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-rw-r--r--x/binutils/bfd/cache.c366
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diff --git a/x/binutils/bfd/cache.c b/x/binutils/bfd/cache.c
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+/* BFD library -- caching of file descriptors.
+
+ Copyright 1990, 1991, 1992, 1993, 1994, 1996, 2000, 2001, 2002,
+ 2003, 2004 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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"
+
+static bfd_boolean bfd_cache_delete (bfd *);
+
+/*
+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
+
+*/
+
+/* The number of BFD files we have open. */
+
+static int open_files;
+
+/*
+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
+ Check to see if the required BFD is the same as the last one
+ looked up. If so, then it can use the stream 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))
+
+ */
+
+/* Insert a BFD into the cache. */
+
+static void
+insert (bfd *abfd)
+{
+ if (bfd_last_cache == NULL)
+ {
+ abfd->lru_next = abfd;
+ abfd->lru_prev = abfd;
+ }
+ else
+ {
+ abfd->lru_next = bfd_last_cache;
+ abfd->lru_prev = bfd_last_cache->lru_prev;
+ abfd->lru_prev->lru_next = abfd;
+ abfd->lru_next->lru_prev = abfd;
+ }
+ bfd_last_cache = abfd;
+}
+
+/* Remove a BFD from the cache. */
+
+static void
+snip (bfd *abfd)
+{
+ abfd->lru_prev->lru_next = abfd->lru_next;
+ abfd->lru_next->lru_prev = abfd->lru_prev;
+ if (abfd == bfd_last_cache)
+ {
+ bfd_last_cache = abfd->lru_next;
+ if (abfd == bfd_last_cache)
+ bfd_last_cache = NULL;
+ }
+}
+
+/* We need to open a new file, and the cache is full. Find the least
+ recently used cacheable BFD and close it. */
+
+static bfd_boolean
+close_one (void)
+{
+ register bfd *kill;
+
+ if (bfd_last_cache == NULL)
+ kill = NULL;
+ else
+ {
+ for (kill = bfd_last_cache->lru_prev;
+ ! kill->cacheable;
+ kill = kill->lru_prev)
+ {
+ if (kill == bfd_last_cache)
+ {
+ kill = NULL;
+ break;
+ }
+ }
+ }
+
+ if (kill == NULL)
+ {
+ /* There are no open cacheable BFD's. */
+ return TRUE;
+ }
+
+ kill->where = real_ftell ((FILE *) kill->iostream);
+
+ return bfd_cache_delete (kill);
+}
+
+/* Close a BFD and remove it from the cache. */
+
+static bfd_boolean
+bfd_cache_delete (bfd *abfd)
+{
+ bfd_boolean ret;
+
+ if (fclose ((FILE *) abfd->iostream) == 0)
+ ret = TRUE;
+ else
+ {
+ ret = FALSE;
+ bfd_set_error (bfd_error_system_call);
+ }
+
+ snip (abfd);
+
+ abfd->iostream = NULL;
+ --open_files;
+
+ return ret;
+}
+
+/*
+INTERNAL_FUNCTION
+ bfd_cache_init
+
+SYNOPSIS
+ bfd_boolean bfd_cache_init (bfd *abfd);
+
+DESCRIPTION
+ Add a newly opened BFD to the cache.
+*/
+
+bfd_boolean
+bfd_cache_init (bfd *abfd)
+{
+ BFD_ASSERT (abfd->iostream != NULL);
+ if (open_files >= BFD_CACHE_MAX_OPEN)
+ {
+ if (! close_one ())
+ return FALSE;
+ }
+ insert (abfd);
+ ++open_files;
+ return TRUE;
+}
+
+/*
+INTERNAL_FUNCTION
+ bfd_cache_close
+
+SYNOPSIS
+ bfd_boolean bfd_cache_close (bfd *abfd);
+
+DESCRIPTION
+ Remove the BFD @var{abfd} from the cache. If the attached file is open,
+ then close it too.
+
+RETURNS
+ <<FALSE>> is returned if closing the file fails, <<TRUE>> is
+ returned if all is well.
