1 /* BFD library -- caching of file descriptors.
3 Copyright (C) 1990-2017 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"
47 #include "bfd_stdint.h"
53 /* In some cases we can optimize cache operation when reopening files.
54 For instance, a flush is entirely unnecessary if the file is already
55 closed, so a flush would use CACHE_NO_OPEN. Similarly, a seek using
56 SEEK_SET or SEEK_END need not first seek to the current position.
57 For stat we ignore seek errors, just in case the file has changed
58 while we weren't looking. If it has, then it's possible that the
59 file is shorter and we don't want a seek error to prevent us doing
65 CACHE_NO_SEEK_ERROR
= 4
68 /* The maximum number of files which the cache will keep open at
69 one time. When needed call bfd_cache_max_open to initialize. */
71 static int max_open_files
= 0;
73 /* Set max_open_files, if not already set, to 12.5% of the allowed open
74 file descriptors, but at least 10, and return the value. */
76 bfd_cache_max_open (void)
78 if (max_open_files
== 0)
81 #if defined(__sun) && !defined(__sparcv9) && !defined(__x86_64__)
82 /* PR ld/19260: 32-bit Solaris has very inelegant handling of the 255
83 file descriptor limit. The problem is that setrlimit(2) can raise
84 RLIMIT_NOFILE to a value that is not supported by libc, resulting
85 in "Too many open files" errors. This can happen here even though
86 max_open_files is set to rlim.rlim_cur / 8. For example, if
87 a parent process has set rlim.rlim_cur to 65536, then max_open_files
88 will be computed as 8192.
90 This check essentially reverts to the behavior from binutils 2.23.1
91 for 32-bit Solaris only. (It is hoped that the 32-bit libc
92 limitation will be removed soon). 64-bit Solaris libc does not have
99 if (getrlimit (RLIMIT_NOFILE
, &rlim
) == 0
100 && rlim
.rlim_cur
!= (rlim_t
) RLIM_INFINITY
)
101 max
= rlim
.rlim_cur
/ 8;
105 max
= sysconf (_SC_OPEN_MAX
) / 8;
109 #endif /* not 32-bit Solaris */
111 max_open_files
= max
< 10 ? 10 : max
;
114 return max_open_files
;
117 /* The number of BFD files we have open. */
119 static int open_files
;
121 /* Zero, or a pointer to the topmost BFD on the chain. This is
122 used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to
123 determine when it can avoid a function call. */
125 static bfd
*bfd_last_cache
= NULL
;
127 /* Insert a BFD into the cache. */
132 if (bfd_last_cache
== NULL
)
134 abfd
->lru_next
= abfd
;
135 abfd
->lru_prev
= abfd
;
139 abfd
->lru_next
= bfd_last_cache
;
140 abfd
->lru_prev
= bfd_last_cache
->lru_prev
;
141 abfd
->lru_prev
->lru_next
= abfd
;
142 abfd
->lru_next
->lru_prev
= abfd
;
144 bfd_last_cache
= abfd
;
147 /* Remove a BFD from the cache. */
152 abfd
->lru_prev
->lru_next
= abfd
->lru_next
;
153 abfd
->lru_next
->lru_prev
= abfd
->lru_prev
;
154 if (abfd
== bfd_last_cache
)
156 bfd_last_cache
= abfd
->lru_next
;
157 if (abfd
== bfd_last_cache
)
158 bfd_last_cache
= NULL
;
162 /* Close a BFD and remove it from the cache. */
165 bfd_cache_delete (bfd
*abfd
)
169 if (fclose ((FILE *) abfd
->iostream
) == 0)
174 bfd_set_error (bfd_error_system_call
);
179 abfd
->iostream
= NULL
;
185 /* We need to open a new file, and the cache is full. Find the least
186 recently used cacheable BFD and close it. */
191 register bfd
