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cbb099e8 TT |
1 | /* Definitions for BFD wrappers used by GDB. |
2 | ||
6ec53d05 | 3 | Copyright (C) 2011, 2012 |
cbb099e8 TT |
4 | Free Software Foundation, Inc. |
5 | ||
6 | This file is part of GDB. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 3 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "defs.h" | |
22 | #include "gdb_bfd.h" | |
23 | #include "gdb_assert.h" | |
a4453b7e | 24 | #include "gdb_string.h" |
6ec53d05 | 25 | #include "hashtab.h" |
4bf44c1c TT |
26 | #ifdef HAVE_ZLIB_H |
27 | #include <zlib.h> | |
28 | #endif | |
29 | #ifdef HAVE_MMAP | |
30 | #include <sys/mman.h> | |
31 | #ifndef MAP_FAILED | |
32 | #define MAP_FAILED ((void *) -1) | |
33 | #endif | |
34 | #endif | |
35 | ||
36 | /* An object of this type is stored in the section's user data when | |
37 | mapping a section. */ | |
38 | ||
39 | struct gdb_bfd_section_data | |
40 | { | |
41 | /* Size of the data. */ | |
42 | bfd_size_type size; | |
43 | /* If the data was mmapped, this is the length of the map. */ | |
44 | bfd_size_type map_len; | |
45 | /* The data. If NULL, the section data has not been read. */ | |
46 | void *data; | |
47 | /* If the data was mmapped, this is the map address. */ | |
48 | void *map_addr; | |
49 | }; | |
a4453b7e TT |
50 | |
51 | /* See gdb_bfd.h. */ | |
52 | ||
53 | void | |
54 | gdb_bfd_stash_filename (struct bfd *abfd) | |
55 | { | |
56 | char *name = bfd_get_filename (abfd); | |
57 | char *data; | |
58 | ||
59 | data = bfd_alloc (abfd, strlen (name) + 1); | |
60 | strcpy (data, name); | |
61 | ||
62 | /* Unwarranted chumminess with BFD. */ | |
63 | abfd->filename = data; | |
64 | } | |
cbb099e8 | 65 | |
6ec53d05 TT |
66 | /* An object of this type is stored in each BFD's user data. */ |
67 | ||
68 | struct gdb_bfd_data | |
69 | { | |
70 | /* The reference count. */ | |
71 | int refc; | |
72 | ||
73 | /* The mtime of the BFD at the point the cache entry was made. */ | |
74 | time_t mtime; | |
75 | }; | |
76 | ||
77 | /* A hash table storing all the BFDs maintained in the cache. */ | |
78 | ||
79 | static htab_t gdb_bfd_cache; | |
80 | ||
81 | /* The type of an object being looked up in gdb_bfd_cache. We use | |
82 | htab's capability of storing one kind of object (BFD in this case) | |
83 | and using a different sort of object for searching. */ | |
84 | ||
85 | struct gdb_bfd_cache_search | |
86 | { | |
87 | /* The filename. */ | |
88 | const char *filename; | |
89 | /* The mtime. */ | |
90 | time_t mtime; | |
91 | }; | |
92 | ||
93 | /* A hash function for BFDs. */ | |
94 | ||
95 | static hashval_t | |
96 | hash_bfd (const void *b) | |
97 | { | |
98 | const bfd *abfd = b; | |
99 | ||
100 | /* It is simplest to just hash the filename. */ | |
101 | return htab_hash_string (bfd_get_filename (abfd)); | |
102 | } | |
103 | ||
104 | /* An equality function for BFDs. Note that this expects the caller | |
105 | to search using struct gdb_bfd_cache_search only, not BFDs. */ | |
106 | ||
107 | static int | |
108 | eq_bfd (const void *a, const void *b) | |
109 | { | |
110 | const bfd *abfd = a; | |
111 | const struct gdb_bfd_cache_search *s = b; | |
