[PATCH v3][BZ 21340] add support for POSIX_SPAWN_SETSID

[daurnimator <quae at daurnimator dot com>]

I forgot to actually run my new test when I sent in v2.
Turns out I made a terrible mistake and didn't actually have the right
result check in the linux code. (setsid returns the new sid on success; not 0)

--- >8 ---
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

2017-04-05  Daurnimator  <quae@daurnimator.com>

    [BZ #21340]
    * conform/data/spawn.h-data: Add POSIX_SPAWN_SETSID flag.
    * posix/Makefile: Add tst-posix_spawn-setsid to list of tests.
    * posix/spawn.h: define POSIX_SPAWN_SETSID flag.
    * posix/spawnattr_setflags.c: Add POSIX_SPAWN_SETSID to valid flags.
    * posix/tst-posix_spawn-setsid.c: Add test for POSIX_SPAWN_SETSID.
    * sysdeps/mach/hurd/spawni.c: Implementation of POSIX_SPAWN_SETSID.
    * sysdeps/posix/spawni.c: Likewise.
    * sysdeps/unix/sysv/linux/spawni.c: Likewise.
---
 conform/data/spawn.h-data        |  1 +
 posix/Makefile                   |  2 +-
 posix/spawn.h                    |  1 +
 posix/spawnattr_setflags.c       |  1 +
 posix/tst-posix_spawn-setsid.c   | 70 ++++++++++++++++++++++++++++++++++++++++
 sysdeps/mach/hurd/spawni.c       |  3 ++
 sysdeps/posix/spawni.c           |  7 +++-
 sysdeps/unix/sysv/linux/spawni.c |  4 +++
 8 files changed, 87 insertions(+), 2 deletions(-)
 create mode 100644 posix/tst-posix_spawn-setsid.c

diff --git a/conform/data/spawn.h-data b/conform/data/spawn.h-data
index fb206f7ecf..bcba36c492 100644
--- a/conform/data/spawn.h-data
+++ b/conform/data/spawn.h-data
@@ -14,6 +14,7 @@ constant POSIX_SPAWN_SETSCHEDPARAM
 constant POSIX_SPAWN_SETSCHEDULER
 constant POSIX_SPAWN_SETSIGDEF
 constant POSIX_SPAWN_SETSIGMASK
+constant POSIX_SPAWN_SETSID
 
 function int posix_spawnattr_destroy (posix_spawnattr_t*)
 function int posix_spawnattr_getsigdefault (const posix_spawnattr_t*, sigset_t*)
diff --git a/posix/Makefile b/posix/Makefile
index ae17646323..a9f53a973d 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -90,7 +90,7 @@ tests		:= test-errno tstgetopt testfnm runtests runptests \
 		   bug-getopt5 tst-getopt_long1 bug-regex34 bug-regex35 \
 		   tst-pathconf tst-getaddrinfo4 tst-rxspencer-no-utf8 \
 		   tst-fnmatch3 bug-regex36 tst-getaddrinfo5 \
-		   tst-posix_spawn-fd \
+		   tst-posix_spawn-fd tst-posix_spawn-setsid \
 		   tst-posix_fadvise tst-posix_fadvise64
 xtests		:= bug-ga2
 ifeq (yes,$(build-shared))
diff --git a/posix/spawn.h b/posix/spawn.h
index 36e3867e17..8d2ace1b87 100644
--- a/posix/spawn.h
+++ b/posix/spawn.h
@@ -60,6 +60,7 @@ typedef struct
 #ifdef __USE_GNU
 # define POSIX_SPAWN_USEVFORK		0x40
 #endif
+#define POSIX_SPAWN_SETSID		0x80
 
 
 __BEGIN_DECLS
diff --git a/posix/spawnattr_setflags.c b/posix/spawnattr_setflags.c
index 9b3d1e022a..62d2f00c20 100644
--- a/posix/spawnattr_setflags.c
+++ b/posix/spawnattr_setflags.c
@@ -25,6 +25,7 @@
 		   | POSIX_SPAWN_SETSIGMASK				      \
 		   | POSIX_SPAWN_SETSCHEDPARAM				      \
 		   | POSIX_SPAWN_SETSCHEDULER				      \
+		   | POSIX_SPAWN_SETSID					      \
 		   | POSIX_SPAWN_USEVFORK)
 
