module/alsa: monitors volume and muted state of selected card/mixer

CMakeLists.txt

@@ -22,6 +22,7 @@ pkg_check_modules(XCB_XKB REQUIRED xcb-xkb)                         # Module/xkb
 pkg_check_modules(JSON REQUIRED json-c)                             # Module/i3
 pkg_check_modules(UDEV REQUIRED libudev)                            # Module/battery
 pkg_check_modules(MPD REQUIRED libmpdclient)                        # Module/mpd
+pkg_check_modules(ALSA REQUIRED alsa)                               # Module/alsa
 
 add_executable(f00bar
   bar.c bar.h
@@ -48,6 +49,7 @@ add_executable(f00bar
   particles/ramp.c particles/ramp.h
   particles/string.c particles/string.h
 
+  modules/alsa.c modules/alsa.h
   modules/backlight.c modules/backlight.h
   modules/battery.c modules/battery.h
   modules/clock.c modules/clock.h
@@ -70,6 +72,7 @@ target_compile_options(f00bar PRIVATE
   ${JSON_CFLAGS_OTHER}
   ${UDEV_CFLAGS_OTHER}
   ${MPD_CFLAGS_OTHER}
+  ${ALSA_CFLAGS_OTHER}
   )
 
 target_include_directories(f00bar PRIVATE
@@ -80,6 +83,7 @@ target_include_directories(f00bar PRIVATE
   ${JSON_INCLUDE_DIRS}
   ${UDEV_INCLUDE_DIRS}
   ${MPD_INCLUDE_DIRS}
+  ${ALSA_INCLUDE_DIRS}
   )
 
 target_link_libraries(f00bar
@@ -91,4 +95,5 @@ target_link_libraries(f00bar
   ${JSON_LIBRARIES}
   ${UDEV_LIBRARIES}
   ${MPD_LIBRARIES}
+  ${ALSA_LIBRARIES}
   )

config.c

@@ -21,6 +21,7 @@
 #include "particles/string.h"
 
 #include "module.h"
+#include "modules/alsa.h"
 #include "modules/backlight.h"
 #include "modules/battery.h"
 #include "modules/clock.h"
@@ -568,6 +569,24 @@ module_removables_from_config(const struct yml_node *node,
         particle_from_config(content, parent_font), left, right);
 }
 
+static struct module *
+module_alsa_from_config(const struct yml_node *node,
+                        const struct font *parent_font)
+{
+    const struct yml_node *card = yml_get_value(node, "card");
+    const struct yml_node *mixer = yml_get_value(node, "mixer");
+    const struct yml_node *content = yml_get_value(node, "content");
+
+    assert(yml_is_scalar(card));
+    assert(yml_is_scalar(mixer));
+    assert(content != NULL);
+
+    return module_alsa(
+        yml_value_as_string(card),
+        yml_value_as_string(mixer),
+        particle_from_config(content, parent_font));
+}
+
 struct bar *
 conf_to_bar(const struct yml_node *bar)
 {
@@ -682,6 +701,8 @@ conf_to_bar(const struct yml_node *bar)
                     mods[idx] = module_network_from_config(it.node, font);
                 else if (strcmp(mod_name, "removables") == 0)
                     mods[idx] = module_removables_from_config(it.node, font);
+                else if (strcmp(mod_name, "alsa") == 0)
+                    mods[idx] = module_alsa_from_config(it.node, font);
                 else
                     assert(false);
             }

