dcae966ca2b815513b2b0a2d04c89d714174bbae
2 * Copyright (C) 2015 Antoine Busque <abusque@efficios.com>
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include <lttng/align.h>
22 #include <lttng/ust-elf.h>
23 #include <sys/types.h>
27 #include "lttng-tracer-core.h"
32 * Retrieve the nth (where n is the `index` argument) phdr (program
33 * header) from the given elf instance.
35 * A pointer to the phdr is returned on success, NULL on failure.
38 struct lttng_ust_elf_phdr
*lttng_ust_elf_get_phdr(struct lttng_ust_elf
*elf
,
41 struct lttng_ust_elf_phdr
*phdr
= NULL
;
48 if (index
>= elf
->ehdr
->e_phnum
) {
52 phdr
= zmalloc(sizeof(struct lttng_ust_elf_phdr
));
57 offset
= (off_t
) elf
->ehdr
->e_phoff
58 + (off_t
) index
* elf
->ehdr
->e_phentsize
;
59 if (lseek(elf
->fd
, offset
, SEEK_SET
) < 0) {
63 if (is_elf_32_bit(elf
)) {
66 if (lttng_ust_read(elf
->fd
, &elf_phdr
, sizeof(elf_phdr
))
70 if (!is_elf_native_endian(elf
)) {
73 copy_phdr(elf_phdr
, *phdr
);
77 if (lttng_ust_read(elf
->fd
, &elf_phdr
, sizeof(elf_phdr
))
81 if (!is_elf_native_endian(elf
)) {
84 copy_phdr(elf_phdr
, *phdr
);
95 * Retrieve the nth (where n is the `index` argument) shdr (section
96 * header) from the given elf instance.
98 * A pointer to the shdr is returned on success, NULL on failure.
101 struct lttng_ust_elf_shdr
*lttng_ust_elf_get_shdr(struct lttng_ust_elf
*elf
,
104 struct lttng_ust_elf_shdr
*shdr
= NULL
;
111 if (index
>= elf
->ehdr
->e_shnum
) {
115 shdr
= zmalloc(sizeof(struct lttng_ust_elf_shdr
));
120 offset
= (off_t
) elf
->ehdr
->e_shoff
121 + (off_t
) index
* elf
->ehdr
->e_shentsize
;
122 if (lseek(elf
->fd
, offset
, SEEK_SET
) < 0) {
126 if (is_elf_32_bit(elf
)) {
129 if (lttng_ust_read(elf
->fd
, &elf_shdr
, sizeof(elf_shdr
))
130 < sizeof(elf_shdr
)) {
133 if (!is_elf_native_endian(elf
)) {
134 bswap_shdr(elf_shdr
);
136 copy_shdr(elf_shdr
, *shdr
);
140 if (lttng_ust_read(elf
->fd
, &elf_shdr
, sizeof(elf_shdr
))
141 < sizeof(elf_shdr
)) {
144 if (!is_elf_native_endian(elf
)) {
145 bswap_shdr(elf_shdr
);
147 copy_shdr(elf_shdr
, *shdr
);
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.
162 * If no name is found, NULL is returned.
165 char *lttng_ust_elf_get_section_name(struct lttng_ust_elf
*elf
, off_t offset
)
168 size_t len
= 0, to_read
; /* len does not include \0 */
174 if (offset
>= elf
->section_names_size
) {
178 if (lseek(elf
->fd
, elf
->section_names_offset
+ offset
, SEEK_SET
) < 0) {
182 to_read
= elf
->section_names_size
- offset
;
184 /* Find first \0 after or at current location, remember len. */
193 read_len
= lttng_ust_read(elf
->fd
, buf
,
194 min_t(size_t, BUF_LEN
, to_read
));
198 for (i
= 0; i
< read_len
; i
++) {
199 if (buf
[i
] == '\0') {
208 name
= zmalloc(sizeof(char) * (len
+ 1)); /* + 1 for \0 */
212 if (lseek(elf
->fd
, elf
->section_names_offset
+ offset
,
216 if (lttng_ust_read(elf
->fd
, name
, len
+ 1) < len
+ 1) {
228 * Create an instance of lttng_ust_elf for the ELF file located at
231 * Return a pointer to the instance on success, NULL on failure.