112 | struct gdb_bfd_data *gdata = bfd_usrdata (abfd); | |
113 | ||
114 | return (gdata->mtime == s->mtime | |
115 | && strcmp (bfd_get_filename (abfd), s->filename) == 0); | |
116 | } | |
117 | ||
118 | /* See gdb_bfd.h. */ | |
119 | ||
120 | struct bfd * | |
121 | gdb_bfd_open (const char *name, const char *target, int fd) | |
122 | { | |
123 | hashval_t hash; | |
124 | void **slot; | |
125 | bfd *abfd; | |
126 | struct gdb_bfd_cache_search search; | |
127 | struct stat st; | |
128 | ||
129 | if (gdb_bfd_cache == NULL) | |
130 | gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL, | |
131 | xcalloc, xfree); | |
132 | ||
133 | if (fd == -1) | |
134 | { | |
135 | fd = open (name, O_RDONLY | O_BINARY); | |
136 | if (fd == -1) | |
137 | { | |
138 | bfd_set_error (bfd_error_system_call); | |
139 | return NULL; | |
140 | } | |
141 | } | |
142 | ||
143 | search.filename = name; | |
144 | if (fstat (fd, &st) < 0) | |
145 | { | |
146 | /* Weird situation here. */ | |
147 | search.mtime = 0; | |
148 | } | |
149 | else | |
150 | search.mtime = st.st_mtime; | |
151 | ||
152 | /* Note that this must compute the same result as hash_bfd. */ | |
153 | hash = htab_hash_string (name); | |
154 | /* Note that we cannot use htab_find_slot_with_hash here, because | |
155 | opening the BFD may fail; and this would violate hashtab | |
156 | invariants. */ | |
157 | abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash); | |
158 | if (abfd != NULL) | |
159 | { | |
160 | close (fd); | |
161 | return gdb_bfd_ref (abfd); | |
162 | } | |
163 | ||
164 | abfd = bfd_fopen (name, target, FOPEN_RB, fd); | |
165 | if (abfd == NULL) | |
166 | return NULL; | |
167 | ||
168 | slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT); | |
169 | gdb_assert (!*slot); | |
170 | *slot = abfd; | |
171 | ||
172 | gdb_bfd_stash_filename (abfd); | |
173 | return gdb_bfd_ref (abfd); | |
174 | } | |
175 | ||
4bf44c1c TT |
176 | /* A helper function that releases any section data attached to the |
177 | BFD. */ | |
178 | ||
179 | static void | |
180 | free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore) | |
181 | { | |
182 | struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp); | |
183 | ||
184 | if (sect != NULL && sect->data != NULL) | |
185 | { | |
186 | #ifdef HAVE_MMAP | |
187 | if (sect->map_addr != NULL) | |
188 | { | |
189 | int res; | |
190 | ||
191 | res = munmap (sect->map_addr, sect->map_len); | |
192 | gdb_assert (res == 0); | |
193 | } | |
194 | else | |
195 | #endif | |
196 | xfree (sect->data); | |
197 | } | |
198 | } | |
199 | ||
cbb099e8 TT |
200 | /* Close ABFD, and warn if that fails. */ |
201 | ||
202 | static int | |
203 | gdb_bfd_close_or_warn (struct bfd *abfd) | |
204 | { | |
205 | int ret; | |
206 | char *name = bfd_get_filename (abfd); | |
207 | ||
4bf44c1c TT |
208 | bfd_map_over_sections (abfd, free_one_bfd_section, NULL); |
209 | ||
cbb099e8 TT |
210 | ret = bfd_close (abfd); |
211 | ||
212 | if (!ret) | |
213 | warning (_("cannot close \"%s\": %s"), | |
214 | name, bfd_errmsg (bfd_get_error ())); | |
215 | ||
216 | return ret; | |
217 | } | |
218 | ||
219 | /* Add reference to ABFD. Returns ABFD. */ | |
220 | ||
221 | struct bfd * | |
