Re: [patch] fix "broken pipe" message from lseek test

[Bruno Haible]

Hi Ben,

> I noticed that (sometimes?) the lseek check prints a "broken
> pipe" message in the middle of "configure" output, e.g.
>         checking whether lseek detects pipes... ../configure: line 30326: 
> echo: write error: Broken pipe
> as reported here under step 19:
>         http://benpfaff.org/~blp/pspp-master/20100220040512/

Below is a proposed fix (untested).

> I think that we should redirect stderr to /dev/null for that
> test.

I would not do this. "2> /dev/null" is a recipe for creating buggy software:
When an error creeps in, for whatever reason, you won't notice it.

Bruno


2010-02-20  Bruno Haible  <address@hidden>

        Silence a "broken pipe" message from bash.
        * m4/lseek.m4 (gl_FUNC_LSEEK): Ignore SIGPIPE in a subcommand.
        Reported by Ben Pfaff <address@hidden>.

--- m4/lseek.m4.orig    Sat Feb 20 21:18:21 2010
+++ m4/lseek.m4 Sat Feb 20 21:17:50 2010
@@ -1,4 +1,4 @@
-# lseek.m4 serial 4
+# lseek.m4 serial 5
 dnl Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,7 +21,12 @@
 }],
          [if test -s conftest$ac_exeext \
              && ./conftest$ac_exeext < conftest.$ac_ext \
-             && { echo hi | ./conftest$ac_exeext; test $? = 1; }; then
+             && { : "Avoid error message from bash."; \
+                  : "See func_reset_sigpipe in gnulib-tool."; \
+                  if test -n "$BASH_VERSION"; then trap - SIGPIPE; fi; \
+                  echo hi | ./conftest$ac_exeext; \
+                  test $? = 1; \
+                }; then
             gl_cv_func_lseek_pipe=yes
           else
             gl_cv_func_lseek_pipe=no