Mercurial > hg > octave-lojdl > gnulib-hg
annotate lib/savewd.c @ 9309:bbbbbf4cd1c5
Change copyright notice from GPLv2+ to GPLv3+.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Sun, 07 Oct 2007 19:14:58 +0200 |
| parents | 7dc60fc8f2b4 |
| children | 909daff94315 |
| rev | line source |
|---|---|
| 7315 | 1 /* Save and restore the working directory, possibly using a child process. |
| 2 | |
|
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exit.h is replaced with stdlib.h.
Bruno Haible <bruno@clisp.org>
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diff
changeset
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3 Copyright (C) 2006, 2007 Free Software Foundation, Inc. |
| 7315 | 4 |
|
9309
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Change copyright notice from GPLv2+ to GPLv3+.
Bruno Haible <bruno@clisp.org>
parents:
9216
diff
changeset
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5 This program is free software: you can redistribute it and/or modify |
| 7315 | 6 it under the terms of the GNU General Public License as published by |
|
9309
bbbbbf4cd1c5
Change copyright notice from GPLv2+ to GPLv3+.
Bruno Haible <bruno@clisp.org>
parents:
9216
diff
changeset
|
7 the Free Software Foundation; either version 3 of the License, or |
|
bbbbbf4cd1c5
Change copyright notice from GPLv2+ to GPLv3+.
Bruno Haible <bruno@clisp.org>
parents:
9216
diff
changeset
|
8 (at your option) any later version. |
| 7315 | 9 |
| 10 This program is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 13 GNU General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU General Public License | |
|
9309
bbbbbf4cd1c5
Change copyright notice from GPLv2+ to GPLv3+.
Bruno Haible <bruno@clisp.org>
parents:
9216
diff
changeset
|
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 7315 | 17 |
| 18 /* Written by Paul Eggert. */ | |
| 19 | |
| 20 #include <config.h> | |
| 21 | |
| 22 #include "savewd.h" | |
| 23 | |
| 24 #include <assert.h> | |
| 25 #include <errno.h> | |
| 26 #include <fcntl.h> | |
| 7375 | 27 #include <signal.h> |
| 7315 | 28 #include <stdbool.h> |
|
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exit.h is replaced with stdlib.h.
Bruno Haible <bruno@clisp.org>
parents:
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diff
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29 #include <stdlib.h> |
| 7315 | 30 #include <sys/types.h> |
| 31 #include <sys/wait.h> | |
| 32 #include <unistd.h> | |
| 33 | |
| 34 #include "dirname.h" | |
| 35 #include "fcntl-safer.h" | |
| 36 | |
|
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* lib/savewd.c (ESTALE) [!defined]: Define.
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37 #ifndef ESTALE |
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* lib/savewd.c (ESTALE) [!defined]: Define.
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38 # define ESTALE -1 |
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* lib/savewd.c (ESTALE) [!defined]: Define.
Jim Meyering <jim@meyering.net>
parents:
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diff
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39 #endif |
| 7315 | 40 |
| 41 /* Save the working directory into *WD, if it hasn't been saved | |
| 42 already. Return true if a child has been forked to do the real | |
| 43 work. */ | |
| 44 static bool | |
| 45 savewd_save (struct savewd *wd) | |
| 46 { | |
| 47 switch (wd->state) | |
| 48 { | |
| 49 case INITIAL_STATE: | |
| 50 /* Save the working directory, or prepare to fall back if possible. */ | |
| 51 { | |
| 52 int fd = open_safer (".", O_RDONLY); | |
| 53 if (0 <= fd) | |
| 54 { | |
| 55 wd->state = FD_STATE; | |
| 56 wd->val.fd = fd; | |
| 57 break; | |
| 58 } | |
|
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When trying to open ".", treat ESTALE like EACCES.