222 | gdb_bfd_ref (struct bfd *abfd) | |
223 | { | |
6ec53d05 | 224 | struct gdb_bfd_data *gdata; |
cbb099e8 TT |
225 | |
226 | if (abfd == NULL) | |
227 | return NULL; | |
228 | ||
6ec53d05 | 229 | gdata = bfd_usrdata (abfd); |
cbb099e8 | 230 | |
6ec53d05 | 231 | if (gdata != NULL) |
cbb099e8 | 232 | { |
6ec53d05 | 233 | gdata->refc += 1; |
cbb099e8 TT |
234 | return abfd; |
235 | } | |
236 | ||
6ec53d05 TT |
237 | gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data)); |
238 | gdata->refc = 1; | |
239 | gdata->mtime = bfd_get_mtime (abfd); | |
240 | bfd_usrdata (abfd) = gdata; | |
cbb099e8 TT |
241 | |
242 | return abfd; | |
243 | } | |
244 | ||
245 | /* Unreference and possibly close ABFD. */ | |
246 | ||
247 | void | |
248 | gdb_bfd_unref (struct bfd *abfd) | |
249 | { | |
6ec53d05 TT |
250 | struct gdb_bfd_data *gdata; |
251 | struct gdb_bfd_cache_search search; | |
cbb099e8 TT |
252 | |
253 | if (abfd == NULL) | |
254 | return; | |
255 | ||
6ec53d05 TT |
256 | gdata = bfd_usrdata (abfd); |
257 | gdb_assert (gdata->refc >= 1); | |
cbb099e8 | 258 | |
6ec53d05 TT |
259 | gdata->refc -= 1; |
260 | if (gdata->refc > 0) | |
cbb099e8 TT |
261 | return; |
262 | ||
6ec53d05 TT |
263 | search.filename = bfd_get_filename (abfd); |
264 | ||
265 | if (gdb_bfd_cache && search.filename) | |
266 | { | |
267 | hashval_t hash = htab_hash_string (search.filename); | |
268 | void **slot; | |
269 | ||
270 | search.mtime = gdata->mtime; | |
271 | slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, | |
272 | NO_INSERT); | |
273 | ||
274 | if (slot && *slot) | |
275 | htab_clear_slot (gdb_bfd_cache, slot); | |
276 | } | |
277 | ||
cbb099e8 TT |
278 | bfd_usrdata (abfd) = NULL; /* Paranoia. */ |
279 | ||
cbb099e8 TT |
280 | gdb_bfd_close_or_warn (abfd); |
281 | } | |
4bf44c1c TT |
282 | |
283 | /* A helper function that returns the section data descriptor | |
284 | associated with SECTION. If no such descriptor exists, a new one | |
285 | is allocated and cleared. */ | |
286 | ||
287 | static struct gdb_bfd_section_data * | |
288 | get_section_descriptor (asection *section) | |
289 | { | |
290 | struct gdb_bfd_section_data *result; | |
291 | ||
292 | result = bfd_get_section_userdata (section->owner, section); | |
293 | ||
294 | if (result == NULL) | |
295 | { | |
296 | result = bfd_zalloc (section->owner, sizeof (*result)); | |
297 | bfd_set_section_userdata (section->owner, section, result); | |
298 | } | |
299 | ||
300 | return result; | |
301 | } | |
302 | ||
303 | /* Decompress a section that was compressed using zlib. Store the | |
304 | decompressed buffer, and its size, in DESCRIPTOR. */ | |
305 | ||
306 | static void | |
307 | zlib_decompress_section (asection *sectp, | |
308 | struct gdb_bfd_section_data *descriptor) | |
309 | { | |
310 | bfd *abfd = sectp->owner; | |
311 | #ifndef HAVE_ZLIB_H | |
312 | error (_("Support for zlib-compressed data (from '%s', section '%s') " | |
313 | "is disabled in this copy of GDB"), | |
314 | bfd_get_filename (abfd), | |
315 | bfd_get_section_name (sectp)); | |
316 | #else | |
317 | bfd_size_type compressed_size = bfd_get_section_size (sectp); | |
318 | gdb_byte *compressed_buffer = xmalloc (compressed_size); | |
