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 RH |
38 | |
39 | */ | |
40 | ||
41 | #include "bfd.h" | |
42 | #include "sysdep.h" | |
43 | #include "libbfd.h" | |
bb14f524 | 44 | #include "libiberty.h" |
252b5132 | 45 | |
c58b9523 | 46 | static bfd_boolean bfd_cache_delete (bfd *); |
252b5132 | 47 | |
40838a72 AC |
48 | |
49 | static file_ptr | |
50 | cache_btell (struct bfd *abfd) | |
51 | { | |
52 | return real_ftell (bfd_cache_lookup (abfd)); | |
53 | } | |
54 | ||
55 | static int | |
56 | cache_bseek (struct bfd *abfd, file_ptr offset, int whence) | |
57 | { | |
58 | return real_fseek (bfd_cache_lookup (abfd), offset, whence); | |
59 | } | |
60 | ||
61 | /* Note that archive entries don't have streams; they share their parent's. | |
62 | This allows someone to play with the iostream behind BFD's back. | |
63 | ||
64 | Also, note that the origin pointer points to the beginning of a file's | |
65 | contents (0 for non-archive elements). For archive entries this is the | |
66 | first octet in the file, NOT the beginning of the archive header. */ | |
67 | ||
68 | static file_ptr | |
69 | cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes) | |
70 | { | |
71 | file_ptr nread; | |
72 | /* FIXME - this looks like an optimization, but it's really to cover | |
73 | up for a feature of some OSs (not solaris - sigh) that | |
74 | ld/pe-dll.c takes advantage of (apparently) when it creates BFDs | |
75 | internally and tries to link against them. BFD seems to be smart | |
76 | enough to realize there are no symbol records in the "file" that | |
77 | doesn't exist but attempts to read them anyway. On Solaris, | |
78 | attempting to read zero bytes from a NULL file results in a core | |
79 | dump, but on other platforms it just returns zero bytes read. | |
80 | This makes it to something reasonable. - DJ */ | |
81 | if (nbytes == 0) | |
82 | return 0; | |
83 | ||
84 | #if defined (__VAX) && defined (VMS) | |
85 | /* Apparently fread on Vax VMS does not keep the record length | |
86 | information. */ | |
87 | nread = read (fileno (bfd_cache_lookup (abfd)), buf, nbytes); | |
88 | /* Set bfd_error if we did not read as much data as we expected. If | |
89 | the read failed due to an error set the bfd_error_system_call, | |
90 | else set bfd_error_file_truncated. */ | |
91 | if (nread == (file_ptr)-1) | |
92 | { | |
93 | bfd_set_error (bfd_error_system_call); | |
94 | return -1; | |
95 | } | |
96 | #else | |
97 | nread = fread (buf, 1, nbytes, bfd_cache_lookup (abfd)); | |
98 | /* Set bfd_error if we did not read as much data as we expected. If | |
99 | the read failed due to an error set the bfd_error_system_call, | |
100 | else set bfd_error_file_truncated. */ | |
101 | if (nread < nbytes && ferror (bfd_cache_lookup (abfd))) | |
102 | { | |
103 | bfd_set_error (bfd_error_system_call); | |
104 | return -1; | |
105 | } | |
106 | #endif | |
107 | return nread; | |
108 | } | |
109 | ||
110 | static file_ptr | |
111 | cache_bwrite (struct bfd *abfd, const void *where, file_ptr nbytes) | |
112 | { | |
113 | file_ptr nwrite = fwrite (where, 1, nbytes, bfd_cache_lookup (abfd)); | |
114 | if (nwrite < nbytes && ferror (bfd_cache_lookup (abfd))) | |
115 | { | |
116 | bfd_set_error (bfd_error_system_call); | |
117 | return -1; | |
118 | } | |
119 | return nwrite; | |
120 | } | |
121 | ||
122 | static int | |
123 | cache_bclose (struct bfd *abfd) | |
124 | { | |
125 | return bfd_cache_close (abfd); | |
126 | } | |
127 | ||
128 | static int | |
129 | cache_bflush (struct bfd *abfd) | |
130 | { | |
131 | int sts = fflush (bfd_cache_lookup (abfd)); | |
132 | if (sts < 0) | |
133 | bfd_set_error (bfd_error_system_call); | |
134 | return sts; | |
135 | } | |
136 | ||
137 | static int | |
138 | cache_bstat (struct bfd *abfd, struct stat *sb) | |