 /* Store flags in the attribute structure.  */
diff --git a/posix/tst-posix_spawn-setsid.c b/posix/tst-posix_spawn-setsid.c
new file mode 100644
index 0000000000..b3cd5e54b1
--- /dev/null
+++ b/posix/tst-posix_spawn-setsid.c
@@ -0,0 +1,70 @@
+/* Test that spawn attribute setsid works.
+   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>
+
+static int
+do_test (void)
+{
+  posix_spawnattr_t attrp;
+  int res;
+  int child_pid;
+  int sid, child_sid;
+  char *args[2];
+
+  /* record sid for current process */
+  sid = getsid(0);
+
+  posix_spawnattr_init(&attrp);
+  if (posix_spawnattr_setflags(&attrp, POSIX_SPAWN_SETSID))
+    {
+      printf("error: posix_spawnattr_setflags: %m\n");
+      return 1;
+    }
+
+  /* run the program 'true' */
+  args[0] = (char *)"true";
+  args[1] = NULL;
+
+  res = posix_spawnp(&child_pid, "true", NULL, &attrp, args, environ);
+  posix_spawnattr_destroy(&attrp);
+  if (res)
+    {
+      printf("error: posix_spawnp: %m\n");
+      return 1;
+    }
+
+  /* child should have a different sid */
+  child_sid = getsid(child_pid);
+  if (child_sid == sid)
+    {
+      printf("error: child sid matches\n");
+      return 1;
+    }
+
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/sysdeps/mach/hurd/spawni.c b/sysdeps/mach/hurd/spawni.c
index 284875ac30..74303839e4 100644
--- a/sysdeps/mach/hurd/spawni.c
+++ b/sysdeps/mach/hurd/spawni.c
@@ -281,6 +281,9 @@ __spawni (pid_t *pid, const char *file,
     }
 #endif
 
+  if (!err && (flags & POSIX_SPAWN_SETSID) != 0)
+    err = __proc_setsid (proc);
+
   /* Set the process group ID.  */
   if (!err && (flags & POSIX_SPAWN_SETPGROUP) != 0)
     err = __proc_setpgrp (proc, new_pid, attrp->__pgrp);
diff --git a/sysdeps/posix/spawni.c b/sysdeps/posix/spawni.c
index 5cc2ad1363..9cad25ca4e 100644
--- a/sysdeps/posix/spawni.c
+++ b/sysdeps/posix/spawni.c
@@ -101,7 +101,8 @@ __spawni (pid_t *pid, const char *file,
 	 to POSIX.  */
       || ((flags & (POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSIGDEF
 		    | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER
-		    | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS)) == 0
+		    | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS
+		    | POSIX_SPAWN_SETSID)) == 0
 	  && file_actions == NULL))
     new_pid = __vfork ();
   else
@@ -159,6 +160,10 @@ __spawni (pid_t *pid, const char *file,
     }
 #endif
 
+  if ((flags & POSIX_SPAWN_SETSID) != 0
+      && __setsid () < 0)
+    _exit (SPAWN_ERROR);
+
   /* Set the process group ID.  */
   if ((flags & POSIX_SPAWN_SETPGROUP) != 0
       && __setpgid (0, attrp->__pgrp) != 0)
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index d7f9e83575..3cf77d50c3 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -177,6 +177,10 @@ __spawni_child (void *arguments)
     }
 #endif
 
+  if ((attr->__flags & POSIX_SPAWN_SETSID) != 0
+      && (ret = __setsid ()) < 0)
+    goto fail;
+
   /* Set the process group ID.  */
   if ((attr->__flags & POSIX_SPAWN_SETPGROUP) != 0
       && (ret = __setpgid (0, attr->__pgrp)) != 0)
-- 
2.11.1