[PATCH] test-getcwd.c: avoid new set-but-not-used warning

[Jim Meyering]

Eric Blake wrote:
> * gnulib: Update to latest.
> * bootstrap.conf (gnulib_modules): Add xgetgroups.
> ---
>
> Okay to push?
>
> * gnulib a81348d...d6d01fd (70):

Thanks, but not yet.
That would pull in changes that induce two build failures
when configuring coreutils with --enable-gcc-warnings:

    test-hash.c: In function 'main':
    test-hash.c:213:23: error: declaration of 'dup' shadows a global 
declaration\
      [-Werror=shadow]
    test-getcwd.c: In function 'test_abort_bug':
    test-getcwd.c:49:7: error: variable 'fail' set but not used\
      [-Werror=unused-but-set-variable]

I've already pushed the trivial fix for test-hash.c:

  http://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=20abe9a92c71d7cc

I'm about to push this, to fix the second one:

>From c1bb7ba6ba9e685da05f48da5368d9342ba272c1 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Fri, 29 Apr 2011 09:53:25 +0200
Subject: [PATCH] test-getcwd.c: avoid new set-but-not-used warning

* tests/test-getcwd.c (test_abort_bug): Exit nonzero for any problem,
not just the glibc/abort one that getcwd-abort-bug.m4 detects.
This also adds an additional test for an unlikely chdir("..") failure.
* m4/getcwd-abort-bug.m4: Update this now-duplicated code to match,
and adjust the code that sets gl_cv_func_getcwd_abort_bug accordingly.
---
 ChangeLog              |    6 ++++++
 m4/getcwd-abort-bug.m4 |   17 ++++++++++++-----
 tests/test-getcwd.c    |    9 ++++++---
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3cc245e..dc01efd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2011-04-29  Jim Meyering  <address@hidden>

+       test-getcwd.c: avoid new set-but-not-used warning
+       * tests/test-getcwd.c (test_abort_bug): Exit nonzero for any problem,
+       not just the glibc/abort one that getcwd-abort-bug.m4 detects.
+       * m4/getcwd-abort-bug.m4: Update this now-duplicated code to match,
+       and adjust the code that sets gl_cv_func_getcwd_abort_bug accordingly.
+
        test-hash.c: avoid a new shadowing warning
        * tests/test-hash.c (main): Don't shadow "dup".

diff --git a/m4/getcwd-abort-bug.m4 b/m4/getcwd-abort-bug.m4
index 0b59a6b..fd6820d 100644
--- a/m4/getcwd-abort-bug.m4
+++ b/m4/getcwd-abort-bug.m4
@@ -1,4 +1,4 @@
-# serial 3
+# serial 4
 # Determine whether getcwd aborts when the length of the working directory
 # name is unusually large.  Any length between 4k and 16k trigger the bug
 # when using glibc-2.4.90-9 or older.
@@ -65,7 +65,7 @@ main ()

   cwd = getcwd (NULL, 0);
   if (cwd == NULL)
-    return 0;
+    return 2;

   initial_cwd_len = strlen (cwd);
   free (cwd);
@@ -92,15 +92,22 @@ main ()
   while (0 < d--)
     {
       if (chdir ("..") < 0)
-        break;
+        {
+          fail = 5;
+          break;
+        }
       rmdir (dir_name);
     }

-  return 0;
+  return fail;
 }
           ]])],
     [gl_cv_func_getcwd_abort_bug=no],
-    [gl_cv_func_getcwd_abort_bug=yes],
+    dnl A "regular" nonzero return does not indicate this bug.
+    dnl An abort will provoke an exit code of something like 134 (128 + 6).
+    [test $? -gt 128 \
+      && gl_cv_func_getcwd_abort_bug=yes \
+      || gl_cv_func_getcwd_abort_bug=no],
     [gl_cv_func_getcwd_abort_bug=yes])
   ])
   AS_IF([test $gl_cv_func_getcwd_abort_bug = yes], [$1], [$2])
diff --git a/tests/test-getcwd.c b/tests/test-getcwd.c
index 0e0f90f..14a526f 100644
--- a/tests/test-getcwd.c
+++ b/tests/test-getcwd.c
@@ -55,7 +55,7 @@ test_abort_bug (void)

   cwd = getcwd (NULL, 0);
   if (cwd == NULL)
-    return 0;
+    return 2;

   initial_cwd_len = strlen (cwd);
   free (cwd);
@@ -82,11 +82,14 @@ test_abort_bug (void)
   while (0 < d--)
     {
       if (chdir ("..") < 0)
-        break;
+        {
+          fail = 5;
+          break;
+        }
       rmdir (dir_name);
     }

-  return 0;
+  return fail;
 }

 /* The length of this name must be 8.  */
--
1.7.5.421.g9d34e