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/*** cache.c -- Allows you to have more bfds open than your system has fds. */
/* Copyright (C) 1990, 1991 Free Software Foundation, Inc.
This file is part of BFD, the Binary File Diddler.
BFD is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.
BFD is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with BFD; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* $Id$ */
#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
/* These declarations should not be needed; libbfd.h's inclusion should
have handled it.
int fclose();
int fseek();
*/
/* The maximum number of FDs opened by bfd */
#define BFD_CACHE_MAX_OPEN 10
/* when this exceeds BFD_CACHE_MAX_OPEN, we get to work */
static int open_files;
static bfd *cache_sentinel; /* Chain of bfds with active fds we've
opened */
static void
bfd_cache_delete();
bfd *bfd_last_cache;
static void
close_one()
{
bfd *kill = cache_sentinel;
if (kill == 0) /* Nothing in the cache */
return ;
/* We can only close files that want to play this game. */
while (!kill->cacheable) {
kill = kill->lru_prev;
if (kill == cache_sentinel) /* Nobody wants to play */
return ;
}
kill->where = ftell((FILE *)(kill->iostream));
bfd_cache_delete(kill);
}
/* Cuts the bfd abfd out of the chain in the cache */
static void
snip (abfd)
bfd *abfd;
{
abfd->lru_prev->lru_next = abfd->lru_next;
abfd->lru_next->lru_prev = abfd->lru_prev;
if (cache_sentinel == abfd) cache_sentinel = (bfd *)NULL;
}
static void
bfd_cache_delete (abfd)
bfd *abfd;
{
fclose ((FILE *)(abfd->iostream));
snip (abfd);
abfd->iostream = NULL;
open_files--;
}
static bfd *
insert(x,y)
bfd *x;
bfd *y;
{
if (y) {
x->lru_next = y;
x->lru_prev = y->lru_prev;
y->lru_prev->lru_next = x;
y->lru_prev = x;
}
else {
x->lru_prev = x;
x->lru_next = x;
}
return x;
}
/* Initialize a BFD by putting it on the cache LRU. */
void
bfd_cache_init(abfd)
bfd *abfd;
{
cache_sentinel = insert(abfd, cache_sentinel);
}
void
bfd_cache_close(abfd)
bfd *abfd;
{
/* If this file is open then remove from the chain */
if (abfd->iostream)
{
bfd_cache_delete(abfd);
}
}
/* Call the OS to open a file for this BFD. Returns the FILE *
(possibly null) that results from this operation. Sets up the
BFD so that future accesses know the file is open. */
FILE *
bfd_open_file (abfd)
bfd *abfd;
{
abfd->cacheable = true; /* Allow it to be closed later. */
if(open_files >= BFD_CACHE_MAX_OPEN) {
close_one();
}
switch (abfd->direction) {
case read_direction:
case no_direction:
abfd->iostream = (char *) fopen(abfd->filename, "r");
break;
case both_direction:
case write_direction:
if (abfd->opened_once == true) {
abfd->iostream = (char *) fopen(abfd->filename, "r+");
if (!abfd->iostream) {
abfd->iostream = (char *) fopen(abfd->filename, "w+");
}
} else {
/*open for creat */
abfd->iostream = (char *) fopen(abfd->filename, "w");
abfd->opened_once = true;
}
break;
}
if (abfd->iostream) {
open_files++;
bfd_cache_init (abfd);
}
return (FILE *)(abfd->iostream);
}
/* Find a file descriptor for this BFD. If necessary, open it.
If there are already more than BFD_CACHE_MAX_OPEN files open, try to close
one first, to avoid running out of file descriptors. */
FILE *
bfd_cache_lookup_worker (abfd)
bfd *abfd;
{
if (abfd->my_archive)
{
abfd = abfd->my_archive;
}
/* Is this file already open .. if so then quick exit */
if (abfd->iostream)
{
if (abfd != cache_sentinel) {
/* Place onto head of lru chain */
snip (abfd);
cache_sentinel = insert(abfd, cache_sentinel);
}
}
/* This is a bfd without a stream -
so it must have been closed or never opened.
find an empty cache entry and use it. */
else
{
if (open_files >= BFD_CACHE_MAX_OPEN)
{
close_one();
}
BFD_ASSERT(bfd_open_file (abfd) != (FILE *)NULL) ;
fseek((FILE *)(abfd->iostream), abfd->where, false);
}
bfd_last_cache = abfd;
return (FILE *)(abfd->iostream);
}
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