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 /* The maximum number of FDs opened by bfd */
27 #define BFD_CACHE_MAX_OPEN 10
29 /* when this exceeds BFD_CACHE_MAX_OPEN, we get to work */
30 static int open_files;
32 static bfd *cache_sentinel; /* Chain of bfds with active fds we've
35 bfd *bfd_last_cache; /* Zero, or a pointer to the topmost
36 bfd on the chain. This is used by the
37 bfd_cache_lookup() macro in libbfd.h
38 to determine when it can avoid a function
41 static void bfd_cache_delete();
47 bfd *kill = cache_sentinel;
48 if (kill == 0) /* Nothing in the cache */
51 /* We can only close files that want to play this game. */
52 while (!kill->cacheable) {
53 kill = kill->lru_prev;
54 if (kill == cache_sentinel) /* Nobody wants to play */
58 kill->where = ftell((FILE *)(kill->iostream));
59 bfd_cache_delete(kill);
62 /* Cuts the bfd abfd out of the chain in the cache */
67 abfd->lru_prev->lru_next = abfd->lru_next;
68 abfd->lru_next->lru_prev = abfd->lru_prev;
69 if (cache_sentinel == abfd) cache_sentinel = (bfd *)NULL;
73 DEFUN(bfd_cache_delete,(abfd),
76 fclose ((FILE *)(abfd->iostream));
78 abfd->iostream = NULL;
90 x->lru_prev = y->lru_prev;
91 y->lru_prev->lru_next = x;
103 /* Initialize a BFD by putting it on the cache LRU. */
105 DEFUN(bfd_cache_init,(abfd),
108 cache_sentinel = insert(abfd, cache_sentinel);
112 DEFUN(bfd_cache_close,(abfd),
115 /* If this file is open then remove from the chain */
118 bfd_cache_delete(abfd);
122 /* Call the OS to open a file for this BFD. Returns the FILE *
123 (possibly null) that results from this operation. Sets up the
124 BFD so that future accesses know the file is open. */
127 DEFUN(bfd_open_file, (abfd),
130 abfd->cacheable = true; /* Allow it to be closed later. */
131 if(open_files >= BFD_CACHE_MAX_OPEN) {
134 switch (abfd->direction) {
137 abfd->iostream = (char *) fopen(abfd->filename, "r");
140 case write_direction:
141 if (abfd->opened_once == true) {
142 abfd->iostream = (char *) fopen(abfd->filename, "r+");
143 if (!abfd->iostream) {
144 abfd->iostream = (char *) fopen(abfd->filename, "w+");
148 abfd->iostream = (char *) fopen(abfd->filename, "w");
149 abfd->opened_once = true;
153 if (abfd->iostream) {
155 bfd_cache_init (abfd);
158 return (FILE *)(abfd->iostream);
161 /* Find a file descriptor for this BFD. If necessary, open it.
162 If there are already more than BFD_CACHE_MAX_OPEN files open, try to close
163 one first, to avoid running out of file descriptors. */
166 DEFUN(bfd_cache_lookup_worker,(abfd),
169 if (abfd->my_archive)
171 abfd = abfd->my_archive;
173 /* Is this file already open .. if so then quick exit */
176 if (abfd != cache_sentinel) {
177 /* Place onto head of lru chain */
179 cache_sentinel = insert(abfd, cache_sentinel);
182 /* This is a bfd without a stream -
183 so it must have been closed or never opened.
184 find an empty cache entry and use it. */
188 if (open_files >= BFD_CACHE_MAX_OPEN)
193 BFD_ASSERT(bfd_open_file (abfd) != (FILE *)NULL) ;
194 fseek((FILE *)(abfd->iostream), abfd->where, false);
196 bfd_last_cache = abfd;
197 return (FILE *)(abfd->iostream);