*to_kill
;
193 if (bfd_last_cache
== NULL
)
197 for (to_kill
= bfd_last_cache
->lru_prev
;
198 ! to_kill
->cacheable
;
199 to_kill
= to_kill
->lru_prev
)
201 if (to_kill
== bfd_last_cache
)
211 /* There are no open cacheable BFD's. */
215 to_kill
->where
= real_ftell ((FILE *) to_kill
->iostream
);
217 return bfd_cache_delete (to_kill
);
220 /* Check to see if the required BFD is the same as the last one
221 looked up. If so, then it can use the stream in the BFD with
222 impunity, since it can't have changed since the last lookup;
223 otherwise, it has to perform the complicated lookup function. */
225 #define bfd_cache_lookup(x, flag) \
226 ((x) == bfd_last_cache \
227 ? (FILE *) (bfd_last_cache->iostream) \
228 : bfd_cache_lookup_worker (x, flag))
230 /* Called when the macro <<bfd_cache_lookup>> fails to find a
231 quick answer. Find a file descriptor for @var{abfd}. If
232 necessary, it open it. If there are already more than
233 <<bfd_cache_max_open>> files open, it tries to close one first, to
234 avoid running out of file descriptors. It will return NULL
235 if it is unable to (re)open the @var{abfd}. */
238 bfd_cache_lookup_worker (bfd
*abfd
, enum cache_flag flag
)
240 bfd
*orig_bfd
= abfd
;
241 if ((abfd
->flags
& BFD_IN_MEMORY
) != 0)
244 while (abfd
->my_archive
!= NULL
245 && !bfd_is_thin_archive (abfd
->my_archive
))
246 abfd
= abfd
->my_archive
;
248 if (abfd
->iostream
!= NULL
)
250 /* Move the file to the start of the cache. */
251 if (abfd
!= bfd_last_cache
)
256 return (FILE *) abfd
->iostream
;
259 if (flag
& CACHE_NO_OPEN
)
262 if (bfd_open_file (abfd
) == NULL
)
264 else if (!(flag
& CACHE_NO_SEEK
)
265 && real_fseek ((FILE *) abfd
->iostream
, abfd
->where
, SEEK_SET
) != 0
266 && !(flag
& CACHE_NO_SEEK_ERROR
))
267 bfd_set_error (bfd_error_system_call
);
269 return (FILE *) abfd
->iostream
;
271 /* xgettext:c-format */
272 _bfd_error_handler (_("reopening %B: %s\n"),
273 orig_bfd
, bfd_errmsg (bfd_get_error ()));
278 cache_btell (struct bfd
*abfd
)
280 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_OPEN
);
283 return real_ftell (f
);
287 cache_bseek (struct bfd
*abfd
, file_ptr offset
, int whence
)
289 FILE *f
= bfd_cache_lookup (abfd
, whence
!= SEEK_CUR
? CACHE_NO_SEEK
: CACHE_NORMAL
);
292 return real_fseek (f
, offset
, whence
);
295 /* Note that archive entries don't have streams; they share their parent's.
296 This allows someone to play with the iostream behind BFD's back.
298 Also, note that the origin pointer points to the beginning of a file's
299 contents (0 for non-archive elements). For archive entries this is the
300 first octet in the file, NOT the beginning of the archive header. */
303 cache_bread_1 (struct bfd
*abfd
, void *buf
, file_ptr nbytes
)
307 /* FIXME - this looks like an optimization, but it's really to cover
308 up for a feature of some OSs (not solaris - sigh) that
309 ld/pe-dll.c takes advantage of (apparently) when it creates BFDs
310 internally and tries to link against them. BFD seems to be smart
311 enough to realize there are no symbol records in the "file" that
312 doesn't exist but attempts to read them anyway. On Solaris,
313 attempting to read zero bytes from a NULL file results in a core
314 dump, but on other platforms it just returns zero bytes read.
