*) add support for pid files

*) we now require pid_file to specified in the config
*) new prefered method for killing mpd: mpd --kill
*) cleaned up some nastiness with decode_pid handling

git-svn-id: https://svn.musicpd.org/mpd/trunk@3042 09075e82-0dd4-0310-85a5-a0d7c8717e4f

5 files changed, 127 insertions, 39 deletions

diff --git a/doc/mpdconf.example b/doc/mpdconf.example
index f4f64a76e..4d4b19827 100644
--- a/doc/mpdconf.example
+++ b/doc/mpdconf.example
@@ -8,6 +8,7 @@ playlist_directory 	"~/music"
 db_file 		"~/.mpd/mpd.db"
 log_file 		"~/.mpd/mpd.log"
 error_file 		"~/.mpd/mpd.error"
+pid_file 		"~/.mpd/mpd.pid"
 ##########################################################
 
 ##########################################################
diff --git a/src/conf.c b/src/conf.c
index 2d5bcc5a4..18d6c16fb 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -116,6 +116,7 @@ void initConf() {
 	configEntriesList = makeList((ListFreeDataFunc *)freeConfigEntry, 1);
 
 	registerConfigParam(CONF_PORT, 				0,	0);
+	registerConfigParam(CONF_PID_FILE, 			0,	0);
 	registerConfigParam(CONF_MUSIC_DIR,			0,	0);
 	registerConfigParam(CONF_PLAYLIST_DIR,			0,	0);
 	registerConfigParam(CONF_LOG_FILE,			0,	0);
diff --git a/src/conf.h b/src/conf.h
index ca9eb058e..36d7b429e 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -22,6 +22,7 @@
 #include "../config.h"
 
 #define CONF_PORT			"port"
+#define CONF_PID_FILE			"pid_file"
 #define CONF_MUSIC_DIR			"music_directory"
 #define CONF_PLAYLIST_DIR		"playlist_directory"
 #define CONF_LOG_FILE			"log_file"
diff --git a/src/decode.c b/src/decode.c
index b0e08dc34..83d0936c9 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -37,40 +37,46 @@
 #include <unistd.h>
 #include <string.h>
 
-volatile int * volatile decode_pid = NULL;
+static int decode_pid = 0;
 
 void decodeSigHandler(int sig, siginfo_t * si, void * v) {
 	if(sig==SIGCHLD) {
 		int status;
-		if(decode_pid && *decode_pid==wait3(&status,WNOHANG,NULL)) {
-			if(WIFSIGNALED(status) && WTERMSIG(status)!=SIGTERM &&
-					WTERMSIG(status)!=SIGINT) 
-			{
-				ERROR("decode process died from signal: %i\n",
-						WTERMSIG(status));
+		if(decode_pid==wait3(&status,WNOHANG,NULL)) {
+			if(WIFSIGNALED(status)) {
+				if(WTERMSIG(status)!=SIGTERM && 
+					WTERMSIG(status)!=SIGINT)
+				{
+					ERROR("decode process died from "
+							"signal: %i\n",
+							WTERMSIG(status));
+				}
 			}
-			*decode_pid = 0;
+			decode_pid = 0;
+			getPlayerData()->playerControl.decode_pid = 0;
 		}
 	}
-	/* this is causing problems for alsa and other things that generate
-	 * extra processes. it causes them to not die */
-	/*else if(sig==SIGTERM && si->si_pid==getppid()) {
-		DEBUG("player/decoder got SIGTERM from parent process\n");*/
 	else if(sig==SIGTERM) {
-		if(decode_pid) {
-			int pid = *decode_pid;
-			if(pid>0) kill(pid,SIGTERM);
+		int pid = decode_pid;
+		if(pid > 0) {
+			DEBUG("player (or child) got SIGTERM\n");
+			kill(pid,SIGTERM);
 		}
+		else DEBUG("decoder (or child) got SIGTERM\n");
 		exit(EXIT_SUCCESS);
 	}
+	else if(sig==SIGINT) {
+		if(decode_pid > 0) {
+			DEBUG("player (or child) got SIGINT\n");
+		}
+		else DEBUG("decoder (or child) got SIGINT\n");
+	}
 }
 
 void stopDecode(DecoderControl * dc) {
-	if(decode_pid && *decode_pid>0 && 
-			(dc->start || dc->state!=DECODE_STATE_STOP)) 
-	{
+	if(decode_pid>0 && (dc->start || dc->state!=DECODE_STATE_STOP)) {
 		dc->stop = 1;
-		while(decode_pid && *decode_pid>0 && dc->stop) my_usleep(10000);
+		while(decode_pid>0 && dc->stop) my_usleep(10000);
 	}
 }
 