139 | { | |
140 | int sts = fstat (fileno (bfd_cache_lookup (abfd)), sb); | |
141 | if (sts < 0) | |
142 | bfd_set_error (bfd_error_system_call); | |
143 | return sts; | |
144 | } | |
145 | ||
146 | static const struct bfd_iovec cache_iovec = { | |
147 | &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek, | |
148 | &cache_bclose, &cache_bflush, &cache_bstat | |
149 | }; | |
150 | ||
252b5132 RH |
151 | /* |
152 | INTERNAL_FUNCTION | |
153 | BFD_CACHE_MAX_OPEN macro | |
154 | ||
155 | DESCRIPTION | |
156 | The maximum number of files which the cache will keep open at | |
157 | one time. | |
158 | ||
159 | .#define BFD_CACHE_MAX_OPEN 10 | |
160 | ||
161 | */ | |
162 | ||
163 | /* The number of BFD files we have open. */ | |
164 | ||
165 | static int open_files; | |
166 | ||
167 | /* | |
168 | INTERNAL_FUNCTION | |
169 | bfd_last_cache | |
170 | ||
171 | SYNOPSIS | |
172 | extern bfd *bfd_last_cache; | |
173 | ||
174 | DESCRIPTION | |
175 | Zero, or a pointer to the topmost BFD on the chain. This is | |
176 | used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to | |
177 | determine when it can avoid a function call. | |
178 | */ | |
179 | ||
1787c340 | 180 | bfd *bfd_last_cache = NULL; |
252b5132 RH |
181 | |
182 | /* | |
183 | INTERNAL_FUNCTION | |
184 | bfd_cache_lookup | |
e60b52c6 | 185 | |
252b5132 RH |
186 | DESCRIPTION |
187 | Check to see if the required BFD is the same as the last one | |
188 | looked up. If so, then it can use the stream in the BFD with | |
189 | impunity, since it can't have changed since the last lookup; | |
190 | otherwise, it has to perform the complicated lookup function. | |
e60b52c6 | 191 | |
252b5132 | 192 | .#define bfd_cache_lookup(x) \ |
06fc8a8c NC |
193 | . ((x) == bfd_last_cache ? \ |
194 | . (FILE *) (bfd_last_cache->iostream): \ | |
195 | . bfd_cache_lookup_worker (x)) | |
e60b52c6 | 196 | |
252b5132 RH |
197 | */ |
198 | ||
199 | /* Insert a BFD into the cache. */ | |
200 | ||
c58b9523 AM |
201 | static void |
202 | insert (bfd *abfd) | |
252b5132 RH |
203 | { |
204 | if (bfd_last_cache == NULL) | |
205 | { | |
206 | abfd->lru_next = abfd; | |
207 | abfd->lru_prev = abfd; | |
208 | } | |
209 | else | |
210 | { | |
211 | abfd->lru_next = bfd_last_cache; | |
212 | abfd->lru_prev = bfd_last_cache->lru_prev; | |
213 | abfd->lru_prev->lru_next = abfd; | |
214 | abfd->lru_next->lru_prev = abfd; | |
215 | } | |
216 | bfd_last_cache = abfd; | |
217 | } | |
218 | ||
219 | /* Remove a BFD from the cache. */ | |
220 | ||
c58b9523 AM |
221 | static void |
222 | snip (bfd *abfd) | |
252b5132 RH |
223 | { |
224 | abfd->lru_prev->lru_next = abfd->lru_next; | |
225 | abfd->lru_next->lru_prev = abfd->lru_prev; | |
226 | if (abfd == bfd_last_cache) | |
227 | { | |
228 | bfd_last_cache = abfd->lru_next; | |
229 | if (abfd == bfd_last_cache) | |
230 | bfd_last_cache = NULL; | |
231 | } | |
232 | } | |
233 | ||
234 | /* We need to open a new file, and the cache is full. Find the least | |
235 | recently used cacheable BFD and close it. */ | |
236 | ||
b34976b6 | 237 | static bfd_boolean |
c58b9523 | 238 | close_one (void) |
252b5132 RH |
239 | { |
240 | register bfd *kill; | |
241 | ||
242 | if (bfd_last_cache == NULL) | |
243 | kill = NULL; | |
244 | else | |
245 | { | |
246 | for (kill = bfd_last_cache->lru_prev; | |
247 | ! kill->cacheable; | |
248 | kill = kill->lru_prev) | |
249 | { | |
250 | if (kill == bfd_last_cache) | |
251 | { | |
252 | kill = NULL; | |
253 | break; | |
254 | } | |
255 | } | |
256 | } | |
257 | ||
258 | if (kill == NULL) | |
259 | { | |
260 | /* There are no open cacheable BFD's. */ | |
b34976b6 | 261 | return TRUE; |
252b5132 RH |
262 | } |
263 | ||
7c192733 | 264 | kill->where = real_ftell ((FILE *) kill->iostream); |
