Commit | Line | Data |
---|---|---|
8e2aed3f | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-or-later |
8e2aed3f | 3 | * |
c0c0989a | 4 | * Copyright (C) 2015 Antoine Busque <abusque@efficios.com> |
8e2aed3f AB |
5 | */ |
6 | ||
3fbec7dc | 7 | #define _LGPL_SOURCE |
fb31eb73 | 8 | #include <fcntl.h> |
864a1eda | 9 | #include <ust-helper.h> |
8e2aed3f AB |
10 | #include <lttng/align.h> |
11 | #include <lttng/ust-elf.h> | |
fb31eb73 FD |
12 | #include <stdbool.h> |
13 | #include <stdint.h> | |
14 | #include <string.h> | |
405be658 | 15 | #include <sys/stat.h> |
fb31eb73 | 16 | #include <sys/types.h> |
405be658 | 17 | #include <unistd.h> |
fb31eb73 | 18 | |
ba8dcc8c | 19 | #include <ust-fd.h> |
fb31eb73 | 20 | |
405be658 | 21 | #include "lttng-tracer-core.h" |
2a8db464 | 22 | #include "lttng-ust-elf.h" |
ddabe860 | 23 | #include "ust-helper.h" |
405be658 MD |
24 | |
25 | #define BUF_LEN 4096 | |
8e2aed3f | 26 | |
2df586a6 PP |
27 | #ifndef NT_GNU_BUILD_ID |
28 | # define NT_GNU_BUILD_ID 3 | |
29 | #endif | |
30 | ||
8e2aed3f AB |
31 | /* |
32 | * Retrieve the nth (where n is the `index` argument) phdr (program | |
33 | * header) from the given elf instance. | |
34 | * | |
35 | * A pointer to the phdr is returned on success, NULL on failure. | |
36 | */ | |
37 | static | |
38 | struct lttng_ust_elf_phdr *lttng_ust_elf_get_phdr(struct lttng_ust_elf *elf, | |
39 | uint16_t index) | |
40 | { | |
41 | struct lttng_ust_elf_phdr *phdr = NULL; | |
f5a6717a | 42 | off_t offset; |
8e2aed3f AB |
43 | |
44 | if (!elf) { | |
45 | goto error; | |
46 | } | |
47 | ||
48 | if (index >= elf->ehdr->e_phnum) { | |
49 | goto error; | |
50 | } | |
51 | ||
52 | phdr = zmalloc(sizeof(struct lttng_ust_elf_phdr)); | |
53 | if (!phdr) { | |
54 | goto error; | |
55 | } | |
56 | ||
f5a6717a MD |
57 | offset = (off_t) elf->ehdr->e_phoff |
58 | + (off_t) index * elf->ehdr->e_phentsize; | |
405be658 | 59 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { |
8e2aed3f AB |
60 | goto error; |
61 | } | |
62 | ||
63 | if (is_elf_32_bit(elf)) { | |
64 | Elf32_Phdr elf_phdr; | |
65 | ||
405be658 MD |
66 | if (lttng_ust_read(elf->fd, &elf_phdr, sizeof(elf_phdr)) |
67 | < sizeof(elf_phdr)) { | |
8e2aed3f AB |
68 | goto error; |
69 | } | |
70 | if (!is_elf_native_endian(elf)) { | |
71 | bswap_phdr(elf_phdr); | |
72 | } | |
73 | copy_phdr(elf_phdr, *phdr); | |
74 | } else { | |
75 | Elf64_Phdr elf_phdr; | |
76 | ||
405be658 MD |
77 | if (lttng_ust_read(elf->fd, &elf_phdr, sizeof(elf_phdr)) |
78 | < sizeof(elf_phdr)) { | |
8e2aed3f AB |
79 | goto error; |
80 | } | |
81 | if (!is_elf_native_endian(elf)) { | |
82 | bswap_phdr(elf_phdr); | |
83 | } | |
84 | copy_phdr(elf_phdr, *phdr); | |
85 | } | |
86 | ||
87 | return phdr; | |
88 | ||
89 | error: | |
90 | free(phdr); | |
91 | return NULL; | |
92 | } | |
93 | ||
94 | /* | |
95 | * Retrieve the nth (where n is the `index` argument) shdr (section | |
96 | * header) from the given elf instance. | |
97 | * | |
98 | * A pointer to the shdr is returned on success, NULL on failure. | |
99 | */ | |
100 | static | |
101 | struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf, | |
102 | uint16_t index) | |
103 | { | |
104 | struct lttng_ust_elf_shdr *shdr = NULL; | |
4c5dac0d | 105 | off_t offset; |
