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-rw-r--r--gnu/usr.bin/gdb/bfd/cache.c311
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diff --git a/gnu/usr.bin/gdb/bfd/cache.c b/gnu/usr.bin/gdb/bfd/cache.c
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+/* BFD library -- caching of file descriptors.
+ Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
+ Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com).
+
+This file is part of BFD, the Binary File Descriptor library.
+
+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 2 of the License, or
+(at your option) any later version.
+
+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 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.
+
+*/
+
+#include "bfd.h"
+#include "sysdep.h"
+#include "libbfd.h"
+
+/*
+INTERNAL_FUNCTION
+ BFD_CACHE_MAX_OPEN macro
+
+DESCRIPTION
+ The maximum number of files which the cache will keep open at
+ one time.
+
+.#define BFD_CACHE_MAX_OPEN 10
+
+*/
+
+
+static boolean
+bfd_cache_delete PARAMS ((bfd *));
+
+/* Number of bfds on the chain. All such bfds have their file open;
+ if it closed, they get snipd()d from the chain. */
+
+static int open_files;
+
+static bfd *cache_sentinel; /* Chain of BFDs with active fds we've
+ opened */
+
+/*
+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;
+
+/*
+ * 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
+DEFUN_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));
+ (void) bfd_cache_delete(kill);
+}
+
+/* Cuts the BFD abfd out of the chain in the cache */
+static void
+DEFUN(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 boolean
+DEFUN(bfd_cache_delete,(abfd),
+ bfd *abfd)
+{
+ boolean ret;
+
+ if (fclose ((FILE *)(abfd->iostream)) == 0)
+ ret = true;
+ else
+ {
+ ret = false;
+ bfd_error = system_call_error;
+ }
+ snip (abfd);
+ abfd->iostream = NULL;
+ open_files--;
+ bfd_last_cache = 0;
+ return ret;
+}
+
+static bfd *
+DEFUN(insert,(x,y),
+ bfd *x AND
+ 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
+DEFUN(bfd_cache_init,(abfd),
+ bfd *abfd)
+{
+ if (open_files >= BFD_CACHE_MAX_OPEN)
+ close_one ();
+ cache_sentinel = insert(abfd, cache_sentinel);
+ ++open_files;
+}
+
+
+/*
+INTERNAL_FUNCTION
+ bfd_cache_close
+
+DESCRIPTION
+ Remove the BFD from the cache. If the attached file is open,
+ then close it too.
+
+SYNOPSIS
+ boolean bfd_cache_close (bfd *);
+
+RETURNS
+ <<false>> is returned if closing the file fails, <<true>> is
+ returned if all is well.
+*/
+boolean
+DEFUN(bfd_cache_close,(abfd),
+ bfd *abfd)
+{
+ /* If this file is open then remove from the chain */
+ if (abfd->iostream)
+ {
+ return bfd_cache_delete(abfd);
+ }
+ else
+ {
+ return true;
+ }
+}
+
+/*
+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 *
+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, 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) {
+ bfd_cache_init (abfd);
+ }
+
+ return (FILE *)(abfd->iostream);
+}
+
+/*
+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 *
+DEFUN(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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