| 1 | /* |
| 2 | * State diagram and cleanup |
| 3 | * ------------------------- |
| 4 | * |
| 5 | * If the program exits while a temporary file is active, we want to |
| 6 | * make sure that we remove it. This is done by remembering the active |
| 7 | * temporary files in a linked list, `tempfile_list`. An `atexit(3)` |
| 8 | * handler and a signal handler are registered, to clean up any active |
| 9 | * temporary files. |
| 10 | * |
| 11 | * Because the signal handler can run at any time, `tempfile_list` and |
| 12 | * the `tempfile` objects that comprise it must be kept in |
| 13 | * self-consistent states at all times. |
| 14 | * |
| 15 | * The possible states of a `tempfile` object are as follows: |
| 16 | * |
| 17 | * - Inactive/unallocated. The only way to get a tempfile is via a creation |
| 18 | * function like create_tempfile(). Once allocated, the tempfile is on the |
| 19 | * global tempfile_list and considered active. |
| 20 | * |
| 21 | * - Active, file open (after `create_tempfile()` or |
| 22 | * `reopen_tempfile()`). In this state: |
| 23 | * |
| 24 | * - the temporary file exists |
| 25 | * - `filename` holds the filename of the temporary file |
| 26 | * - `fd` holds a file descriptor open for writing to it |
| 27 | * - `fp` holds a pointer to an open `FILE` object if and only if |
| 28 | * `fdopen_tempfile()` has been called on the object |
| 29 | * - `owner` holds the PID of the process that created the file |
| 30 | * |
| 31 | * - Active, file closed (after `close_tempfile_gently()`). Same |
| 32 | * as the previous state, except that the temporary file is closed, |
| 33 | * `fd` is -1, and `fp` is `NULL`. |
| 34 | * |
| 35 | * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, or a |
| 36 | * failed attempt to create a temporary file). The struct is removed from |
| 37 | * the global tempfile_list and deallocated. |
| 38 | * |
| 39 | * A temporary file is owned by the process that created it. The |
| 40 | * `tempfile` has an `owner` field that records the owner's PID. This |
| 41 | * field is used to prevent a forked process from deleting a temporary |
| 42 | * file created by its parent. |
| 43 | */ |
| 44 | |
| 45 | #include "git-compat-util.h" |
| 46 | #include "abspath.h" |
| 47 | #include "path.h" |
| 48 | #include "tempfile.h" |
| 49 | #include "sigchain.h" |
| 50 | |
| 51 | static VOLATILE_LIST_HEAD(tempfile_list); |
| 52 | |
| 53 | static int remove_template_directory(struct tempfile *tempfile, |
| 54 | int in_signal_handler) |
| 55 | { |
| 56 | if (tempfile->directory) { |
| 57 | if (in_signal_handler) |
| 58 | return rmdir(tempfile->directory); |
| 59 | else |
| 60 | return rmdir_or_warn(tempfile->directory); |
| 61 | } |
| 62 | |
| 63 | return 0; |
| 64 | } |
| 65 | |
| 66 | static void remove_tempfiles(int in_signal_handler) |
| 67 | { |
| 68 | pid_t me = getpid(); |
| 69 | volatile struct volatile_list_head *pos; |
| 70 | |
| 71 | list_for_each(pos, &tempfile_list) { |
| 72 | struct tempfile *p = list_entry(pos, struct tempfile, list); |
| 73 | |
| 74 | if (!is_tempfile_active(p) || p->owner != me) |
| 75 | continue; |
| 76 | |
| 77 | if (p->fd >= 0) |
| 78 | close(p->fd); |
| 79 | |
| 80 | if (in_signal_handler) |
| 81 | unlink(p->filename.buf); |
| 82 | else |