252b5132 RH |
265 | |
266 | return bfd_cache_delete (kill); | |
267 | } | |
268 | ||
269 | /* Close a BFD and remove it from the cache. */ | |
270 | ||
b34976b6 | 271 | static bfd_boolean |
c58b9523 | 272 | bfd_cache_delete (bfd *abfd) |
252b5132 | 273 | { |
b34976b6 | 274 | bfd_boolean ret; |
252b5132 RH |
275 | |
276 | if (fclose ((FILE *) abfd->iostream) == 0) | |
b34976b6 | 277 | ret = TRUE; |
252b5132 RH |
278 | else |
279 | { | |
b34976b6 | 280 | ret = FALSE; |
252b5132 RH |
281 | bfd_set_error (bfd_error_system_call); |
282 | } | |
283 | ||
284 | snip (abfd); | |
285 | ||
286 | abfd->iostream = NULL; | |
287 | --open_files; | |
288 | ||
289 | return ret; | |
290 | } | |
291 | ||
292 | /* | |
293 | INTERNAL_FUNCTION | |
294 | bfd_cache_init | |
295 | ||
296 | SYNOPSIS | |
b34976b6 | 297 | bfd_boolean bfd_cache_init (bfd *abfd); |
252b5132 RH |
298 | |
299 | DESCRIPTION | |
300 | Add a newly opened BFD to the cache. | |
301 | */ | |
302 | ||
b34976b6 | 303 | bfd_boolean |
c58b9523 | 304 | bfd_cache_init (bfd *abfd) |
252b5132 RH |
305 | { |
306 | BFD_ASSERT (abfd->iostream != NULL); | |
307 | if (open_files >= BFD_CACHE_MAX_OPEN) | |
308 | { | |
309 | if (! close_one ()) | |
b34976b6 | 310 | return FALSE; |
252b5132 | 311 | } |
40838a72 | 312 | abfd->iovec = &cache_iovec; |
252b5132 RH |
313 | insert (abfd); |
314 | ++open_files; | |
b34976b6 | 315 | return TRUE; |
252b5132 RH |
316 | } |
317 | ||
318 | /* | |
319 | INTERNAL_FUNCTION | |
320 | bfd_cache_close | |
321 | ||
322 | SYNOPSIS | |
b34976b6 | 323 | bfd_boolean bfd_cache_close (bfd *abfd); |
252b5132 RH |
324 | |
325 | DESCRIPTION | |
326 | Remove the BFD @var{abfd} from the cache. If the attached file is open, | |
327 | then close it too. | |
328 | ||
329 | RETURNS | |
b34976b6 | 330 | <<FALSE>> is returned if closing the file fails, <<TRUE>> is |
252b5132 RH |
331 | returned if all is well. |
332 | */ | |
333 | ||
b34976b6 | 334 | bfd_boolean |
c58b9523 | 335 | bfd_cache_close (bfd *abfd) |
252b5132 | 336 | { |
40838a72 | 337 | if (abfd->iovec != &cache_iovec) |
b34976b6 | 338 | return TRUE; |
252b5132 | 339 | |
fe2e161a AC |
340 | if (abfd->iostream == NULL) |
341 | /* Previously closed. */ | |
342 | return TRUE; | |
343 | ||
252b5132 RH |
344 | return bfd_cache_delete (abfd); |
345 | } | |
346 | ||
02d5a37b JG |
347 | /* |
348 | FUNCTION | |
349 | bfd_cache_close_all | |
350 | ||
351 | SYNOPSIS | |
352 | bfd_boolean bfd_cache_close_all (void); | |
353 | ||
354 | DESCRIPTION | |
355 | Remove all BFDs from the cache. If the attached file is open, | |
356 | then close it too. | |
357 | ||
358 | RETURNS | |
359 | <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is | |
360 | returned if all is well. | |
361 | */ | |
362 | ||
363 | bfd_boolean | |
364 | bfd_cache_close_all () | |
365 | { | |
366 | bfd_boolean ret = TRUE; | |
367 | ||
368 | while (bfd_last_cache != NULL) | |
369 | ret &= bfd_cache_close (bfd_last_cache); | |
c9b549b2 JG |
370 | |
371 | return ret; | |
02d5a37b JG |
372 | } |
373 | ||
252b5132 RH |
374 | /* |
375 | INTERNAL_FUNCTION | |
376 | bfd_open_file | |
377 | ||
378 | SYNOPSIS | |
c58b9523 | 379 | FILE* bfd_open_file (bfd *abfd); |
252b5132 RH |
380 | |
381 | DESCRIPTION | |
382 | Call the OS to open a file for @var{abfd}. Return the <<FILE *>> | |
383 | (possibly <<NULL>>) that results from this operation. Set up the | |
384 | BFD so that future accesses know the file is open. If the <<FILE *>> | |
385 | returned is <<NULL>>, then it won't have been put in the | |
386 | cache, so it won't have to be removed from it. | |
387 | */ | |
388 | ||
389 | FILE * | |
c58b9523 | 390 | bfd_open_file (bfd *abfd) |
252b5132 | 391 | { |
b34976b6 | 392 | abfd->cacheable = TRUE; /* Allow it to be closed later. */ |
252b5132 RH |
393 | |