319 | struct cleanup *cleanup = make_cleanup (xfree, compressed_buffer); | |
320 | struct cleanup *inner_cleanup; | |
321 | bfd_size_type uncompressed_size; | |
322 | gdb_byte *uncompressed_buffer; | |
323 | z_stream strm; | |
324 | int rc; | |
325 | int header_size = 12; | |
326 | struct dwarf2_per_bfd_section *section_data; | |
327 | ||
328 | if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0 | |
329 | || bfd_bread (compressed_buffer, | |
330 | compressed_size, abfd) != compressed_size) | |
331 | error (_("can't read data from '%s', section '%s'"), | |
332 | bfd_get_filename (abfd), | |
333 | bfd_get_section_name (abfd, sectp)); | |
334 | ||
335 | /* Read the zlib header. In this case, it should be "ZLIB" followed | |
336 | by the uncompressed section size, 8 bytes in big-endian order. */ | |
337 | if (compressed_size < header_size | |
338 | || strncmp (compressed_buffer, "ZLIB", 4) != 0) | |
339 | error (_("corrupt ZLIB header from '%s', section '%s'"), | |
340 | bfd_get_filename (abfd), | |
341 | bfd_get_section_name (abfd, sectp)); | |
342 | uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8; | |
343 | uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8; | |
344 | uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8; | |
345 | uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8; | |
346 | uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8; | |
347 | uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8; | |
348 | uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8; | |
349 | uncompressed_size += compressed_buffer[11]; | |
350 | ||
351 | /* It is possible the section consists of several compressed | |
352 | buffers concatenated together, so we uncompress in a loop. */ | |
353 | strm.zalloc = NULL; | |
354 | strm.zfree = NULL; | |
355 | strm.opaque = NULL; | |
356 | strm.avail_in = compressed_size - header_size; | |
357 | strm.next_in = (Bytef*) compressed_buffer + header_size; | |
358 | strm.avail_out = uncompressed_size; | |
359 | uncompressed_buffer = xmalloc (uncompressed_size); | |
360 | inner_cleanup = make_cleanup (xfree, uncompressed_buffer); | |
361 | rc = inflateInit (&strm); | |
362 | while (strm.avail_in > 0) | |
363 | { | |
364 | if (rc != Z_OK) | |
365 | error (_("setting up uncompression in '%s', section '%s': %d"), | |
366 | bfd_get_filename (abfd), | |
367 | bfd_get_section_name (abfd, sectp), | |
368 | rc); | |
369 | strm.next_out = ((Bytef*) uncompressed_buffer | |
370 | + (uncompressed_size - strm.avail_out)); | |
371 | rc = inflate (&strm, Z_FINISH); | |
372 | if (rc != Z_STREAM_END) | |
373 | error (_("zlib error uncompressing from '%s', section '%s': %d"), | |
374 | bfd_get_filename (abfd), | |
375 | bfd_get_section_name (abfd, sectp), | |
376 | rc); | |
377 | rc = inflateReset (&strm); | |
378 | } | |
379 | rc = inflateEnd (&strm); | |
380 | if (rc != Z_OK | |
381 | || strm.avail_out != 0) | |
382 | error (_("concluding uncompression in '%s', section '%s': %d"), | |
383 | bfd_get_filename (abfd), | |
384 | bfd_get_section_name (abfd, sectp), | |
385 | rc); | |
386 | ||
387 | discard_cleanups (inner_cleanup); | |
388 | do_cleanups (cleanup); | |
389 | ||
