[BZ 21340] add support for POSIX_SPAWN_SETSID

This patch adds support for the POSIX_SPAWN_SETSID flag.

It was recently accepted by the Austin Group:
http://austingroupbugs.net/view.php?id=1044

Checked on x86_64

	Daurnimator  <quae@daurnimator.com>
	Adhemerval Zanella  <adhemerval.zanella@linaro.org>

	[BZ #21340]
	* posix/Makefile (tests): Add tst-posix_spawn-setsid to list of tests.
	* posix/spawn.h: define POSIX_SPAWN_SETSID flag.
	* posix/spawnattr_setflags.c (ALL_FLAGS): Add POSIX_SPAWN_SETSID to
	valid flags.
	* posix/tst-posix_spawn-setsid.c: Add test for POSIX_SPAWN_SETSID.
	* sysdeps/mach/hurd/spawni.c (__spawni): Implementation of
	POSIX_SPAWN_SETSID.
	* sysdeps/posix/spawni.c (__spawni): Likewise.
	* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Likewise.
	* NEWS: Add note about POSIX_SPAWN_SETSID support.

1 files changed, 95 insertions, 0 deletions

diff --git a/posix/tst-posix_spawn-setsid.c b/posix/tst-posix_spawn-setsid.c
new file mode 100644
index 0000000000..256bd721b8
--- /dev/null
+++ b/posix/tst-posix_spawn-setsid.c
@@ -0,0 +1,95 @@
+/* Test posix_spawn setsid attribute.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <spawn.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+#include <support/check.h>
+
+static void
+do_test_setsid (bool test_setsid)
+{
+  pid_t sid, child_sid;
+  int res;
+
+  /* Current session ID.  */
+  sid = getsid(0);
+  if (sid == (pid_t) -1)
+    FAIL_EXIT1 ("getsid (0): %m");
+
+  posix_spawnattr_t attrp;
+  /* posix_spawnattr_init should not fail (it basically memset the
+     attribute).  */
+  posix_spawnattr_init (&attrp);
+  if (test_setsid)
+    {
+      res = posix_spawnattr_setflags (&attrp, POSIX_SPAWN_SETSID);
+      if (res != 0)
+	{
+	  errno = res;
+	  FAIL_EXIT1 ("posix_spawnattr_setflags: %m");
+	}
+    }
+
+  /* Program to run.  */
+  char *args[2] = { (char *) "true", NULL };
+  pid_t child;
+
+  res = posix_spawnp (&child, "true", NULL, &attrp, args, environ);
+  /* posix_spawnattr_destroy is noop.  */
+  posix_spawnattr_destroy (&attrp);
+
+  if (res != 0)
+    {
+      errno = res;
+      FAIL_EXIT1 ("posix_spawnp: %m");
+    }
+
+  /* Child should have a different session ID than parent.  */
+  child_sid = getsid (child);
+
+  if (child_sid == (pid_t) -1)
+    FAIL_EXIT1 ("getsid (%i): %m", child);
+
+  if (test_setsid)
+    {
+      if (child_sid == sid)
+	FAIL_EXIT1 ("child session ID matched parent one");
+    }
+  else
+    {
+      if (child_sid != sid)
+	FAIL_EXIT1 ("child session ID did not match parent one");
+    }
+}
+
+static int
+do_test (void)
+{
+  do_test_setsid (false);
+  do_test_setsid (true);
+
+  return 0;
+}
+
+#include <support/test-driver.c>