8e2aed3f AB |
106 | |
107 | if (!elf) { | |
108 | goto error; | |
109 | } | |
110 | ||
111 | if (index >= elf->ehdr->e_shnum) { | |
112 | goto error; | |
113 | } | |
114 | ||
115 | shdr = zmalloc(sizeof(struct lttng_ust_elf_shdr)); | |
116 | if (!shdr) { | |
117 | goto error; | |
118 | } | |
119 | ||
4c5dac0d | 120 | offset = (off_t) elf->ehdr->e_shoff |
5a26ac54 | 121 | + (off_t) index * elf->ehdr->e_shentsize; |
405be658 | 122 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { |
8e2aed3f AB |
123 | goto error; |
124 | } | |
125 | ||
126 | if (is_elf_32_bit(elf)) { | |
127 | Elf32_Shdr elf_shdr; | |
128 | ||
405be658 MD |
129 | if (lttng_ust_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) |
130 | < sizeof(elf_shdr)) { | |
8e2aed3f AB |
131 | goto error; |
132 | } | |
133 | if (!is_elf_native_endian(elf)) { | |
134 | bswap_shdr(elf_shdr); | |
135 | } | |
136 | copy_shdr(elf_shdr, *shdr); | |
137 | } else { | |
138 | Elf64_Shdr elf_shdr; | |
139 | ||
405be658 MD |
140 | if (lttng_ust_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) |
141 | < sizeof(elf_shdr)) { | |
8e2aed3f AB |
142 | goto error; |
143 | } | |
144 | if (!is_elf_native_endian(elf)) { | |
145 | bswap_shdr(elf_shdr); | |
146 | } | |
147 | copy_shdr(elf_shdr, *shdr); | |
148 | } | |
149 | ||
150 | return shdr; | |
151 | ||
152 | error: | |
153 | free(shdr); | |
154 | return NULL; | |
155 | } | |
156 | ||
157 | /* | |
158 | * Lookup a section's name from a given offset (usually from an shdr's | |
159 | * sh_name value) in bytes relative to the beginning of the section | |
160 | * names string table. | |
161 | * | |
162 | * If no name is found, NULL is returned. | |
163 | */ | |
164 | static | |
f5a6717a | 165 | char *lttng_ust_elf_get_section_name(struct lttng_ust_elf *elf, off_t offset) |
8e2aed3f AB |
166 | { |
167 | char *name = NULL; | |
405be658 | 168 | size_t len = 0, to_read; /* len does not include \0 */ |
8e2aed3f AB |
169 | |
170 | if (!elf) { | |
171 | goto error; | |
172 | } | |
173 | ||
174 | if (offset >= elf->section_names_size) { | |
175 | goto error; | |
176 | } | |
177 | ||
405be658 | 178 | if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) { |
8e2aed3f AB |
179 | goto error; |
180 | } | |
405be658 MD |
181 | |
182 | to_read = elf->section_names_size - offset; | |
183 | ||
184 | /* Find first \0 after or at current location, remember len. */ | |
185 | for (;;) { | |
186 | char buf[BUF_LEN]; | |
187 | ssize_t read_len; | |
188 | size_t i; | |
189 | ||
190 | if (!to_read) { | |
8e2aed3f | 191 | goto error; |
8e2aed3f | 192 | } |
405be658 MD |
193 | read_len = lttng_ust_read(elf->fd, buf, |
194 | min_t(size_t, BUF_LEN, to_read)); | |
195 | if (read_len <= 0) { | |
196 | goto error; | |
197 | } | |
198 | for (i = 0; i < read_len; i++) { | |
199 | if (buf[i] == '\0') { | |
200 | len += i; | |
201 | goto end; | |
202 | } | |
203 | } | |
204 | len += read_len; | |
205 | to_read -= read_len; | |
8e2aed3f | 206 | } |
8e2aed3f | 207 | end: |
405be658 | 208 | name = zmalloc(sizeof(char) * (len + 1)); /* + 1 for \0 */ |
8e2aed3f AB |
209 | if (!name) { |
210 | goto error; | |
211 | } | |
405be658 MD |
212 | if (lseek(elf->fd, elf->section_names_offset + offset, |
213 | SEEK_SET) < 0) { | |
