Commit | Line | Data |
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1d498196 MD |
1 | /* |
2 | * libringbuffer/shm.c | |
3 | * | |
e92f3e28 | 4 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
1d498196 | 5 | * |
e92f3e28 MD |
6 | * This library is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; only | |
9 | * version 2.1 of the License. | |
10 | * | |
11 | * This library 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 GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
1d498196 MD |
19 | */ |
20 | ||
21 | #include "shm.h" | |
22 | #include <unistd.h> | |
23 | #include <fcntl.h> | |
24 | #include <sys/mman.h> | |
a9ff648c | 25 | #include <sys/types.h> |
1d498196 MD |
26 | #include <sys/stat.h> /* For mode constants */ |
27 | #include <fcntl.h> /* For O_* constants */ | |
28 | #include <assert.h> | |
8da6cd6d MD |
29 | #include <stdio.h> |
30 | #include <signal.h> | |
31 | #include <dirent.h> | |
4318ae1b | 32 | #include <lttng/align.h> |
96e80018 | 33 | #include <limits.h> |
3a81f31d MD |
34 | #include <helper.h> |
35 | ||
36 | /* | |
37 | * Ensure we have the required amount of space available by writing 0 | |
38 | * into the entire buffer. Not doing so can trigger SIGBUS when going | |
39 | * beyond the available shm space. | |
40 | */ | |
41 | static | |
42 | int zero_file(int fd, size_t len) | |
43 | { | |
44 | ssize_t retlen; | |
45 | size_t written = 0; | |
46 | char *zeropage; | |
47 | long pagelen; | |
48 | int ret; | |
49 | ||
50 | pagelen = sysconf(_SC_PAGESIZE); | |
51 | if (pagelen < 0) | |
52 | return (int) pagelen; | |
53 | zeropage = calloc(pagelen, 1); | |
54 | if (!zeropage) | |
55 | return -ENOMEM; | |
56 | ||
57 | while (len > written) { | |
58 | do { | |
59 | retlen = write(fd, zeropage, | |
60 | min_t(size_t, pagelen, len - written)); | |
61 | } while (retlen == -1UL && errno == EINTR); | |
62 | if (retlen < 0) { | |
63 | ret = (int) retlen; | |
64 | goto error; | |
65 | } | |
66 | written += retlen; | |
67 | } | |
68 | ret = 0; | |
69 | error: | |
70 | free(zeropage); | |
71 | return ret; | |
72 | } | |
1d498196 MD |
73 | |
74 | struct shm_object_table *shm_object_table_create(size_t max_nb_obj) | |
75 | { | |
76 | struct shm_object_table *table; | |
77 | ||
78 | table = zmalloc(sizeof(struct shm_object_table) + | |
79 | max_nb_obj * sizeof(table->objects[0])); | |
74d48abe MD |
80 | if (!table) |
81 | return NULL; | |
1d498196 MD |
82 | table->size = max_nb_obj; |
83 | return table; | |
84 | } | |
85 | ||
a9ff648c MD |
86 | static |
87 | int create_posix_shm(void) | |
88 | { | |
89 | char tmp_name[NAME_MAX] = "/ust-shm-tmp-XXXXXX"; | |
90 | int shmfd, ret; | |
91 | ||
92 | /* | |
93 | * Allocate shm, and immediately unlink its shm oject, keeping | |
94 | * only the file descriptor as a reference to the object. If it | |
95 | * already exists (caused by short race window during which the | |
96 | * global object exists in a concurrent shm_open), simply retry. | |
97 | * We specifically do _not_ use the / at the beginning of the | |
98 | * pathname so that some OS implementations can keep it local to | |
99 | * the process (POSIX leaves this implementation-defined). | |
100 | */ | |
101 | do { | |
102 | /* | |
103 | * Using mktemp filename with O_CREAT | O_EXCL open | |
104 | * flags. | |
105 | */ | |
106 | (void) mktemp(tmp_name); | |
107 | if (tmp_name[0] == '\0') { | |
108 | PERROR("mktemp"); | |
