diff --git a/glib/glib-unix.c b/glib/glib-unix.c
index 4006a0d4a..e26419e6c 100644
--- a/glib/glib-unix.c
+++ b/glib/glib-unix.c
@@ -1,7 +1,7 @@
/* GLIB - Library of useful routines for C programming
* Copyright (C) 2011 Red Hat, Inc.
*
- * glib-unix.c: Unix specific API wrappers and convenience functions
+ * glib-unix.c: UNIX specific API wrappers and convenience functions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@@ -29,7 +29,7 @@
/**
* SECTION:gunix
- * @short_description: Unix-specific utilities and integration
+ * @short_description: UNIX-specific utilities and integration
* @include: glib-unix.h
*
* Most of GLib is intended to be portable; in constrast, this set of
@@ -77,15 +77,14 @@ g_unix_set_error_from_errno_saved (GError **error,
* @flags: Bitfield of file descriptor flags, see "man 2 fcntl"
* @error: a #GError
*
- * Similar to the Unix pipe() call, but on modern systems like
- * Linux uses the pipe2 system call, which atomically creates
- * a pipe with the configured flags. The only supported flag
- * currently is FD_CLOEXEC. If for example you want to configure
- * O_NONBLOCK, that must still be done separately with fcntl().
+ * Similar to the UNIX pipe() call, but on modern systems like Linux
+ * uses the pipe2 system call, which atomically creates a pipe with
+ * the configured flags. The only supported flag currently is
+ * FD_CLOEXEC. If for example you want to configure O_NONBLOCK, that
+ * must still be done separately with fcntl().
*
- * Note in particular this function does *not* take O_CLOEXEC, it
- * takes FD_CLOEXEC as if for fcntl(); these are different on
- * Linux/glibc.
+ * This function does *not* take O_CLOEXEC, it takes FD_CLOEXEC as if
+ * for fcntl(); these are different on Linux/glibc.
*
* Returns: %TRUE on success, %FALSE if not (and errno will be set).
*
diff --git a/glib/gmain.c b/glib/gmain.c
index c045e1cc8..82cf81073 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -77,6 +77,7 @@
#include
#endif /* HAVE_UNISTD_H */
#include
+#include
#ifdef G_OS_WIN32
#define STRICT
@@ -364,6 +365,8 @@ static void g_main_context_remove_poll_unlocked (GMainContext *context,
GPollFD *fd);
static void g_main_context_wakeup_unlocked (GMainContext *context);
+static void _g_main_wake_up_all_contexts (void);
+
static gboolean g_timeout_prepare (GSource *source,
gint *timeout);
static gboolean g_timeout_check (GSource *source);
@@ -388,6 +391,15 @@ static GMainContext *default_main_context;
static GSList *main_contexts_without_pipe = NULL;
#ifndef G_OS_WIN32
+
+/* The UNIX signal pipe contains a single byte specifying which
+ * signal was received.
+ */
+#define _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR 'C'
+/* Guards unix_signal_wake_up_pipe */
+G_LOCK_DEFINE_STATIC (unix_signal_lock);
+static gint unix_signal_wake_up_pipe[2] = {-1, -1};
+
/* Child status monitoring code */
enum {
CHILD_WATCH_UNINITIALIZED,
@@ -396,7 +408,6 @@ enum {
};
static gint child_watch_init_state = CHILD_WATCH_UNINITIALIZED;
static gint child_watch_count = 1;
-static gint child_watch_wake_up_pipe[2] = {0, 0};
#endif /* !G_OS_WIN32 */
G_LOCK_DEFINE_STATIC (main_context_list);
static GSList *main_context_list = NULL;
@@ -3717,6 +3728,30 @@ g_main_context_get_poll_func (GMainContext *context)
return result;
}
+static void
+_g_main_wake_up_all_contexts (void)
+{
+ GSList *list;
+
+ /* We were woken up. Wake up all other contexts in all other threads */
+ G_LOCK (main_context_list);
+ for (list = main_context_list; list; list = list->next)
+ {
+ GMainContext *context;
+
+ context = list->data;
+ if (g_atomic_int_get (&context->ref_count) > 0)
+ /* Due to racing conditions we can find ref_count == 0, in
+ * that case, however, the context is still not destroyed
+ * and no poll can be active, otherwise the ref_count
+ * wouldn't be 0
+ */
+ g_main_context_wakeup (context);
+ }
+ G_UNLOCK (main_context_list);
+}
+
+
/* HOLDS: context's lock */
/* Wake the main loop up from a poll() */
static void
@@ -4263,7 +4298,8 @@ g_child_watch_signal_handler (int signum)
if (child_watch_init_state == CHILD_WATCH_INITIALIZED_THREADED)
{
- write (child_watch_wake_up_pipe[1], "B", 1);
+ char buf[1] = { _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR };
+ write (unix_signal_wake_up_pipe[1], buf, 1);
}
else
{
@@ -4288,52 +4324,92 @@ g_child_watch_source_init_single (void)
sigaction (SIGCHLD, &action, NULL);
}
-G_GNUC_NORETURN static gpointer
-child_watch_helper_thread (gpointer data)
+static gpointer unix_signal_helper_thread (gpointer data) G_GNUC_NORETURN;
+
+/*
+ * This thread is created whenever anything in GLib needs
+ * to deal with UNIX signals; at present, just SIGCHLD
+ * from g_child_watch_source_new().