8e2aed3f AB |
214 | goto error; |
215 | } | |
405be658 | 216 | if (lttng_ust_read(elf->fd, name, len + 1) < len + 1) { |
8e2aed3f AB |
217 | goto error; |
218 | } | |
219 | ||
220 | return name; | |
221 | ||
222 | error: | |
223 | free(name); | |
224 | return NULL; | |
225 | } | |
226 | ||
227 | /* | |
228 | * Create an instance of lttng_ust_elf for the ELF file located at | |
229 | * `path`. | |
230 | * | |
231 | * Return a pointer to the instance on success, NULL on failure. | |
232 | */ | |
233 | struct lttng_ust_elf *lttng_ust_elf_create(const char *path) | |
234 | { | |
235 | uint8_t e_ident[EI_NIDENT]; | |
236 | struct lttng_ust_elf_shdr *section_names_shdr; | |
405be658 | 237 | struct lttng_ust_elf *elf = NULL; |
f5c453e9 | 238 | int ret, fd; |
8e2aed3f AB |
239 | |
240 | elf = zmalloc(sizeof(struct lttng_ust_elf)); | |
241 | if (!elf) { | |
242 | goto error; | |
243 | } | |
244 | ||
1ac2e79c JR |
245 | /* Initialize fd field to -1. 0 is a valid fd number */ |
246 | elf->fd = -1; | |
ba8dcc8c | 247 | |
8e2aed3f AB |
248 | elf->path = strdup(path); |
249 | if (!elf->path) { | |
250 | goto error; | |
251 | } | |
252 | ||
ba8dcc8c | 253 | lttng_ust_lock_fd_tracker(); |
f5c453e9 JR |
254 | fd = open(elf->path, O_RDONLY | O_CLOEXEC); |
255 | if (fd < 0) { | |
ba8dcc8c | 256 | lttng_ust_unlock_fd_tracker(); |
8e2aed3f AB |
257 | goto error; |
258 | } | |
f5c453e9 JR |
259 | |
260 | ret = lttng_ust_add_fd_to_tracker(fd); | |
261 | if (ret < 0) { | |
262 | ret = close(fd); | |
263 | if (ret) { | |
264 | PERROR("close on elf->fd"); | |
265 | } | |
266 | ret = -1; | |
267 | lttng_ust_unlock_fd_tracker(); | |
268 | goto error; | |
269 | } | |
270 | elf->fd = ret; | |
ba8dcc8c | 271 | lttng_ust_unlock_fd_tracker(); |
8e2aed3f | 272 | |
405be658 | 273 | if (lttng_ust_read(elf->fd, e_ident, EI_NIDENT) < EI_NIDENT) { |
8e2aed3f AB |
274 | goto error; |
275 | } | |
276 | elf->bitness = e_ident[EI_CLASS]; | |
277 | elf->endianness = e_ident[EI_DATA]; | |
405be658 MD |
278 | |
279 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
280 | goto error; | |
281 | } | |
8e2aed3f AB |
282 | |
283 | elf->ehdr = zmalloc(sizeof(struct lttng_ust_elf_ehdr)); | |
284 | if (!elf->ehdr) { | |
285 | goto error; | |
286 | } | |
287 | ||
288 | if (is_elf_32_bit(elf)) { | |
289 | Elf32_Ehdr elf_ehdr; | |
290 | ||
405be658 MD |
291 | if (lttng_ust_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) |
292 | < sizeof(elf_ehdr)) { | |
8e2aed3f AB |
293 | goto error; |
294 | } | |
295 | if (!is_elf_native_endian(elf)) { | |
296 | bswap_ehdr(elf_ehdr); | |
297 | } | |
298 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
299 | } else { | |
300 | Elf64_Ehdr elf_ehdr; | |
301 | ||
405be658 MD |
302 | if (lttng_ust_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) |
303 | < sizeof(elf_ehdr)) { | |
8e2aed3f AB |
304 | goto error; |
305 | } | |
306 | if (!is_elf_native_endian(elf)) { | |
307 | bswap_ehdr(elf_ehdr); | |
308 | } | |
309 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
310 | } | |
311 | ||
312 | section_names_shdr = lttng_ust_elf_get_shdr(elf, elf->ehdr->e_shstrndx); | |
313 | if (!section_names_shdr) { | |
314 | goto error; | |
315 | } | |
316 | ||
317 | elf->section_names_offset = section_names_shdr->sh_offset; | |