109 | goto error_shm_open; | |
110 | } | |
111 | shmfd = shm_open(tmp_name, | |
112 | O_CREAT | O_EXCL | O_RDWR, 0700); | |
113 | } while (shmfd < 0 && (errno == EEXIST || errno == EACCES)); | |
114 | if (shmfd < 0) { | |
115 | PERROR("shm_open"); | |
116 | goto error_shm_open; | |
117 | } | |
118 | ret = shm_unlink(tmp_name); | |
119 | if (ret < 0 && errno != ENOENT) { | |
120 | PERROR("shm_unlink"); | |
121 | goto error_shm_release; | |
122 | } | |
123 | return shmfd; | |
124 | ||
125 | error_shm_release: | |
126 | ret = close(shmfd); | |
127 | if (ret) { | |
128 | PERROR("close"); | |
129 | assert(0); | |
130 | } | |
131 | error_shm_open: | |
132 | return -1; | |
133 | } | |
134 | ||
135 | static | |
136 | int create_shared_file(const char *shm_path) | |
137 | { | |
138 | return open(shm_path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); | |
139 | } | |
140 | ||
74d81a6c MD |
141 | static |
142 | struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, | |
a9ff648c MD |
143 | size_t memory_map_size, |
144 | const char *shm_path) | |
1d498196 | 145 | { |
5a61337d | 146 | int shmfd, waitfd[2], ret, i, sigblocked = 0; |
1d498196 MD |
147 | struct shm_object *obj; |
148 | char *memory_map; | |
8da6cd6d | 149 | sigset_t all_sigs, orig_sigs; |
1d498196 MD |
150 | |
151 | if (table->allocated_len >= table->size) | |
152 | return NULL; | |
7a9c21bd | 153 | obj = &table->objects[table->allocated_len]; |
1d498196 MD |
154 | |
155 | /* wait_fd: create pipe */ | |
156 | ret = pipe(waitfd); | |
157 | if (ret < 0) { | |
158 | PERROR("pipe"); | |
159 | goto error_pipe; | |
160 | } | |
161 | for (i = 0; i < 2; i++) { | |
162 | ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC); | |
163 | if (ret < 0) { | |
164 | PERROR("fcntl"); | |
165 | goto error_fcntl; | |
166 | } | |
167 | } | |
5d61a504 MD |
168 | /* The write end of the pipe needs to be non-blocking */ |
169 | ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK); | |
170 | if (ret < 0) { | |
171 | PERROR("fcntl"); | |
172 | goto error_fcntl; | |
173 | } | |
7a9c21bd | 174 | memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); |
1d498196 MD |
175 | |
176 | /* shm_fd: create shm */ | |
177 | ||
8da6cd6d MD |
178 | /* |
179 | * Theoretically, we could leak a shm if the application crashes | |
180 | * between open and unlink. Disable signals on this thread for | |
181 | * increased safety against this scenario. | |
182 | */ | |
183 | sigfillset(&all_sigs); | |
184 | ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs); | |
185 | if (ret == -1) { | |
186 | PERROR("pthread_sigmask"); | |
187 | goto error_pthread_sigmask; | |
188 | } | |
5a61337d | 189 | sigblocked = 1; |
8da6cd6d | 190 | |
a9ff648c MD |
191 | |
192 | if (!shm_path) { | |
193 | obj->shm_path[0] = '\0'; | |
194 | shmfd = create_posix_shm(); | |
195 | } else { | |
196 | strncpy(obj->shm_path, shm_path, | |
197 | sizeof(obj->shm_path)); | |
198 | obj->shm_path[sizeof(obj->shm_path) - 1] = '\0'; | |
199 | ||
200 | /* Path should already exist, but could fail. */ | |
201 | shmfd = create_shared_file(shm_path); | |
a8803897 | 202 | } |
a9ff648c MD |
203 | if (shmfd < 0) |
204 | goto error_shm_open; | |
205 | ||
5a61337d | 206 | sigblocked = 0; |
8da6cd6d MD |
207 | ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); |
208 | if (ret == -1) { | |
209 | PERROR("pthread_sigmask"); | |
5a61337d | 210 | goto error_sigmask_release; |
