-/*** cache.c -- Allows you to have more bfds open than your system has fds. */
-/* Copyright (C) 1990, 1991 Free Software Foundation, Inc.
+/* BFD library -- caching of file descriptors.
+ Copyright (C) 1990-1991 Free Software Foundation, Inc.
-This file is part of BFD, the Binary File Diddler.
+This file is part of BFD, the Binary File Descriptor library.
-BFD is free software; you can redistribute it and/or modify
+This program 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.
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
-BFD is distributed in the hope that it will be useful,
+This program 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. */
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+/*
+SECTION
+ File Caching
+
+ The file caching mechanism is embedded within BFD and allows
+ the application to open as many BFDs as it wants without
+ regard to the underlying operating system's file descriptor
+ limit (often as low as 20 open files). The module in
+ <<cache.c>> maintains a least recently used list of
+ <<BFD_CACHE_MAX_OPEN>> files, and exports the name
+ <<bfd_cache_lookup>> which runs around and makes sure that
+ the required BFD is open. If not, then it chooses a file to
+ close, closes it and opens the one wanted, returning its file
+ handle.
+
+*/
/* $Id$ */
-#include "sysdep.h"
+
#include "bfd.h"
+#include "sysdep.h"
#include "libbfd.h"
-/* These declarations should not be needed; libbfd.h's inclusion should
- have handled it.
- int fclose();
- int fseek();
-*/
+/*
+INTERNAL_FUNCTION
+ BFD_CACHE_MAX_OPEN macro
+DESCRIPTION
+ The maxiumum number of files which the cache will keep open at
+ one time.
+
+.#define BFD_CACHE_MAX_OPEN 10
+
+*/
-/* 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
+static bfd *cache_sentinel; /* Chain of BFDs with active fds we've
opened */
-static void
-bfd_cache_delete();
+
+/*
+INTERNAL_FUNCTION
+ bfd_last_cache
+
+SYNOPSIS
+ extern bfd *bfd_last_cache;
+
+DESCRIPTION
+ Zero, or a pointer to the topmost BFD on the chain. This is
+ used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to
+ determine when it can avoid a function call.
+*/
bfd *bfd_last_cache;
-\f
+
+/*
+ * INTERNAL_FUNCTION
+ * bfd_cache_lookup
+ *
+ * DESCRIPTION
+ * Checks to see if the required BFD is the same as the last one
+ * looked up. If so then it can use the iostream in the BFD with
+ * impunity, since it can't have changed since the last lookup,
+ * otherwise it has to perform the complicated lookup function
+ *
+ * .#define bfd_cache_lookup(x) \
+ * . ((x)==bfd_last_cache? \
+ * . (FILE*)(bfd_last_cache->iostream): \
+ * . bfd_cache_lookup_worker(x))
+ *
+ *
+ */
+
+static void bfd_cache_delete();
+
static void
-close_one()
+DEFUN_VOID(close_one)
{
bfd *kill = cache_sentinel;
if (kill == 0) /* Nothing in the cache */
kill->where = ftell((FILE *)(kill->iostream));
bfd_cache_delete(kill);
-
}
-/* Cuts the bfd abfd out of the chain in the cache */
+
+/* Cuts the BFD abfd out of the chain in the cache */
static void
-snip (abfd)
- bfd *abfd;
+DEFUN(snip,(abfd),
+ bfd *abfd)
{
abfd->lru_prev->lru_next = abfd->lru_next;
abfd->lru_next->lru_prev = abfd->lru_prev;
}
static void
-bfd_cache_delete (abfd)
- bfd *abfd;
+DEFUN(bfd_cache_delete,(abfd),
+ bfd *abfd)
{
fclose ((FILE *)(abfd->iostream));
snip (abfd);
abfd->iostream = NULL;
open_files--;
+ bfd_last_cache = 0;
}
static bfd *
-insert(x,y)
-bfd *x;
-bfd *y;
+DEFUN(insert,(x,y),
+ bfd *x AND
+ bfd *y)
{
if (y) {
x->lru_next = y;
}
\f
-/* Initialize a BFD by putting it on the cache LRU. */
+/*
+INTERNAL_FUNCTION
+ bfd_cache_init
+
+SYNOPSIS
+ void bfd_cache_init (bfd *);
+
+DESCRIPTION
+ Initialize a BFD by putting it on the cache LRU.
+*/
+
void
-bfd_cache_init(abfd)
-bfd *abfd;
+DEFUN(bfd_cache_init,(abfd),
+ bfd *abfd)
{
cache_sentinel = insert(abfd, cache_sentinel);
}
+
+/*
+INTERNAL_FUNCTION
+ bfd_cache_close
+
+DESCRIPTION
+ Remove the BFD from the cache. If the attached file is open,
+ then close it too.
+
+SYNOPSIS
+ void bfd_cache_close (bfd *);
+*/
void
-bfd_cache_close(abfd)
-bfd *abfd;
+DEFUN(bfd_cache_close,(abfd),
+ bfd *abfd)
{
/* If this file is open then remove from the chain */
if (abfd->iostream)
bfd_cache_delete(abfd);
}
}
-\f
-/* 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. */
+
+/*
+INTERNAL_FUNCTION
+ bfd_open_file
+
+DESCRIPTION
+ 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. If the FILE
+ * returned is null, then there is won't have been put in the
+ cache, so it won't have to be removed from it.
+
+SYNOPSIS
+ FILE* bfd_open_file(bfd *);
+*/
FILE *
-bfd_open_file (abfd)
- bfd *abfd;
+DEFUN(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);
+ 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, FOPEN_RB);
+ break;
+ case both_direction:
+ case write_direction:
+ if (abfd->opened_once == true) {
+ abfd->iostream = (char *) fopen(abfd->filename, FOPEN_RUB);
+ if (!abfd->iostream) {
+ abfd->iostream = (char *) fopen(abfd->filename, FOPEN_WUB);
+ }
+ } else {
+ /*open for creat */
+ abfd->iostream = (char *) fopen(abfd->filename, FOPEN_WB);
+ abfd->opened_once = true;
}
+ break;
+ }
+
+ if (abfd->iostream) {
+ open_files++;
+ bfd_cache_init (abfd);
+ }
- return (FILE *)(abfd->iostream);
+ 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. */
+/*
+INTERNAL_FUNCTION
+ bfd_cache_lookup_worker
+
+DESCRIPTION
+ Called when the macro <<bfd_cache_lookup>> fails to find a
+ quick answer. Finds a file descriptor for this BFD. If
+ necessary, it open it. If there are already more than
+ BFD_CACHE_MAX_OPEN files open, it trys to close one first, to
+ avoid running out of file descriptors.
+
+SYNOPSIS
+ FILE *bfd_cache_lookup_worker(bfd *);
+
+*/
FILE *
-bfd_cache_lookup_worker (abfd)
- bfd *abfd;
+DEFUN(bfd_cache_lookup_worker,(abfd),
+ bfd *abfd)
{
if (abfd->my_archive)
- {
- abfd = 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);
+ {
+ 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 -
+ /* 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();
- }
+ 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;
+ BFD_ASSERT(bfd_open_file (abfd) != (FILE *)NULL) ;
+ fseek((FILE *)(abfd->iostream), abfd->where, false);
+ }
+ bfd_last_cache = abfd;
return (FILE *)(abfd->iostream);
}
projects / binutils.git / blobdiff