1 /* BFD library -- caching of file descriptors.
3 Copyright (C) 1990-2018 Free Software Foundation, Inc.
5 Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com).
7 This file is part of BFD, the Binary File Descriptor library.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
22 MA 02110-1301, USA. */
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
46 #include "libiberty.h"
52 /* In some cases we can optimize cache operation when reopening files.
53 For instance, a flush is entirely unnecessary if the file is already
54 closed, so a flush would use CACHE_NO_OPEN. Similarly, a seek using
55 SEEK_SET or SEEK_END need not first seek to the current position.
56 For stat we ignore seek errors, just in case the file has changed
57 while we weren't looking. If it has, then it's possible that the
58 file is shorter and we don't want a seek error to prevent us doing
64 CACHE_NO_SEEK_ERROR = 4
67 /* The maximum number of files which the cache will keep open at
68 one time. When needed call bfd_cache_max_open to initialize. */
70 static int max_open_files = 0;
72 /* Set max_open_files, if not already set, to 12.5% of the allowed open
73 file descriptors, but at least 10, and return the value. */
75 bfd_cache_max_open (void)
77 if (max_open_files == 0)
80 #if defined(__sun) && !defined(__sparcv9) && !defined(__x86_64__)
81 /* PR ld/19260: 32-bit Solaris has very inelegant handling of the 255
82 file descriptor limit. The problem is that setrlimit(2) can raise
83 RLIMIT_NOFILE to a value that is not supported by libc, resulting
84 in "Too many open files" errors. This can happen here even though
85 max_open_files is set to rlim.rlim_cur / 8. For example, if
86 a parent process has set rlim.rlim_cur to 65536, then max_open_files
87 will be computed as 8192.
89 This check essentially reverts to the behavior from binutils 2.23.1
90 for 32-bit Solaris only. (It is hoped that the 32-bit libc
91 limitation will be removed soon). 64-bit Solaris libc does not have
98 if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
99 && rlim.rlim_cur != (rlim_t) RLIM_INFINITY)
100 max = rlim.rlim_cur / 8;
104 max = sysconf (_SC_OPEN_MAX) / 8;
108 #endif /* not 32-bit Solaris */
110 max_open_files = max < 10 ? 10 : max;
113 return max_open_files;
116 /* The number of BFD files we have open. */
118 static int open_files;
120 /* Zero, or a pointer to the topmost BFD on the chain. This is
121 used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to
122 determine when it can avoid a function call. */
124 static bfd *bfd_last_cache = NULL;
126 /* Insert a BFD into the cache. */
131 if (bfd_last_cache == NULL)
133 abfd->lru_next = abfd;
134 abfd->lru_prev = abfd;
138 abfd->lru_next = bfd_last_cache;
139 abfd->lru_prev = bfd_last_cache->lru_prev;
140 abfd->lru_prev->lru_next = abfd;
141 abfd->lru_next->lru_prev = abfd;
143 bfd_last_cache = abfd;
146 /* Remove a BFD from the cache. */
151 abfd->lru_prev->lru_next = abfd->lru_next;
152 abfd->lru_next->lru_prev = abfd->lru_prev;
153 if (abfd == bfd_last_cache)
155 bfd_last_cache = abfd->lru_next;
156 if (abfd == bfd_last_cache)
157 bfd_last_cache = NULL;
161 /* Close a BFD and remove it from the cache. */
164 bfd_cache_delete (bfd *abfd)
168 if (fclose ((FILE *) abfd->iostream) == 0)
173 bfd_set_error (bfd_error_system_call);
178 abfd->iostream = NULL;
184 /* We need to open a new file, and the cache is full. Find the least
185 recently used cacheable BFD and close it. */
190 register bfd *to_kill;
192 if (bfd_last_cache == NULL)
196 for (to_kill = bfd_last_cache->lru_prev;
197 ! to_kill->cacheable;
198 to_kill = to_kill->lru_prev)
200 if (to_kill == bfd_last_cache)
210 /* There are no open cacheable BFD's. */
214 to_kill->where = _bfd_real_ftell ((FILE *) to_kill->iostream);
216 return bfd_cache_delete (to_kill);