+*/
+
+bfd_boolean
+bfd_cache_close (bfd *abfd)
+{
+ if (abfd->iostream == NULL
+ || (abfd->flags & BFD_IN_MEMORY) != 0)
+ return TRUE;
+
+ return bfd_cache_delete (abfd);
+}
+
+/*
+INTERNAL_FUNCTION
+ bfd_open_file
+
+SYNOPSIS
+ FILE* bfd_open_file (bfd *abfd);
+
+DESCRIPTION
+ Call the OS to open a file for @var{abfd}. Return the <<FILE *>>
+ (possibly <<NULL>>) that results from this operation. Set up the
+ BFD so that future accesses know the file is open. If the <<FILE *>>
+ returned is <<NULL>>, then it won't have been put in the
+ cache, so it won't have to be removed from it.
+*/
+
+FILE *
+bfd_open_file (bfd *abfd)
+{
+ abfd->cacheable = TRUE; /* Allow it to be closed later. */
+
+ if (open_files >= BFD_CACHE_MAX_OPEN)
+ {
+ if (! close_one ())
+ return NULL;
+ }
+
+ switch (abfd->direction)
+ {
+ case read_direction:
+ case no_direction:
+ abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RB);
+ break;
+ case both_direction:
+ case write_direction:
+ if (abfd->opened_once)
+ {
+ abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_RUB);
+ if (abfd->iostream == NULL)
+ abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB);
+ }
+ else
+ {
+ /* Create the file.
+
+ Some operating systems won't let us overwrite a running
+ binary. For them, we want to unlink the file first.
+
+ However, gcc 2.95 will create temporary files using
+ O_EXCL and tight permissions to prevent other users from
+ substituting other .o files during the compilation. gcc
+ will then tell the assembler to use the newly created
+ file as an output file. If we unlink the file here, we
+ open a brief window when another user could still
+ substitute a file.
+
+ So we unlink the output file if and only if it has
+ non-zero size. */
+#ifndef __MSDOS__
+ /* Don't do this for MSDOS: it doesn't care about overwriting
+ a running binary, but if this file is already open by
+ another BFD, we will be in deep trouble if we delete an
+ open file. In fact, objdump does just that if invoked with
+ the --info option. */
+ struct stat s;
+
+ if (stat (abfd->filename, &s) == 0 && s.st_size != 0)
+ unlink (abfd->filename);
+#endif
+ abfd->iostream = (PTR) fopen (abfd->filename, FOPEN_WUB);
+ abfd->opened_once = TRUE;
+ }
+ break;
+ }
+
+ if (abfd->iostream != NULL)
+ {
+ if (! bfd_cache_init (abfd))
+ return NULL;
+ }
+
+ return (FILE *) abfd->iostream;
+}
+
+/*
+INTERNAL_FUNCTION
+ bfd_cache_lookup_worker
+
+SYNOPSIS
+ FILE *bfd_cache_lookup_worker (bfd *abfd);
+
+DESCRIPTION
+ Called when the macro <<bfd_cache_lookup>> fails to find a
+ quick answer. Find a file descriptor for @var{abfd}. If
+ necessary, it open it. If there are already more than
+ <<BFD_CACHE_MAX_OPEN>> files open, it tries to close one first, to
+ avoid running out of file descriptors.
+*/
+
+FILE *
+bfd_cache_lookup_worker (bfd *abfd)
+{
+ if ((abfd->flags & BFD_IN_MEMORY) != 0)
+ abort ();
+
+ if (abfd->my_archive)
+ abfd = abfd->my_archive;
+
+ if (abfd->iostream != NULL)
+ {
+ /* Move the file to the start of the cache. */
+ if (abfd != bfd_last_cache)
+ {
+ snip (abfd);
+ insert (abfd);
+ }
+ }
+ else
+ {
+ if (bfd_open_file (abfd) == NULL)
+ return NULL;
+ if (abfd->where != (unsigned long) abfd->where)
+ return NULL;
+ if (real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0)
+ return NULL;
+ }
+
+ return (FILE *) abfd->iostream;
+}
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