Allow read-only or non-existing sink input volume.

There are two known cases where read-only or non-existing sink input volume is
relevant: passthrough streams and the planned volume sharing logic.
Passthrough streams don't have volume at all, and the volume sharing logic
requires read-only sink input volume. This commit is primarily working towards
the volume sharing feature, but support for non-existing sink input volume is
also added, because it is so closely related to read-only volume.

Some unrelated refactoring in iface-stream.c creeped into this commit too (new
function: stream_to_string()).

src/pulsecore/cli-command.c

@@ -579,11 +579,16 @@ static int pa_cli_command_sink_input_volume(pa_core *c, pa_tokenizer *t, pa_strb
         return -1;
     }
 
-    if (!(si = pa_idxset_get_by_index(c->sink_inputs, (uint32_t) idx))) {
+    if (!(si = pa_idxset_get_by_index(c->sink_inputs, idx))) {
         pa_strbuf_puts(buf, "No sink input found with this index.\n");
         return -1;
     }
 
+    if (!pa_sink_input_is_volume_writable(si)) {
+        pa_strbuf_puts(buf, "This sink input's volume can't be changed.\n");
+        return -1;
+    }
+
     pa_cvolume_set(&cvolume, 1, volume);
     pa_sink_input_set_volume(si, &cvolume, TRUE, TRUE);
     return 0;

src/pulsecore/cli-text.c

@@ -553,8 +553,7 @@ char *pa_sink_input_list_to_string(pa_core *c) {
         pa_usec_t cl;
         const char *cmn;
         pa_cvolume v;
-
-        pa_sink_input_get_volume(i, &v, TRUE);
+        char *volume_str = NULL;
 
         cmn = pa_channel_map_to_pretty_name(&i->channel_map);
 
@@ -565,6 +564,15 @@ char *pa_sink_input_list_to_string(pa_core *c) {
 
         pa_assert(i->sink);
 
+        if (pa_sink_input_is_volume_readable(i)) {
+            pa_sink_input_get_volume(i, &v, TRUE);
+            volume_str = pa_sprintf_malloc("%s\n\t        %s\n\t        balance %0.2f",
+                                           pa_cvolume_snprint(cv, sizeof(cv), &v),
+                                           pa_sw_cvolume_snprint_dB(cvdb, sizeof(cvdb), &v),
+                                           pa_cvolume_get_balance(&v, &i->channel_map));
+        } else
+            volume_str = pa_xstrdup("n/a");
+
         pa_strbuf_printf(
             s,
             "    index: %u\n"
@@ -573,8 +581,6 @@ char *pa_sink_input_list_to_string(pa_core *c) {
             "\tstate: %s\n"
             "\tsink: %u <%s>\n"
             "\tvolume: %s\n"
-            "\t        %s\n"
-            "\t        balance %0.2f\n"
             "\tmuted: %s\n"
             "\tcurrent latency: %0.2f ms\n"
             "\trequested latency: %s\n"
@@ -596,9 +602,7 @@ char *pa_sink_input_list_to_string(pa_core *c) {
             i->flags & PA_SINK_INPUT_KILL_ON_SUSPEND ? "KILL_ON_SUSPEND " : "",
             state_table[pa_sink_input_get_state(i)],
             i->sink->index, i->sink->name,
-            pa_cvolume_snprint(cv, sizeof(cv), &v),
-            pa_sw_cvolume_snprint_dB(cvdb, sizeof(cvdb), &v),
-            pa_cvolume_get_balance(&v, &i->channel_map),
+            volume_str,
             pa_yes_no(pa_sink_input_get_mute(i)),
             (double) pa_sink_input_get_latency(i, NULL) / PA_USEC_PER_MSEC,
             clt,
@@ -608,6 +612,8 @@ char *pa_sink_input_list_to_string(pa_core *c) {
             cmn ? cmn : "",
             pa_resample_method_to_string(pa_sink_input_get_resample_method(i)));
 