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59 if (errno != EACCES && errno != ESTALE) |
| 7315 | 60 { |
| 61 wd->state = ERROR_STATE; | |
| 62 wd->val.errnum = errno; | |
| 63 break; | |
| 64 } | |
| 65 } | |
| 66 wd->state = FORKING_STATE; | |
| 67 wd->val.child = -1; | |
| 68 /* Fall through. */ | |
| 69 case FORKING_STATE: | |
| 70 if (wd->val.child < 0) | |
| 71 { | |
| 72 /* "Save" the initial working directory by forking a new | |
| 73 subprocess that will attempt all the work from the chdir | |
| 74 until until the next savewd_restore. */ | |
| 75 wd->val.child = fork (); | |
| 76 if (wd->val.child != 0) | |
| 77 { | |
| 78 if (0 < wd->val.child) | |
| 79 return true; | |
| 80 wd->state = ERROR_STATE; | |
| 81 wd->val.errnum = errno; | |
| 82 } | |
| 83 } | |
| 84 break; | |
| 85 | |
| 86 case FD_STATE: | |
| 87 case FD_POST_CHDIR_STATE: | |
| 88 case ERROR_STATE: | |
| 89 case FINAL_STATE: | |
| 90 break; | |
| 91 | |
| 92 default: | |
| 93 assert (false); | |
| 94 } | |
| 95 | |
| 96 return false; | |
| 97 } | |
| 98 | |
| 99 int | |
| 100 savewd_chdir (struct savewd *wd, char const *dir, int options, | |
| 101 int open_result[2]) | |
| 102 { | |
| 103 int fd = -1; | |
| 104 int result = 0; | |
| 105 | |
| 106 /* Open the directory if requested, or if avoiding a race condition | |
| 107 is requested and possible. */ | |
| 7408 | 108 if (open_result |
| 109 || (options & (HAVE_WORKING_O_NOFOLLOW ? SAVEWD_CHDIR_NOFOLLOW : 0))) | |
| 7315 | 110 { |
| 111 fd = open (dir, | |
| 112 (O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NONBLOCK | |
| 113 | (options & SAVEWD_CHDIR_NOFOLLOW ? O_NOFOLLOW : 0))); | |
| 114 | |
| 115 if (open_result) | |
| 116 { | |
| 117 open_result[0] = fd; | |
| 118 open_result[1] = errno; | |
| 119 } | |
| 120 | |
| 121 if (fd < 0 && (errno != EACCES || (options & SAVEWD_CHDIR_READABLE))) | |
| 122 result = -1; | |
| 123 } | |
| 124 | |
| 125 if (result == 0 && ! (0 <= fd && options & SAVEWD_CHDIR_SKIP_READABLE)) | |
| 126 { | |
| 127 if (savewd_save (wd)) | |
| 128 { | |
| 129 open_result = NULL; | |
| 130 result = -2; | |
| 131 } | |
| 132 else | |
| 133 { | |
| 134 result = (fd < 0 ? chdir (dir) : fchdir (fd)); | |
| 135 | |
| 136 if (result == 0) | |
| 137 switch (wd->state) | |
| 138 { | |
| 139 case FD_STATE: | |
| 140 wd->state = FD_POST_CHDIR_STATE; | |
| 141 break; | |
| 142 | |
| 143 case ERROR_STATE: | |
| 144 case FD_POST_CHDIR_STATE: | |
| 145 case FINAL_STATE: | |
| 146 break; | |
| 147 | |
| 148 case FORKING_STATE: | |
| 149 assert (wd->val.child == 0); | |
| 150 break; | |
| 151 | |
| 152 default: | |
| 153 assert (false); | |
| 154 } | |
| 155 } | |
| 156 } | |
| 157 | |
| 158 if (0 <= fd && ! open_result) | |
| 159 { | |
| 160 int e = errno; | |
| 161 close (fd); | |
| 162 errno = e; | |
| 163 } | |
| 164 | |
| 165 return result; | |
| 166 } | |
| 167 | |
| 168 int | |
| 169 savewd_restore (struct savewd *wd, int status) | |
| 170 { | |
| 171 switch (wd->state) | |
| 172 { | |
| 173 case INITIAL_STATE: | |
| 174 case FD_STATE: | |
| 175 /* The working directory is the desired directory, so there's no | |
| 176 work to do. */ | |
| 177 break; | |
| 178 | |
| 179 case FD_POST_CHDIR_STATE: | |
| 180 /* Restore the working directory using fchdir. */ | |
| 181 if (fchdir (wd->val.fd) == 0) | |
| 182 { | |
| 183 wd->state = FD_STATE; | |
| 184 break; | |
| 185 } | |
| 186 else | |
| 187 { | |
| 188 int chdir_errno = errno; | |
| 189 close (wd->val.fd); | |
| 190 wd->state = ERROR_STATE; | |
| 191 wd->val.errnum = chdir_errno; | |
| 192 } | |
| 193 /* Fall through. */ | |
| 194 case ERROR_STATE: | |
| 195 /* Report an error if asked to restore the working directory. */ | |
| 196 errno = wd->val.errnum; | |
| 197 return -1; | |
| 198 | |
| 199 case FORKING_STATE: | |
| 200 /* "Restore" the working directory by waiting for the subprocess | |
| 201 to finish. */ | |
| 202 { | |
| 203 pid_t child = wd->val.child; | |
| 204 if (child == 0) | |
| 205 _exit (status); | |
| 206 if (0 < child) | |
| 207 { | |
|
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* savewd.c (savewd_restore): Don't shadow: s/status/child_status/.
