Commit | Line | Data |
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252b5132 | 1 | /* BFD library -- caching of file descriptors. |
7c192733 AC |
2 | |
3 | Copyright 1990, 1991, 1992, 1993, 1994, 1996, 2000, 2001, 2002, | |
4 | 2003, 2004 Free Software Foundation, Inc. | |
5 | ||
252b5132 RH |
6 | Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com). |
7 | ||
8 | This file is part of BFD, the Binary File Descriptor library. | |
9 | ||
10 | This program is free software; you can redistribute it and/or modify | |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | This program is distributed in the hope that it will be useful, | |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
21 | along with this program; if not, write to the Free Software | |
3e110533 | 22 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ |
252b5132 RH |
23 | |
24 | /* | |
25 | SECTION | |
26 | File caching | |
27 | ||
28 | The file caching mechanism is embedded within BFD and allows | |
29 | the application to open as many BFDs as it wants without | |
30 | regard to the underlying operating system's file descriptor | |
31 | limit (often as low as 20 open files). The module in | |
32 | <<cache.c>> maintains a least recently used list of | |
33 | <<BFD_CACHE_MAX_OPEN>> files, and exports the name | |
34 | <<bfd_cache_lookup>>, which runs around and makes sure that | |
35 | the required BFD is open. If not, then it chooses a file to | |
36 | close, closes it and opens the one wanted, returning its file | |
e60b52c6 | 37 | handle. |
252b5132 | 38 | |
1b74d094 BW |
39 | SUBSECTION |
40 | Caching functions | |
252b5132 RH |
41 | */ |
42 | ||
43 | #include "bfd.h" | |
44 | #include "sysdep.h" | |
45 | #include "libbfd.h" | |
bb14f524 | 46 | #include "libiberty.h" |
252b5132 | 47 | |
d0fdd288 AM |
48 | /* |
49 | INTERNAL_FUNCTION | |
50 | BFD_CACHE_MAX_OPEN macro | |
51 | ||
52 | DESCRIPTION | |
53 | The maximum number of files which the cache will keep open at | |
54 | one time. | |
55 | ||
56 | .#define BFD_CACHE_MAX_OPEN 10 | |
57 | ||
58 | */ | |
59 | ||
60 | /* The number of BFD files we have open. */ | |
61 | ||
62 | static int open_files; | |
63 | ||
64 | /* | |
65 | INTERNAL_FUNCTION | |
66 | bfd_last_cache | |
67 | ||
68 | SYNOPSIS | |
69 | extern bfd *bfd_last_cache; | |
70 | ||
71 | DESCRIPTION | |
72 | Zero, or a pointer to the topmost BFD on the chain. This is | |
73 | used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to | |
74 | determine when it can avoid a function call. | |
75 | */ | |
76 | ||
77 | bfd *bfd_last_cache = NULL; | |
252b5132 | 78 | |
d0fdd288 AM |
79 | /* Insert a BFD into the cache. */ |
80 | ||
81 | static void | |
82 | insert (bfd *abfd) | |
83 | { | |
84 | if (bfd_last_cache == NULL) | |
85 | { | |
86 | abfd->lru_next = abfd; | |
87 | abfd->lru_prev = abfd; | |
88 | } | |
89 | else | |
90 | { | |
91 | abfd->lru_next = bfd_last_cache; | |
92 | abfd->lru_prev = bfd_last_cache->lru_prev; | |
93 | abfd->lru_prev->lru_next = abfd; | |
94 | abfd->lru_next->lru_prev = abfd; | |
95 | } | |
96 | bfd_last_cache = abfd; | |
97 | } | |
98 | ||
99 | /* Remove a BFD from the cache. */ | |
100 | ||
101 | static void | |
102 | snip (bfd *abfd) | |
103 | { | |
104 | abfd->lru_prev->lru_next = abfd->lru_next; | |
105 | abfd->lru_next->lru_prev = abfd->lru_prev; | |
106 | if (abfd == bfd_last_cache) | |
107 | { | |
108 | bfd_last_cache = abfd->lru_next; | |
