2000-07-21 Michael Snyder <msnyder@cleaver.cygnus.com>

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

diff --git a/bfd/cache.c b/bfd/cache.c
index f965bdce8eb45f64bd4a198235990f1272cf3e14..91b6c610854b228da67b2023d79ce0ed1e746d53 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.
@@ -285,7 +286,32 @@ 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;
        }