315 This makes it to something reasonable. - DJ */
319 f
= bfd_cache_lookup (abfd
, CACHE_NORMAL
);
323 #if defined (__VAX) && defined (VMS)
324 /* Apparently fread on Vax VMS does not keep the record length
326 nread
= read (fileno (f
), buf
, nbytes
);
327 /* Set bfd_error if we did not read as much data as we expected. If
328 the read failed due to an error set the bfd_error_system_call,
329 else set bfd_error_file_truncated. */
330 if (nread
== (file_ptr
)-1)
332 bfd_set_error (bfd_error_system_call
);
336 nread
= fread (buf
, 1, nbytes
, f
);
337 /* Set bfd_error if we did not read as much data as we expected. If
338 the read failed due to an error set the bfd_error_system_call,
339 else set bfd_error_file_truncated. */
340 if (nread
< nbytes
&& ferror (f
))
342 bfd_set_error (bfd_error_system_call
);
347 /* This may or may not be an error, but in case the calling code
348 bails out because of it, set the right error code. */
349 bfd_set_error (bfd_error_file_truncated
);
354 cache_bread (struct bfd
*abfd
, void *buf
, file_ptr nbytes
)
358 /* Some filesystems are unable to handle reads that are too large
359 (for instance, NetApp shares with oplocks turned off). To avoid
360 hitting this limitation, we read the buffer in chunks of 8MB max. */
361 while (nread
< nbytes
)
363 const file_ptr max_chunk_size
= 0x800000;
364 file_ptr chunk_size
= nbytes
- nread
;
365 file_ptr chunk_nread
;
367 if (chunk_size
> max_chunk_size
)
368 chunk_size
= max_chunk_size
;
370 chunk_nread
= cache_bread_1 (abfd
, (char *) buf
+ nread
, chunk_size
);
372 /* Update the nread count.
374 We just have to be careful of the case when cache_bread_1 returns
375 a negative count: If this is our first read, then set nread to
376 that negative count in order to return that negative value to the
377 caller. Otherwise, don't add it to our total count, or we would
378 end up returning a smaller number of bytes read than we actually
380 if (nread
== 0 || chunk_nread
> 0)
381 nread
+= chunk_nread
;
383 if (chunk_nread
< chunk_size
)
391 cache_bwrite (struct bfd
*abfd
, const void *where
, file_ptr nbytes
)
394 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NORMAL
);
398 nwrite
= fwrite (where
, 1, nbytes
, f
);
399 if (nwrite
< nbytes
&& ferror (f
))
401 bfd_set_error (bfd_error_system_call
);
408 cache_bclose (struct bfd
*abfd
)
410 return bfd_cache_close (abfd
) - 1;
414 cache_bflush (struct bfd
*abfd
)
417 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_OPEN
);
423 bfd_set_error (bfd_error_system_call
);
428 cache_bstat (struct bfd
*abfd
, struct stat
*sb
)
431 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_SEEK_ERROR
);
435 sts
= fstat (fileno (f
), sb
);
437 bfd_set_error (bfd_error_system_call
);
442 cache_bmmap (struct bfd
*abfd ATTRIBUTE_UNUSED
,
443 void *addr ATTRIBUTE_UNUSED
,
444 bfd_size_type len ATTRIBUTE_UNUSED
,
445 int prot ATTRIBUTE_UNUSED
,
446 int flags ATTRIBUTE_UNUSED
,
447 file_ptr offset ATTRIBUTE_UNUSED
,
448 void **map_addr ATTRIBUTE_UNUSED
,
449 bfd_size_type
*map_len ATTRIBUTE_UNUSED
)
451 void *ret
= (void *) -1;
453 if ((abfd
->flags
& BFD_IN_MEMORY
) != 0)
458 static uintptr_t pagesize_m1
;
461 bfd_size_type pg_len
;
463 f
= bfd_cache_lookup (abfd
, CACHE_NO_SEEK_ERROR
);
467 if (pagesize_m1
== 0)
468 pagesize_m1
= getpagesize () - 1;
470 /* Handle archive members. */
471 if (abfd
->my_archive
!= NULL
472 && !bfd_is_thin_archive (abfd
->my_archive
))
473 offset
+= abfd
->origin
;
476 pg_offset
= offset
& ~pagesize_m1
;
477 pg_len
= (len
+ (offset
- pg_offset
) + pagesize_m1
) & ~pagesize_m1
;
479 ret
= mmap (addr
, pg_len
, prot
, flags
, fileno (f
), pg_offset
);
480 if (ret
== (void *) -1)
481 bfd_set_error (bfd_error_system_call
);
486 ret
= (char *) ret
+ (offset
& pagesize_m1
);
494 static const struct bfd_iovec cache_iovec
=
496 &cache_bread
, &cache_bwrite
, &cache_btell
, &cache_bseek
,
497 &cache_bclose
, &cache_bflush
, &cache_bstat
, &cache_bmmap
505 bfd_boolean bfd_cache_init (bfd *abfd);
