alsa-mixer: Introduce "description-key" option for paths

Previously the path description was looked up based on the
path name only. Since there can be multiple paths that use
the same description, it had to be possible to have multiple
paths with the same name.

Having the same name with multiple paths makes identifying
the paths more complex than necessary, so the plan is to
make it impossible to have paths with the same name. This
patch prepares for that by retaining the possibility to
still have the same description with multiple paths. Instead
of the path name, the path description is looked up by using
the "path description key" if it is set (path name is still
used as a fallback lookup key).

src/modules/alsa/alsa-mixer.c

@@ -53,15 +53,18 @@
 static int setting_select(pa_alsa_setting *s, snd_mixer_t *m);
 
 struct description_map {
-    const char *name;
+    const char *key;
     const char *description;
 };
 
-static const char *lookup_description(const char *name, const struct description_map dm[], unsigned n) {
+static const char *lookup_description(const char *key, const struct description_map dm[], unsigned n) {
     unsigned i;
 
+    if (!key)
+        return NULL;
+
     for (i = 0; i < n; i++)
-        if (pa_streq(dm[i].name, name))
+        if (pa_streq(dm[i].key, key))
             return _(dm[i].description);
 
     return NULL;
@@ -2361,12 +2364,16 @@ static int path_verify(pa_alsa_path *p) {
             return -1;
 
     if (!p->description)
-        p->description = pa_xstrdup(lookup_description(p->name,
+        p->description = pa_xstrdup(lookup_description(p->description_key ? p->description_key : p->name,
                                                        well_known_descriptions,
                                                        PA_ELEMENTSOF(well_known_descriptions)));
 
-    if (!p->description)
+    if (!p->description) {
+        if (p->description_key)
+            pa_log_warn("Path %s: Unrecognized description key: %s", p->name, p->description_key);
+
         p->description = pa_xstrdup(p->name);
+    }
 
     return 0;
 }
@@ -2388,6 +2395,7 @@ pa_alsa_path* pa_alsa_path_new(const char *paths_dir, const char *fname, pa_alsa
     pa_config_item items[] = {
         /* [General] */
         { "priority",            pa_config_parse_unsigned,          NULL, "General" },
+        { "description-key",     pa_config_parse_string,            NULL, "General" },
         { "description",         pa_config_parse_string,            NULL, "General" },
         { "name",                pa_config_parse_string,            NULL, "General" },
         { "mute-during-activation", pa_config_parse_bool,           NULL, "General" },
@@ -2427,10 +2435,11 @@ pa_alsa_path* pa_alsa_path_new(const char *paths_dir, const char *fname, pa_alsa
     p->eld_device = -1;
 
     items[0].data = &p->priority;
-    items[1].data = &p->description;
+    items[1].data = &p->description_key;
-    items[2].data = &p->name;
+    items[2].data = &p->description;
-    items[3].data = &mute_during_activation;
+    items[3].data = &p->name;
-    items[4].data = &p->eld_device;
+    items[4].data = &mute_during_activation;
+    items[5].data = &p->eld_device;
 
     if (!paths_dir)
         paths_dir = get_default_paths_dir();

src/modules/alsa/alsa-mixer.h

@@ -180,6 +180,7 @@ struct pa_alsa_path {
     pa_device_port* port;
 
     char *name;
+    char *description_key;
     char *description;
     unsigned priority;
     int eld_device;

src/modules/alsa/mixer/paths/analog-input-aux.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 80
-name = analog-input
+description-key = analog-input
 
 [Element Capture]
 switch = mute

src/modules/alsa/mixer/paths/analog-input-dock-mic.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 78
-name = analog-input-microphone-dock
+description-key = analog-input-microphone-dock
 
 [Jack Dock Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-fm.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 70
-name = analog-input-radio
+description-key = analog-input-radio
 
 [Element Capture]
 switch = mute

src/modules/alsa/mixer/paths/analog-input-front-mic.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 85
-name = analog-input-microphone-front
+description-key = analog-input-microphone-front
 
 [Jack Front Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-headphone-mic.conf

@@ -21,7 +21,7 @@
 
 [General]
 priority = 87
-name = analog-input-microphone
+description-key = analog-input-microphone
 
 [Jack Headphone Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-headset-mic.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 87
-name = analog-input-microphone-headset
+description-key = analog-input-microphone-headset
 
 [Jack Headset Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-internal-mic-always.conf

@@ -21,7 +21,7 @@
 
 [General]
 priority = 89
-name = analog-input-microphone-internal
+description-key = analog-input-microphone-internal
 
 [Jack Mic]
 state.plugged = no

src/modules/alsa/mixer/paths/analog-input-internal-mic.conf

@@ -21,7 +21,7 @@
 
 [General]
 priority = 89
-name = analog-input-microphone-internal
+description-key = analog-input-microphone-internal
 
 [Jack Mic]
 state.plugged = no

src/modules/alsa/mixer/paths/analog-input-mic-line.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 85
-name = analog-input
+description-key = analog-input
 
 [Element Capture]
 switch = mute

src/modules/alsa/mixer/paths/analog-input-mic.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 87
-name = analog-input-microphone
+description-key = analog-input-microphone
 
 [Jack Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-rear-mic.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 82
-name = analog-input-microphone-rear
+description-key = analog-input-microphone-rear
 
 [Jack Rear Mic]
 required-any = any

src/modules/alsa/mixer/paths/analog-input-tvtuner.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 70
-name = analog-input-video
+description-key = analog-input-video
 
 [Element Capture]
 switch = mute

src/modules/alsa/mixer/paths/analog-output-desktop-speaker.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 101
-name = analog-output-speaker
+description-key = analog-output-speaker
 
 [Properties]
 device.icon_name = audio-speakers

src/modules/alsa/mixer/paths/analog-output-headphones-2.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 89
-name = analog-output-headphones
+description-key = analog-output-headphones
 
 [Properties]
 device.icon_name = audio-headphones

src/modules/alsa/mixer/paths/analog-output-headphones.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 90
-name = analog-output-headphones
+description-key = analog-output-headphones
 
 [Properties]
 device.icon_name = audio-headphones

src/modules/alsa/mixer/paths/analog-output-speaker-always.conf

@@ -21,7 +21,7 @@
 
 [General]
 priority = 100
-name = analog-output-speaker
+description-key = analog-output-speaker
 
 [Properties]
 device.icon_name = audio-speakers

src/modules/alsa/mixer/paths/analog-output-speaker.conf

@@ -20,7 +20,7 @@
 
 [General]
 priority = 100
-name = analog-output-speaker
+description-key = analog-output-speaker
 
 [Properties]
 device.icon_name = audio-speakers

src/modules/alsa/mixer/paths/analog-output.conf.common

@@ -55,7 +55,13 @@
 
 ; [General]
 ; priority = ...                         # Priority for this path
-; description = ...
+; description-key = ...                  # The path description is looked up from a table in path_verify() in
+;                                        # src/modules/alsa/alsa-mixer.c. By default the path name (i.e. the file name
+;                                        # minus the ".conf" suffix) is used as the lookup key, but if this option is
+;                                        # set, then the given string is used as the key instead. In any case the
+;                                        # "description" option can be used to override the path description.
+; description = ...                      # Description for this path. Overrides the normal description lookup logic, as
+;                                        # described in the "description-key" documentation above.
 ; mute-during-activation = yes | no      # If this path supports hardware mute, should the hw mute be used while activating this
 ;                                        # path? In some cases this can reduce extra noises during port switching, while in other
 ;                                        # cases this can increase such noises. Default: no.