8da6cd6d | 211 | } |
3a81f31d MD |
212 | ret = zero_file(shmfd, memory_map_size); |
213 | if (ret) { | |
214 | PERROR("zero_file"); | |
215 | goto error_zero_file; | |
216 | } | |
1d498196 MD |
217 | ret = ftruncate(shmfd, memory_map_size); |
218 | if (ret) { | |
219 | PERROR("ftruncate"); | |
220 | goto error_ftruncate; | |
221 | } | |
222 | obj->shm_fd = shmfd; | |
223 | ||
224 | /* memory_map: mmap */ | |
225 | memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, | |
226 | MAP_SHARED, shmfd, 0); | |
227 | if (memory_map == MAP_FAILED) { | |
228 | PERROR("mmap"); | |
229 | goto error_mmap; | |
230 | } | |
74d81a6c | 231 | obj->type = SHM_OBJECT_SHM; |
1d498196 MD |
232 | obj->memory_map = memory_map; |
233 | obj->memory_map_size = memory_map_size; | |
234 | obj->allocated_len = 0; | |
dc613eb9 | 235 | obj->index = table->allocated_len++; |
7a9c21bd | 236 | |
1d498196 MD |
237 | return obj; |
238 | ||
239 | error_mmap: | |
240 | error_ftruncate: | |
3a81f31d | 241 | error_zero_file: |
5a61337d | 242 | error_sigmask_release: |
1d498196 MD |
243 | ret = close(shmfd); |
244 | if (ret) { | |
245 | PERROR("close"); | |
246 | assert(0); | |
247 | } | |
a9ff648c MD |
248 | if (shm_path) { |
249 | ret = unlink(shm_path); | |
250 | if (ret) { | |
251 | PERROR("ret"); | |
252 | } | |
253 | } | |
1d498196 | 254 | error_shm_open: |
5a61337d MD |
255 | if (sigblocked) { |
256 | ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); | |
257 | if (ret == -1) { | |
258 | PERROR("pthread_sigmask"); | |
259 | } | |
260 | } | |
8da6cd6d | 261 | error_pthread_sigmask: |
1d498196 MD |
262 | error_fcntl: |
263 | for (i = 0; i < 2; i++) { | |
264 | ret = close(waitfd[i]); | |
265 | if (ret) { | |
266 | PERROR("close"); | |
267 | assert(0); | |
268 | } | |
269 | } | |
270 | error_pipe: | |
1d498196 | 271 | return NULL; |
1d498196 MD |
272 | } |
273 | ||
74d81a6c MD |
274 | static |
275 | struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table, | |
276 | size_t memory_map_size) | |
277 | { | |
278 | struct shm_object *obj; | |
279 | void *memory_map; | |
ff0f5728 | 280 | int waitfd[2], i, ret; |
74d81a6c MD |
281 | |
282 | if (table->allocated_len >= table->size) | |
283 | return NULL; | |
284 | obj = &table->objects[table->allocated_len]; | |
285 | ||
286 | memory_map = zmalloc(memory_map_size); | |
287 | if (!memory_map) | |
288 | goto alloc_error; | |
289 | ||
ff0f5728 MD |
290 | /* wait_fd: create pipe */ |
291 | ret = pipe(waitfd); | |
292 | if (ret < 0) { | |
293 | PERROR("pipe"); | |
294 | goto error_pipe; | |
295 | } | |
296 | for (i = 0; i < 2; i++) { | |
297 | ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC); | |
298 | if (ret < 0) { | |
299 | PERROR("fcntl"); | |
300 | goto error_fcntl; | |
301 | } | |
302 | } | |
303 | /* The write end of the pipe needs to be non-blocking */ | |
304 | ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK); | |
305 | if (ret < 0) { | |
306 | PERROR("fcntl"); | |
307 | goto error_fcntl; | |
308 | } | |
309 | memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); | |
310 | ||
311 | /* no shm_fd */ | |
74d81a6c MD |
312 | obj->shm_fd = -1; |
313 | ||
314 | obj->type = SHM_OBJECT_MEM; | |
315 | obj->memory_map = memory_map; | |
316 | obj->memory_map_size = memory_map_size; | |
317 | obj->allocated_len = 0; | |
318 | obj->index = table->allocated_len++; | |
319 | ||
320 | return obj; | |
321 | ||