219 /* Check to see if the required BFD is the same as the last one
220 looked up. If so, then it can use the stream in the BFD with
221 impunity, since it can't have changed since the last lookup;
222 otherwise, it has to perform the complicated lookup function. */
224 #define bfd_cache_lookup(x, flag) \
225 ((x) == bfd_last_cache \
226 ? (FILE *) (bfd_last_cache->iostream) \
227 : bfd_cache_lookup_worker (x, flag))
229 /* Called when the macro <<bfd_cache_lookup>> fails to find a
230 quick answer. Find a file descriptor for @var{abfd}. If
231 necessary, it open it. If there are already more than
232 <<bfd_cache_max_open>> files open, it tries to close one first, to
233 avoid running out of file descriptors. It will return NULL
234 if it is unable to (re)open the @var{abfd}. */
237 bfd_cache_lookup_worker (bfd *abfd, enum cache_flag flag)
239 if ((abfd->flags & BFD_IN_MEMORY) != 0)
242 if (abfd->my_archive != NULL
243 && !bfd_is_thin_archive (abfd->my_archive))
246 if (abfd->iostream != NULL)
248 /* Move the file to the start of the cache. */
249 if (abfd != bfd_last_cache)
254 return (FILE *) abfd->iostream;
257 if (flag & CACHE_NO_OPEN)
260 if (bfd_open_file (abfd) == NULL)
262 else if (!(flag & CACHE_NO_SEEK)
263 && _bfd_real_fseek ((FILE *) abfd->iostream,
264 abfd->where, SEEK_SET) != 0
265 && !(flag & CACHE_NO_SEEK_ERROR))
266 bfd_set_error (bfd_error_system_call);
268 return (FILE *) abfd->iostream;
270 /* xgettext:c-format */
271 _bfd_error_handler (_("reopening %pB: %s\n"),
272 abfd, bfd_errmsg (bfd_get_error ()));
277 cache_btell (struct bfd *abfd)
279 FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN);
282 return _bfd_real_ftell (f);
286 cache_bseek (struct bfd *abfd, file_ptr offset, int whence)
288 FILE *f = bfd_cache_lookup (abfd, whence != SEEK_CUR ? CACHE_NO_SEEK : CACHE_NORMAL);
291 return _bfd_real_fseek (f, offset, whence);
294 /* Note that archive entries don't have streams; they share their parent's.
295 This allows someone to play with the iostream behind BFD's back.
297 Also, note that the origin pointer points to the beginning of a file's
298 contents (0 for non-archive elements). For archive entries this is the
299 first octet in the file, NOT the beginning of the archive header. */
302 cache_bread_1 (FILE *f, void *buf, file_ptr nbytes)
306 #if defined (__VAX) && defined (VMS)
307 /* Apparently fread on Vax VMS does not keep the record length
309 nread = read (fileno (f), buf, nbytes);
310 /* Set bfd_error if we did not read as much data as we expected. If
311 the read failed due to an error set the bfd_error_system_call,
312 else set bfd_error_file_truncated. */
313 if (nread == (file_ptr)-1)
315 bfd_set_error (bfd_error_system_call);
319 nread = fread (buf, 1, nbytes, f);
320 /* Set bfd_error if we did not read as much data as we expected. If
321 the read failed due to an error set the bfd_error_system_call,
322 else set bfd_error_file_truncated. */
323 if (nread < nbytes && ferror (f))
325 bfd_set_error (bfd_error_system_call);
330 /* This may or may not be an error, but in case the calling code
331 bails out because of it, set the right error code. */
332 bfd_set_error (bfd_error_file_truncated);
337 cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes)
342 f = bfd_cache_lookup (abfd, CACHE_NORMAL);
346 /* Some filesystems are unable to handle reads that are too large
347 (for instance, NetApp shares with oplocks turned off). To avoid
348 hitting this limitation, we read the buffer in chunks of 8MB max. */
349 while (nread < nbytes)
351 const file_ptr max_chunk_size = 0x800000;
352 file_ptr chunk_size = nbytes - nread;
353 file_ptr chunk_nread;
355 if (chunk_size > max_chunk_size)
356 chunk_size = max_chunk_size;
358 chunk_nread = cache_bread_1 (f, (char *) buf + nread, chunk_size);
360 /* Update the nread count.