109 | if (abfd == bfd_last_cache) | |
110 | bfd_last_cache = NULL; | |
111 | } | |
112 | } | |
113 | ||
114 | /* Close a BFD and remove it from the cache. */ | |
115 | ||
116 | static bfd_boolean | |
117 | bfd_cache_delete (bfd *abfd) | |
118 | { | |
119 | bfd_boolean ret; | |
120 | ||
121 | if (fclose ((FILE *) abfd->iostream) == 0) | |
122 | ret = TRUE; | |
123 | else | |
124 | { | |
125 | ret = FALSE; | |
126 | bfd_set_error (bfd_error_system_call); | |
127 | } | |
128 | ||
129 | snip (abfd); | |
130 | ||
131 | abfd->iostream = NULL; | |
132 | --open_files; | |
133 | ||
134 | return ret; | |
135 | } | |
136 | ||
137 | /* We need to open a new file, and the cache is full. Find the least | |
138 | recently used cacheable BFD and close it. */ | |
139 | ||
140 | static bfd_boolean | |
141 | close_one (void) | |
142 | { | |
143 | register bfd *kill; | |
144 | ||
145 | if (bfd_last_cache == NULL) | |
146 | kill = NULL; | |
147 | else | |
148 | { | |
149 | for (kill = bfd_last_cache->lru_prev; | |
150 | ! kill->cacheable; | |
151 | kill = kill->lru_prev) | |
152 | { | |
153 | if (kill == bfd_last_cache) | |
154 | { | |
155 | kill = NULL; | |
156 | break; | |
157 | } | |
158 | } | |
159 | } | |
160 | ||
161 | if (kill == NULL) | |
162 | { | |
163 | /* There are no open cacheable BFD's. */ | |
164 | return TRUE; | |
165 | } | |
166 | ||
167 | kill->where = real_ftell ((FILE *) kill->iostream); | |
168 | ||
169 | return bfd_cache_delete (kill); | |
170 | } | |
171 | ||
172 | /* | |
173 | INTERNAL_FUNCTION | |
174 | bfd_cache_lookup | |
175 | ||
176 | DESCRIPTION | |
177 | Check to see if the required BFD is the same as the last one | |
178 | looked up. If so, then it can use the stream in the BFD with | |
179 | impunity, since it can't have changed since the last lookup; | |
180 | otherwise, it has to perform the complicated lookup function. | |
181 | ||
182 | .#define bfd_cache_lookup(x) \ | |
183 | . ((x) == bfd_last_cache ? \ | |
184 | . (FILE *) (bfd_last_cache->iostream): \ | |
185 | . bfd_cache_lookup_worker (x)) | |
186 | ||
187 | */ | |
188 | ||
189 | /* | |
190 | INTERNAL_FUNCTION | |
191 | bfd_cache_lookup_worker | |
192 | ||
193 | SYNOPSIS | |
194 | FILE *bfd_cache_lookup_worker (bfd *abfd); | |
195 | ||
196 | DESCRIPTION | |
197 | Called when the macro <<bfd_cache_lookup>> fails to find a | |
198 | quick answer. Find a file descriptor for @var{abfd}. If | |
199 | necessary, it open it. If there are already more than | |
200 | <<BFD_CACHE_MAX_OPEN>> files open, it tries to close one first, to | |
201 | avoid running out of file descriptors. It will return NULL | |
202 | if it is unable to (re)open the @var{abfd}. | |
203 | */ | |
204 | ||
205 | FILE * | |
206 | bfd_cache_lookup_worker (bfd *abfd) | |
207 | { | |
208 | bfd *orig_bfd = abfd; | |
209 | if ((abfd->flags & BFD_IN_MEMORY) != 0) | |
210 | abort (); | |
211 | ||
212 | if (abfd->my_archive) | |
213 | abfd = abfd->my_archive; | |
214 | ||
215 | if (abfd->iostream != NULL) | |
216 | { | |
217 | /* Move the file to the start of the cache. */ | |
218 | if (abfd != bfd_last_cache) | |
219 | { | |
220 | snip (abfd); | |
221 | insert (abfd); | |
222 | } | |
223 | return (FILE *) abfd->iostream; | |
224 | } | |
225 | ||
226 | if (bfd_open_file (abfd) == NULL) | |
227 | ; | |
228 | else if (real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0) | |
229 | bfd_set_error (bfd_error_system_call); | |
