[binutils-gdb] Add "../lib/unbuffer_output.c" and use it in gdb.base/interrupt.c

[Pedro Alves <palves at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6f98576f29a70ed947f102015df0388bccc6aa1a

commit 6f98576f29a70ed947f102015df0388bccc6aa1a
Author: Pedro Alves <palves@redhat.com>
Date:   Fri Feb 27 13:54:22 2015 +0000

    Add "../lib/unbuffer_output.c" and use it in gdb.base/interrupt.c
    
    In some scenarios, GDB or GDBserver can be spawned with input _not_
    connected to a tty, and then tests that rely on stdio fail with
    timeouts, because the inferior's stdout and stderr streams end up
    fully buffered.
    
    See discussion here:
      https://sourceware.org/ml/gdb-patches/2015-02/msg00809.html
    
    We have a hack in place that works around this for Windows testing,
    that forces every test program to link with an .o file that does
    (lib/set_unbuffered_mode.c):
    
     static int __gdb_set_unbuffered_output (void) __attribute__ ((constructor));
     static int
     __gdb_set_unbuffered_output (void)
     {
       setvbuf (stdout, NULL, _IONBF, BUFSIZ);
       setvbuf (stderr, NULL, _IONBF, BUFSIZ);
     }
    
    That's a bit hacky; it ends up done for _all_ tests.
    
    This patch adds a way to do this unbuffering explicitly from the test
    code itself, so it is done only when necessary, and for all
    targets/hosts.  For starters, it adjusts gdb.base/interrupt.c to use
    it.
    
    Tested on x86_64 Fedora 20, native, and against a remote gdbserver
    board file that connects to the target with ssh, with and without -t
    (create pty).
    
    gdb/testsuite/
    2015-02-27  Pedro Alves  <palves@redhat.com>
    
    	* lib/unbuffer_output.c: New file.
    	* gdb.base/interrupt.c: Include "../lib/unbuffer_output.c".
    	(main): Call gdb_unbuffer_output.

Diff:
---
 gdb/testsuite/ChangeLog             |  6 ++++++
 gdb/testsuite/gdb.base/interrupt.c  |  5 +++++
 gdb/testsuite/lib/unbuffer_output.c | 39 +++++++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index a5896be..efc74f6 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2015-02-27  Pedro Alves  <palves@redhat.com>
+
+	* lib/unbuffer_output.c: New file.
+	* gdb.base/interrupt.c: Include "../lib/unbuffer_output.c".
+	(main): Call gdb_unbuffer_output.
+
 2015-02-27  Yao Qi  <yao.qi@linaro.org>
 
 	* gdb.base/catch-syscall.exp: Don't skip it on hppa*-hp-hpux*
diff --git a/gdb/testsuite/gdb.base/interrupt.c b/gdb/testsuite/gdb.base/interrupt.c
index d7bb271..6426015 100644
--- a/gdb/testsuite/gdb.base/interrupt.c
+++ b/gdb/testsuite/gdb.base/interrupt.c
@@ -3,6 +3,8 @@
 #include <unistd.h>
 #include <stdlib.h>
 
+#include "../lib/unbuffer_output.c"
+
 #ifdef SIGNALS
 #include <signal.h>
 
@@ -17,6 +19,9 @@ main ()
 {
   char x;
   int nbytes;
+
+  gdb_unbuffer_output ();
+
 #ifdef SIGNALS
   signal (SIGINT, sigint_handler);
 #endif
diff --git a/gdb/testsuite/lib/unbuffer_output.c b/gdb/testsuite/lib/unbuffer_output.c
new file mode 100644
index 0000000..5093299
--- /dev/null
+++ b/gdb/testsuite/lib/unbuffer_output.c
@@ -0,0 +1,39 @@
+/* Copyright (C) 2008-2015 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Force output to unbuffered mode if not connected to a terminal.  */
+
+#include <stdio.h>
+#ifndef __MINGW32__
+#include <unistd.h>
+#endif
+
+static int
+gdb_unbuffer_output (void)
+{
+  /* Always force this for Windows testing.  To a native Windows
+     program running under a Cygwin shell/ssh, stdin is really a
+     Windows pipe, thus not a tty and its outputs ends up fully
+     buffered.  */
+#ifndef __MINGW32__
+  if (!isatty (fileno (stdin)))
+#endif
+    {
+      setvbuf (stdout, NULL, _IONBF, BUFSIZ);
+      setvbuf (stderr, NULL, _IONBF, BUFSIZ);
+    }
+}