| 83 | unlink_or_warn(p->filename.buf); |
| 84 | remove_template_directory(p, in_signal_handler); |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | static void remove_tempfiles_on_exit(void) |
| 89 | { |
| 90 | remove_tempfiles(0); |
| 91 | } |
| 92 | |
| 93 | static void remove_tempfiles_on_signal(int signo) |
| 94 | { |
| 95 | remove_tempfiles(1); |
| 96 | sigchain_pop(signo); |
| 97 | raise(signo); |
| 98 | } |
| 99 | |
| 100 | static struct tempfile *new_tempfile(void) |
| 101 | { |
| 102 | struct tempfile *tempfile = xmalloc(sizeof(*tempfile)); |
| 103 | tempfile->fd = -1; |
| 104 | tempfile->fp = NULL; |
| 105 | tempfile->owner = 0; |
| 106 | INIT_LIST_HEAD(&tempfile->list); |
| 107 | strbuf_init(&tempfile->filename, 0); |
| 108 | tempfile->directory = NULL; |
| 109 | return tempfile; |
| 110 | } |
| 111 | |
| 112 | static void activate_tempfile(struct tempfile *tempfile) |
| 113 | { |
| 114 | static int initialized; |
| 115 | |
| 116 | if (!initialized) { |
| 117 | sigchain_push_common(remove_tempfiles_on_signal); |
| 118 | atexit(remove_tempfiles_on_exit); |
| 119 | initialized = 1; |
| 120 | } |
| 121 | |
| 122 | volatile_list_add(&tempfile->list, &tempfile_list); |
| 123 | tempfile->owner = getpid(); |
| 124 | } |
| 125 | |
| 126 | static void deactivate_tempfile(struct tempfile *tempfile) |
| 127 | { |
| 128 | volatile_list_del(&tempfile->list); |
| 129 | strbuf_release(&tempfile->filename); |
| 130 | free(tempfile->directory); |
| 131 | free(tempfile); |
| 132 | } |
| 133 | |
| 134 | /* Make sure errno contains a meaningful value on error */ |
| 135 | struct tempfile *repo_create_tempfile_mode(struct repository *r, |
| 136 | const char *path, int mode) |
| 137 | { |
| 138 | struct tempfile *tempfile = new_tempfile(); |
| 139 | |
| 140 | strbuf_add_absolute_path(&tempfile->filename, path); |
| 141 | tempfile->fd = open(tempfile->filename.buf, |
| 142 | O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, mode); |
| 143 | if (O_CLOEXEC && tempfile->fd < 0 && errno == EINVAL) |
| 144 | /* Try again w/o O_CLOEXEC: the kernel might not support it */ |
| 145 | tempfile->fd = open(tempfile->filename.buf, |
| 146 | O_RDWR | O_CREAT | O_EXCL, mode); |
| 147 | if (tempfile->fd < 0) { |
| 148 | deactivate_tempfile(tempfile); |
| 149 | return NULL; |
| 150 | } |
| 151 | activate_tempfile(tempfile); |
| 152 | if (adjust_shared_perm(r, tempfile->filename.buf)) { |
| 153 | int save_errno = errno; |
| 154 | error("cannot fix permission bits on %s", tempfile->filename.buf); |
| 155 | delete_tempfile(&tempfile); |
| 156 | errno = save_errno; |
| 157 | return NULL; |
| 158 | } |
| 159 | |
| 160 | return tempfile; |
| 161 | } |
| 162 | |
| 163 | struct tempfile *register_tempfile(const char *path) |
| 164 | { |
| 165 | struct tempfile *tempfile = new_tempfile(); |
| 166 | strbuf_add_absolute_path(&tempfile->filename, path); |
| 167 | activate_tempfile(tempfile); |
| 168 | return tempfile; |
| 169 | } |
| 170 | |
| 171 | struct tempfile *mks_tempfile_sm(const char *filename_template, int suffixlen, int mode) |
| 172 | { |
| 173 | struct tempfile *tempfile = new_tempfile(); |
| 174 | |
| 175 | strbuf_add_absolute_path(&tempfile->filename, filename_template); |
| 176 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); |