233 struct lttng_ust_elf
*lttng_ust_elf_create(const char *path
)
235 uint8_t e_ident
[EI_NIDENT
];
236 struct lttng_ust_elf_shdr
*section_names_shdr
;
237 struct lttng_ust_elf
*elf
= NULL
;
239 elf
= zmalloc(sizeof(struct lttng_ust_elf
));
244 elf
->path
= strdup(path
);
249 elf
->fd
= open(elf
->path
, O_RDONLY
| O_CLOEXEC
);
254 if (lttng_ust_read(elf
->fd
, e_ident
, EI_NIDENT
) < EI_NIDENT
) {
257 elf
->bitness
= e_ident
[EI_CLASS
];
258 elf
->endianness
= e_ident
[EI_DATA
];
260 if (lseek(elf
->fd
, 0, SEEK_SET
) < 0) {
264 elf
->ehdr
= zmalloc(sizeof(struct lttng_ust_elf_ehdr
));
269 if (is_elf_32_bit(elf
)) {
272 if (lttng_ust_read(elf
->fd
, &elf_ehdr
, sizeof(elf_ehdr
))
273 < sizeof(elf_ehdr
)) {
276 if (!is_elf_native_endian(elf
)) {
277 bswap_ehdr(elf_ehdr
);
279 copy_ehdr(elf_ehdr
, *(elf
->ehdr
));
283 if (lttng_ust_read(elf
->fd
, &elf_ehdr
, sizeof(elf_ehdr
))
284 < sizeof(elf_ehdr
)) {
287 if (!is_elf_native_endian(elf
)) {
288 bswap_ehdr(elf_ehdr
);
290 copy_ehdr(elf_ehdr
, *(elf
->ehdr
));
293 section_names_shdr
= lttng_ust_elf_get_shdr(elf
, elf
->ehdr
->e_shstrndx
);
294 if (!section_names_shdr
) {
298 elf
->section_names_offset
= section_names_shdr
->sh_offset
;
299 elf
->section_names_size
= section_names_shdr
->sh_size
;
301 free(section_names_shdr
);
308 if (close(elf
->fd
)) {
319 * Destroy the given lttng_ust_elf instance.
321 void lttng_ust_elf_destroy(struct lttng_ust_elf
*elf
)
328 if (close(elf
->fd
)) {
336 * Compute the total in-memory size of the ELF file, in bytes.
338 * Returns 0 if successful, -1 if not. On success, the memory size is
339 * returned through the out parameter `memsz`.
341 int lttng_ust_elf_get_memsz(struct lttng_ust_elf
*elf
, uint64_t *memsz
)
346 if (!elf
|| !memsz
) {
350 for (i
= 0; i
< elf
->ehdr
->e_phnum
; ++i
) {
351 struct lttng_ust_elf_phdr
*phdr
;
354 phdr
= lttng_ust_elf_get_phdr(elf
, i
);
360 * Only PT_LOAD segments contribute to memsz. Skip
363 if (phdr
->p_type
!= PT_LOAD
) {
368 * A p_align of 0 means no alignment, i.e. aligned to
371 align
= phdr
->p_align
== 0 ? 1 : phdr
->p_align
;
372 /* Align the start of the segment. */
373 _memsz
+= offset_align(_memsz
, align
);
374 _memsz
+= phdr
->p_memsz
;
376 * Add padding at the end of the segment, so it ends
377 * on a multiple of the align value (which usually
378 * means a page boundary). This makes the computation
379 * valid even in cases where p_align would change from
380 * one segment to the next.
382 _memsz
+= offset_align(_memsz
, align
);
394 * Internal method used to try and get the build_id from a PT_NOTE
395 * segment ranging from `offset` to `segment_end`.
397 * If the function returns successfully, the out parameter `found`
398 * indicates whether the build id information was present in the
399 * segment or not. If `found` is not 0, the out parameters `build_id`
400 * and `length` will both have been set with the retrieved
403 * Returns 0 on success, -1 if an error occurred.
406 int lttng_ust_elf_get_build_id_from_segment(
407 struct lttng_ust_elf
*elf
, uint8_t **build_id
, size_t *length
,
408 off_t offset
, off_t segment_end
)
410 uint8_t *_build_id
= NULL
; /* Silence old gcc warning. */
411 size_t _length
= 0; /* Silence old gcc warning. */
413 while (offset
< segment_end
) {
414 struct lttng_ust_elf_nhdr nhdr
;
417 /* Align start of note entry */
418 offset
+= offset_align(offset
, ELF_NOTE_ENTRY_ALIGN
);
419 if (offset
>= segment_end
) {
423 * We seek manually because if the note isn't the
424 * build id the data following the header will not
427 if (lseek(elf
->fd
, offset
, SEEK_SET
) < 0) {
430 if (lttng_ust_read(elf
->fd
, &nhdr
, sizeof(nhdr
))
435 if (!is_elf_native_endian(elf
)) {
436 nhdr
.n_namesz
= bswap_32(nhdr
.n_namesz
);
437 nhdr
.n_descsz
= bswap_32(nhdr
.n_descsz
);
438 nhdr
.n_type
= bswap_32(nhdr
.n_type
);
441 offset
+= sizeof(nhdr
) + nhdr
.n_namesz
;
442 /* Align start of desc entry */
443 offset
+= offset_align(offset
, ELF_NOTE_DESC_ALIGN
);
445 if (nhdr
.n_type
!= NT_GNU_BUILD_ID
) {
447 * Ignore non build id notes but still
448 * increase the offset.