modules/alsa.c

@@ -0,0 +1,148 @@
+#include "alsa.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <alsa/asoundlib.h>
+
+#define LOG_MODULE "alsa"
+#define LOG_ENABLE_DBG 1
+#include "../log.h"
+#include "../bar.h"
+
+struct private {
+    char *card;
+    char *mixer;
+    struct particle *label;
+
+    long vol_min;
+    long vol_max;
+    long vol_cur;
+    bool muted;
+};
+
+static void
+destroy(struct module *mod)
+{
+    struct private *m = mod->private;
+    m->label->destroy(m->label);
+    free(m->card);
+    free(m->mixer);
+    free(m);
+    module_default_destroy(mod);
+}
+
+static struct exposable *
+content(struct module *mod)
+{
+    struct private *m = mod->private;
+
+    mtx_lock(&mod->lock);
+    struct tag_set tags = {
+        .tags = (struct tag *[]){
+            tag_new_int_range(mod, "volume", m->vol_cur, m->vol_min, m->vol_max),
+            tag_new_bool(mod, "muted", m->muted),
+        },
+        .count = 2,
+    };
+    mtx_unlock(&mod->lock);
+
+    struct exposable *exposable = m->label->instantiate(m->label, &tags);
+
+    tag_set_destroy(&tags);
+    return exposable;
+}
+
+static void
+update_state(struct module *mod, snd_mixer_elem_t *elem)
+{
+    struct private *m = mod->private;
+
+    long cur, min, max;
+    snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_MONO, &cur);
+    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+
+    int unmuted;
+    snd_mixer_selem_get_playback_switch(elem, SND_MIXER_SCHN_MONO, &unmuted);
+
+    LOG_DBG("muted=%d, cur=%ld, min=%ld, max=%ld", !unmuted, cur, min, max);
+
+    mtx_lock(&mod->lock);
+    m->vol_min = min;
+    m->vol_max = max;
+    m->vol_cur = cur;
+    m->muted = !unmuted;
+    mtx_unlock(&mod->lock);
+
+    mod->bar->refresh(mod->bar);
+}
+
+static int
+run(struct module_run_context *ctx)
+{
+    struct module *mod = ctx->module;
+    struct private *m = mod->private;
+
+    module_signal_ready(ctx);
+
+    snd_mixer_t *handle;
+    snd_mixer_open(&handle, 0);
+    snd_mixer_attach(handle, m->card);
+    snd_mixer_selem_register(handle, NULL, NULL);
+    snd_mixer_load(handle);
+
+    snd_mixer_selem_id_t *sid;
+    snd_mixer_selem_id_alloca(&sid);
+    snd_mixer_selem_id_set_index(sid, 0);
+    snd_mixer_selem_id_set_name(sid, m->mixer);
+    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
+
+    /* Initial state */
+    update_state(mod, elem);
+
+    while (true) {
+        int fd_count = snd_mixer_poll_descriptors_count(handle);
+        assert(fd_count >= 1);
+
+        struct pollfd fds[1 + fd_count];
+
+        fds[0] = (struct pollfd){.fd = ctx->abort_fd, .events = POLLIN};
+        snd_mixer_poll_descriptors(handle, &fds[1], fd_count);
+
+        poll(fds, fd_count + 1, -1);
+
+        if (fds[0].revents & POLLIN)
+            break;
+
+        if (fds[1].revents & POLLHUP) {
+            /* Don't know if this can happen */
+            LOG_ERR("disconnected from alsa");
+            break;
+        }
+
+        snd_mixer_handle_events(handle);
+        update_state(mod, elem);
+    }
+
+    snd_mixer_close(handle);
+    snd_config_update_free_global();
+    return 0;
+}
+
+struct module *
+module_alsa(const char *card, const char *mixer, struct particle *label)
+{
+    struct private *priv = malloc(sizeof(*priv));
+    priv->label = label;
+    priv->card = strdup(card);
+    priv->mixer = strdup(mixer);
+    priv->vol_cur = priv->vol_min = priv->vol_max = 0;
+    priv->muted = true;
+
+    struct module *mod = module_common_new();
+    mod->private = priv;
+    mod->run = &run;
+    mod->destroy = &destroy;
+    mod->content = &content;
+    return mod;
+}

modules/alsa.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include "../module.h"
+#include "../particle.h"
+
+struct module *module_alsa(
+    const char *card, const char *mixer, struct particle *label);