318 | elf->section_names_size = section_names_shdr->sh_size; | |
319 | ||
320 | free(section_names_shdr); | |
8e2aed3f AB |
321 | return elf; |
322 | ||
323 | error: | |
ba8dcc8c | 324 | lttng_ust_elf_destroy(elf); |
8e2aed3f AB |
325 | return NULL; |
326 | } | |
327 | ||
f5eb039d AB |
328 | /* |
329 | * Test whether the ELF file is position independent code (PIC) | |
330 | */ | |
331 | uint8_t lttng_ust_elf_is_pic(struct lttng_ust_elf *elf) | |
332 | { | |
333 | /* | |
334 | * PIC has and e_type value of ET_DYN, see ELF specification | |
335 | * version 1.1 p. 1-3. | |
336 | */ | |
337 | return elf->ehdr->e_type == ET_DYN; | |
338 | } | |
339 | ||
8e2aed3f AB |
340 | /* |
341 | * Destroy the given lttng_ust_elf instance. | |
342 | */ | |
343 | void lttng_ust_elf_destroy(struct lttng_ust_elf *elf) | |
344 | { | |
ba8dcc8c JR |
345 | int ret; |
346 | ||
8e2aed3f AB |
347 | if (!elf) { |
348 | return; | |
349 | } | |
350 | ||
ba8dcc8c JR |
351 | if (elf->fd >= 0) { |
352 | lttng_ust_lock_fd_tracker(); | |
353 | ret = close(elf->fd); | |
354 | if (!ret) { | |
355 | lttng_ust_delete_fd_from_tracker(elf->fd); | |
356 | } else { | |
357 | PERROR("close"); | |
358 | abort(); | |
359 | } | |
360 | lttng_ust_unlock_fd_tracker(); | |
405be658 | 361 | } |
ba8dcc8c JR |
362 | |
363 | free(elf->ehdr); | |
8e2aed3f AB |
364 | free(elf->path); |
365 | free(elf); | |
366 | } | |
367 | ||
368 | /* | |
369 | * Compute the total in-memory size of the ELF file, in bytes. | |
370 | * | |
371 | * Returns 0 if successful, -1 if not. On success, the memory size is | |
372 | * returned through the out parameter `memsz`. | |
373 | */ | |
374 | int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz) | |
375 | { | |
376 | uint16_t i; | |
e1f0c569 | 377 | uint64_t low_addr = UINT64_MAX, high_addr = 0; |
8e2aed3f AB |
378 | |
379 | if (!elf || !memsz) { | |
380 | goto error; | |
381 | } | |
382 | ||
383 | for (i = 0; i < elf->ehdr->e_phnum; ++i) { | |
384 | struct lttng_ust_elf_phdr *phdr; | |
8e2aed3f AB |
385 | |
386 | phdr = lttng_ust_elf_get_phdr(elf, i); | |
387 | if (!phdr) { | |
388 | goto error; | |
389 | } | |
390 | ||
391 | /* | |
392 | * Only PT_LOAD segments contribute to memsz. Skip | |
393 | * other segments. | |
394 | */ | |
395 | if (phdr->p_type != PT_LOAD) { | |
396 | goto next_loop; | |
397 | } | |
398 | ||
8886accb MD |
399 | low_addr = min_t(uint64_t, low_addr, phdr->p_vaddr); |
400 | high_addr = max_t(uint64_t, high_addr, | |
401 | phdr->p_vaddr + phdr->p_memsz); | |
8e2aed3f AB |
402 | next_loop: |
403 | free(phdr); | |
404 | } | |
405 | ||
e1f0c569 AB |
406 | if (high_addr < low_addr) { |
407 | /* No PT_LOAD segments or corrupted data. */ | |
408 | goto error; | |
409 | } | |
410 | ||
411 | *memsz = high_addr - low_addr; | |
8e2aed3f AB |
412 | return 0; |
413 | error: | |
414 | return -1; | |
415 | } | |
416 | ||
417 | /* | |
418 | * Internal method used to try and get the build_id from a PT_NOTE | |
419 | * segment ranging from `offset` to `segment_end`. | |
420 | * | |
421 | * If the function returns successfully, the out parameter `found` | |
422 | * indicates whether the build id information was present in the | |
423 | * segment or not. If `found` is not 0, the out parameters `build_id` | |
