state because, while gdb might have been compiled | |
254 | against a libc that supplies O_CLOEXEC, there is no guarantee that | |
255 | the kernel supports it. */ | |
256 | ||
257 | static int trust_o_cloexec; | |
258 | ||
259 | /* Mark FD as close-on-exec, ignoring errors. Update | |
260 | TRUST_O_CLOEXEC. */ | |
261 | ||
262 | static void | |
263 | mark_cloexec (int fd) | |
264 | { | |
5d71132c | 265 | #ifdef HAVE_F_GETFD |
614c279d TT |
266 | int old = fcntl (fd, F_GETFD, 0); |
267 | ||
268 | if (old != -1) | |
269 | { | |
270 | fcntl (fd, F_SETFD, old | FD_CLOEXEC); | |
271 | ||
272 | if (trust_o_cloexec == 0) | |
273 | { | |
274 | if ((old & FD_CLOEXEC) != 0) | |
275 | trust_o_cloexec = 1; | |
276 | else | |
277 | trust_o_cloexec = -1; | |
278 | } | |
279 | } | |
5d71132c | 280 | #endif /* HAVE_F_GETFD */ |
614c279d TT |
281 | } |
282 | ||
283 | /* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */ | |
284 | ||
285 | static void | |
286 | maybe_mark_cloexec (int fd) | |
287 | { | |
288 | if (trust_o_cloexec <= 0) | |
289 | mark_cloexec (fd); | |
290 | } | |
291 | ||
8658d16d PA |
292 | #ifdef HAVE_SOCKETS |
293 | ||
614c279d TT |
294 | /* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */ |
295 | ||
296 | static void | |
297 | socket_mark_cloexec (int fd) | |
298 | { | |
299 | if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0) | |
300 | mark_cloexec (fd); | |
301 | } | |
302 | ||
8658d16d PA |
303 | #endif |
304 | ||
614c279d TT |
305 | \f |
306 | ||
307 | /* See filestuff.h. */ | |
308 | ||
309 | int | |
5d71132c | 310 | gdb_open_cloexec (const char *filename, int flags, unsigned long mode) |
614c279d TT |
311 | { |
312 | int fd = open (filename, flags | O_CLOEXEC, mode); | |
313 | ||
314 | if (fd >= 0) | |
315 | maybe_mark_cloexec (fd); | |
316 | ||
317 | return fd; | |
318 | } | |
319 | ||
320 | /* See filestuff.h. */ | |
321 | ||
d419f42d | 322 | gdb_file_up |
614c279d TT |
323 | gdb_fopen_cloexec (const char *filename, const char *opentype) |
324 | { | |
c74e1ccf | 325 | FILE *result; |
88505fac PM |
326 | /* Probe for "e" support once. But, if we can tell the operating |
327 | system doesn't know about close on exec mode "e" without probing, | |
328 | skip it. E.g., the Windows runtime issues an "Invalid parameter | |
329 | passed to C runtime function" OutputDebugString warning for | |
330 | unknown modes. Assume that if O_CLOEXEC is zero, then "e" isn't | |
970d89d8 EZ |
331 | supported. On MinGW, O_CLOEXEC is an alias of O_NOINHERIT, and |
332 | "e" isn't supported. */ | |
333 | static int fopen_e_ever_failed_einval = | |
334 | O_CLOEXEC == 0 || O_CLOEXEC == O_NOINHERIT; | |
614c279d | 335 | |
c74e1ccf | 336 | if (!fopen_e_ever_failed_einval) |
614c279d TT |
337 | { |
338 | char *copy; | |
339 | ||
224c3ddb | 340 | copy = (char *) alloca (strlen (opentype) + 2); |
614c279d TT |
341 | strcpy (copy, opentype); |
342 | /* This is a glibc extension but we try it unconditionally on | |
343 | this path. */ | |
344 | strcat (copy, "e"); | |
345 | result = fopen (filename, copy); | |
614c279d | 346 | |
c74e1ccf JK |
347 | if (result == NULL && errno == EINVAL) |
348 | { | |
349 | result = fopen (filename, opentype); | |
350 | if (result != NULL) | |
351 | fopen_e_ever_failed_einval = 1; | |
352 | } | |
614c279d | 353 | } |
c74e1ccf JK |
354 | else |
355 | result = fopen (filename, opentype); | |
614c279d TT |
356 | |
357 | if (result != NULL) | |
358 | maybe_mark_cloexec (fileno (result)); | |
359 | ||
d419f42d | 360 | return gdb_file_up (result); |
614c279d TT |
361 | } |
362 | ||
8658d16d | 363 | #ifdef HAVE_SOCKETS |
614c279d TT |
364 | /* See filestuff.h. */ |
365 | ||
366 | int | |
fe978cb0 PA |
367 | gdb_socketpair_cloexec (int domain, int style, int protocol, |
368 | int filedes[2]) | |
614c279d | 369 | { |
5d71132c | 370 | #ifdef HAVE_SOCKETPAIR |
fe978cb0 | 371 | int result = socketpair (domain, style | SOCK_CLOEXEC, protocol, filedes); |
614c279d TT |
372 | |
373 | if (result != -1) | |
374 | { | |
375 | socket_mark_cloexec (filedes[0]); | |
