pactl, pacmd, cli-command: Add send-message command

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/51>

doc/messaging_api.txt

@@ -0,0 +1,15 @@
+Message API reference
+
+The message API allows any object within pulseaudio to register a message
+handler. A message handler is a function that can be called by clients using
+PA_COMMAND_SEND_OBJECT_MESSAGE. A message consists at least of an object path
+and a message command, both specified as strings. Additional parameters can
+be specified using a single string, but are not mandatory. The message handler
+returns an error number as defined in def.h and also returns a string in
+the "response" variable. The following reference lists available messages,
+their parameters and return values.
+
+Recipient:
+Message:
+Parameters:
+Return value:

man/pactl.1.xml.in

@@ -253,6 +253,13 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
       for possible encodings. </p></optdesc>
     </option>
 
+    <option>
+      <p><opt>send-message</opt> <arg>RECIPIENT</arg> <arg>MESSAGE</arg> <arg>MESSAGE_PARAMETERS</arg></p>
+      <optdesc><p>Send a message to the specified recipient object. If applicable an additional string containing
+      message parameters can be specified. A string is returned as a response to the message. For available messages
+      see https://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/doc/messaging_api.txt.</p></optdesc>
+    </option>
+
     <option>
       <p><opt>subscribe</opt></p>
       <optdesc><p>Subscribe to events, pactl does not exit by itself, but keeps waiting for new events.</p></optdesc>

man/pulse-cli-syntax.5.xml.in

@@ -306,6 +306,13 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
       <optdesc><p>Debug: Show shared properties.</p></optdesc>
     </option>
 
+    <option>
+      <p><opt>send-message</opt> <arg>recipient</arg> <arg>message</arg> <arg>message_parameters</arg></p>
+      <optdesc><p>Send a message to the specified recipient object. If applicable an additional string containing
+      message parameters can be specified. A string is returned as a response to the message. For available messages
+      see https://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/doc/messaging_api.txt.</p></optdesc>
+    </option>
+
     <option>
       <p><opt>exit</opt></p>
       <optdesc><p>Terminate the daemon. If you want to terminate a CLI

shell-completion/bash/pulseaudio

@@ -121,7 +121,7 @@ _pactl() {
                     set-source-volume set-sink-input-volume set-source-output-volume
                     set-sink-mute set-source-mute set-sink-input-mute
                     set-source-output-mute set-sink-formats set-port-latency-offset
-                    subscribe help)
+                    subscribe send-message help)
 
     _init_completion -n = || return
     preprev=${words[$cword-2]}
@@ -271,7 +271,7 @@ _pacmd() {
                     move-sink-input move-source-output suspend-sink suspend-source
                     suspend set-card-profile set-sink-port set-source-port
                     set-port-latency-offset set-log-target set-log-level set-log-meta
-                    set-log-time set-log-backtrace)
+                    set-log-time set-log-backtrace send-message)
     _init_completion -n = || return
     preprev=${words[$cword-2]}
 

shell-completion/zsh/_pulseaudio

@@ -263,6 +263,7 @@ _pactl_completion() {
             'set-sink-input-mute: mute a stream'
             'set-source-output-mute: mute a recording stream'
             'set-sink-formats: set supported formats of a sink'
+            'send-message: send a message to a pulseaudio object'
             'subscribe: subscribe to events'
         )
 
@@ -561,6 +562,7 @@ _pacmd_completion() {
             'dump: show daemon configuration'
             'dump-volumes: show the state of all volumes'
             'shared: show shared properties'
+            'send-message: send a message to a pulseaudio object'
             'exit: ask the PulseAudio daemon to exit'
         )
         _describe 'pacmd commands' _pacmd_commands

src/pulse/introspect.h

@@ -500,7 +500,8 @@ pa_operation* pa_context_unload_module(pa_context *c, uint32_t idx, pa_context_s
 /** Callback prototype for pa_context_send_message_to_object() \since 15.0 */
 typedef void (*pa_context_string_cb_t)(pa_context *c, int success, const char *response, void *userdata);
 