424 | * and `length` will both have been set with the retrieved | |
425 | * information. | |
426 | * | |
427 | * Returns 0 on success, -1 if an error occurred. | |
428 | */ | |
429 | static | |
430 | int lttng_ust_elf_get_build_id_from_segment( | |
431 | struct lttng_ust_elf *elf, uint8_t **build_id, size_t *length, | |
82ee1ee4 | 432 | off_t offset, off_t segment_end) |
8e2aed3f | 433 | { |
814d07b1 MD |
434 | uint8_t *_build_id = NULL; /* Silence old gcc warning. */ |
435 | size_t _length = 0; /* Silence old gcc warning. */ | |
8e2aed3f AB |
436 | |
437 | while (offset < segment_end) { | |
438 | struct lttng_ust_elf_nhdr nhdr; | |
405be658 | 439 | size_t read_len; |
8e2aed3f AB |
440 | |
441 | /* Align start of note entry */ | |
b72687b8 | 442 | offset += lttng_ust_offset_align(offset, ELF_NOTE_ENTRY_ALIGN); |
8e2aed3f AB |
443 | if (offset >= segment_end) { |
444 | break; | |
445 | } | |
446 | /* | |
447 | * We seek manually because if the note isn't the | |
448 | * build id the data following the header will not | |
449 | * have been read. | |
450 | */ | |
405be658 | 451 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { |
8e2aed3f AB |
452 | goto error; |
453 | } | |
405be658 MD |
454 | if (lttng_ust_read(elf->fd, &nhdr, sizeof(nhdr)) |
455 | < sizeof(nhdr)) { | |
8e2aed3f AB |
456 | goto error; |
457 | } | |
458 | ||
459 | if (!is_elf_native_endian(elf)) { | |
460 | nhdr.n_namesz = bswap_32(nhdr.n_namesz); | |
461 | nhdr.n_descsz = bswap_32(nhdr.n_descsz); | |
462 | nhdr.n_type = bswap_32(nhdr.n_type); | |
463 | } | |
464 | ||
465 | offset += sizeof(nhdr) + nhdr.n_namesz; | |
466 | /* Align start of desc entry */ | |
b72687b8 | 467 | offset += lttng_ust_offset_align(offset, ELF_NOTE_DESC_ALIGN); |
8e2aed3f AB |
468 | |
469 | if (nhdr.n_type != NT_GNU_BUILD_ID) { | |
470 | /* | |
471 | * Ignore non build id notes but still | |
472 | * increase the offset. | |
473 | */ | |
474 | offset += nhdr.n_descsz; | |
475 | continue; | |
476 | } | |
477 | ||
478 | _length = nhdr.n_descsz; | |
479 | _build_id = zmalloc(sizeof(uint8_t) * _length); | |
5ada26b4 | 480 | if (!_build_id) { |
8e2aed3f AB |
481 | goto error; |
482 | } | |
483 | ||
405be658 | 484 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { |
8e2aed3f AB |
485 | goto error; |
486 | } | |
405be658 MD |
487 | read_len = sizeof(*_build_id) * _length; |
488 | if (lttng_ust_read(elf->fd, _build_id, read_len) < read_len) { | |
8e2aed3f AB |
489 | goto error; |
490 | } | |
491 | ||
8e2aed3f AB |
492 | break; |
493 | } | |
494 | ||
82ee1ee4 | 495 | if (_build_id) { |
8e2aed3f AB |
496 | *build_id = _build_id; |
497 | *length = _length; | |
498 | } | |
499 | ||
8e2aed3f AB |
500 | return 0; |
501 | error: | |
83215d66 | 502 | free(_build_id); |
8e2aed3f AB |
503 | return -1; |
504 | } | |
505 | ||
506 | /* | |
507 | * Retrieve a build ID (an array of bytes) from the corresponding | |
508 | * section in the ELF file. The length of the build ID can be either | |
509 | * 16 or 20 bytes depending on the method used to generate it, hence | |
510 | * the length out parameter. | |
511 | * | |
512 | * If the function returns successfully, the out parameter `found` | |
513 | * indicates whether the build id information was present in the ELF | |