230 | else | |
231 | return (FILE *) abfd->iostream; | |
232 | ||
233 | (*_bfd_error_handler) (_("reopening %B: %s\n"), | |
234 | orig_bfd, bfd_errmsg (bfd_get_error ())); | |
235 | return NULL; | |
236 | } | |
40838a72 AC |
237 | |
238 | static file_ptr | |
239 | cache_btell (struct bfd *abfd) | |
240 | { | |
3dff57e8 AM |
241 | FILE *f = bfd_cache_lookup (abfd); |
242 | if (f == NULL) | |
243 | return -1; | |
244 | return real_ftell (f); | |
40838a72 AC |
245 | } |
246 | ||
247 | static int | |
248 | cache_bseek (struct bfd *abfd, file_ptr offset, int whence) | |
249 | { | |
3dff57e8 AM |
250 | FILE *f = bfd_cache_lookup (abfd); |
251 | if (f == NULL) | |
252 | return -1; | |
253 | return real_fseek (f, offset, whence); | |
40838a72 AC |
254 | } |
255 | ||
256 | /* Note that archive entries don't have streams; they share their parent's. | |
257 | This allows someone to play with the iostream behind BFD's back. | |
258 | ||
259 | Also, note that the origin pointer points to the beginning of a file's | |
260 | contents (0 for non-archive elements). For archive entries this is the | |
261 | first octet in the file, NOT the beginning of the archive header. */ | |
262 | ||
263 | static file_ptr | |
264 | cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes) | |
265 | { | |
3dff57e8 | 266 | FILE *f; |
40838a72 AC |
267 | file_ptr nread; |
268 | /* FIXME - this looks like an optimization, but it's really to cover | |
269 | up for a feature of some OSs (not solaris - sigh) that | |
270 | ld/pe-dll.c takes advantage of (apparently) when it creates BFDs | |
271 | internally and tries to link against them. BFD seems to be smart | |
272 | enough to realize there are no symbol records in the "file" that | |
273 | doesn't exist but attempts to read them anyway. On Solaris, | |
274 | attempting to read zero bytes from a NULL file results in a core | |
275 | dump, but on other platforms it just returns zero bytes read. | |
276 | This makes it to something reasonable. - DJ */ | |
277 | if (nbytes == 0) | |
278 | return 0; | |
279 | ||
3dff57e8 AM |
280 | f = bfd_cache_lookup (abfd); |
281 | if (f == NULL) | |
282 | return 0; | |
283 | ||
40838a72 AC |
284 | #if defined (__VAX) && defined (VMS) |
285 | /* Apparently fread on Vax VMS does not keep the record length | |
286 | information. */ | |
3dff57e8 | 287 | nread = read (fileno (f), buf, nbytes); |
40838a72 AC |
288 | /* Set bfd_error if we did not read as much data as we expected. If |
289 | the read failed due to an error set the bfd_error_system_call, | |
290 | else set bfd_error_file_truncated. */ | |
291 | if (nread == (file_ptr)-1) | |
292 | { | |
293 | bfd_set_error (bfd_error_system_call); | |
294 | return -1; | |
295 | } | |
296 | #else | |
3dff57e8 | 297 | nread = fread (buf, 1, nbytes, f); |
40838a72 AC |
298 | /* Set bfd_error if we did not read as much data as we expected. If |
299 | the read failed due to an error set the bfd_error_system_call, | |
300 | else set bfd_error_file_truncated. */ | |
3dff57e8 | 301 | if (nread < nbytes && ferror (f)) |
40838a72 AC |
302 | { |
303 | bfd_set_error (bfd_error_system_call); | |
304 | return -1; | |
305 | } | |
306 | #endif | |
307 | return nread; | |
308 | } | |
309 | ||
310 | static file_ptr | |
311 | cache_bwrite (struct bfd *abfd, const void *where, file_ptr nbytes) | |
312 | { | |
3dff57e8 AM |
313 | file_ptr nwrite; |