376 | socket_mark_cloexec (filedes[1]); | |
377 | } | |
378 | ||
379 | return result; | |
5d71132c TT |
380 | #else |
381 | gdb_assert_not_reached (_("socketpair not available on this host")); | |
382 | #endif | |
614c279d TT |
383 | } |
384 | ||
385 | /* See filestuff.h. */ | |
386 | ||
387 | int | |
fe978cb0 | 388 | gdb_socket_cloexec (int domain, int style, int protocol) |
614c279d | 389 | { |
fe978cb0 | 390 | int result = socket (domain, style | SOCK_CLOEXEC, protocol); |
614c279d TT |
391 | |
392 | if (result != -1) | |
393 | socket_mark_cloexec (result); | |
394 | ||
395 | return result; | |
396 | } | |
8658d16d | 397 | #endif |
614c279d TT |
398 | |
399 | /* See filestuff.h. */ | |
400 | ||
401 | int | |
402 | gdb_pipe_cloexec (int filedes[2]) | |
403 | { | |
404 | int result; | |
405 | ||
406 | #ifdef HAVE_PIPE2 | |
407 | result = pipe2 (filedes, O_CLOEXEC); | |
408 | if (result != -1) | |
409 | { | |
410 | maybe_mark_cloexec (filedes[0]); | |
411 | maybe_mark_cloexec (filedes[1]); | |
412 | } | |
413 | #else | |
5d71132c | 414 | #ifdef HAVE_PIPE |
614c279d TT |
415 | result = pipe (filedes); |
416 | if (result != -1) | |
417 | { | |
418 | mark_cloexec (filedes[0]); | |
419 | mark_cloexec (filedes[1]); | |
420 | } | |
5d71132c TT |
421 | #else /* HAVE_PIPE */ |
422 | gdb_assert_not_reached (_("pipe not available on this host")); | |
423 | #endif /* HAVE_PIPE */ | |
424 | #endif /* HAVE_PIPE2 */ | |
614c279d TT |
425 | |
426 | return result; | |
427 | } | |
ca095836 | 428 | |
3c025cfe SDJ |
429 | /* See common/filestuff.h. */ |
430 | ||
431 | bool | |
432 | is_regular_file (const char *name, int *errno_ptr) | |
433 | { | |
434 | struct stat st; | |
435 | const int status = stat (name, &st); | |
436 | ||
437 | /* Stat should never fail except when the file does not exist. | |
438 | If stat fails, analyze the source of error and return true | |
439 | unless the file does not exist, to avoid returning false results | |
440 | on obscure systems where stat does not work as expected. */ | |
441 | ||
442 | if (status != 0) | |
443 | { | |
444 | if (errno != ENOENT) | |
445 | return true; | |
446 | *errno_ptr = ENOENT; | |
447 | return false; | |
448 | } | |
449 | ||
450 | if (S_ISREG (st.st_mode)) | |
451 | return true; | |
452 | ||
453 | if (S_ISDIR (st.st_mode)) | |
454 | *errno_ptr = EISDIR; | |
455 | else | |
456 | *errno_ptr = EINVAL; | |
457 | return false; | |
458 | } | |
e418a61a TT |
459 | |
460 | /* See common/filestuff.h. */ | |
461 | ||
462 | bool | |
463 | mkdir_recursive (const char *dir) | |
464 | { | |
465 | gdb::unique_xmalloc_ptr<char> holder (xstrdup (dir)); | |
466 | char * const start = holder.get (); | |
467 | char *component_start = start; | |
468 | char *component_end = start; | |
469 | ||
470 | while (1) | |
471 | { | |
472 | /* Find the beginning of the next component. */ | |
473 | while (*component_start == '/') | |
474 | component_start++; | |
475 | ||
476 | /* Are we done? */ | |
477 | if (*component_start == '\0') | |
478 | return true; | |
479 | ||
480 | /* Find the slash or null-terminator after this component. */ | |
481 | component_end = component_start; | |
482 | while (*component_end != '/' && *component_end != '\0') | |
483 | component_end++; | |
484 | ||
485 | /* Temporarily replace the slash with a null terminator, so we can create | |
486 | the directory up to this component. */ | |
487 | char saved_char = *component_end; | |
488 | *component_end = '\0'; | |
489 | ||
490 | /* If we get EEXIST and the existing path is a directory, then we're | |
491 | happy. If it exists, but it's a regular file and this is not the last | |
492 | component, we'll fail at the next component. If this is the last | |
493 | component, the caller will fail with ENOTDIR when trying to | |
494 | open/create a file under that path. */ | |
495 | if (mkdir (start, 0700) != 0) | |
496 | if (errno != EEXIST) | |
497 | return false; | |
498 | ||
499 | /* Restore the overwritten char. */ | |
500 | *component_end = saved_char; | |
501 | component_start = component_end; | |
502 | } | |
503 | } |