514 | * file or not. If `found` is not 0, the out parameters `build_id` and | |
515 | * `length` will both have been set with the retrieved information. | |
516 | * | |
517 | * Returns 0 on success, -1 if an error occurred. | |
518 | */ | |
519 | int lttng_ust_elf_get_build_id(struct lttng_ust_elf *elf, uint8_t **build_id, | |
520 | size_t *length, int *found) | |
521 | { | |
522 | uint16_t i; | |
8c83dbda MD |
523 | uint8_t *_build_id = NULL; /* Silence old gcc warning. */ |
524 | size_t _length = 0; /* Silence old gcc warning. */ | |
8e2aed3f AB |
525 | |
526 | if (!elf || !build_id || !length || !found) { | |
527 | goto error; | |
528 | } | |
529 | ||
530 | for (i = 0; i < elf->ehdr->e_phnum; ++i) { | |
f5a6717a | 531 | off_t offset, segment_end; |
8e2aed3f | 532 | struct lttng_ust_elf_phdr *phdr; |
5b3bbf98 | 533 | int ret = 0; |
8e2aed3f AB |
534 | |
535 | phdr = lttng_ust_elf_get_phdr(elf, i); | |
536 | if (!phdr) { | |
537 | goto error; | |
538 | } | |
539 | ||
540 | /* Build ID will be contained in a PT_NOTE segment. */ | |
541 | if (phdr->p_type != PT_NOTE) { | |
542 | goto next_loop; | |
543 | } | |
544 | ||
545 | offset = phdr->p_offset; | |
546 | segment_end = offset + phdr->p_filesz; | |
547 | ret = lttng_ust_elf_get_build_id_from_segment( | |
82ee1ee4 | 548 | elf, &_build_id, &_length, offset, segment_end); |
8e2aed3f AB |
549 | next_loop: |
550 | free(phdr); | |
551 | if (ret) { | |
552 | goto error; | |
553 | } | |
82ee1ee4 | 554 | if (_build_id) { |
8e2aed3f AB |
555 | break; |
556 | } | |
557 | } | |
558 | ||
82ee1ee4 | 559 | if (_build_id) { |
8e2aed3f AB |
560 | *build_id = _build_id; |
561 | *length = _length; | |
82ee1ee4 AB |
562 | *found = 1; |
563 | } else { | |
564 | *found = 0; | |
8e2aed3f AB |
565 | } |
566 | ||
8e2aed3f AB |
567 | return 0; |
568 | error: | |
99b7132d | 569 | free(_build_id); |
8e2aed3f AB |
570 | return -1; |
571 | } | |
572 | ||
573 | /* | |
574 | * Try to retrieve filename and CRC from given ELF section `shdr`. | |
575 | * | |
576 | * If the function returns successfully, the out parameter `found` | |
577 | * indicates whether the debug link information was present in the ELF | |
578 | * section or not. If `found` is not 0, the out parameters `filename` and | |
579 | * `crc` will both have been set with the retrieved information. | |
580 | * | |
581 | * Returns 0 on success, -1 if an error occurred. | |
582 | */ | |
8e2aed3f AB |
583 | int lttng_ust_elf_get_debug_link_from_section(struct lttng_ust_elf *elf, |
584 | char **filename, uint32_t *crc, | |
8e2aed3f AB |
585 | struct lttng_ust_elf_shdr *shdr) |
586 | { | |
8c83dbda | 587 | char *_filename = NULL; /* Silence old gcc warning. */ |
405be658 | 588 | size_t filename_len; |
8e2aed3f | 589 | char *section_name = NULL; |
8c83dbda | 590 | uint32_t _crc = 0; /* Silence old gcc warning. */ |
8e2aed3f | 591 | |
82ee1ee4 | 592 | if (!elf || !filename || !crc || !shdr) { |
8e2aed3f AB |
593 | goto error; |
594 | } | |
595 | ||
596 | /* | |
597 | * The .gnu_debuglink section is of type SHT_PROGBITS, | |
598 | * skip the other sections. | |
599 | */ | |
600 | if (shdr->sh_type != SHT_PROGBITS) { | |
601 | goto end; | |
602 | } | |
603 | ||
604 | section_name = lttng_ust_elf_get_section_name(elf, | |