ff0f5728 MD |
322 | error_fcntl: |
323 | for (i = 0; i < 2; i++) { | |
324 | ret = close(waitfd[i]); | |
325 | if (ret) { | |
326 | PERROR("close"); | |
327 | assert(0); | |
328 | } | |
329 | } | |
330 | error_pipe: | |
331 | free(memory_map); | |
74d81a6c MD |
332 | alloc_error: |
333 | return NULL; | |
334 | } | |
335 | ||
336 | struct shm_object *shm_object_table_alloc(struct shm_object_table *table, | |
337 | size_t memory_map_size, | |
a9ff648c MD |
338 | enum shm_object_type type, |
339 | const char *shm_path) | |
74d81a6c MD |
340 | { |
341 | switch (type) { | |
342 | case SHM_OBJECT_SHM: | |
a9ff648c MD |
343 | return _shm_object_table_alloc_shm(table, memory_map_size, |
344 | shm_path); | |
74d81a6c MD |
345 | case SHM_OBJECT_MEM: |
346 | return _shm_object_table_alloc_mem(table, memory_map_size); | |
347 | default: | |
348 | assert(0); | |
349 | } | |
350 | return NULL; | |
351 | } | |
352 | ||
353 | struct shm_object *shm_object_table_append_shm(struct shm_object_table *table, | |
354 | int shm_fd, int wakeup_fd, uint32_t stream_nr, | |
355 | size_t memory_map_size) | |
193183fb MD |
356 | { |
357 | struct shm_object *obj; | |
358 | char *memory_map; | |
74d81a6c | 359 | int ret; |
193183fb MD |
360 | |
361 | if (table->allocated_len >= table->size) | |
362 | return NULL; | |
74d81a6c MD |
363 | /* streams _must_ be received in sequential order, else fail. */ |
364 | if (stream_nr + 1 != table->allocated_len) | |
365 | return NULL; | |
366 | ||
193183fb MD |
367 | obj = &table->objects[table->allocated_len]; |
368 | ||
74d81a6c MD |
369 | /* wait_fd: set write end of the pipe. */ |
370 | obj->wait_fd[0] = -1; /* read end is unset */ | |
371 | obj->wait_fd[1] = wakeup_fd; | |
193183fb MD |
372 | obj->shm_fd = shm_fd; |
373 | ||
74d81a6c MD |
374 | ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); |
375 | if (ret < 0) { | |
376 | PERROR("fcntl"); | |
377 | goto error_fcntl; | |
378 | } | |
379 | /* The write end of the pipe needs to be non-blocking */ | |
380 | ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK); | |
381 | if (ret < 0) { | |
382 | PERROR("fcntl"); | |
383 | goto error_fcntl; | |
384 | } | |
385 | ||
193183fb MD |
386 | /* memory_map: mmap */ |
387 | memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, | |
388 | MAP_SHARED, shm_fd, 0); | |
389 | if (memory_map == MAP_FAILED) { | |
390 | PERROR("mmap"); | |
391 | goto error_mmap; | |
392 | } | |
74d81a6c | 393 | obj->type = SHM_OBJECT_SHM; |
193183fb MD |
394 | obj->memory_map = memory_map; |
395 | obj->memory_map_size = memory_map_size; | |
396 | obj->allocated_len = memory_map_size; | |
397 | obj->index = table->allocated_len++; | |
398 | ||
399 | return obj; | |
400 | ||
74d81a6c | 401 | error_fcntl: |
193183fb MD |
402 | error_mmap: |
403 | return NULL; | |
404 | } | |
405 | ||
74d81a6c MD |
406 | /* |
407 | * Passing ownership of mem to object. | |
408 | */ | |
409 | struct shm_object *shm_object_table_append_mem(struct shm_object_table *table, | |
ff0f5728 | 410 | void *mem, size_t memory_map_size, int wakeup_fd) |
74d81a6c MD |
411 | { |
412 | struct shm_object *obj; | |
ff0f5728 | 413 | int ret; |
74d81a6c MD |
414 | |
415 | if (table->allocated_len >= table->size) | |
416 | return NULL; | |
417 | obj = &table->objects[table->allocated_len]; | |
418 | ||
ff0f5728 MD |
419 | obj->wait_fd[0] = -1; /* read end is unset */ |
420 | obj->wait_fd[1] = wakeup_fd; | |