508 Add a newly opened BFD to the cache.
512 bfd_cache_init (bfd
*abfd
)
514 BFD_ASSERT (abfd
->iostream
!= NULL
);
515 if (open_files
>= bfd_cache_max_open ())
520 abfd
->iovec
= &cache_iovec
;
531 bfd_boolean bfd_cache_close (bfd *abfd);
534 Remove the BFD @var{abfd} from the cache. If the attached file is open,
538 <<FALSE>> is returned if closing the file fails, <<TRUE>> is
539 returned if all is well.
543 bfd_cache_close (bfd
*abfd
)
545 if (abfd
->iovec
!= &cache_iovec
)
548 if (abfd
->iostream
== NULL
)
549 /* Previously closed. */
552 return bfd_cache_delete (abfd
);
560 bfd_boolean bfd_cache_close_all (void);
563 Remove all BFDs from the cache. If the attached file is open,
567 <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is
568 returned if all is well.
572 bfd_cache_close_all (void)
574 bfd_boolean ret
= TRUE
;
576 while (bfd_last_cache
!= NULL
)
577 ret
&= bfd_cache_close (bfd_last_cache
);
587 FILE* bfd_open_file (bfd *abfd);
590 Call the OS to open a file for @var{abfd}. Return the <<FILE *>>
591 (possibly <<NULL>>) that results from this operation. Set up the
592 BFD so that future accesses know the file is open. If the <<FILE *>>
593 returned is <<NULL>>, then it won't have been put in the
594 cache, so it won't have to be removed from it.
598 bfd_open_file (bfd
*abfd
)
600 abfd
->cacheable
= TRUE
; /* Allow it to be closed later. */
602 if (open_files
>= bfd_cache_max_open ())
608 switch (abfd
->direction
)
612 abfd
->iostream
= real_fopen (abfd
->filename
, FOPEN_RB
);
615 case write_direction
:
616 if (abfd
->opened_once
)
618 abfd
->iostream
= real_fopen (abfd
->filename
, FOPEN_RUB
);
619 if (abfd
->iostream
== NULL
)
620 abfd
->iostream
= real_fopen (abfd
->filename
, FOPEN_WUB
);
626 Some operating systems won't let us overwrite a running
627 binary. For them, we want to unlink the file first.
629 However, gcc 2.95 will create temporary files using
630 O_EXCL and tight permissions to prevent other users from
631 substituting other .o files during the compilation. gcc
632 will then tell the assembler to use the newly created
633 file as an output file. If we unlink the file here, we
634 open a brief window when another user could still
637 So we unlink the output file if and only if it has
640 /* Don't do this for MSDOS: it doesn't care about overwriting
641 a running binary, but if this file is already open by
642 another BFD, we will be in deep trouble if we delete an
643 open file. In fact, objdump does just that if invoked with
644 the --info option. */
647 if (stat (abfd
->filename
, &s
) == 0 && s
.st_size
!= 0)
648 unlink_if_ordinary (abfd
->filename
);
650 abfd
->iostream
= real_fopen (abfd
->filename
, FOPEN_WUB
);
651 abfd
->opened_once
= TRUE
;
656 if (abfd
->iostream
== NULL
)
657 bfd_set_error (bfd_error_system_call
);
660 if (! bfd_cache_init (abfd
))
664 return (FILE *) abfd
->iostream
;