605 | shdr->sh_name); | |
606 | if (!section_name) { | |
607 | goto end; | |
608 | } | |
609 | if (strcmp(section_name, ".gnu_debuglink")) { | |
610 | goto end; | |
611 | } | |
612 | ||
613 | /* | |
614 | * The length of the filename is the sh_size excluding the CRC | |
615 | * which comes after it in the section. | |
616 | */ | |
617 | _filename = zmalloc(sizeof(char) * (shdr->sh_size - ELF_CRC_SIZE)); | |
618 | if (!_filename) { | |
619 | goto error; | |
620 | } | |
405be658 | 621 | if (lseek(elf->fd, shdr->sh_offset, SEEK_SET) < 0) { |
8e2aed3f AB |
622 | goto error; |
623 | } | |
405be658 MD |
624 | filename_len = sizeof(*_filename) * (shdr->sh_size - ELF_CRC_SIZE); |
625 | if (lttng_ust_read(elf->fd, _filename, filename_len) < filename_len) { | |
8e2aed3f AB |
626 | goto error; |
627 | } | |
405be658 | 628 | if (lttng_ust_read(elf->fd, &_crc, sizeof(_crc)) < sizeof(_crc)) { |
8e2aed3f AB |
629 | goto error; |
630 | } | |
631 | if (!is_elf_native_endian(elf)) { | |
632 | _crc = bswap_32(_crc); | |
633 | } | |
634 | ||
8e2aed3f AB |
635 | end: |
636 | free(section_name); | |
82ee1ee4 | 637 | if (_filename) { |
8e2aed3f AB |
638 | *filename = _filename; |
639 | *crc = _crc; | |
640 | } | |
8e2aed3f AB |
641 | |
642 | return 0; | |
643 | ||
644 | error: | |
83215d66 MD |
645 | free(_filename); |
646 | free(section_name); | |
8e2aed3f AB |
647 | return -1; |
648 | } | |
649 | ||
650 | /* | |
651 | * Retrieve filename and CRC from ELF's .gnu_debuglink section, if any. | |
652 | * | |
653 | * If the function returns successfully, the out parameter `found` | |
654 | * indicates whether the debug link information was present in the ELF | |
655 | * file or not. If `found` is not 0, the out parameters `filename` and | |
656 | * `crc` will both have been set with the retrieved information. | |
657 | * | |
658 | * Returns 0 on success, -1 if an error occurred. | |
659 | */ | |
660 | int lttng_ust_elf_get_debug_link(struct lttng_ust_elf *elf, char **filename, | |
661 | uint32_t *crc, int *found) | |
662 | { | |
663 | int ret; | |
664 | uint16_t i; | |
8c83dbda MD |
665 | char *_filename = NULL; /* Silence old gcc warning. */ |
666 | uint32_t _crc = 0; /* Silence old gcc warning. */ | |
8e2aed3f AB |
667 | |
668 | if (!elf || !filename || !crc || !found) { | |
669 | goto error; | |
670 | } | |
671 | ||
672 | for (i = 0; i < elf->ehdr->e_shnum; ++i) { | |
673 | struct lttng_ust_elf_shdr *shdr = NULL; | |
674 | ||
675 | shdr = lttng_ust_elf_get_shdr(elf, i); | |
676 | if (!shdr) { | |
677 | goto error; | |
678 | } | |
679 | ||
680 | ret = lttng_ust_elf_get_debug_link_from_section( | |
82ee1ee4 | 681 | elf, &_filename, &_crc, shdr); |
8e2aed3f AB |
682 | free(shdr); |
683 | ||
684 | if (ret) { | |
685 | goto error; | |
686 | } | |
82ee1ee4 | 687 | if (_filename) { |
8e2aed3f AB |
688 | break; |
689 | } | |
690 | } | |
691 | ||
82ee1ee4 | 692 | if (_filename) { |
8e2aed3f AB |
693 | *filename = _filename; |
694 | *crc = _crc; | |
82ee1ee4 AB |
695 | *found = 1; |
696 | } else { | |
697 | *found = 0; | |
8e2aed3f AB |
698 | } |
699 | ||
8e2aed3f | 700 | return 0; |
82ee1ee4 | 701 | |
8e2aed3f | 702 | error: |
99b7132d | 703 | free(_filename); |
8e2aed3f AB |
704 | return -1; |
705 | } |