74d81a6c MD |
421 | obj->shm_fd = -1; |
422 | ||
ff0f5728 MD |
423 | ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); |
424 | if (ret < 0) { | |
425 | PERROR("fcntl"); | |
426 | goto error_fcntl; | |
427 | } | |
428 | /* The write end of the pipe needs to be non-blocking */ | |
429 | ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK); | |
430 | if (ret < 0) { | |
431 | PERROR("fcntl"); | |
432 | goto error_fcntl; | |
433 | } | |
434 | ||
74d81a6c MD |
435 | obj->type = SHM_OBJECT_MEM; |
436 | obj->memory_map = mem; | |
437 | obj->memory_map_size = memory_map_size; | |
438 | obj->allocated_len = memory_map_size; | |
439 | obj->index = table->allocated_len++; | |
440 | ||
441 | return obj; | |
ff0f5728 MD |
442 | |
443 | error_fcntl: | |
444 | return NULL; | |
74d81a6c MD |
445 | } |
446 | ||
1d498196 MD |
447 | static |
448 | void shmp_object_destroy(struct shm_object *obj) | |
449 | { | |
74d81a6c MD |
450 | switch (obj->type) { |
451 | case SHM_OBJECT_SHM: | |
452 | { | |
453 | int ret, i; | |
1d498196 | 454 | |
7a784989 MD |
455 | ret = munmap(obj->memory_map, obj->memory_map_size); |
456 | if (ret) { | |
457 | PERROR("umnmap"); | |
458 | assert(0); | |
459 | } | |
ef9ff354 MD |
460 | ret = close(obj->shm_fd); |
461 | if (ret) { | |
462 | PERROR("close"); | |
463 | assert(0); | |
464 | } | |
a9ff648c MD |
465 | if (obj->shm_path[0]) { |
466 | ret = unlink(obj->shm_path); | |
467 | if (ret) { | |
468 | PERROR("ret"); | |
469 | } | |
470 | } | |
74d81a6c MD |
471 | for (i = 0; i < 2; i++) { |
472 | if (obj->wait_fd[i] < 0) | |
473 | continue; | |
474 | ret = close(obj->wait_fd[i]); | |
475 | if (ret) { | |
476 | PERROR("close"); | |
477 | assert(0); | |
478 | } | |
1d498196 | 479 | } |
74d81a6c MD |
480 | break; |
481 | } | |
482 | case SHM_OBJECT_MEM: | |
ff0f5728 MD |
483 | { |
484 | int ret, i; | |
485 | ||
486 | for (i = 0; i < 2; i++) { | |
487 | if (obj->wait_fd[i] < 0) | |
488 | continue; | |
489 | ret = close(obj->wait_fd[i]); | |
490 | if (ret) { | |
491 | PERROR("close"); | |
492 | assert(0); | |
493 | } | |
494 | } | |
74d81a6c MD |
495 | free(obj->memory_map); |
496 | break; | |
ff0f5728 | 497 | } |
74d81a6c MD |
498 | default: |
499 | assert(0); | |
1d498196 MD |
500 | } |
501 | } | |
502 | ||
503 | void shm_object_table_destroy(struct shm_object_table *table) | |
504 | { | |
505 | int i; | |
506 | ||
507 | for (i = 0; i < table->allocated_len; i++) | |
508 | shmp_object_destroy(&table->objects[i]); | |
509 | free(table); | |
510 | } | |
511 | ||
512 | /* | |
513 | * zalloc_shm - allocate memory within a shm object. | |
514 | * | |
515 | * Shared memory is already zeroed by shmget. | |
516 | * *NOT* multithread-safe (should be protected by mutex). | |
517 | * Returns a -1, -1 tuple on error. | |
518 | */ | |
519 | struct shm_ref zalloc_shm(struct shm_object *obj, size_t len) | |
520 | { | |
521 | struct shm_ref ref; | |
522 | struct shm_ref shm_ref_error = { -1, -1 }; | |
523 | ||
524 | if (obj->memory_map_size - obj->allocated_len < len) | |
525 | return shm_ref_error; | |
526 | ref.index = obj->index; | |
527 | ref.offset = obj->allocated_len; | |
528 | obj->allocated_len += len; | |
529 | return ref; | |
530 | } | |
531 | ||
532 | void align_shm(struct shm_object *obj, size_t align) | |
533 | { | |
534 | size_t offset_len = offset_align(obj->allocated_len, align); | |
535 | obj->allocated_len += offset_len; | |
536 | } |