2000-11-28 Kazu Hirata <kazu@hxi.com>

[deliverable/binutils-gdb.git] / bfd / cache.c

diff --git a/bfd/cache.c b/bfd/cache.c
index f965bdce8eb45f64bd4a198235990f1272cf3e14..c4becf8e32f974e4017526f0f8c07faf26452d1c 100644 (file)
--- a/bfd/cache.c
+++ b/bfd/cache.c
@@ -1,5 +1,6 @@
 /* BFD library -- caching of file descriptors.
-   Copyright 1990, 1991, 1992, 1994 Free Software Foundation, Inc.
+   Copyright 1990, 91, 92, 93, 94, 95, 1996, 2000
+   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.
@@ -31,7 +32,7 @@ SECTION
        <<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. 
+       handle.
 
 */
 
@@ -78,19 +79,18 @@ 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): \
+  .      (FILE*) (bfd_last_cache->iostream): \
   .       bfd_cache_lookup_worker(x))
- 
- 
+
  */
 
 /* Insert a BFD into the cache.  */
@@ -261,7 +261,7 @@ FILE *
 bfd_open_file (abfd)
      bfd *abfd;
 {
-  abfd->cacheable = true;      /* Allow it to be closed later. */
+  abfd->cacheable = true;      /* Allow it to be closed later.  */
 
   if (open_files >= BFD_CACHE_MAX_OPEN)
     {
@@ -285,7 +285,32 @@ bfd_open_file (abfd)
        }
       else
        {
-         /*open for creat */
+         /* 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_WB);
          abfd->opened_once = true;
        }
@@ -313,7 +338,7 @@ DESCRIPTION
        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.  
+       avoid running out of file descriptors.
 */
 
 FILE *
@@ -323,7 +348,7 @@ bfd_cache_lookup_worker (abfd)
   if ((abfd->flags & BFD_IN_MEMORY) != 0)
     abort ();
 
-  if (abfd->my_archive) 
+  if (abfd->my_archive)
     abfd = abfd->my_archive;
 
   if (abfd->iostream != NULL)