450 offset
+= nhdr
.n_descsz
;
454 _length
= nhdr
.n_descsz
;
455 _build_id
= zmalloc(sizeof(uint8_t) * _length
);
460 if (lseek(elf
->fd
, offset
, SEEK_SET
) < 0) {
463 read_len
= sizeof(*_build_id
) * _length
;
464 if (lttng_ust_read(elf
->fd
, _build_id
, read_len
) < read_len
) {
472 *build_id
= _build_id
;
483 * Retrieve a build ID (an array of bytes) from the corresponding
484 * section in the ELF file. The length of the build ID can be either
485 * 16 or 20 bytes depending on the method used to generate it, hence
486 * the length out parameter.
488 * If the function returns successfully, the out parameter `found`
489 * indicates whether the build id information was present in the ELF
490 * file or not. If `found` is not 0, the out parameters `build_id` and
491 * `length` will both have been set with the retrieved information.
493 * Returns 0 on success, -1 if an error occurred.
495 int lttng_ust_elf_get_build_id(struct lttng_ust_elf
*elf
, uint8_t **build_id
,
496 size_t *length
, int *found
)
499 uint8_t *_build_id
= NULL
; /* Silence old gcc warning. */
500 size_t _length
= 0; /* Silence old gcc warning. */
502 if (!elf
|| !build_id
|| !length
|| !found
) {
506 for (i
= 0; i
< elf
->ehdr
->e_phnum
; ++i
) {
507 off_t offset
, segment_end
;
508 struct lttng_ust_elf_phdr
*phdr
;
511 phdr
= lttng_ust_elf_get_phdr(elf
, i
);
516 /* Build ID will be contained in a PT_NOTE segment. */
517 if (phdr
->p_type
!= PT_NOTE
) {
521 offset
= phdr
->p_offset
;
522 segment_end
= offset
+ phdr
->p_filesz
;
523 ret
= lttng_ust_elf_get_build_id_from_segment(
524 elf
, &_build_id
, &_length
, offset
, segment_end
);
536 *build_id
= _build_id
;
550 * Try to retrieve filename and CRC from given ELF section `shdr`.
552 * If the function returns successfully, the out parameter `found`
553 * indicates whether the debug link information was present in the ELF
554 * section or not. If `found` is not 0, the out parameters `filename` and
555 * `crc` will both have been set with the retrieved information.
557 * Returns 0 on success, -1 if an error occurred.
559 int lttng_ust_elf_get_debug_link_from_section(struct lttng_ust_elf
*elf
,
560 char **filename
, uint32_t *crc
,
561 struct lttng_ust_elf_shdr
*shdr
)
563 char *_filename
= NULL
; /* Silence old gcc warning. */
565 char *section_name
= NULL
;
566 uint32_t _crc
= 0; /* Silence old gcc warning. */
568 if (!elf
|| !filename
|| !crc
|| !shdr
) {
573 * The .gnu_debuglink section is of type SHT_PROGBITS,
574 * skip the other sections.
576 if (shdr
->sh_type
!= SHT_PROGBITS
) {
580 section_name
= lttng_ust_elf_get_section_name(elf
,
585 if (strcmp(section_name
, ".gnu_debuglink")) {
590 * The length of the filename is the sh_size excluding the CRC
591 * which comes after it in the section.
593 _filename
= zmalloc(sizeof(char) * (shdr
->sh_size
- ELF_CRC_SIZE
));
597 if (lseek(elf
->fd
, shdr
->sh_offset
, SEEK_SET
) < 0) {
600 filename_len
= sizeof(*_filename
) * (shdr
->sh_size
- ELF_CRC_SIZE
);
601 if (lttng_ust_read(elf
->fd
, _filename
, filename_len
) < filename_len
) {
604 if (lttng_ust_read(elf
->fd
, &_crc
, sizeof(_crc
)) < sizeof(_crc
)) {
607 if (!is_elf_native_endian(elf
)) {
608 _crc
= bswap_32(_crc
);
614 *filename
= _filename
;
627 * Retrieve filename and CRC from ELF's .gnu_debuglink section, if any.
629 * If the function returns successfully, the out parameter `found`
630 * indicates whether the debug link information was present in the ELF
631 * file or not. If `found` is not 0, the out parameters `filename` and
632 * `crc` will both have been set with the retrieved information.
634 * Returns 0 on success, -1 if an error occurred.
636 int lttng_ust_elf_get_debug_link(struct lttng_ust_elf
*elf
, char **filename
,
637 uint32_t *crc
, int *found
)
641 char *_filename
= NULL
; /* Silence old gcc warning. */
642 uint32_t _crc
= 0; /* Silence old gcc warning. */
644 if (!elf
|| !filename
|| !crc
|| !found
) {
648 for (i
= 0; i
< elf
->ehdr
->e_shnum
; ++i
) {
649 struct lttng_ust_elf_shdr
*shdr
= NULL
;
651 shdr
= lttng_ust_elf_get_shdr(elf
, i
);
656 ret
= lttng_ust_elf_get_debug_link_from_section(
657 elf
, &_filename
, &_crc
, shdr
);
669 *filename
= _filename
;
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