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
= _bfd_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 && _bfd_real_fseek ((FILE *) abfd
->iostream
,
266 abfd
->where
, SEEK_SET
) != 0
267 && !(flag
& CACHE_NO_SEEK_ERROR
))
268 bfd_set_error (bfd_error_system_call
);
270 return (FILE *) abfd
->iostream
;
272 /* xgettext:c-format */
273 _bfd_error_handler (_("reopening %B: %s\n"),
274 orig_bfd
, bfd_errmsg (bfd_get_error ()));
279 cache_btell (struct bfd
*abfd
)
281 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_OPEN
);
284 return _bfd_real_ftell (f
);
288 cache_bseek (struct bfd
*abfd
, file_ptr offset
, int whence
)
290 FILE *f
= bfd_cache_lookup (abfd
, whence
!= SEEK_CUR
? CACHE_NO_SEEK
: CACHE_NORMAL
);
293 return _bfd_real_fseek (f
, offset
, whence
);
296 /* Note that archive entries don't have streams; they share their parent's.
297 This allows someone to play with the iostream behind BFD's back.
299 Also, note that the origin pointer points to the beginning of a file's
300 contents (0 for non-archive elements). For archive entries this is the
301 first octet in the file, NOT the beginning of the archive header. */
304 cache_bread_1 (struct bfd
*abfd
, void *buf
, file_ptr nbytes
)
308 /* FIXME - this looks like an optimization, but it's really to cover
309 up for a feature of some OSs (not solaris - sigh) that
310 ld/pe-dll.c takes advantage of (apparently) when it creates BFDs
311 internally and tries to link against them. BFD seems to be smart
312 enough to realize there are no symbol records in the "file" that
313 doesn't exist but attempts to read them anyway. On Solaris,
314 attempting to read zero bytes from a NULL file results in a core
315 dump, but on other platforms it just returns zero bytes read.
316 This makes it to something reasonable. - DJ */
320 f
= bfd_cache_lookup (abfd
, CACHE_NORMAL
);
324 #if defined (__VAX) && defined (VMS)
325 /* Apparently fread on Vax VMS does not keep the record length
327 nread
= read (fileno (f
), buf
, nbytes
);
328 /* Set bfd_error if we did not read as much data as we expected. If
329 the read failed due to an error set the bfd_error_system_call,
330 else set bfd_error_file_truncated. */
331 if (nread
== (file_ptr
)-1)
333 bfd_set_error (bfd_error_system_call
);
337 nread
= fread (buf
, 1, nbytes
, f
);
338 /* Set bfd_error if we did not read as much data as we expected. If
339 the read failed due to an error set the bfd_error_system_call,
340 else set bfd_error_file_truncated. */
341 if (nread
< nbytes
&& ferror (f
))
343 bfd_set_error (bfd_error_system_call
);
348 /* This may or may not be an error, but in case the calling code
349 bails out because of it, set the right error code. */
350 bfd_set_error (bfd_error_file_truncated
);
355 cache_bread (struct bfd
*abfd
, void *buf
, file_ptr nbytes
)
359 /* Some filesystems are unable to handle reads that are too large
360 (for instance, NetApp shares with oplocks turned off). To avoid
361 hitting this limitation, we read the buffer in chunks of 8MB max. */
362 while (nread
< nbytes
)
364 const file_ptr max_chunk_size
= 0x800000;
365 file_ptr chunk_size
= nbytes
- nread
;
366 file_ptr chunk_nread
;
368 if (chunk_size
> max_chunk_size
)
369 chunk_size
= max_chunk_size
;
371 chunk_nread
= cache_bread_1 (abfd
, (char *) buf
+ nread
, chunk_size
);
373 /* Update the nread count.