-/** Send a message to an object that registered a message handler. \since 15.0 */
+/** Send a message to an object that registered a message handler. For more information
+ * see https://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/doc/messaging_api.txt. \since 15.0 */
 pa_operation* pa_context_send_message_to_object(pa_context *c, const char *recipient_name, const char *message, const char *message_parameters, pa_context_string_cb_t cb, void *userdata);
 
 /** @} */

src/pulsecore/cli-command.c

@@ -53,6 +53,7 @@
 #include <pulsecore/sound-file-stream.h>
 #include <pulsecore/shared.h>
 #include <pulsecore/core-util.h>
+#include <pulsecore/message-handler.h>
 #include <pulsecore/core-error.h>
 #include <pulsecore/modinfo.h>
 #include <pulsecore/dynarray.h>
@@ -135,6 +136,7 @@ static int pa_cli_command_sink_port(pa_core *c, pa_tokenizer *t, pa_strbuf *buf,
 static int pa_cli_command_source_port(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail);
 static int pa_cli_command_port_offset(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail);
 static int pa_cli_command_dump_volumes(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail);
+static int pa_cli_command_send_message_to_object(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail);
 
 /* A method table for all available commands */
 
@@ -191,6 +193,7 @@ static const struct command commands[] = {
     { "set-log-meta",            pa_cli_command_log_meta,           "Show source code location in log messages (args: bool)", 2},
     { "set-log-time",            pa_cli_command_log_time,           "Show timestamps in log messages (args: bool)", 2},
     { "set-log-backtrace",       pa_cli_command_log_backtrace,      "Show backtrace in log messages (args: frames)", 2},
+    { "send-message",            pa_cli_command_send_message_to_object, "Send a message to an object (args: recipient, message, message_parameters)", 4},
     { "play-file",               pa_cli_command_play_file,          "Play a sound file (args: filename, sink|index)", 3},
     { "dump",                    pa_cli_command_dump,               "Dump daemon configuration", 1},
     { "dump-volumes",            pa_cli_command_dump_volumes,       "Debug: Show the state of all volumes", 1 },
@@ -1784,6 +1787,47 @@ static int pa_cli_command_port_offset(pa_core *c, pa_tokenizer *t, pa_strbuf *bu
     return 0;
 }
 
+static int pa_cli_command_send_message_to_object(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail) {
+    const char *object_path, *message, *message_parameters;
+    char *response = NULL;
+    int ret;
+
+    pa_core_assert_ref(c);
+    pa_assert(t);
+    pa_assert(buf);
+    pa_assert(fail);
+
+
+    if (!(object_path = pa_tokenizer_get(t, 1))) {
+        pa_strbuf_puts(buf, "You need to specify an object path as recipient for the message.\n");
+           return -1;
+    }
+
+    if (!(message = pa_tokenizer_get(t, 2))) {
+        pa_strbuf_puts(buf, "You need to specify a message name.\n");
+        return -1;
+    }
+
+    /* parameters may be NULL */
+    message_parameters = pa_tokenizer_get(t, 3);
+
+    ret = pa_message_handler_send_message(c, object_path, message, message_parameters, &response);
+
+    if (ret < 0) {
+        pa_strbuf_printf(buf, "Send message failed: %s\n", pa_strerror(ret));
+        ret = -1;
+
+    } else {
+        if (response)
+            pa_strbuf_puts(buf, response);
+        pa_strbuf_puts(buf, "\n");
+        ret = 0;
+    }
+
+    pa_xfree(response);
+    return ret;
+}
+
 static int pa_cli_command_dump(pa_core *c, pa_tokenizer *t, pa_strbuf *buf, bool *fail) {
     pa_module *m;
     pa_sink *sink;

src/utils/pacmd.c

@@ -77,6 +77,7 @@ static void help(const char *argv0) {
     printf("%s %s %s\n", argv0, "set-log-meta", _("1|0"));
     printf("%s %s %s\n", argv0, "set-log-time", _("1|0"));
     printf("%s %s %s\n", argv0, "set-log-backtrace", _("FRAMES"));
+    printf("%s %s %s\n", argv0, "send-message", _("RECIPIENT MESSAGE [MESSAGE_PARAMETERS]"));
 
