ea8c7ac7d0
This is a greatly pared down version of the full gdb-4.12, all the config stuff has been removed and the supporting libraries have been stripped to a minimum. This is a 1.1.5 only port, I'll do a more complete port for 2.0 which will have all the config stuff and will install the gnu support libraries as system libraries like we do for readline. There wasn't much point for 1.1.5 since only gdb would use them so I went for saving space instead. For 2.0 I'll config all the other gnu tools to use them as well.
312 lines
7.0 KiB
C
312 lines
7.0 KiB
C
/* BFD library -- caching of file descriptors.
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Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
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Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com).
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/*
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SECTION
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File Caching
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The file caching mechanism is embedded within BFD and allows
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the application to open as many BFDs as it wants without
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regard to the underlying operating system's file descriptor
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limit (often as low as 20 open files). The module in
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<<cache.c>> maintains a least recently used list of
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<<BFD_CACHE_MAX_OPEN>> files, and exports the name
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<<bfd_cache_lookup>> which runs around and makes sure that
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the required BFD is open. If not, then it chooses a file to
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close, closes it and opens the one wanted, returning its file
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handle.
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*/
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#include "bfd.h"
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#include "sysdep.h"
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#include "libbfd.h"
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/*
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INTERNAL_FUNCTION
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BFD_CACHE_MAX_OPEN macro
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DESCRIPTION
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The maximum number of files which the cache will keep open at
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one time.
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.#define BFD_CACHE_MAX_OPEN 10
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*/
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static boolean
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bfd_cache_delete PARAMS ((bfd *));
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/* Number of bfds on the chain. All such bfds have their file open;
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if it closed, they get snipd()d from the chain. */
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static int open_files;
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static bfd *cache_sentinel; /* Chain of BFDs with active fds we've
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opened */
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/*
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INTERNAL_FUNCTION
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bfd_last_cache
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SYNOPSIS
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extern bfd *bfd_last_cache;
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DESCRIPTION
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Zero, or a pointer to the topmost BFD on the chain. This is
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used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to
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determine when it can avoid a function call.
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*/
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bfd *bfd_last_cache;
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/*
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* INTERNAL_FUNCTION
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* bfd_cache_lookup
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*
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* DESCRIPTION
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* Checks to see if the required BFD is the same as the last one
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* looked up. If so then it can use the iostream in the BFD with
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* impunity, since it can't have changed since the last lookup,
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* otherwise it has to perform the complicated lookup function
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*
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* .#define bfd_cache_lookup(x) \
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* . ((x)==bfd_last_cache? \
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* . (FILE*)(bfd_last_cache->iostream): \
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* . bfd_cache_lookup_worker(x))
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*
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*
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*/
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static void
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DEFUN_VOID(close_one)
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{
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bfd *kill = cache_sentinel;
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if (kill == 0) /* Nothing in the cache */
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return ;
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/* We can only close files that want to play this game. */
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while (!kill->cacheable) {
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kill = kill->lru_prev;
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if (kill == cache_sentinel) /* Nobody wants to play */
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return ;
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}
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kill->where = ftell((FILE *)(kill->iostream));
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(void) bfd_cache_delete(kill);
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}
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/* Cuts the BFD abfd out of the chain in the cache */
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static void
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DEFUN(snip,(abfd),
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bfd *abfd)
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{
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abfd->lru_prev->lru_next = abfd->lru_next;
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abfd->lru_next->lru_prev = abfd->lru_prev;
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if (cache_sentinel == abfd) cache_sentinel = (bfd *)NULL;
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}
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static boolean
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DEFUN(bfd_cache_delete,(abfd),
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bfd *abfd)
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{
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boolean ret;
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if (fclose ((FILE *)(abfd->iostream)) == 0)
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ret = true;
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else
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{
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ret = false;
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bfd_error = system_call_error;
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}
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snip (abfd);
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abfd->iostream = NULL;
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open_files--;
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bfd_last_cache = 0;
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return ret;
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}
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static bfd *
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DEFUN(insert,(x,y),
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bfd *x AND
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bfd *y)
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{
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if (y) {
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x->lru_next = y;
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x->lru_prev = y->lru_prev;
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y->lru_prev->lru_next = x;
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y->lru_prev = x;
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}
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else {
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x->lru_prev = x;
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x->lru_next = x;
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}
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return x;
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}
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/* Initialize a BFD by putting it on the cache LRU. */
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void
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DEFUN(bfd_cache_init,(abfd),
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bfd *abfd)
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{
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if (open_files >= BFD_CACHE_MAX_OPEN)
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close_one ();
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cache_sentinel = insert(abfd, cache_sentinel);
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++open_files;
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}
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/*
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INTERNAL_FUNCTION
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bfd_cache_close
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DESCRIPTION
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Remove the BFD from the cache. If the attached file is open,
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then close it too.