+        pa_xfree(volume_str);
+
         if (i->module)
             pa_strbuf_printf(s, "\tmodule: %u\n", i->module->index);
         if (i->client)

src/pulsecore/protocol-native.c

@@ -3056,12 +3056,19 @@ static void sink_input_fill_tagstruct(pa_native_connection *c, pa_tagstruct *t,
     pa_sample_spec fixed_ss;
     pa_usec_t sink_latency;
     pa_cvolume v;
+    pa_bool_t has_volume = FALSE;
 
     pa_assert(t);
     pa_sink_input_assert_ref(s);
 
     fixup_sample_spec(c, &fixed_ss, &s->sample_spec);
 
+    has_volume = pa_sink_input_is_volume_readable(s);
+    if (has_volume)
+        pa_sink_input_get_volume(s, &v, TRUE);
+    else
+        pa_cvolume_reset(&v, fixed_ss.channels);
+
     pa_tagstruct_putu32(t, s->index);
     pa_tagstruct_puts(t, pa_strnull(pa_proplist_gets(s->proplist, PA_PROP_MEDIA_NAME)));
     pa_tagstruct_putu32(t, s->module ? s->module->index : PA_INVALID_INDEX);
@@ -3069,7 +3076,7 @@ static void sink_input_fill_tagstruct(pa_native_connection *c, pa_tagstruct *t,
     pa_tagstruct_putu32(t, s->sink->index);
     pa_tagstruct_put_sample_spec(t, &fixed_ss);
     pa_tagstruct_put_channel_map(t, &s->channel_map);
-    pa_tagstruct_put_cvolume(t, pa_sink_input_get_volume(s, &v, TRUE));
+    pa_tagstruct_put_cvolume(t, &v);
     pa_tagstruct_put_usec(t, pa_sink_input_get_latency(s, &sink_latency));
     pa_tagstruct_put_usec(t, sink_latency);
     pa_tagstruct_puts(t, pa_resample_method_to_string(pa_sink_input_get_resample_method(s)));
@@ -3080,6 +3087,10 @@ static void sink_input_fill_tagstruct(pa_native_connection *c, pa_tagstruct *t,
         pa_tagstruct_put_proplist(t, s->proplist);
     if (c->version >= 19)
         pa_tagstruct_put_boolean(t, (pa_sink_input_get_state(s) == PA_SINK_INPUT_CORKED));
+    if (c->version >= 20) {
+        pa_tagstruct_put_boolean(t, has_volume);
+        pa_tagstruct_put_boolean(t, has_volume ? !pa_sink_input_is_volume_writable(s) : FALSE);
+    }
 }
 
 static void source_output_fill_tagstruct(pa_native_connection *c, pa_tagstruct *t, pa_source_output *s) {
@@ -3461,6 +3472,7 @@ static void command_set_volume(
         pa_log_debug("Client %s changes volume of source %s.", client_name, source->name);
         pa_source_set_volume(source, &volume, TRUE);
     } else if (si) {
+        CHECK_VALIDITY(c->pstream, pa_sink_input_is_volume_writable(si), tag, PA_ERR_INVALID);
         CHECK_VALIDITY(c->pstream, volume.channels == 1 || pa_cvolume_compatible(&volume, &si->sample_spec), tag, PA_ERR_INVALID);
 
         pa_log_debug("Client %s changes volume of sink input %s.",

src/pulsecore/sink-input.c

@@ -112,8 +112,15 @@ void pa_sink_input_new_data_set_channel_map(pa_sink_input_new_data *data, const
         data->channel_map = *map;
 }
 
+pa_bool_t pa_sink_input_new_data_is_volume_writable(pa_sink_input_new_data *data) {
+    pa_assert(data);
+
+    return !(data->flags & PA_SINK_INPUT_PASSTHROUGH);
+}
+
 void pa_sink_input_new_data_set_volume(pa_sink_input_new_data *data, const pa_cvolume *volume) {
     pa_assert(data);
+    pa_assert(pa_sink_input_new_data_is_volume_writable(data));
 
     if ((data->volume_is_set = !!volume))
         data->volume = *volume;
@@ -205,6 +212,7 @@ int pa_sink_input_new(
     if ((r = pa_hook_fire(&core->hooks[PA_CORE_HOOK_SINK_INPUT_NEW], data)) < 0)
         return r;
 
