remove gdb_dirent.h
[deliverable/binutils-gdb.git] / gdb / common / filestuff.c
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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"
0e9f083f 23#include <string.h>
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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
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34#ifdef USE_WIN32API
35#include <winsock2.h>
36#include <windows.h>
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37#define HAVE_SOCKETS 1
38#elif defined HAVE_SYS_SOCKET_H
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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
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43#endif
44
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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>
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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
70static int
71fdwalk (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
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160static 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
165static int
166do_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
174void
175notice_open_fds (void)
176{
177 fdwalk (do_mark_open_fd, NULL);
178}
179
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180/* See filestuff.h. */
181
182void
183mark_fd_no_cloexec (int fd)
184{
185 do_mark_open_fd (NULL, fd);
186}
187
188/* See filestuff.h. */
189
190void
191unmark_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
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207/* Helper function for close_most_fds that closes the file descriptor
208 if appropriate. */
209
210static int
211do_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
230void
231close_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
245static int trust_o_cloexec;
246
247/* Mark FD as close-on-exec, ignoring errors. Update
248 TRUST_O_CLOEXEC. */
249
250static void
251mark_cloexec (int fd)
252{
5d71132c 253#ifdef HAVE_F_GETFD
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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 */
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269}
270
271/* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */
272
273static void
274maybe_mark_cloexec (int fd)
275{
276 if (trust_o_cloexec <= 0)
277 mark_cloexec (fd);
278}
279
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280#ifdef HAVE_SOCKETS
281
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282/* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */
283
284static void
285socket_mark_cloexec (int fd)
286{
287 if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0)
288 mark_cloexec (fd);
289}
290
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291#endif
292
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293\f
294
295/* See filestuff.h. */
296
297int
5d71132c 298gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
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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
310FILE *
311gdb_fopen_cloexec (const char *filename, const char *opentype)
312{
c74e1ccf 313 FILE *result;
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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)
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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
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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 }
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340 else
341 result = fopen (filename, opentype);
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342
343 if (result != NULL)
344 maybe_mark_cloexec (fileno (result));
345
346 return result;
347}
348
8658d16d 349#ifdef HAVE_SOCKETS
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350/* See filestuff.h. */
351
352int
353gdb_socketpair_cloexec (int namespace, int style, int protocol, int filedes[2])
354{
5d71132c 355#ifdef HAVE_SOCKETPAIR
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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;
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365#else
366 gdb_assert_not_reached (_("socketpair not available on this host"));
367#endif
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368}
369
370/* See filestuff.h. */
371
372int
373gdb_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
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383
384/* See filestuff.h. */
385
386int
387gdb_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
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400 result = pipe (filedes);
401 if (result != -1)
402 {
403 mark_cloexec (filedes[0]);
404 mark_cloexec (filedes[1]);
405 }
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406#else /* HAVE_PIPE */
407 gdb_assert_not_reached (_("pipe not available on this host"));
408#endif /* HAVE_PIPE */
409#endif /* HAVE_PIPE2 */
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410
411 return result;
412}
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