+ *
+ * Note: We could eventually make this thread a more public interface
+ * and allow e.g. GDBus to use it instead of its own worker thread.
+ */
+static gpointer
+unix_signal_helper_thread (gpointer data)
{
while (1)
{
- gchar b[20];
- GSList *list;
+ gchar b[128];
+ ssize_t i, bytes_read;
- read (child_watch_wake_up_pipe[0], b, 20);
-
- /* We were woken up. Wake up all other contexts in all other threads */
- G_LOCK (main_context_list);
- for (list = main_context_list; list; list = list->next)
+ bytes_read = read (unix_signal_wake_up_pipe[0], b, sizeof (b));
+ if (bytes_read < 0)
{
- GMainContext *context;
-
- context = list->data;
- if (g_atomic_int_get (&context->ref_count) > 0)
- /* Due to racing conditions we can find ref_count == 0, in
- * that case, however, the context is still not destroyed
- * and no poll can be active, otherwise the ref_count
- * wouldn't be 0 */
- g_main_context_wakeup (context);
+ g_warning ("Failed to read from child watch wake up pipe: %s",
+ strerror (errno));
+ /* Not much we can do here sanely; just wait a second and hope
+ * it was transient.
+ */
+ g_usleep (G_USEC_PER_SEC);
+ continue;
+ }
+ for (i = 0; i < bytes_read; i++)
+ {
+ switch (b[i])
+ {
+ case _UNIX_SIGNAL_PIPE_SIGCHLD_CHAR:
+ /* The child watch source will call waitpid() in its
+ * prepare() and check() methods; however, we don't
+ * know which pid exited, so we need to wake up
+ * all contexts. Note: actually we could get the pid
+ * from the "siginfo_t" via the handler, but to pass
+ * that info down the pipe would require a more structured
+ * data stream (as opposed to a single byte).
+ */
+ _g_main_wake_up_all_contexts ();
+ break;
+ default:
+ g_warning ("Invalid char '%c' read from child watch pipe", b[i]);
+ break;
+ }
}
- G_UNLOCK (main_context_list);
}
}
+static void
+_g_main_init_unix_signal_wakeup_pipe (void)
+{
+ GError *error = NULL;
+
+ G_LOCK (unix_signal_lock);
+
+ if (unix_signal_wake_up_pipe[0] >= 0)
+ goto out;
+
+ g_assert (g_thread_supported());
+
+ if (!g_unix_pipe_flags (unix_signal_wake_up_pipe, FD_CLOEXEC, &error))
+ g_error ("Cannot create UNIX signal wake up pipe: %s\n", error->message);
+ fcntl (unix_signal_wake_up_pipe[1], F_SETFL, O_NONBLOCK | fcntl (unix_signal_wake_up_pipe[1], F_GETFL));
+
+ /* We create a helper thread that polls on the wakeup pipe indefinitely */
+ /* FIXME: Think this through for races */
+ if (g_thread_create (unix_signal_helper_thread, NULL, FALSE, &error) == NULL)
+ g_error ("Cannot create a thread to monitor UNIX signals: %s\n", error->message);
+
+ out:
+ G_UNLOCK (unix_signal_lock);
+}
+
static void
g_child_watch_source_init_multi_threaded (void)
{
- GError *error = NULL;
struct sigaction action;
+
+ _g_main_init_unix_signal_wakeup_pipe ();
- g_assert (g_thread_supported());
-
- if (!g_unix_pipe_flags (child_watch_wake_up_pipe, FD_CLOEXEC, &error))
- g_error ("Cannot create wake up pipe: %s\n", error->message);
- fcntl (child_watch_wake_up_pipe[1], F_SETFL, O_NONBLOCK | fcntl (child_watch_wake_up_pipe[1], F_GETFL));
-
- /* We create a helper thread that polls on the wakeup pipe indefinitely */
- /* FIXME: Think this through for races */
- if (g_thread_create (child_watch_helper_thread, NULL, FALSE, &error) == NULL)
- g_error ("Cannot create a thread to monitor child exit status: %s\n", error->message);
child_watch_init_state = CHILD_WATCH_INITIALIZED_THREADED;
-
+
action.sa_handler = g_child_watch_signal_handler;
sigemptyset (&action.sa_mask);
action.sa_flags = SA_RESTART | SA_NOCLDSTOP;