314 | FILE *f = bfd_cache_lookup (abfd); | |
315 | if (f == NULL) | |
316 | return 0; | |
317 | nwrite = fwrite (where, 1, nbytes, f); | |
318 | if (nwrite < nbytes && ferror (f)) | |
40838a72 AC |
319 | { |
320 | bfd_set_error (bfd_error_system_call); | |
321 | return -1; | |
322 | } | |
323 | return nwrite; | |
324 | } | |
325 | ||
326 | static int | |
327 | cache_bclose (struct bfd *abfd) | |
328 | { | |
329 | return bfd_cache_close (abfd); | |
330 | } | |
331 | ||
332 | static int | |
333 | cache_bflush (struct bfd *abfd) | |
334 | { | |
3dff57e8 AM |
335 | int sts; |
336 | FILE *f = bfd_cache_lookup (abfd); | |
337 | if (f == NULL) | |
338 | return -1; | |
339 | sts = fflush (f); | |
40838a72 AC |
340 | if (sts < 0) |
341 | bfd_set_error (bfd_error_system_call); | |
342 | return sts; | |
343 | } | |
344 | ||
345 | static int | |
346 | cache_bstat (struct bfd *abfd, struct stat *sb) | |
347 | { | |
3dff57e8 AM |
348 | int sts; |
349 | FILE *f = bfd_cache_lookup (abfd); | |
350 | if (f == NULL) | |
351 | return -1; | |
352 | sts = fstat (fileno (f), sb); | |
40838a72 AC |
353 | if (sts < 0) |
354 | bfd_set_error (bfd_error_system_call); | |
355 | return sts; | |
356 | } | |
357 | ||
358 | static const struct bfd_iovec cache_iovec = { | |
359 | &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek, | |
360 | &cache_bclose, &cache_bflush, &cache_bstat | |
361 | }; | |
362 | ||
252b5132 RH |
363 | /* |
364 | INTERNAL_FUNCTION | |
365 | bfd_cache_init | |
366 | ||
367 | SYNOPSIS | |
b34976b6 | 368 | bfd_boolean bfd_cache_init (bfd *abfd); |
252b5132 RH |
369 | |
370 | DESCRIPTION | |
371 | Add a newly opened BFD to the cache. | |
372 | */ | |
373 | ||
b34976b6 | 374 | bfd_boolean |
c58b9523 | 375 | bfd_cache_init (bfd *abfd) |
252b5132 RH |
376 | { |
377 | BFD_ASSERT (abfd->iostream != NULL); | |
378 | if (open_files >= BFD_CACHE_MAX_OPEN) | |
379 | { | |
380 | if (! close_one ()) | |
b34976b6 | 381 | return FALSE; |
252b5132 | 382 | } |
40838a72 | 383 | abfd->iovec = &cache_iovec; |
252b5132 RH |
384 | insert (abfd); |
385 | ++open_files; | |
b34976b6 | 386 | return TRUE; |
252b5132 RH |
387 | } |
388 | ||
389 | /* | |
390 | INTERNAL_FUNCTION | |
391 | bfd_cache_close | |
392 | ||
393 | SYNOPSIS | |
b34976b6 | 394 | bfd_boolean bfd_cache_close (bfd *abfd); |
252b5132 RH |
395 | |
396 | DESCRIPTION | |
397 | Remove the BFD @var{abfd} from the cache. If the attached file is open, | |
398 | then close it too. | |
399 | ||
400 | RETURNS | |
b34976b6 | 401 | <<FALSE>> is returned if closing the file fails, <<TRUE>> is |
252b5132 RH |
402 | returned if all is well. |
403 | */ | |
404 | ||
b34976b6 | 405 | bfd_boolean |
c58b9523 | 406 | bfd_cache_close (bfd *abfd) |
252b5132 | 407 | { |
40838a72 | 408 | if (abfd->iovec != &cache_iovec) |
b34976b6 | 409 | return TRUE; |
252b5132 | 410 | |
fe2e161a AC |
411 | if (abfd->iostream == NULL) |
412 | /* Previously closed. */ | |
413 | return TRUE; | |
414 | ||
252b5132 RH |
415 | return bfd_cache_delete (abfd); |
416 | } | |
417 | ||
02d5a37b JG |
418 | /* |
419 | FUNCTION | |
420 | bfd_cache_close_all | |
421 | ||
422 | SYNOPSIS | |
423 | bfd_boolean bfd_cache_close_all (void); | |
424 | ||
425 | DESCRIPTION | |
426 | Remove all BFDs from the cache. If the attached file is open, | |
427 | then close it too. | |
428 | ||
429 | RETURNS | |
430 | <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is | |
431 | returned if all is well. | |
