1 files changed, 187 insertions, 0 deletions
diff --git a/src/modules/module-always-sink.c b/src/modules/module-always-sink.c
new file mode 100644
index 0000000..0660bc2
--- /dev/null
+++ b/src/modules/module-always-sink.c
@@ -0,0 +1,187 @@
+/***
+    This file is part of PulseAudio.
+
+    Copyright 2008 Colin Guthrie
+
+    PulseAudio 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.
+
+    PulseAudio 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 Lesser General Public License
+    along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/core.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/i18n.h>
+#include <pulsecore/sink.h>
+#include <pulsecore/modargs.h>
+#include <pulsecore/log.h>
+
+PA_MODULE_AUTHOR("Colin Guthrie");
+PA_MODULE_DESCRIPTION(_("Always keeps at least one sink loaded even if it's a null one"));
+PA_MODULE_VERSION(PACKAGE_VERSION);
+PA_MODULE_LOAD_ONCE(true);
+PA_MODULE_USAGE(
+        "sink_name=<name of sink>");
+
+#define DEFAULT_SINK_NAME "auto_null"
+
+static const char* const valid_modargs[] = {
+    "sink_name",
+    NULL,
+};
+
+struct userdata {
+    uint32_t null_module;
+    bool ignore;
+    char *sink_name;
+};
+
+static void load_null_sink_if_needed(pa_core *c, pa_sink *sink, struct userdata* u) {
+    pa_sink *target;
+    uint32_t idx;
+    char *t;
+    pa_module *m;
+
+    pa_assert(c);
+    pa_assert(u);
+
+    if (u->null_module != PA_INVALID_INDEX)
+        return; /* We've already got a null-sink loaded */
+
+    /* Loop through all sinks and check to see if we have *any*
+     * sinks. Ignore the sink passed in (if it's not null), and
+     * don't count filter sinks. */
+    PA_IDXSET_FOREACH(target, c->sinks, idx)
+        if (!sink || ((target != sink) && !pa_sink_is_filter(target)))
+            break;
+
+    if (target)
+        return;
+
+    pa_log_debug("Autoloading null-sink as no other sinks detected.");
+
+    u->ignore = true;
+
+    t = pa_sprintf_malloc("sink_name=%s sink_properties='device.description=\"%s\"'", u->sink_name,
+                          _("Dummy Output"));
+    pa_module_load(&m, c, "module-null-sink", t);
+    u->null_module = m ? m->index : PA_INVALID_INDEX;
+    pa_xfree(t);
+
+    u->ignore = false;
+
+    if (!m)
+        pa_log_warn("Unable to load module-null-sink");
+}
+
+static pa_hook_result_t put_hook_callback(pa_core *c, pa_sink *sink, void* userdata) {
+    struct userdata *u = userdata;
+
+    pa_assert(c);
+    pa_assert(sink);
+    pa_assert(u);
+
+    /* This is us detecting ourselves on load... just ignore this. */
+    if (u->ignore)
+        return PA_HOOK_OK;
+
+    /* There's no point in doing anything if the core is shut down anyway */
+    if (c->state == PA_CORE_SHUTDOWN)
+        return PA_HOOK_OK;
+
+    /* Auto-loaded null-sink not active, so ignoring newly detected sink. */
+    if (u->null_module == PA_INVALID_INDEX)
+        return PA_HOOK_OK;
+
+    /* This is us detecting ourselves on load in a different way... just ignore this too. */
+    if (sink->module && sink->module->index == u->null_module)
+        return PA_HOOK_OK;
+
+    /* We don't count filter sinks since they need a real sink */
+    if (pa_sink_is_filter(sink))
+        return PA_HOOK_OK;
+
+    pa_log_info("A new sink has been discovered. Unloading null-sink.");
+
+    pa_module_unload_request_by_index(c, u->null_module, true);
+    u->null_module = PA_INVALID_INDEX;
+
+    return PA_HOOK_OK;
+}
+
+static pa_hook_result_t unlink_hook_callback(pa_core *c, pa_sink *sink, void* userdata) {
+    struct userdata *u = userdata;
+
+    pa_assert(c);
+    pa_assert(sink);
+    pa_assert(u);
+
+    /* First check to see if it's our own null-sink that's been removed... */
+    if (u->null_module != PA_INVALID_INDEX && sink->module && sink->module->index == u->null_module) {
+        pa_log_debug("Autoloaded null-sink removed");
+        u->null_module = PA_INVALID_INDEX;
+        return PA_HOOK_OK;
+    }
+
+    /* There's no point in doing anything if the core is shut down anyway */
+    if (c->state == PA_CORE_SHUTDOWN)
+        return PA_HOOK_OK;
+
+    load_null_sink_if_needed(c, sink, u);
+
+    return PA_HOOK_OK;
+}
+
+int pa__init(pa_module*m) {
+    pa_modargs *ma = NULL;
+    struct userdata *u;
+
+    pa_assert(m);
+
+    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
+        pa_log("Failed to parse module arguments");
+        return -1;
+    }
+
+    m->userdata = u = pa_xnew(struct userdata, 1);
+    u->sink_name = pa_xstrdup(pa_modargs_get_value(ma, "sink_name", DEFAULT_SINK_NAME));
+    pa_module_hook_connect(m, &m->core->hooks[PA_CORE_HOOK_SINK_PUT], PA_HOOK_LATE, (pa_hook_cb_t) put_hook_callback, u);
+    pa_module_hook_connect(m, &m->core->hooks[PA_CORE_HOOK_SINK_UNLINK], PA_HOOK_EARLY, (pa_hook_cb_t) unlink_hook_callback, u);
+    u->null_module = PA_INVALID_INDEX;
+    u->ignore = false;
+
+    pa_modargs_free(ma);
+
+    load_null_sink_if_needed(m->core, NULL, u);
+
+    return 0;
+}
+
+void pa__done(pa_module*m) {
+    struct userdata *u;
+
+    pa_assert(m);
+
+    if (!(u = m->userdata))
+        return;
+
+    if (u->null_module != PA_INVALID_INDEX && m->core->state != PA_CORE_SHUTDOWN)
+        pa_module_unload_request_by_index(m->core, u->null_module, true);
+
+    pa_xfree(u->sink_name);
+    pa_xfree(u);
+}