Re: AC_FUNC_MMAP not testing what the comments say

Paul Eggert <[email protected]> Fri, 15 Dec 2023 18:24:05 -0800

Newsgroups	gmane.comp.sysutils.autoconf.general
Organization	UCLA Computer Science Department
Message-ID	<[email protected]>

Thanks for the diagnosis. Proposed patch attached. I haven't installed 
it on Savannah, as Autoconf is currently in a prerelease freeze and Zack 
wants a look-see at all patches before they go in.

0001-Fix-AC_FUNC_MMAP-on-CheriBSD.patch (text/x-patch, 1.1 KB)

From 0845c59400378f3441686cbcde48b49fce638f97 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Fri, 15 Dec 2023 18:21:39 -0800
Subject: [PATCH] Fix AC_FUNC_MMAP on CheriBSD
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Problem reported by Brooks Davis in:
https://lists.gnu.org/r/autoconf/2023-12/msg00022.html
* lib/autoconf/functions.m4: Don’t unmap, since we
want to test remapping something already mapped,
and unmapping breaks on CheriBSD.
---
 lib/autoconf/functions.m4 | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/autoconf/functions.m4 b/lib/autoconf/functions.m4
index 4cfb5142..9b3f3c02 100644
--- a/lib/autoconf/functions.m4
+++ b/lib/autoconf/functions.m4
@@ -1385,8 +1385,7 @@ main (void)
     if (*(data2 + i))
       return 7;
   close (fd2);
-  if (munmap (data2, pagesize))
-    return 8;
+  /* 'return 8;' not currently used.  */
 
   /* Next, try to mmap the file at a fixed address which already has
      something else allocated at it.  If we can, also make sure that
-- 
2.43.0