+    pa_assert(!data->volume_is_set || pa_sink_input_new_data_is_volume_writable(data));
     pa_return_val_if_fail(!data->driver || pa_utf8_valid(data->driver), -PA_ERR_INVALID);
 
     if (!data->sink) {
@@ -1058,13 +1066,24 @@ static void set_real_ratio(pa_sink_input *i, const pa_cvolume *v) {
     /* We don't copy the data to the thread_info data. That's left for someone else to do */
 }
 
+/* Called from main context */
+pa_bool_t pa_sink_input_is_volume_readable(pa_sink_input *i) {
+    pa_sink_input_assert_ref(i);
+    pa_assert_ctl_context();
+
+    return !(i->flags & PA_SINK_INPUT_PASSTHROUGH);
+}
+
+/* Called from main context */
+pa_bool_t pa_sink_input_is_volume_writable(pa_sink_input *i) {
+    pa_sink_input_assert_ref(i);
+    pa_assert_ctl_context();
+
+    return !(i->flags & PA_SINK_INPUT_PASSTHROUGH);
+}
+
 /* Called from main context */
 void pa_sink_input_set_volume(pa_sink_input *i, const pa_cvolume *volume, pa_bool_t save, pa_bool_t absolute) {
-
-    /* Do not allow for volume changes for non-audio types */
-    if (i->flags & PA_SINK_INPUT_PASSTHROUGH)
-        return;
-
     /* test ramping -> return pa_sink_input_set_volume_with_ramping(i, volume, save, absolute, 2000 * PA_USEC_PER_MSEC); */
     return pa_sink_input_set_volume_with_ramping(i, volume, save, absolute, 0);
 }
@@ -1074,6 +1093,7 @@ pa_cvolume *pa_sink_input_get_volume(pa_sink_input *i, pa_cvolume *volume, pa_bo
     pa_sink_input_assert_ref(i);
     pa_assert_ctl_context();
     pa_assert(PA_SINK_INPUT_IS_LINKED(i->state));
+    pa_assert(pa_sink_input_is_volume_readable(i));
 
     if (absolute || !(i->sink->flags & PA_SINK_FLAT_VOLUME))
         *volume = i->volume;
@@ -1854,6 +1874,7 @@ void pa_sink_input_set_volume_with_ramping(pa_sink_input *i, const pa_cvolume *v
     pa_assert(volume);
     pa_assert(pa_cvolume_valid(volume));
     pa_assert(volume->channels == 1 || pa_cvolume_compatible(volume, &i->sample_spec));
+    pa_assert(pa_sink_input_is_volume_writable(i));
 
     if ((i->sink->flags & PA_SINK_FLAT_VOLUME) && !absolute) {
         v = i->sink->reference_volume;

src/pulsecore/sink-input.h

@@ -312,6 +312,7 @@ typedef struct pa_sink_input_new_data {
 pa_sink_input_new_data* pa_sink_input_new_data_init(pa_sink_input_new_data *data);
 void pa_sink_input_new_data_set_sample_spec(pa_sink_input_new_data *data, const pa_sample_spec *spec);
 void pa_sink_input_new_data_set_channel_map(pa_sink_input_new_data *data, const pa_channel_map *map);
+pa_bool_t pa_sink_input_new_data_is_volume_writable(pa_sink_input_new_data *data);
 void pa_sink_input_new_data_set_volume(pa_sink_input_new_data *data, const pa_cvolume *volume);
 void pa_sink_input_new_data_apply_volume_factor(pa_sink_input_new_data *data, const pa_cvolume *volume_factor);
 void pa_sink_input_new_data_apply_volume_factor_sink(pa_sink_input_new_data *data, const pa_cvolume *volume_factor);
@@ -356,6 +357,8 @@ void pa_sink_input_kill(pa_sink_input*i);
 
 pa_usec_t pa_sink_input_get_latency(pa_sink_input *i, pa_usec_t *sink_latency);
 
+pa_bool_t pa_sink_input_is_volume_readable(pa_sink_input *i);
+pa_bool_t pa_sink_input_is_volume_writable(pa_sink_input *i);
 void pa_sink_input_set_volume(pa_sink_input *i, const pa_cvolume *volume, pa_bool_t save, pa_bool_t absolute);
 pa_cvolume *pa_sink_input_get_volume(pa_sink_input *i, pa_cvolume *volume, pa_bool_t absolute);