1 /*** cache.c -- Allows you to have more bfds open than your system has fds. */
3 /* Copyright (C) 1990, 1991 Free Software Foundation, Inc.
5 This file is part of BFD, the Binary File Diddler.
7 BFD is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 1, or (at your option)
12 BFD is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with BFD; see the file COPYING. If not, write to
19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
26 /* These declarations should not be needed; libbfd.h's inclusion should
33 /* The maximum number of FDs opened by bfd */
34 #define BFD_CACHE_MAX_OPEN 10
36 /* when this exceeds BFD_CACHE_MAX_OPEN, we get to work */
37 static int open_files;
39 static bfd *cache_sentinel; /* Chain of bfds with active fds we've
50 bfd *kill = cache_sentinel;
51 if (kill == 0) /* Nothing in the cache */
54 /* We can only close files that want to play this game. */
55 while (!kill->cacheable) {
56 kill = kill->lru_prev;
57 if (kill == cache_sentinel) /* Nobody wants to play */
61 kill->where = ftell((FILE *)(kill->iostream));
62 bfd_cache_delete(kill);
65 /* Cuts the bfd abfd out of the chain in the cache */
70 abfd->lru_prev->lru_next = abfd->lru_next;
71 abfd->lru_next->lru_prev = abfd->lru_prev;
72 if (cache_sentinel == abfd) cache_sentinel = (bfd *)NULL;
76 bfd_cache_delete (abfd)
79 fclose ((FILE *)(abfd->iostream));
81 abfd->iostream = NULL;
92 x->lru_prev = y->lru_prev;
93 y->lru_prev->lru_next = x;
105 /* Initialize a BFD by putting it on the cache LRU. */
110 cache_sentinel = insert(abfd, cache_sentinel);
114 bfd_cache_close(abfd)
117 /* If this file is open then remove from the chain */
120 bfd_cache_delete(abfd);
124 /* Call the OS to open a file for this BFD. Returns the FILE *
125 (possibly null) that results from this operation. Sets up the
126 BFD so that future accesses know the file is open. */
132 abfd->cacheable = true; /* Allow it to be closed later. */
133 if(open_files >= BFD_CACHE_MAX_OPEN) {
136 switch (abfd->direction) {
139 abfd->iostream = (char *) fopen(abfd->filename, "r");
142 case write_direction:
143 if (abfd->opened_once == true) {
144 abfd->iostream = (char *) fopen(abfd->filename, "r+");
145 if (!abfd->iostream) {
146 abfd->iostream = (char *) fopen(abfd->filename, "w+");
150 abfd->iostream = (char *) fopen(abfd->filename, "w");
151 abfd->opened_once = true;
155 if (abfd->iostream) {
157 bfd_cache_init (abfd);
160 return (FILE *)(abfd->iostream);
163 /* Find a file descriptor for this BFD. If necessary, open it.
164 If there are already more than BFD_CACHE_MAX_OPEN files open, try to close
165 one first, to avoid running out of file descriptors. */
168 bfd_cache_lookup_worker (abfd)
171 if (abfd->my_archive)
173 abfd = abfd->my_archive;
175 /* Is this file already open .. if so then quick exit */
178 if (abfd != cache_sentinel) {
179 /* Place onto head of lru chain */
181 cache_sentinel = insert(abfd, cache_sentinel);
184 /* This is a bfd without a stream -
185 so it must have been closed or never opened.
186 find an empty cache entry and use it. */
190 if (open_files >= BFD_CACHE_MAX_OPEN)
195 BFD_ASSERT(bfd_open_file (abfd) != (FILE *)NULL) ;
196 fseek((FILE *)(abfd->iostream), abfd->where, false);
198 bfd_last_cache = abfd;
199 return (FILE *)(abfd->iostream);