362 We just have to be careful of the case when cache_bread_1 returns
363 a negative count: If this is our first read, then set nread to
364 that negative count in order to return that negative value to the
365 caller. Otherwise, don't add it to our total count, or we would
366 end up returning a smaller number of bytes read than we actually
368 if (nread == 0 || chunk_nread > 0)
369 nread += chunk_nread;
371 if (chunk_nread < chunk_size)
379 cache_bwrite (struct bfd *abfd, const void *from, file_ptr nbytes)
382 FILE *f = bfd_cache_lookup (abfd, CACHE_NORMAL);
386 nwrite = fwrite (from, 1, nbytes, f);
387 if (nwrite < nbytes && ferror (f))
389 bfd_set_error (bfd_error_system_call);
396 cache_bclose (struct bfd *abfd)
398 return bfd_cache_close (abfd) - 1;
402 cache_bflush (struct bfd *abfd)
405 FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN);
411 bfd_set_error (bfd_error_system_call);
416 cache_bstat (struct bfd *abfd, struct stat *sb)
419 FILE *f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR);
423 sts = fstat (fileno (f), sb);
425 bfd_set_error (bfd_error_system_call);
430 cache_bmmap (struct bfd *abfd ATTRIBUTE_UNUSED,
431 void *addr ATTRIBUTE_UNUSED,
432 bfd_size_type len ATTRIBUTE_UNUSED,
433 int prot ATTRIBUTE_UNUSED,
434 int flags ATTRIBUTE_UNUSED,
435 file_ptr offset ATTRIBUTE_UNUSED,
436 void **map_addr ATTRIBUTE_UNUSED,
437 bfd_size_type *map_len ATTRIBUTE_UNUSED)
439 void *ret = (void *) -1;
441 if ((abfd->flags & BFD_IN_MEMORY) != 0)
446 static uintptr_t pagesize_m1;
449 bfd_size_type pg_len;
451 f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR);
455 if (pagesize_m1 == 0)
456 pagesize_m1 = getpagesize () - 1;
459 pg_offset = offset & ~pagesize_m1;
460 pg_len = (len + (offset - pg_offset) + pagesize_m1) & ~pagesize_m1;
462 ret = mmap (addr, pg_len, prot, flags, fileno (f), pg_offset);
463 if (ret == (void *) -1)
464 bfd_set_error (bfd_error_system_call);
469 ret = (char *) ret + (offset & pagesize_m1);
477 static const struct bfd_iovec cache_iovec =
479 &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek,
480 &cache_bclose, &cache_bflush, &cache_bstat, &cache_bmmap
488 bfd_boolean bfd_cache_init (bfd *abfd);
491 Add a newly opened BFD to the cache.
495 bfd_cache_init (bfd *abfd)
497 BFD_ASSERT (abfd->iostream != NULL);
498 if (open_files >= bfd_cache_max_open ())
503 abfd->iovec = &cache_iovec;
514 bfd_boolean bfd_cache_close (bfd *abfd);
517 Remove the BFD @var{abfd} from the cache. If the attached file is open,
521 <<FALSE>> is returned if closing the file fails, <<TRUE>> is
522 returned if all is well.
526 bfd_cache_close (bfd *abfd)
528 if (abfd->iovec != &cache_iovec)
531 if (abfd->iostream == NULL)
532 /* Previously closed. */
535 return bfd_cache_delete (abfd);
543 bfd_boolean bfd_cache_close_all (void);
546 Remove all BFDs from the cache. If the attached file is open,
550 <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is
551 returned if all is well.
555 bfd_cache_close_all (void)
557 bfd_boolean ret = TRUE;
559 while (bfd_last_cache != NULL)
560 ret &= bfd_cache_close (bfd_last_cache);
570 FILE* bfd_open_file (bfd *abfd);
573 Call the OS to open a file for @var{abfd}. Return the <<FILE *>>
574 (possibly <<NULL>>) that results from this operation. Set up the
575 BFD so that future accesses know the file is open. If the <<FILE *>>
576 returned is <<NULL>>, then it won't have been put in the
577 cache, so it won't have to be removed from it.
581 bfd_open_file (bfd *abfd)
583 abfd->cacheable = TRUE; /* Allow it to be closed later. */
585 if (open_files >= bfd_cache_max_open ())
591 switch (abfd->direction)
595 abfd->iostream = _bfd_real_fopen (abfd->filename, FOPEN_RB);
598 case write_direction:
599 if (abfd->opened_once)
601 abfd->iostream = _bfd_real_fopen (abfd->filename, FOPEN_RUB);
602 if (abfd->iostream == NULL)
603 abfd->iostream = _bfd_real_fopen (abfd->filename, FOPEN_WUB);
609 Some operating systems won't let us overwrite a running
610 binary. For them, we want to unlink the file first.
612 However, gcc 2.95 will create temporary files using
613 O_EXCL and tight permissions to prevent other users from
614 substituting other .o files during the compilation. gcc
615 will then tell the assembler to use the newly created
616 file as an output file. If we unlink the file here, we
617 open a brief window when another user could still
620 So we unlink the output file if and only if it has
623 /* Don't do this for MSDOS: it doesn't care about overwriting
624 a running binary, but if this file is already open by
625 another BFD, we will be in deep trouble if we delete an
626 open file. In fact, objdump does just that if invoked with
627 the --info option. */
630 if (stat (abfd->filename, &s) == 0 && s.st_size != 0)
631 unlink_if_ordinary (abfd->filename);
633 abfd->iostream = _bfd_real_fopen (abfd->filename, FOPEN_WUB);
634 abfd->opened_once = TRUE;
639 if (abfd->iostream == NULL)
640 bfd_set_error (bfd_error_system_call);
643 if (! bfd_cache_init (abfd))
647 return (FILE *) abfd->iostream;