[patch] remove config.status race condition

[Lars J. Aas]

This patch removes a race condition in config.status.

The culprit is the initial tests in config.status for finding how to
link files and how to test for executable files.  In this phase, the file
"conftest.file" is created and removed in the current directory twice.
This will of course randomly fail when config.status is run in parallell,
which might happen during parallell builds, and certainly happens when
config.status is used multiple times in a pipe.

The problem is resolved by moving to a temporary directory during the
problematic tests.  I don't really think config.status should contain
"configure tests" at all, but I don't have intimate knowledge on why the
tests are run in config.status and not just precomputed by configure,
so I left them in.

  Lars J

2001-02-13  Lars J. Aas  <address@hidden>

        * m4sh.m4 (AS_SHELL_SANITIZE): Invoke AS_TMPDIR(acs) and perform
        the _AS_EXPR_PREPARE, _AS_LN_S_PREPARE, _AS_TEST_PREPARE, and
        _AS_UNSET_PREPARE tests in the temporary directory to avoid race
        condition problem.

Index: m4sh.m4
===================================================================
RCS file: /cvs/autoconf/m4sh.m4,v
retrieving revision 1.30
diff -u -r1.30 m4sh.m4
--- m4sh.m4     2001/01/29 15:24:11     1.30
+++ m4sh.m4     2001/02/13 13:25:04
@@ -66,10 +66,17 @@
   set -o posix
 fi
 
+# to avoid race condition, we need our own sandbox
+as_save_cwd=`pwd`
+AS_TMPDIR(acs)
+cd $tmp
 _AS_EXPR_PREPARE
 _AS_LN_S_PREPARE
 _AS_TEST_PREPARE
 _AS_UNSET_PREPARE
+cd $as_save_cwd
+rm -rf $tmp
+AS_UNSET([as_save_cwd])
 
 # NLS nuisances.
 AS_UNSET([LANG],        [C])