375 We just have to be careful of the case when cache_bread_1 returns
376 a negative count: If this is our first read, then set nread to
377 that negative count in order to return that negative value to the
378 caller. Otherwise, don't add it to our total count, or we would
379 end up returning a smaller number of bytes read than we actually
381 if (nread
== 0 || chunk_nread
> 0)
382 nread
+= chunk_nread
;
384 if (chunk_nread
< chunk_size
)
392 cache_bwrite (struct bfd
*abfd
, const void *where
, file_ptr nbytes
)
395 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NORMAL
);
399 nwrite
= fwrite (where
, 1, nbytes
, f
);
400 if (nwrite
< nbytes
&& ferror (f
))
402 bfd_set_error (bfd_error_system_call
);
409 cache_bclose (struct bfd
*abfd
)
411 return bfd_cache_close (abfd
) - 1;
415 cache_bflush (struct bfd
*abfd
)
418 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_OPEN
);
424 bfd_set_error (bfd_error_system_call
);
429 cache_bstat (struct bfd
*abfd
, struct stat
*sb
)
432 FILE *f
= bfd_cache_lookup (abfd
, CACHE_NO_SEEK_ERROR
);
436 sts
= fstat (fileno (f
), sb
);
438 bfd_set_error (bfd_error_system_call
);
443 cache_bmmap (struct bfd
*abfd ATTRIBUTE_UNUSED
,
444 void *addr ATTRIBUTE_UNUSED
,
445 bfd_size_type len ATTRIBUTE_UNUSED
,
446 int prot ATTRIBUTE_UNUSED
,
447 int flags ATTRIBUTE_UNUSED
,
448 file_ptr offset ATTRIBUTE_UNUSED
,
449 void **map_addr ATTRIBUTE_UNUSED
,
450 bfd_size_type
*map_len ATTRIBUTE_UNUSED
)
452 void *ret
= (void *) -1;
454 if ((abfd
->flags
& BFD_IN_MEMORY
) != 0)
459 static uintptr_t pagesize_m1
;
462 bfd_size_type pg_len
;
464 f
= bfd_cache_lookup (abfd
, CACHE_NO_SEEK_ERROR
);
468 if (pagesize_m1
== 0)
469 pagesize_m1
= getpagesize () - 1;
471 /* Handle archive members. */
472 if (abfd
->my_archive
!= NULL
473 && !bfd_is_thin_archive (abfd
->my_archive
))
474 offset
+= abfd
->origin
;
477 pg_offset
= offset
& ~pagesize_m1
;
478 pg_len
= (len
+ (offset
- pg_offset
) + pagesize_m1
) & ~pagesize_m1
;
480 ret
= mmap (addr
, pg_len
, prot
, flags
, fileno (f
), pg_offset
);
481 if (ret
== (void *) -1)
482 bfd_set_error (bfd_error_system_call
);
487 ret
= (char *) ret
+ (offset
& pagesize_m1
);
495 static const struct bfd_iovec cache_iovec
=
497 &cache_bread
, &cache_bwrite
, &cache_btell
, &cache_bseek
,
498 &cache_bclose
, &cache_bflush
, &cache_bstat
, &cache_bmmap
506 bfd_boolean bfd_cache_init (bfd *abfd);
509 Add a newly opened BFD to the cache.
513 bfd_cache_init (bfd
*abfd
)
515 BFD_ASSERT (abfd
->iostream
!= NULL
);
516 if (open_files
>= bfd_cache_max_open ())
521 abfd
->iovec
= &cache_iovec
;
532 bfd_boolean bfd_cache_close (bfd *abfd);
535 Remove the BFD @var{abfd} from the cache. If the attached file is open,
539 <<FALSE>> is returned if closing the file fails, <<TRUE>> is
540 returned if all is well.
544 bfd_cache_close (bfd
*abfd
)
546 if (abfd
->iovec
!= &cache_iovec
)
549 if (abfd
->iostream
== NULL
)
550 /* Previously closed. */
553 return bfd_cache_delete (abfd
);
561 bfd_boolean bfd_cache_close_all (void);
564 Remove all BFDs from the cache. If the attached file is open,
568 <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is
569 returned if all is well.
573 bfd_cache_close_all (void)
575 bfd_boolean ret
= TRUE
;
577 while (bfd_last_cache
!= NULL
)
578 ret
&= bfd_cache_close (bfd_last_cache
);
588 FILE* bfd_open_file (bfd *abfd);
591 Call the OS to open a file for @var{abfd}. Return the <<FILE *>>
592 (possibly <<NULL>>) that results from this operation. Set up the
593 BFD so that future accesses know the file is open. If the <<FILE *>>
594 returned is <<NULL>>, then it won't have been put in the
595 cache, so it won't have to be removed from it.
599 bfd_open_file (bfd
*abfd
)
601 abfd
->cacheable
= TRUE
; /* Allow it to be closed later. */
603 if (open_files
>= bfd_cache_max_open ())
609 switch (abfd
->direction
)
613 abfd
->iostream
= _bfd_real_fopen (abfd
->filename
, FOPEN_RB
);
616 case write_direction
:
617 if (abfd
->opened_once
)
619 abfd
->iostream
= _bfd_real_fopen (abfd
->filename
, FOPEN_RUB
);
620 if (abfd
->iostream
== NULL
)
621 abfd
->iostream
= _bfd_real_fopen (abfd
->filename
, FOPEN_WUB
);
627 Some operating systems won't let us overwrite a running
628 binary. For them, we want to unlink the file first.
630 However, gcc 2.95 will create temporary files using
631 O_EXCL and tight permissions to prevent other users from
632 substituting other .o files during the compilation. gcc
633 will then tell the assembler to use the newly created
634 file as an output file. If we unlink the file here, we
635 open a brief window when another user could still
638 So we unlink the output file if and only if it has
641 /* Don't do this for MSDOS: it doesn't care about overwriting
642 a running binary, but if this file is already open by
643 another BFD, we will be in deep trouble if we delete an
644 open file. In fact, objdump does just that if invoked with
645 the --info option. */
648 if (stat (abfd
->filename
, &s
) == 0 && s
.st_size
!= 0)
649 unlink_if_ordinary (abfd
->filename
);
651 abfd
->iostream
= _bfd_real_fopen (abfd
->filename
, FOPEN_WUB
);
652 abfd
->opened_once
= TRUE
;
657 if (abfd
->iostream
== NULL
)
658 bfd_set_error (bfd_error_system_call
);
661 if (! bfd_cache_init (abfd
))
665 return (FILE *) abfd
->iostream
;