alsactl: add the daemon mode

For the plug-and-play hardware, like USB devices, it may be helpful
to manage the sound state periodically, before the devices are removed.

This change implements new commands 'daemon' and 'rdaemon' to save
the sound state in defined intervals when the sound controls are changed.

The udev rules can notify the daemon using the 'kill' or 'nrestore'
commands to rescan available cards in the system.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 13 insertions, 5 deletions

diff --git a/alsactl/state.c b/alsactl/state.c
index 8b309ba..bd53d21 100644
--- a/alsactl/state.c
+++ b/alsactl/state.c
@@ -1562,6 +1562,8 @@ int save_state(const char *file, const char *cardname)
 		}
 		strcpy(nfile, file);
 		strcat(nfile, ".new");
+		if (state_lock(file, 1, 10) != 0)
+			goto out;
 	}
 	if (!stdio && (err = snd_input_stdio_open(&in, file, "r")) >= 0) {
 		err = snd_config_load(config, in);
@@ -1628,12 +1630,13 @@ int save_state(const char *file, const char *cardname)
 	if (err < 0) {
 		error("snd_config_save: %s", snd_strerror(err));
 	} else {
-		//unlink(file);
 		err = rename(nfile, file);
 		if (err < 0)
 			error("rename failed: %s (%s)", strerror(-err), file);
 	}
 out:
+	if (!stdio)
+		state_lock(file, 0, 10);
 	free(nfile);
 	snd_config_delete(config);
 	snd_config_update_free_global();
@@ -1646,7 +1649,7 @@ int load_state(const char *file, const char *initfile, const char *cardname,
 	int err, finalerr = 0;
 	snd_config_t *config;
 	snd_input_t *in;
-	int stdio;
+	int stdio, locked = 0;
 
 	err = snd_config_top(&config);
 	if (err < 0) {
@@ -1654,13 +1657,18 @@ int load_state(const char *file, const char *initfile, const char *cardname,
 		return err;
 	}
 	stdio = !strcmp(file, "-");
-	if (stdio)
+	if (stdio) {
 		err = snd_input_stdio_attach(&in, stdin, 0);
-	else
-		err = snd_input_stdio_open(&in, file, "r");
+	} else {
+		err = state_lock(file, 1, 10);
+		locked = err >= 0;
+		err = err >= 0 ? snd_input_stdio_open(&in, file, "r") : err;
+	}
 	if (err >= 0) {
 		err = snd_config_load(config, in);
 		snd_input_close(in);
+		if (locked)
+			state_lock(file, 0, 10);
 		if (err < 0) {
 			error("snd_config_load error: %s", snd_strerror(err));
 			goto out;