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SYNOPSIS
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boolean bfd_cache_close (bfd *);
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RETURNS
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<<false>> is returned if closing the file fails, <<true>> is
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returned if all is well.
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*/
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boolean
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DEFUN(bfd_cache_close,(abfd),
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bfd *abfd)
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{
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/* If this file is open then remove from the chain */
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if (abfd->iostream)
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{
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return bfd_cache_delete(abfd);
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}
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else
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{
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return true;
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}
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}
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/*
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INTERNAL_FUNCTION
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bfd_open_file
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DESCRIPTION
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Call the OS to open a file for this BFD. Returns the FILE *
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(possibly null) that results from this operation. Sets up the
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BFD so that future accesses know the file is open. If the FILE
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* returned is null, then there is won't have been put in the
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cache, so it won't have to be removed from it.
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SYNOPSIS
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FILE* bfd_open_file(bfd *);
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*/
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FILE *
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DEFUN(bfd_open_file, (abfd),
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bfd *abfd)
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{
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abfd->cacheable = true; /* Allow it to be closed later. */
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if(open_files >= BFD_CACHE_MAX_OPEN) {
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close_one();
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}
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switch (abfd->direction) {
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case read_direction:
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case no_direction:
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abfd->iostream = (char *) fopen(abfd->filename, FOPEN_RB);
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break;
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case both_direction:
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case write_direction:
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if (abfd->opened_once == true) {
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abfd->iostream = (char *) fopen(abfd->filename, FOPEN_RUB);
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if (!abfd->iostream) {
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abfd->iostream = (char *) fopen(abfd->filename, FOPEN_WUB);
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}
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} else {
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/*open for creat */
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abfd->iostream = (char *) fopen(abfd->filename, FOPEN_WB);
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abfd->opened_once = true;
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}
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break;
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}
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if (abfd->iostream) {
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bfd_cache_init (abfd);
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}
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return (FILE *)(abfd->iostream);
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}
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/*
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INTERNAL_FUNCTION
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bfd_cache_lookup_worker
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DESCRIPTION
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Called when the macro <<bfd_cache_lookup>> fails to find a
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quick answer. Finds a file descriptor for this BFD. If
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necessary, it open it. If there are already more than
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BFD_CACHE_MAX_OPEN files open, it trys to close one first, to
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avoid running out of file descriptors.
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SYNOPSIS
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FILE *bfd_cache_lookup_worker(bfd *);
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*/
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FILE *
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DEFUN(bfd_cache_lookup_worker,(abfd),
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bfd *abfd)
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{
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if (abfd->my_archive)
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{
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abfd = abfd->my_archive;
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}
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/* Is this file already open .. if so then quick exit */
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if (abfd->iostream)
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{
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if (abfd != cache_sentinel) {
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/* Place onto head of lru chain */
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snip (abfd);
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cache_sentinel = insert(abfd, cache_sentinel);
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}
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}
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/* This is a BFD without a stream -
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so it must have been closed or never opened.
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find an empty cache entry and use it. */
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else
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{
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if (open_files >= BFD_CACHE_MAX_OPEN)
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{
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close_one();
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}
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BFD_ASSERT(bfd_open_file (abfd) != (FILE *)NULL) ;
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fseek((FILE *)(abfd->iostream), abfd->where, false);
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}
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bfd_last_cache = abfd;
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return (FILE *)(abfd->iostream);
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}
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