Jim Meyering <jim@meyering.net>
parents:
7315
diff
changeset
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208 int child_status; |
|
251167cff509
* savewd.c (savewd_restore): Don't shadow: s/status/child_status/.
Jim Meyering <jim@meyering.net>
parents:
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diff
changeset
|
209 while (waitpid (child, &child_status, 0) < 0) |
| 7315 | 210 assert (errno == EINTR); |
| 211 wd->val.child = -1; | |
|
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* savewd.c (savewd_restore): Don't shadow: s/status/child_status/.
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parents:
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212 if (! WIFEXITED (child_status)) |
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* savewd.c (savewd_restore): Don't shadow: s/status/child_status/.
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213 raise (WTERMSIG (child_status)); |
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* savewd.c (savewd_restore): Don't shadow: s/status/child_status/.
Jim Meyering <jim@meyering.net>
parents:
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diff
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214 return WEXITSTATUS (child_status); |
| 7315 | 215 } |
| 216 } | |
| 217 break; | |
| 218 | |
| 219 default: | |
| 220 assert (false); | |
| 221 } | |
| 222 | |
| 223 return 0; | |
| 224 } | |
| 225 | |
| 226 void | |
| 227 savewd_finish (struct savewd *wd) | |
| 228 { | |
| 229 switch (wd->state) | |
| 230 { | |
| 231 case INITIAL_STATE: | |
| 232 case ERROR_STATE: | |
| 233 break; | |
| 234 | |
| 235 case FD_STATE: | |
| 236 case FD_POST_CHDIR_STATE: | |
| 237 close (wd->val.fd); | |
| 238 break; | |
| 239 | |
| 240 case FORKING_STATE: | |
| 241 assert (wd->val.child < 0); | |
| 242 break; | |
| 243 | |
| 244 default: | |
| 245 assert (false); | |
| 246 } | |
| 247 | |
| 248 wd->state = FINAL_STATE; | |
| 249 } | |
| 250 | |
| 251 /* Return true if the actual work is currently being done by a | |
| 252 subprocess. | |
| 253 | |
| 254 A true return means that the caller and the subprocess should | |
| 255 resynchronize later with savewd_restore, using only their own | |
| 256 memory to decide when to resynchronize; they should not consult the | |
| 257 file system to decide, because that might lead to race conditions. | |
| 258 This is why savewd_chdir is broken out into another function; | |
| 259 savewd_chdir's callers _can_ inspect the file system to decide | |
| 260 whether to call savewd_chdir. */ | |
| 261 static inline bool | |
| 262 savewd_delegating (struct savewd const *wd) | |
| 263 { | |
| 264 return wd->state == FORKING_STATE && 0 < wd->val.child; | |
| 265 } | |
| 266 | |
| 267 int | |
| 268 savewd_process_files (int n_files, char **file, | |
| 269 int (*act) (char *, struct savewd *, void *), | |
| 270 void *options) | |
| 271 { | |
| 272 int i = 0; | |
| 273 int last_relative; | |
| 274 int exit_status = EXIT_SUCCESS; | |
| 275 struct savewd wd; | |
| 276 savewd_init (&wd); | |
| 277 | |
| 278 for (last_relative = n_files - 1; 0 <= last_relative; last_relative--) | |
| 279 if (! IS_ABSOLUTE_FILE_NAME (file[last_relative])) | |
| 280 break; | |
| 281 | |
| 282 for (; i < last_relative; i++) | |
| 283 { | |
| 284 if (! savewd_delegating (&wd)) | |
| 285 { | |
| 286 int s = act (file[i], &wd, options); | |
| 287 if (exit_status < s) | |
| 288 exit_status = s; | |
| 289 } | |
| 290 | |
| 291 if (! IS_ABSOLUTE_FILE_NAME (file[i + 1])) | |
| 292 { | |
| 293 int r = savewd_restore (&wd, exit_status); | |
| 294 if (exit_status < r) | |
| 295 exit_status = r; | |
| 296 } | |
| 297 } | |
| 298 | |
| 299 savewd_finish (&wd); | |
| 300 | |
| 301 for (; i < n_files; i++) | |
| 302 { | |
| 303 int s = act (file[i], &wd, options); | |
| 304 if (exit_status < s) | |
| 305 exit_status = s; | |
| 306 } | |
| 307 | |
| 308 return exit_status; | |
| 309 } |