| 177 | if (tempfile->fd < 0) { |
| 178 | deactivate_tempfile(tempfile); |
| 179 | return NULL; |
| 180 | } |
| 181 | activate_tempfile(tempfile); |
| 182 | return tempfile; |
| 183 | } |
| 184 | |
| 185 | struct tempfile *mks_tempfile_tsm(const char *filename_template, int suffixlen, int mode) |
| 186 | { |
| 187 | struct tempfile *tempfile = new_tempfile(); |
| 188 | const char *tmpdir; |
| 189 | |
| 190 | tmpdir = getenv("TMPDIR"); |
| 191 | if (!tmpdir) |
| 192 | tmpdir = "/tmp"; |
| 193 | |
| 194 | strbuf_addf(&tempfile->filename, "%s/%s", tmpdir, filename_template); |
| 195 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); |
| 196 | if (tempfile->fd < 0) { |
| 197 | deactivate_tempfile(tempfile); |
| 198 | return NULL; |
| 199 | } |
| 200 | activate_tempfile(tempfile); |
| 201 | return tempfile; |
| 202 | } |
| 203 | |
| 204 | struct tempfile *mks_tempfile_dt(const char *directory_template, |
| 205 | const char *filename) |
| 206 | { |
| 207 | struct tempfile *tempfile; |
| 208 | const char *tmpdir; |
| 209 | struct strbuf sb = STRBUF_INIT; |
| 210 | int fd; |
| 211 | size_t directorylen; |
| 212 | |
| 213 | if (!ends_with(directory_template, "XXXXXX")) { |
| 214 | errno = EINVAL; |
| 215 | return NULL; |
| 216 | } |
| 217 | |
| 218 | tmpdir = getenv("TMPDIR"); |
| 219 | if (!tmpdir) |
| 220 | tmpdir = "/tmp"; |
| 221 | |
| 222 | strbuf_addf(&sb, "%s/%s", tmpdir, directory_template); |
| 223 | directorylen = sb.len; |
| 224 | if (!mkdtemp(sb.buf)) { |
| 225 | int orig_errno = errno; |
| 226 | strbuf_release(&sb); |
| 227 | errno = orig_errno; |
| 228 | return NULL; |
| 229 | } |
| 230 | |
| 231 | strbuf_addf(&sb, "/%s", filename); |
| 232 | fd = open(sb.buf, O_CREAT | O_EXCL | O_RDWR, 0600); |
| 233 | if (fd < 0) { |
| 234 | int orig_errno = errno; |
| 235 | strbuf_setlen(&sb, directorylen); |
| 236 | rmdir(sb.buf); |
| 237 | strbuf_release(&sb); |
| 238 | errno = orig_errno; |
| 239 | return NULL; |
| 240 | } |
| 241 | |
| 242 | tempfile = new_tempfile(); |
| 243 | strbuf_swap(&tempfile->filename, &sb); |
| 244 | tempfile->directory = xmemdupz(tempfile->filename.buf, directorylen); |
| 245 | tempfile->fd = fd; |
| 246 | activate_tempfile(tempfile); |
| 247 | return tempfile; |
| 248 | } |
| 249 | |
| 250 | struct tempfile *xmks_tempfile_m(const char *filename_template, int mode) |
| 251 | { |
| 252 | struct tempfile *tempfile; |
| 253 | struct strbuf full_template = STRBUF_INIT; |
| 254 | |
| 255 | strbuf_add_absolute_path(&full_template, filename_template); |
| 256 | tempfile = mks_tempfile_m(full_template.buf, mode); |
| 257 | if (!tempfile) |
| 258 | die_errno("Unable to create temporary file '%s'", |
| 259 | full_template.buf); |
| 260 | |
| 261 | strbuf_release(&full_template); |
| 262 | return tempfile; |
| 263 | } |
| 264 | |
| 265 | FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode) |
| 266 | { |
| 267 | if (!is_tempfile_active(tempfile)) |
| 268 | BUG("fdopen_tempfile() called for inactive object"); |
| 269 | if (tempfile->fp) |
| 270 | BUG("fdopen_tempfile() called for open object"); |
| 271 | |
| 272 | tempfile->fp = fdopen(tempfile->fd, mode); |
| 273 | return tempfile->fp; |
| 274 | } |
| 275 | |
| 276 | const char *get_tempfile_path(struct tempfile *tempfile) |
| 277 | { |
