[PATCH] build: avoid test failure on HPUX

[Eric Blake]

POSIX permits implementations to open fd 0, 1, and 2 on exec(), even
when the user tried to close them.  HPUX-11.21 is one of the
implementations that does not allow closed standard descriptors,
leading to a failure of test 005.command_li.  But a test that makes
sure we behave gracefully in the face of closed standard descriptors
makes no sense on a platform where we can never have them closed, so
add some code to skip the test on "helpful" platforms.

* doc/m4.texi (Command line files): Skip tests on systems where it
is impossible to start with stdin/out closed.
Reported by Gary V. Vaughan.

Signed-off-by: Eric Blake <address@hidden>
---

Gary, I think this will fix the issue you saw, but would like some
confirmation before I push it.

 ChangeLog   | 5 +++++
 doc/m4.texi | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 8798406..191a849 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2013-03-12  Eric Blake  <address@hidden>

+       build: avoid test failure on HPUX
+       * doc/m4.texi (Command line files): Skip tests on systems where it
+       is impossible to start with stdin/out closed.
+       Reported by Gary V. Vaughan.
+
        maint: update to latest gnulib
        * gnulib: Update to latest, for mingw compile fixes.

diff --git a/doc/m4.texi b/doc/m4.texi
index b8b1704..5d9bd6f 100644
--- a/doc/m4.texi
+++ b/doc/m4.texi
@@ -993,6 +993,9 @@ Command line files
 ifdef(`__unix__', ,
       `errprint(` skipping: syscmd does not have unix semantics
 ')m4exit(`77')')dnl
+syscmd(`cat <&- 2>/dev/null')ifelse(sysval, `0',
+       `errprint(` skipping: system does not allow closing stdin
+')m4exit(`77')')dnl
 changequote(`[', `]')dnl
 syscmd([echo | ']__program__[' >&-])dnl
 @error{}m4: write error: Bad file descriptor
@@ -1004,6 +1007,9 @@ Command line files
 ifdef(`__unix__', ,
       `errprint(` skipping: syscmd does not have unix semantics
 ')m4exit(`77')')dnl
+syscmd(`cat <&- 2>/dev/null')ifelse(sysval, `0',
+       `errprint(` skipping: system does not allow closing stdin
+')m4exit(`77')')dnl
 changequote(`[', `]')dnl
 syscmd([echo 'esyscmd(echo hi >&2 && echo err"print(bye
 )d"nl)dnl' > tmp.m4 \
-- 
1.8.1.4