Initial revision

1 files changed, 200 insertions, 0 deletions

diff --git a/bfd/cache.c b/bfd/cache.c
new file mode 100644
index 0000000..39ffc7a
--- /dev/null
+++ b/bfd/cache.c
@@ -0,0 +1,200 @@
+/*** 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);
+}