| 278 | if (!is_tempfile_active(tempfile)) |
| 279 | BUG("get_tempfile_path() called for inactive object"); |
| 280 | return tempfile->filename.buf; |
| 281 | } |
| 282 | |
| 283 | int get_tempfile_fd(struct tempfile *tempfile) |
| 284 | { |
| 285 | if (!is_tempfile_active(tempfile)) |
| 286 | BUG("get_tempfile_fd() called for inactive object"); |
| 287 | return tempfile->fd; |
| 288 | } |
| 289 | |
| 290 | FILE *get_tempfile_fp(struct tempfile *tempfile) |
| 291 | { |
| 292 | if (!is_tempfile_active(tempfile)) |
| 293 | BUG("get_tempfile_fp() called for inactive object"); |
| 294 | return tempfile->fp; |
| 295 | } |
| 296 | |
| 297 | int close_tempfile_gently(struct tempfile *tempfile) |
| 298 | { |
| 299 | int fd; |
| 300 | FILE *fp; |
| 301 | int err; |
| 302 | |
| 303 | if (!is_tempfile_active(tempfile) || tempfile->fd < 0) |
| 304 | return 0; |
| 305 | |
| 306 | fd = tempfile->fd; |
| 307 | fp = tempfile->fp; |
| 308 | tempfile->fd = -1; |
| 309 | if (fp) { |
| 310 | tempfile->fp = NULL; |
| 311 | if (ferror(fp)) { |
| 312 | err = -1; |
| 313 | if (!fclose(fp)) |
| 314 | errno = EIO; |
| 315 | } else { |
| 316 | err = fclose(fp); |
| 317 | } |
| 318 | } else { |
| 319 | err = close(fd); |
| 320 | } |
| 321 | |
| 322 | return err ? -1 : 0; |
| 323 | } |
| 324 | |
| 325 | int reopen_tempfile(struct tempfile *tempfile) |
| 326 | { |
| 327 | if (!is_tempfile_active(tempfile)) |
| 328 | BUG("reopen_tempfile called for an inactive object"); |
| 329 | if (0 <= tempfile->fd) |
| 330 | BUG("reopen_tempfile called for an open object"); |
| 331 | tempfile->fd = open(tempfile->filename.buf, O_WRONLY|O_TRUNC); |
| 332 | return tempfile->fd; |
| 333 | } |
| 334 | |
| 335 | int rename_tempfile(struct tempfile **tempfile_p, const char *path) |
| 336 | { |
| 337 | struct tempfile *tempfile = *tempfile_p; |
| 338 | |
| 339 | if (!is_tempfile_active(tempfile)) |
| 340 | BUG("rename_tempfile called for inactive object"); |
| 341 | |
| 342 | if (close_tempfile_gently(tempfile)) { |
| 343 | delete_tempfile(tempfile_p); |
| 344 | return -1; |
| 345 | } |
| 346 | |
| 347 | if (rename(tempfile->filename.buf, path)) { |
| 348 | int save_errno = errno; |
| 349 | delete_tempfile(tempfile_p); |
| 350 | errno = save_errno; |
| 351 | return -1; |
| 352 | } |
| 353 | |
| 354 | deactivate_tempfile(tempfile); |
| 355 | *tempfile_p = NULL; |
| 356 | return 0; |
| 357 | } |
| 358 | |
| 359 | int delete_tempfile(struct tempfile **tempfile_p) |
| 360 | { |
| 361 | struct tempfile *tempfile = *tempfile_p; |
| 362 | int err = 0; |
| 363 | |
| 364 | if (!is_tempfile_active(tempfile)) |
| 365 | return 0; |
| 366 | |
| 367 | err |= close_tempfile_gently(tempfile); |
| 368 | err |= unlink_or_warn(tempfile->filename.buf); |
| 369 | err |= remove_template_directory(tempfile, 0); |
| 370 | deactivate_tempfile(tempfile); |
| 371 | *tempfile_p = NULL; |
| 372 | |
| 373 | return err ? -1 : 0; |
| 374 | } |
| 375 | |
| 376 | void reassign_tempfile_ownership(pid_t from, pid_t to) |
| 377 | { |
| 378 | volatile struct volatile_list_head *pos; |
| 379 | |
| 380 | list_for_each(pos, &tempfile_list) { |
| 381 | struct tempfile *p = list_entry(pos, struct tempfile, list); |
| 382 | |
| 383 | if (is_tempfile_active(p) && p->owner == from) |
| 384 | p->owner = to; |
| 385 | } |
| 386 | } |