realpath on AIX 7.1

realpath on AIX 7.1

[Bruno Haible]

Hi Eric,

On AIX 7.1 I'm seeing this test failure:

  test-canonicalize-lgpl.c:69: assertion failed
  FAIL: test-canonicalize-lgpl

The reason is apparently a bug in realpath. Here's a test case:

================================================================================
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
int
main ()
{
  char *result;

  result = realpath ("conftest.dir", NULL);
  if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno);

  result = realpath ("conftest.dir//.", NULL);
  if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)
;

  result = realpath ("conftest.dir//./..", NULL);
  if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)
;

  result = realpath ("conftest.dir/./../conftest.dir", NULL);
  if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)
;

  result = realpath ("conftest.dir//./../conftest.dir", NULL);
  if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)
;

  return 0;
}
================================================================================
$ gcc -D_ALL_SOURCE foo.c -Wall
Output:
/home/haible/testdir1/gltests/conftest.dir
/home/haible/testdir1/gltests/conftest.dir/
/home/haible/testdir1/gltests/conftest.dir
/home/haible/testdir1/gltests/conftest.dir
errno=2

Do you think we should work around it?

Bruno
-- 
In memoriam Eduard Lederer <http://de.wikipedia.org/wiki/Eduard_Lederer>

Re: realpath on AIX 7.1

[Eric Blake]

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On 06/05/2011 09:27 AM, Bruno Haible wrote:
> Hi Eric,
> 
> On AIX 7.1 I'm seeing this test failure:
> 
>   test-canonicalize-lgpl.c:69: assertion failed
>   FAIL: test-canonicalize-lgpl
> 
> The reason is apparently a bug in realpath. Here's a test case:

> 
>   result = realpath ("conftest.dir//.", NULL);
>   if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)

> /home/haible/testdir1/gltests/conftest.dir/

Suspicious to have a trailing slash here when no one else does, but
allowed by POSIX.

>   result = realpath ("conftest.dir//./..", NULL);
>   if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)

> /home/haible/testdir1/gltests/conftest.dir

Flat out wrong.  This should be /home/haible/testdir1/gltests.

>   result = realpath ("conftest.dir//./../conftest.dir", NULL);
>   if (result != NULL) printf ("%s\n", result); else printf ("errno=%d\n", errno)

> errno=2

Flat out wrong.  The mere change from / to // in the middle of the
string should have no impact.

> 
> Do you think we should work around it?

Yes.  I'll work on that, and see if I can come up with anything in the
next hour or so.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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[PATCH] canonicalize-lgpl: work around AIX realpath bug

[Eric Blake]

AIX 7.1 realpath() gets horribly confused by consecutive /
in the name to be resolved.

* m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Expose AIX bug.
* doc/posix-functions/realpath.texi (realpath): Document it.
Reported by Bruno Haible.

Signed-off-by: Eric Blake <eblake@redhat.com>
---

Not too hard, once I actually got on an AIX machine.

 ChangeLog                         |    5 +++++
 doc/posix-functions/realpath.texi |    3 +++
 m4/canonicalize.m4                |   11 ++++++++++-
 3 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 35497d0..6e466e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2011-06-06  Eric Blake  <eblake@redhat.com>

+	canonicalize-lgpl: work around AIX realpath bug
+	* m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Expose AIX bug.
+	* doc/posix-functions/realpath.texi (realpath): Document it.
+	Reported by Bruno Haible.
+
 	strerror: work around FreeBSD bug
 	* lib/strerror.c (strerror): Special case 0.
 	Reported by Bruno Haible.
diff --git a/doc/posix-functions/realpath.texi b/doc/posix-functions/realpath.texi
index cc20709..fd3f160 100644
--- a/doc/posix-functions/realpath.texi
+++ b/doc/posix-functions/realpath.texi
@@ -27,6 +27,9 @@ realpath
 This function fails to recognize non-directories followed @samp{..} on
 some platforms:
 cygwin.
+@item
+This function misbehaves on consecutive slashes on some platforms:
+AIX 7.1.
 @end itemize

 Portability problems not fixed by Gnulib:
diff --git a/m4/canonicalize.m4 b/m4/canonicalize.m4
index 9a099bd..dffdcc3 100644
--- a/m4/canonicalize.m4
+++ b/m4/canonicalize.m4
@@ -1,4 +1,4 @@
-# canonicalize.m4 serial 19
+# canonicalize.m4 serial 20

 dnl Copyright (C) 2003-2007, 2009-2011 Free Software Foundation, Inc.

@@ -62,10 +62,12 @@ AC_DEFUN([gl_FUNC_REALPATH_WORKS],
   AC_CHECK_FUNCS_ONCE([realpath])
   AC_CACHE_CHECK([whether realpath works], [gl_cv_func_realpath_works], [
     touch conftest.a
+    mkdir conftest.d
     AC_RUN_IFELSE([
       AC_LANG_PROGRAM([[
         ]GL_NOCRASH[
         #include <stdlib.h>
+        #include <string.h>
       ]], [[
         int result = 0;
         {
@@ -83,10 +85,17 @@ AC_DEFUN([gl_FUNC_REALPATH_WORKS],
           if (name != NULL)
             result |= 4;
         }
+        {
+          char *name1 = realpath (".", NULL);
+          char *name2 = realpath ("conftest.d//./..", NULL);
+          if (strcmp (name1, name2) != 0)
+            result |= 8;
+        }
         return result;
       ]])
     ], [gl_cv_func_realpath_works=yes], [gl_cv_func_realpath_works=no],
        [gl_cv_func_realpath_works="guessing no"])
+    rm -Rf conftest.a conftest.d
   ])
   if test "$gl_cv_func_realpath_works" = yes; then
     AC_DEFINE([FUNC_REALPATH_WORKS], [1], [Define to 1 if realpath()
-- 
1.7.4.4

Re: [PATCH] canonicalize-lgpl: work around AIX realpath bug

[Bruno Haible]

Eric Blake wrote:
> +    rm -Rf conftest.a conftest.d

       rm -rf conftest.a conftest.d

would be more portable, I think: The autoconf documentation mentions

  `rm'
       The `-f' and `-r' options are portable.

whereas it does not say that '-R' is portable.

Bruno
-- 
In memoriam Robert F. Kennedy <http://en.wikipedia.org/wiki/Robert_F._Kennedy>

Re: [PATCH] canonicalize-lgpl: work around AIX realpath bug

[Eric Blake]

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On 06/06/2011 05:11 PM, Bruno Haible wrote:
> Eric Blake wrote:
>> +    rm -Rf conftest.a conftest.d
> 
>        rm -rf conftest.a conftest.d
> 
> would be more portable, I think: The autoconf documentation mentions
> 
>   `rm'
>        The `-f' and `-r' options are portable.
> 
> whereas it does not say that '-R' is portable.

Fair enough.  POSIX requires -R as a synonym to -r, but on the
off-chance that someone still lacks the newer spelling, it would be nice
to know who so that autoconf can give better details.  I've made that
change.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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