Add g_spawn_check_exit_status()

Many (if not "almost all") programs that spawn other programs via
g_spawn_sync() or the like simply want to check whether or not the
child exited successfully, but doing so requires use of
platform-specific functionality and there's actually a fair amount of
boilerplate involved.

This new API will help drain a *lot* of mostly duplicated code in
GNOME, from gnome-session to gdm.  And we can see that some bits even
inside GLib were doing it wrong; for example checking the exit status
on Unix, but ignoring it on Windows.

https://bugzilla.gnome.org/show_bug.cgi?id=679691

gio/gdbusaddress.c

@@ -43,7 +43,6 @@
 
 #ifdef G_OS_UNIX
 #include <gio/gunixsocketaddress.h>
-#include <sys/wait.h>
 #endif
 
 #ifdef G_OS_WIN32
@@ -1062,40 +1061,16 @@ get_session_address_dbus_launch (GError **error)
                                   &launch_stderr,
                                   &exit_status,
                                   error))
+    {
+      goto out;
+    }
+
+  if (!g_spawn_check_exit_status (exit_status, error))
     {
       g_prefix_error (error, _("Error spawning command line `%s': "), command_line);
       goto out;
     }
 
-  if (!WIFEXITED (exit_status))
-    {
-      gchar *escaped_stderr;
-      escaped_stderr = g_strescape (launch_stderr, "");
-      g_set_error (error,
-                   G_IO_ERROR,
-                   G_IO_ERROR_FAILED,
-                   _("Abnormal program termination spawning command line `%s': %s"),
-                   command_line,
-                   escaped_stderr);
-      g_free (escaped_stderr);
-      goto out;
-    }
-
-  if (WEXITSTATUS (exit_status) != 0)
-    {
-      gchar *escaped_stderr;
-      escaped_stderr = g_strescape (launch_stderr, "");
-      g_set_error (error,
-                   G_IO_ERROR,
-                   G_IO_ERROR_FAILED,
-                   _("Command line `%s' exited with non-zero exit status %d: %s"),
-                   command_line,
-                   WEXITSTATUS (exit_status),
-                   escaped_stderr);
-      g_free (escaped_stderr);
-      goto out;
-    }
-
   /* From the dbus-launch(1) man page:
    *
    *   --binary-syntax Write to stdout a nul-terminated bus address,

gio/gdesktopappinfo.c

@@ -26,7 +26,6 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
-#include <sys/wait.h>
 
 #ifdef HAVE_CRT_EXTERNS_H
 #include <crt_externs.h>
@@ -1850,8 +1849,7 @@ update_program_done (GPid     pid,
 		     gpointer data)
 {
   /* Did the application exit correctly */
-  if (WIFEXITED (status) &&
-      WEXITSTATUS (status) == 0)
+  if (g_spawn_check_exit_status (status, NULL))
     {
       /* Here we could clean out any caches in use */
     }

gio/glib-compile-resources.c

@@ -33,9 +33,6 @@
 #ifdef G_OS_WIN32
 #include <io.h>
 #endif
-#ifdef HAVE_SYS_WAIT_H
-#include <sys/wait.h>
-#endif
 
 #include <gio/gmemoryoutputstream.h>
 #include <gio/gzlibcompressor.h>
@@ -331,14 +328,14 @@ end_element (GMarkupParseContext  *context,
                   g_propagate_error (error, my_error);
                   goto cleanup;
                 }
-#ifdef HAVE_SYS_WAIT_H
-              if (!WIFEXITED (status) || WEXITSTATUS (status) != 0)
+	      
+	      /* Ugly...we shoud probably just let stderr be inherited */
+	      if (!g_spawn_check_exit_status (status, NULL))
                 {
                   g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                _("Error processing input file with xmllint:\n%s"), stderr_child);
                   goto cleanup;
                 }
-#endif
 
               g_free (stderr_child);
               g_free (real_file);
@@ -387,14 +384,13 @@ end_element (GMarkupParseContext  *context,
                   g_propagate_error (error, my_error);
                   goto cleanup;
                 }
-#ifdef HAVE_SYS_WAIT_H
-              if (!WIFEXITED (status) || WEXITSTATUS (status) != 0)
+	      
+	      if (!g_spawn_check_exit_status (status, NULL))
                 {
                   g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 			       _("Error processing input file with to-pixdata:\n%s"), stderr_child);
                   goto cleanup;
                 }
-#endif
 
               g_free (stderr_child);
               g_free (real_file);

gio/tests/gdbus-connection-slow.c

@@ -25,9 +25,6 @@
 #include <string.h>
 
 #include <sys/types.h>
-#ifdef HAVE_SYS_WAIT_H
-#include <sys/wait.h>
-#endif
 
 #include "gdbus-tests.h"
 
@@ -97,10 +94,8 @@ test_connection_flush (void)
                                        &exit_status,
                                        &error);
       g_assert_no_error (error);
-#ifdef HAVE_SYS_WAIT_H
-      g_assert (WIFEXITED (exit_status));
-      g_assert_cmpint (WEXITSTATUS (exit_status), ==, 0);
-#endif
+      g_spawn_check_exit_status (exit_status, &error);
+      g_assert_no_error (error);
       g_assert (ret);
 
       timeout_mainloop_id = g_timeout_add (1000, test_connection_flush_on_timeout, GUINT_TO_POINTER (n));

gio/tests/gdbus-connection.c

@@ -141,7 +141,7 @@ test_connection_life_cycle (void)
    *
    */
   c = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, &error);
-  _g_assert_error_domain (error, G_IO_ERROR);
+  g_assert (error != NULL);
   g_assert (!g_dbus_error_is_remote_error (error));
   g_assert (c == NULL);
   g_error_free (error);