@@ -110,7 +116,7 @@ int calculateCrossFadeChunks(PlayerControl * pc, AudioFormat * af) {
 
 #define handleDecodeStart() \
         if(decodeWaitedOn) { \
-                if(dc->state!=DECODE_STATE_START &&  *decode_pid > 0 && \
+                if(dc->state!=DECODE_STATE_START &&  decode_pid > 0 && \
                                 dc->error==DECODE_ERROR_NOERROR) \
                 { \
                         decodeWaitedOn = 0; \
@@ -131,7 +137,7 @@ int calculateCrossFadeChunks(PlayerControl * pc, AudioFormat * af) {
 					cb->audioFormat.channels/ \
 					cb->audioFormat.sampleRate; \
                 } \
-                else if(dc->state!=DECODE_STATE_START || *decode_pid <= 0) { \
+                else if(dc->state!=DECODE_STATE_START || decode_pid <= 0) { \
 		        strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN); \
 		        pc->erroredUrl[MAXPATHLEN] = '\0'; \
 		        pc->error = PLAYER_ERROR_FILE; \
@@ -151,7 +157,7 @@ int waitOnDecode(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb,
         pc->currentUrl[MAXPATHLEN] = '\0';
 	MpdTag * tag = NULL;
 
-	while(decode_pid && *decode_pid>0 && dc->start) my_usleep(10000);
+	while(decode_pid>0 && dc->start) my_usleep(10000);
 
 	if(dc->start || dc->error!=DECODE_ERROR_NOERROR) {
 		strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN);
@@ -181,7 +187,7 @@ int decodeSeek(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb,
 {
         int ret = -1;
 
-	if(decode_pid && *decode_pid>0) {
+	if(decode_pid>0) {
 		if(dc->state==DECODE_STATE_STOP || dc->error || 
 				strcmp(dc->utf8url, pc->utf8url)!=0) 
 		{
@@ -193,7 +199,7 @@ int decodeSeek(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb,
 			dc->start = 1;
 			waitOnDecode(pc,dc,cb,decodeWaitedOn);
 		}
-		if(*decode_pid>0 && dc->state!=DECODE_STATE_STOP && 
+		if(decode_pid>0 && dc->state!=DECODE_STATE_STOP && 
                                 dc->seekable) 
                 {
 			*next = -1;
@@ -203,7 +209,7 @@ int decodeSeek(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb,
 			dc->seekWhere = 0 > dc->seekWhere ? 0 : dc->seekWhere;
                         dc->seekError = 0;
 			dc->seek = 1;
-                        while(*decode_pid>0 && dc->seek) my_usleep(10000);
+                        while(decode_pid>0 && dc->seek) my_usleep(10000);
                         if(!dc->seekError) {
                                 pc->elapsedTime = dc->seekWhere;
                                 ret = 0;
@@ -369,14 +375,11 @@ void decodeStart(PlayerControl * pc, OutputBuffer * cb, DecoderControl * dc) {
 }
 
 int decoderInit(PlayerControl * pc, OutputBuffer * cb, DecoderControl * dc) {
-			
-	int pid;
-	decode_pid = &(pc->decode_pid);
-
 	blockSignals();
-	pid = fork();
+	getPlayerData()->playerControl.decode_pid = 0;
+	decode_pid = fork();
 
-	if(pid==0) {
+	if(decode_pid==0) {
 		/* CHILD */
 		unblockSignals();
 