394 | if (open_files >= BFD_CACHE_MAX_OPEN) | |
395 | { | |
396 | if (! close_one ()) | |
397 | return NULL; | |
398 | } | |
399 | ||
400 | switch (abfd->direction) | |
401 | { | |
402 | case read_direction: | |
403 | case no_direction: | |
404 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RB); | |
405 | break; | |
406 | case both_direction: | |
407 | case write_direction: | |
82e51918 | 408 | if (abfd->opened_once) |
252b5132 RH |
409 | { |
410 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RUB); | |
411 | if (abfd->iostream == NULL) | |
412 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB); | |
413 | } | |
414 | else | |
415 | { | |
9e422a2e ILT |
416 | /* Create the file. |
417 | ||
418 | Some operating systems won't let us overwrite a running | |
419 | binary. For them, we want to unlink the file first. | |
420 | ||
421 | However, gcc 2.95 will create temporary files using | |
422 | O_EXCL and tight permissions to prevent other users from | |
423 | substituting other .o files during the compilation. gcc | |
424 | will then tell the assembler to use the newly created | |
425 | file as an output file. If we unlink the file here, we | |
426 | open a brief window when another user could still | |
427 | substitute a file. | |
428 | ||
429 | So we unlink the output file if and only if it has | |
430 | non-zero size. */ | |
5af11cab AM |
431 | #ifndef __MSDOS__ |
432 | /* Don't do this for MSDOS: it doesn't care about overwriting | |
433 | a running binary, but if this file is already open by | |
434 | another BFD, we will be in deep trouble if we delete an | |
435 | open file. In fact, objdump does just that if invoked with | |
436 | the --info option. */ | |
9e422a2e ILT |
437 | struct stat s; |
438 | ||
439 | if (stat (abfd->filename, &s) == 0 && s.st_size != 0) | |
bb14f524 | 440 | unlink_if_ordinary (abfd->filename); |
5af11cab | 441 | #endif |
c46b7515 | 442 | abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB); |
b34976b6 | 443 | abfd->opened_once = TRUE; |
252b5132 RH |
444 | } |
445 | break; | |
446 | } | |
447 | ||
448 | if (abfd->iostream != NULL) | |
449 | { | |
450 | if (! bfd_cache_init (abfd)) | |
451 | return NULL; | |
452 | } | |
453 | ||
454 | return (FILE *) abfd->iostream; | |
455 | } | |
456 | ||
457 | /* | |
458 | INTERNAL_FUNCTION | |
459 | bfd_cache_lookup_worker | |
460 | ||
461 | SYNOPSIS | |
c58b9523 | 462 | FILE *bfd_cache_lookup_worker (bfd *abfd); |
252b5132 RH |
463 | |
464 | DESCRIPTION | |
465 | Called when the macro <<bfd_cache_lookup>> fails to find a | |
466 | quick answer. Find a file descriptor for @var{abfd}. If | |
467 | necessary, it open it. If there are already more than | |
468 | <<BFD_CACHE_MAX_OPEN>> files open, it tries to close one first, to | |
06fc8a8c NC |
469 | avoid running out of file descriptors. It will abort rather than |
470 | returning NULL if it is unable to (re)open the @var{abfd}. | |
252b5132 RH |
471 | */ |
472 | ||
473 | FILE * | |
c58b9523 | 474 | bfd_cache_lookup_worker (bfd *abfd) |
252b5132 RH |
475 | { |
476 | if ((abfd->flags & BFD_IN_MEMORY) != 0) | |
477 | abort (); | |
478 | ||
e60b52c6 | 479 | if (abfd->my_archive) |
252b5132 RH |
480 | abfd = abfd->my_archive; |
481 | ||
482 | if (abfd->iostream != NULL) | |
483 | { | |
484 | /* Move the file to the start of the cache. */ | |
485 | if (abfd != bfd_last_cache) | |
486 | { | |
487 | snip (abfd); | |
488 | insert (abfd); | |
489 | } | |
490 | } | |
491 | else | |
492 | { | |
06fc8a8c NC |
493 | if (bfd_open_file (abfd) == NULL |
494 | || abfd->where != (unsigned long) abfd->where | |
495 | || real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0) | |
496 | abort (); | |
252b5132 RH |
497 | } |
498 | ||
499 | return (FILE *) abfd->iostream; | |
500 | } |