390 | /* Attach the data to the BFD section. */ | |
391 | descriptor->data = uncompressed_buffer; | |
392 | descriptor->size = uncompressed_size; | |
393 | #endif | |
394 | } | |
395 | ||
396 | /* See gdb_bfd.h. */ | |
397 | ||
398 | const gdb_byte * | |
399 | gdb_bfd_map_section (asection *sectp, bfd_size_type *size) | |
400 | { | |
401 | bfd *abfd; | |
402 | gdb_byte *buf, *retbuf; | |
403 | unsigned char header[4]; | |
404 | struct gdb_bfd_section_data *descriptor; | |
405 | ||
406 | gdb_assert ((sectp->flags & SEC_RELOC) == 0); | |
407 | gdb_assert (size != NULL); | |
408 | ||
409 | abfd = sectp->owner; | |
410 | ||
411 | descriptor = get_section_descriptor (sectp); | |
412 | ||
413 | /* If the data was already read for this BFD, just reuse it. */ | |
414 | if (descriptor->data != NULL) | |
415 | goto done; | |
416 | ||
417 | /* Check if the file has a 4-byte header indicating compression. */ | |
418 | if (bfd_get_section_size (sectp) > sizeof (header) | |
419 | && bfd_seek (abfd, sectp->filepos, SEEK_SET) == 0 | |
420 | && bfd_bread (header, sizeof (header), abfd) == sizeof (header)) | |
421 | { | |
422 | /* Upon decompression, update the buffer and its size. */ | |
423 | if (strncmp (header, "ZLIB", sizeof (header)) == 0) | |
424 | { | |
425 | zlib_decompress_section (sectp, descriptor); | |
426 | goto done; | |
427 | } | |
428 | } | |
429 | ||
430 | #ifdef HAVE_MMAP | |
431 | { | |
432 | /* The page size, used when mmapping. */ | |
433 | static int pagesize; | |
434 | ||
435 | if (pagesize == 0) | |
436 | pagesize = getpagesize (); | |
437 | ||
438 | /* Only try to mmap sections which are large enough: we don't want | |
439 | to waste space due to fragmentation. */ | |
440 | ||
441 | if (bfd_get_section_size (sectp) > 4 * pagesize) | |
442 | { | |
443 | descriptor->size = bfd_get_section_size (sectp); | |
444 | descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ, | |
445 | MAP_PRIVATE, sectp->filepos, | |
446 | &descriptor->map_addr, | |
447 | &descriptor->map_len); | |
448 | ||
449 | if ((caddr_t)descriptor->data != MAP_FAILED) | |
450 | { | |
451 | #if HAVE_POSIX_MADVISE | |
452 | posix_madvise (descriptor->map_addr, descriptor->map_len, | |
453 | POSIX_MADV_WILLNEED); | |
454 | #endif | |
455 | goto done; | |
456 | } | |
457 | ||
458 | /* On failure, clear out the section data and try again. */ | |
459 | memset (descriptor, 0, sizeof (*descriptor)); | |
460 | } | |
461 | } | |
462 | #endif /* HAVE_MMAP */ | |
463 | ||
464 | /* If we get here, we are a normal, not-compressed section. */ | |
465 | ||
466 | descriptor->size = bfd_get_section_size (sectp); | |
467 | descriptor->data = xmalloc (descriptor->size); | |
468 | ||
469 | if (bfd_seek (abfd, sectp->filepos, SEEK_SET) != 0 | |
470 | || bfd_bread (descriptor->data, bfd_get_section_size (sectp), | |
471 | abfd) != bfd_get_section_size (sectp)) | |
472 | { | |
473 | xfree (descriptor->data); | |
474 | descriptor->data = NULL; | |
475 | error (_("Can't read data for section '%s'"), | |
476 | bfd_get_filename (abfd)); | |
477 | } | |
478 | ||
479 | done: | |
480 | gdb_assert (descriptor->data != NULL); | |
481 | *size = descriptor->size; | |
482 | return descriptor->data; | |
483 | } |