     printf(_("\n"
          "  -h, --help                            Show this help\n"

src/utils/pactl.c

@@ -56,7 +56,10 @@ static char
     *card_name = NULL,
     *profile_name = NULL,
     *port_name = NULL,
-    *formats = NULL;
+    *formats = NULL,
+    *object_path = NULL,
+    *message = NULL,
+    *message_args = NULL;
 
 static uint32_t
     sink_input_idx = PA_INVALID_INDEX,
@@ -130,6 +133,7 @@ static enum {
     SET_SOURCE_OUTPUT_MUTE,
     SET_SINK_FORMATS,
     SET_PORT_LATENCY_OFFSET,
+    SEND_MESSAGE,
     SUBSCRIBE
 } action = NONE;
 
@@ -878,6 +882,19 @@ static void index_callback(pa_context *c, uint32_t idx, void *userdata) {
     complete_action();
 }
 
+static void send_message_callback(pa_context *c, int success, const char *response, void *userdata) {
+
+    if (!success) {
+        pa_log(_("Send message failed: %s"), pa_strerror(pa_context_errno(c)));
+        quit(1);
+        return;
+    }
+
+    printf("%s\n", response);
+
+    complete_action();
+}
+
 static void volume_relative_adjust(pa_cvolume *cv) {
     pa_assert(volume_flags & VOL_RELATIVE);
 
@@ -1450,6 +1467,10 @@ static void context_state_callback(pa_context *c, void *userdata) {
                     o = pa_context_set_port_latency_offset(c, card_name, port_name, latency_offset, simple_callback, NULL);
                     break;
 
+                case SEND_MESSAGE:
+                    o = pa_context_send_message_to_object(c, object_path, message, message_args, send_message_callback, NULL);
+                    break;
+
                 case SUBSCRIBE:
                     pa_context_set_subscribe_callback(c, context_subscribe_callback, NULL);
 
@@ -1626,6 +1647,7 @@ static void help(const char *argv0) {
     printf("%s %s %s %s\n", argv0, _("[options]"), "set-(sink-input|source-output)-mute", _("#N 1|0|toggle"));
     printf("%s %s %s %s\n", argv0, _("[options]"), "set-sink-formats", _("#N FORMATS"));
     printf("%s %s %s %s\n", argv0, _("[options]"), "set-port-latency-offset", _("CARD-NAME|CARD-#N PORT OFFSET"));
+    printf("%s %s %s %s\n", argv0, _("[options]"), "send-message", _("RECIPIENT MESSAGE [MESSAGE_PARAMETERS]"));
     printf("%s %s %s\n",    argv0, _("[options]"), "subscribe");
     printf(_("\nThe special names @DEFAULT_SINK@, @DEFAULT_SOURCE@ and @DEFAULT_MONITOR@\n"
              "can be used to specify the default sink, source and monitor.\n"));
@@ -2061,6 +2083,22 @@ int main(int argc, char *argv[]) {
                 goto quit;
             }
 
+        } else if (pa_streq(argv[optind], "send-message")) {
+            action = SEND_MESSAGE;
+
+            if (argc < optind+3) {
+                pa_log(_("You have to specify at least an object path and a message name"));
+                goto quit;
+            }
+
+            object_path = pa_xstrdup(argv[optind + 1]);
+            message = pa_xstrdup(argv[optind + 2]);
+            if (argc >= optind+4)
+                message_args = pa_xstrdup(argv[optind + 3]);
+
+            if (argc > optind+4)
+                pa_log(_("Excess arguments given, they will be ignored. Note that all message parameters must be given as a single string."));
+
         } else if (pa_streq(argv[optind], "subscribe"))
 
             action = SUBSCRIBE;
@@ -2154,6 +2192,9 @@ quit:
     pa_xfree(profile_name);
     pa_xfree(port_name);
     pa_xfree(formats);
+    pa_xfree(object_path);
+    pa_xfree(message);
+    pa_xfree(message_args);
 
     if (sndfile)
         sf_close(sndfile);