pactl, pacmd: Allow to unset the configured default sink or source

Currently there is no way to unset the default sink or source once it was
configured manually by the user.
This patch introduces the special name @NONE@, which can be used with the pacmd
or pactl set-default-sink and set-default-source commands to unset the user
configured default. When the default is unset, pulseaudio will return to the
standard default sink or source selection mechanism based on priority.

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/785>

4 files changed, 35 insertions, 15 deletions

diff --git a/man/pactl.1.xml.in b/man/pactl.1.xml.in
index d4eb03458..ca365dc23 100644
--- a/man/pactl.1.xml.in
+++ b/man/pactl.1.xml.in
@@ -174,7 +174,9 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
 
     <option>
       <p><opt>set-default-sink</opt> <arg>SINK</arg></p>
-      <optdesc><p>Make the specified sink (identified by its symbolic name or numerical index) the default sink.</p></optdesc>
+      <optdesc><p>Make the specified sink (identified by its symbolic name or numerical index) the default sink.
+         Use the special name \@NONE@ to unset the user defined default sink. This will make pulseaudio return to the default
+         sink selection based on sink priority.</p></optdesc>
     </option>
 
     <option>
@@ -189,7 +191,9 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
 
     <option>
       <p><opt>set-default-source</opt> <arg>SOURCE</arg></p>
-      <optdesc><p>Make the specified source (identified by its symbolic name or numerical index) the default source.</p></optdesc>
+      <optdesc><p>Make the specified source (identified by its symbolic name or numerical index) the default source.
+         Use the special name \@NONE@ to unset the user defined default source. This will make pulseaudio return to the default
+         source selection based on source priority.</p></optdesc>
     </option>
 
     <option>
diff --git a/man/pulse-cli-syntax.5.xml.in b/man/pulse-cli-syntax.5.xml.in
index 5bc94b9c9..ecd495a79 100644
--- a/man/pulse-cli-syntax.5.xml.in
+++ b/man/pulse-cli-syntax.5.xml.in
@@ -143,8 +143,10 @@ License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
       <p><opt>set-default-sink|set-default-source</opt> <arg>index|name</arg></p>
       <optdesc><p>Make a sink (resp. source) the default. You may specify the
       sink (resp. source) by its index in the sink (resp. source) list or by its
-      name.</p><p>Note that defaults may be overridden by various policy modules
-      or by specific stream configurations.</p></optdesc>
+      name. Use the special name \@NONE@ to unset the user defined default sink or
+      source. In this case, pulseaudio will return to the default sink or source
+      selection based on priority.</p><p>Note that defaults may be overridden by
+      various policy modules or by specific stream configurations.</p></optdesc>
     </option>
 
     <option>
diff --git a/src/pulsecore/cli-command.c b/src/pulsecore/cli-command.c
index ae75064f0..1a49677be 100644
--- a/src/pulsecore/cli-command.c
+++ b/src/pulsecore/cli-command.c
@@ -1038,7 +1038,9 @@ static int pa_cli_command_sink_default(pa_core *c, pa_tokenizer *t, pa_strbuf *b
         return -1;
     }
 
-    if ((s = pa_namereg_get(c, n, PA_NAMEREG_SINK)))
+    if (pa_streq(n, "@NONE@"))
+        pa_core_set_configured_default_sink(c, NULL);
+    else if ((s = pa_namereg_get(c, n, PA_NAMEREG_SINK)))
         pa_core_set_configured_default_sink(c, s->name);
     else
         pa_strbuf_printf(buf, "Sink %s does not exist.\n", n);
@@ -1060,7 +1062,9 @@ static int pa_cli_command_source_default(pa_core *c, pa_tokenizer *t, pa_strbuf
         return -1;
     }
 
-    if ((s = pa_namereg_get(c, n, PA_NAMEREG_SOURCE)))
+    if (pa_streq(n, "@NONE@"))
+        pa_core_set_configured_default_source(c, NULL);
+    else if ((s = pa_namereg_get(c, n, PA_NAMEREG_SOURCE)))
         pa_core_set_configured_default_source(c, s->name);
     else
         pa_strbuf_printf(buf, "Source %s does not exist.\n", n);
diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 98b8795d9..231d640aa 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -4379,23 +4379,33 @@ static void command_set_default_sink_or_source(pa_pdispatch *pd, uint32_t comman
     }
 
     CHECK_VALIDITY(c->pstream, c->authorized, tag, PA_ERR_ACCESS);
-    CHECK_VALIDITY(c->pstream, !s || pa_namereg_is_valid_name(s), tag, PA_ERR_INVALID);
+    CHECK_VALIDITY(c->pstream, !s || pa_namereg_is_valid_name(s) || pa_safe_streq(s,"@NONE@"), tag, PA_ERR_INVALID);
 
     if (command == PA_COMMAND_SET_DEFAULT_SOURCE) {
-        pa_source *source;
+        char *source_name = NULL;
 
-        source = pa_namereg_get(c->protocol->core, s, PA_NAMEREG_SOURCE);
-        CHECK_VALIDITY(c->pstream, source, tag, PA_ERR_NOENTITY);
+        if (!pa_safe_streq(s,"@NONE@")) {
+            pa_source *source;
+
+            source = pa_namereg_get(c->protocol->core, s, PA_NAMEREG_SOURCE);
+            CHECK_VALIDITY(c->pstream, source, tag, PA_ERR_NOENTITY);
+            source_name = source->name;
+        }
 
-        pa_core_set_configured_default_source(c->protocol->core, source->name);
+        pa_core_set_configured_default_source(c->protocol->core, source_name);
     } else {
-        pa_sink *sink;
+        char *sink_name = NULL;
         pa_assert(command == PA_COMMAND_SET_DEFAULT_SINK);
 
-        sink = pa_namereg_get(c->protocol->core, s, PA_NAMEREG_SINK);
-        CHECK_VALIDITY(c->pstream, sink, tag, PA_ERR_NOENTITY);
+        if (!pa_safe_streq(s,"@NONE@")) {
+            pa_sink *sink;
+
+            sink = pa_namereg_get(c->protocol->core, s, PA_NAMEREG_SINK);
+            CHECK_VALIDITY(c->pstream, sink, tag, PA_ERR_NOENTITY);
+            sink_name = sink->name;
+        }
 
-        pa_core_set_configured_default_sink(c->protocol->core, sink->name);
+        pa_core_set_configured_default_sink(c->protocol->core, sink_name);
     }
 
     pa_pstream_send_simple_ack(c->pstream, tag);