432 | */ | |
433 | ||
434 | bfd_boolean | |
435 | bfd_cache_close_all () | |
436 | { | |
437 | bfd_boolean ret = TRUE; | |
438 | ||
439 | while (bfd_last_cache != NULL) | |
440 | ret &= bfd_cache_close (bfd_last_cache); | |
c9b549b2 JG |
441 | |
442 | return ret; | |
02d5a37b JG |
443 | } |
444 | ||
252b5132 RH |
445 | /* |
446 | INTERNAL_FUNCTION | |
447 | bfd_open_file | |
448 | ||
449 | SYNOPSIS | |
c58b9523 | 450 | FILE* bfd_open_file (bfd *abfd); |
252b5132 RH |
451 | |
452 | DESCRIPTION | |
453 | Call the OS to open a file for @var{abfd}. Return the <<FILE *>> | |
454 | (possibly <<NULL>>) that results from this operation. Set up the | |
455 | BFD so that future accesses know the file is open. If the <<FILE *>> | |
456 | returned is <<NULL>>, then it won't have been put in the | |
457 | cache, so it won't have to be removed from it. | |
458 | */ | |
459 | ||
460 | FILE * | |
c58b9523 | 461 | bfd_open_file (bfd *abfd) |
252b5132 | 462 | { |
b34976b6 | 463 | abfd->cacheable = TRUE; /* Allow it to be closed later. */ |
252b5132 RH |
464 | |
465 | if (open_files >= BFD_CACHE_MAX_OPEN) | |
466 | { | |
467 | if (! close_one ()) | |
468 | return NULL; | |
469 | } | |
470 | ||
471 | switch (abfd->direction) | |
472 | { | |
473 | case read_direction: | |
474 | case no_direction: | |
475 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RB); | |
476 | break; | |
477 | case both_direction: | |
478 | case write_direction: | |
82e51918 | 479 | if (abfd->opened_once) |
252b5132 RH |
480 | { |
481 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RUB); | |
482 | if (abfd->iostream == NULL) | |
483 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB); | |
484 | } | |
485 | else | |
486 | { | |
9e422a2e ILT |
487 | /* Create the file. |
488 | ||
489 | Some operating systems won't let us overwrite a running | |
490 | binary. For them, we want to unlink the file first. | |
491 | ||
492 | However, gcc 2.95 will create temporary files using | |
493 | O_EXCL and tight permissions to prevent other users from | |
494 | substituting other .o files during the compilation. gcc | |
495 | will then tell the assembler to use the newly created | |
496 | file as an output file. If we unlink the file here, we | |
497 | open a brief window when another user could still | |
498 | substitute a file. | |
499 | ||
500 | So we unlink the output file if and only if it has | |
501 | non-zero size. */ | |
5af11cab AM |
502 | #ifndef __MSDOS__ |
503 | /* Don't do this for MSDOS: it doesn't care about overwriting | |
504 | a running binary, but if this file is already open by | |
505 | another BFD, we will be in deep trouble if we delete an | |
506 | open file. In fact, objdump does just that if invoked with | |
507 | the --info option. */ | |
9e422a2e ILT |
508 | struct stat s; |
509 | ||
510 | if (stat (abfd->filename, &s) == 0 && s.st_size != 0) | |
bb14f524 | 511 | unlink_if_ordinary (abfd->filename); |
5af11cab | 512 | #endif |
c46b7515 | 513 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB); |
b34976b6 | 514 | abfd->opened_once = TRUE; |
252b5132 RH |
515 | } |
516 | break; | |
517 | } | |
518 | ||
5c91cdfb AM |
519 | if (abfd->iostream == NULL) |
520 | bfd_set_error (bfd_error_system_call); | |
521 | else | |
252b5132 RH |
522 | { |
523 | if (! bfd_cache_init (abfd)) | |
524 | return NULL; | |
525 | } | |
526 | ||
527 | return (FILE *) abfd->iostream; | |
528 | } |