src/modules/module-always-sink.c

   1 /***
   2     This file is part of PulseAudio.
   3
   4     Copyright 2008 Colin Guthrie
   5
   6     PulseAudio is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU Lesser General Public License as published
   8     by the Free Software Foundation; either version 2.1 of the License,
   9     or (at your option) any later version.
  10
  11     PulseAudio is distributed in the hope that it will be useful, but
  12     WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14     General Public License for more details.
  15
  16     You should have received a copy of the GNU Lesser General Public License
  17     along with PulseAudio; if not, write to the Free Software
  18     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19     USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <pulse/xmalloc.h>
  27 #include <pulse/i18n.h>
  28
  29 #include <pulsecore/core.h>
  30 #include <pulsecore/sink.h>
  31 #include <pulsecore/modargs.h>
  32 #include <pulsecore/log.h>
  33 #include <pulsecore/core-util.h>
  34
  35 #include "module-always-sink-symdef.h"
  36
  37 PA_MODULE_AUTHOR("Colin Guthrie");
  38 PA_MODULE_DESCRIPTION(_("Always keeps at least one sink loaded even if it's a null one"));
  39 PA_MODULE_VERSION(PACKAGE_VERSION);
  40 PA_MODULE_LOAD_ONCE(TRUE);
  41 PA_MODULE_USAGE(
  42         "sink_name=<name of sink>");
  43
  44 #define DEFAULT_SINK_NAME "auto_null"
  45
  46 static const char* const valid_modargs[] = {
  47     "sink_name",
  48     NULL,
  49 };
  50
  51 struct userdata {
  52     pa_hook_slot *put_slot, *unlink_slot;
  53     uint32_t null_module;
  54     pa_bool_t ignore;
  55     char *sink_name;
  56 };
  57
  58 static void load_null_sink_if_needed(pa_core *c, pa_sink *sink, struct userdata* u) {
  59     pa_sink *target;
  60     uint32_t idx;
  61     char *t;
  62     pa_module *m;
  63
  64     pa_assert(c);
  65     pa_assert(u);
  66     pa_assert(u->null_module == PA_INVALID_INDEX);
  67
  68     /* Loop through all sinks and check to see if we have *any*
  69      * sinks. Ignore the sink passed in (if it's not null) */
  70     for (target = pa_idxset_first(c->sinks, &idx); target; target = pa_idxset_next(c->sinks, &idx))
  71         if (!sink || target != sink)
  72             break;
  73
  74     if (target)
  75         return;
  76
  77     pa_log_debug("Autoloading null-sink as no other sinks detected.");
  78
  79     u->ignore = TRUE;
  80
  81     t = pa_sprintf_malloc("sink_name=%s sink_properties='device.description=\"%s\"'", u->sink_name,
  82                           _("Dummy Output"));
  83     m = pa_module_load(c, "module-null-sink", t);
  84     u->null_module = m ? m->index : PA_INVALID_INDEX;
  85     pa_xfree(t);
  86
  87     u->ignore = FALSE;
  88
  89     if (!m)
  90         pa_log_warn("Unable to load module-null-sink");
  91 }
  92
  93 static pa_hook_result_t put_hook_callback(pa_core *c, pa_sink *sink, void* userdata) {
  94     struct userdata *u = userdata;
  95
  96     pa_assert(c);
  97     pa_assert(sink);
  98     pa_assert(u);
  99
 100     /* This is us detecting ourselves on load... just ignore this. */
 101     if (u->ignore)
 102         return PA_HOOK_OK;
 103
 104     /* There's no point in doing anything if the core is shut down anyway */
 105     if (c->state == PA_CORE_SHUTDOWN)
 106         return PA_HOOK_OK;
 107
 108     /* Auto-loaded null-sink not active, so ignoring newly detected sink. */
 109     if (u->null_module == PA_INVALID_INDEX)
 110         return PA_HOOK_OK;
 111
 112     /* This is us detecting ourselves on load in a different way... just ignore this too. */
 113     if (sink->module && sink->module->index == u->null_module)
 114         return PA_HOOK_OK;
 115
 116     pa_log_info("A new sink has been discovered. Unloading null-sink.");
 117
 118     pa_module_unload_request_by_index(c, u->null_module, TRUE);
 119     u->null_module = PA_INVALID_INDEX;
 120
 121     return PA_HOOK_OK;
 122 }
 123
 124 static pa_hook_result_t unlink_hook_callback(pa_core *c, pa_sink *sink, void* userdata) {
 125     struct userdata *u = userdata;
 126
 127     pa_assert(c);
 128     pa_assert(sink);
 129     pa_assert(u);
 130
 131     /* First check to see if it's our own null-sink that's been removed... */
 132     if (u->null_module != PA_INVALID_INDEX && sink->module && sink->module->index == u->null_module) {
 133         pa_log_debug("Autoloaded null-sink removed");
 134         u->null_module = PA_INVALID_INDEX;
 135         return PA_HOOK_OK;
 136     }
 137
 138     /* There's no point in doing anything if the core is shut down anyway */
 139     if (c->state == PA_CORE_SHUTDOWN)
 140         return PA_HOOK_OK;
 141
 142     load_null_sink_if_needed(c, sink, u);
 143
 144     return PA_HOOK_OK;
 145 }
 146
 147 int pa__init(pa_module*m) {
 148     pa_modargs *ma = NULL;
 149     struct userdata *u;
 150
 151     pa_assert(m);
 152
 153     if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
 154         pa_log("Failed to parse module arguments");
 155         return -1;
 156     }
 157
 158     m->userdata = u = pa_xnew(struct userdata, 1);
 159     u->sink_name = pa_xstrdup(pa_modargs_get_value(ma, "sink_name", DEFAULT_SINK_NAME));
 160     u->put_slot = pa_hook_connect(&m->core->hooks[PA_CORE_HOOK_SINK_PUT], PA_HOOK_LATE, (pa_hook_cb_t) put_hook_callback, u);
 161     u->unlink_slot = pa_hook_connect(&m->core->hooks[PA_CORE_HOOK_SINK_UNLINK], PA_HOOK_EARLY, (pa_hook_cb_t) unlink_hook_callback, u);
 162     u->null_module = PA_INVALID_INDEX;
 163     u->ignore = FALSE;
 164
 165     pa_modargs_free(ma);
 166
 167     load_null_sink_if_needed(m->core, NULL, u);
 168
 169     return 0;
 170 }
 171
 172 void pa__done(pa_module*m) {
 173     struct userdata *u;
 174
 175     pa_assert(m);
 176
 177     if (!(u = m->userdata))
 178         return;
 179
 180     if (u->put_slot)
 181         pa_hook_slot_free(u->put_slot);
 182     if (u->unlink_slot)
 183         pa_hook_slot_free(u->unlink_slot);
 184     if (u->null_module != PA_INVALID_INDEX && m->core->state != PA_CORE_SHUTDOWN)
 185         pa_module_unload_request_by_index(m->core, u->null_module, TRUE);
 186
 187     pa_xfree(u->sink_name);
 188     pa_xfree(u);
 189 }