Re: grep-2.10 on OSF/1

[Jim Meyering]

Jim Meyering wrote:
> Eric Blake wrote:
>> On 11/20/2011 06:11 AM, Bruno Haible wrote:
>>>     Fix test failures on OSF/1 5.1.
>>>     * tests/ignore-mmap: Pass a regular file, not /dev/null, to 'compare'.
>>>     * tests/max-count-vs-context: Likewise.
>>
>> Autoconf learned that it is always more efficient to use 'test -s file'
>> rather than comparison against /dev/null when you are checking for
>> (non-)emptiness (one less fork, and in the case of buggy compare that
>> can't handle /dev/null, one less portability problem).
>>
>>> +++ tests/max-count-vs-context      2011-11-20 14:08:59.000000000 +0100
>>> @@ -13,11 +13,12 @@
>>>  EOF
>>>
>>>  sed 4q in > exp || framework_failure_
>>> +: > errexp || framework_failure_
>>>
>>>  fail=0
>>>  grep -m1 -A5 needle in > out 2>err || fail=1
>>>
>>>  compare out exp || fail=1
>>> -compare err /dev/null || fail=1
>>> +compare err errexp || fail=1
>>
>> That is, rather than creating an empty errexp, I'd rather see this test
>> rewritten to use a form of test -s.
>
> How about having compare "know" about /dev/null.
> Then it can perform the test -s and warn if the file is nonempty.
> With that, all existing (and there are many) /dev/null-using
> compare uses will benefit.

I've implemented that.
What do you think?

>From 87a00b2ab8e274c4a832f7e630944d38010f585c Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 21 Nov 2011 21:50:23 +0100
Subject: [PATCH] init.sh: work around OSF/1 5.1's mishandling of /dev/null

* tests/init.sh: Make our compare function slightly more portable.
Reported by Bruno Haible in
http://thread.gmane.org/gmane.comp.gnu.grep.bugs/4020
---
 ChangeLog     |    7 +++++++
 tests/init.sh |   45 +++++++++++++++++++++++++++++++++++++++------
 2 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8173a2e..8136dd8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2011-11-21  Jim Meyering  <address@hidden>
+
+       init.sh: work around OSF/1 5.1's mishandling of /dev/null
+       * tests/init.sh: Make our compare function slightly more portable.
+       Reported by Bruno Haible in
+       http://thread.gmane.org/gmane.comp.gnu.grep.bugs/4020
+
 2011-11-20  Simon Josefsson  <address@hidden>

        * m4/manywarnings.m4: Add more warnings from gcc 4.6.2.
diff --git a/tests/init.sh b/tests/init.sh
index c78e5b6..bd18a2d 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -221,11 +221,33 @@ export MALLOC_PERTURB_
 # a partition, or to undo any other global state changes.
 cleanup_ () { :; }

+# Arrange not to let diff or cmp operate on /dev/null,
+# since on some systems (at least OSF/1 5.1), that doesn't work.
+# When there are not two arguments, return 2.
+# When one argument is /dev/null and the other is not empty,
+# cat the nonempty file to stderr and return 1.
+# Otherwise, return 0.
+compare_dev_null_ ()
+{
+  local err
+  test $# = 2 || return 2
+
+  if test "$1" = /dev/null; then
+    test -s "$2" && err="$2"
+  elif test "$2" = /dev/null; then
+    test -s "$1" && err="$1"
+  fi
+  test -z "$err" && return 0
+
+  cat "$err" 1>&2
+  return 1
+}
+
 if diff_out_=`( diff -u "$0" "$0" < /dev/null ) 2>/dev/null`; then
   if test -z "$diff_out_"; then
-    compare () { diff -u "$@"; }
+    compare_ () { diff -u "$@"; }
   else
-    compare ()
+    compare_ ()
     {
       if diff -u "$@" > diff.out; then
         # No differences were found, but Solaris 'diff' produces output
@@ -241,9 +263,9 @@ if diff_out_=`( diff -u "$0" "$0" < /dev/null ) 
2>/dev/null`; then
   fi
 elif diff_out_=`( diff -c "$0" "$0" < /dev/null ) 2>/dev/null`; then
   if test -z "$diff_out_"; then
-    compare () { diff -c "$@"; }
+    compare_ () { diff -c "$@"; }
   else
-    compare ()
+    compare_ ()
     {
       if diff -c "$@" > diff.out; then
         # No differences were found, but AIX and HP-UX 'diff' produce output
@@ -259,11 +281,22 @@ elif diff_out_=`( diff -c "$0" "$0" < /dev/null ) 
2>/dev/null`; then
     }
   fi
 elif ( cmp --version < /dev/null 2>&1 | grep GNU ) > /dev/null 2>&1; then
-  compare () { cmp -s "$@"; }
+  compare_ () { cmp -s "$@"; }
 else
-  compare () { cmp "$@"; }
+  compare_ () { cmp "$@"; }
 fi

+# Given compare_dev_null_'s preprocessing, for 0 or 2, defer to compare_.
+# Otherwise, differences have already been printed, so return 1.
+compare ()
+{
+  compare_dev_null_ "$@"
+  case $? in
+    0|2) compare_ "$@";;
+    1) return 1;;
+  esac
+}
+
 # An arbitrary prefix to help distinguish test directories.
 testdir_prefix_ () { printf gt; }

--
1.7.8.rc2.3.g0911