@@ -396,7 +399,7 @@ int decoderInit(PlayerControl * pc, OutputBuffer * cb, DecoderControl * dc) {
 		exit(EXIT_SUCCESS);
 		/* END OF CHILD */
 	}
-	else if(pid<0) {
+	else if(decode_pid<0) {
 		unblockSignals();
 		strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN);
 		pc->erroredUrl[MAXPATHLEN] = '\0';
@@ -404,7 +407,7 @@ int decoderInit(PlayerControl * pc, OutputBuffer * cb, DecoderControl * dc) {
 		return -1;
 	}
 
-	*decode_pid = pid;
+	getPlayerData()->playerControl.decode_pid = decode_pid;
 	unblockSignals();
 
 	return 0;
@@ -488,7 +491,7 @@ void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb) {
 	pc->play = 0;
 	kill(getppid(),SIGUSR1);
 
-	while(*decode_pid>0 && cb->end-cb->begin<bbp && 
+	while(decode_pid>0 && cb->end-cb->begin<bbp && 
 				cb->end!=buffered_chunks-1 &&
 				dc->state!=DECODE_STATE_STOP) 
 	{
@@ -642,7 +645,7 @@ void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer * cb) {
 				kill(getppid(),SIGUSR1);
 			}
 		}
-		else if(*decode_pid<=0 || 
+		else if(decode_pid<=0 || 
 				(dc->state==DECODE_STATE_STOP && !dc->start)) 
 		{
 			quit = 1;
@@ -678,7 +681,7 @@ void decode() {
         dc->stop = 0;
 	dc->start = 1;
         
-	if(decode_pid==NULL || *decode_pid<=0) {
+	if(decode_pid<=0) {
 		if(decoderInit(pc,cb,dc)<0) return;
 	}
 
diff --git a/src/main.c b/src/main.c
index 563bbf2ff..50726af85 100644
--- a/src/main.c
+++ b/src/main.c
@@ -55,6 +55,7 @@
 #define USER_CONFIG_FILE_LOCATION	"/.mpdconf"
 
 typedef struct _Options {
+	int kill;
         int daemon;
         int stdOutput;
         int createDB;
@@ -70,11 +71,12 @@ void usage(char * argv[]) {
         ERROR("\n");
         ERROR("options:\n");
         ERROR("   --help             this usage statement\n");
+        ERROR("   --create-db        force (re)creation database and exit\n");
+        ERROR("   --kill             kill mpd\n");
+        ERROR("   --no-create-db     don't create database\n");
         ERROR("   --no-daemon        don't detach from console\n");
         ERROR("   --stdout           print msgs to stdout and stderr\n");
-        ERROR("   --create-db        force (re)creation database and exit\n");
         /*ERROR("   --update-db        create database and exit\n");*/
-        ERROR("   --no-create-db     don't create database\n");
         ERROR("   --verbose          verbose logging\n");
         ERROR("   --version          prints version information\n");
 }
@@ -99,6 +101,7 @@ void parseOptions(int argc, char ** argv, Options * options) {
         options->stdOutput = 0;
         options->createDB = 0;
         options->updateDB = 0;
+	options->kill = 0;
 
         if(argc>1) {
                 int i = 1;
@@ -108,6 +111,10 @@ void parseOptions(int argc, char ** argv, Options * options) {
                                         usage(argv);
                                         exit(EXIT_SUCCESS);
                                 }
+                                else if(strcmp(argv[i],"--kill")==0) {
+                                        options->kill = 1;
+                                        argcLeft--;
+                                }
                                 else if(strcmp(argv[i],"--no-daemon")==0) {
                                         options->daemon = 0;
                                         argcLeft--;
@@ -282,6 +289,20 @@ void openDB(Options * options, char * argv0) {
 }
 
 void daemonize(Options * options) {
+	FILE * fp;
+	ConfigParam * pidFileParam = parseConfigFilePath(CONF_PID_FILE, 1);
+	
+	/* do this before daemon'izing so we can fail gracefully if we can't
+	 * write to the pid file */
+	DEBUG("opening pid file\n");
+	fp = fopen(pidFileParam->value, "w+");
+	if(!fp) {
+		ERROR("could not open %s \"%s\" (at line %i) for writing: %s\n",
+				CONF_PID_FILE, pidFileParam->value,
+				pidFileParam->line, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
         if(options->daemon) {
                 int pid;
 
@@ -309,8 +330,14 @@ void daemonize(Options * options) {
                 else if(pid<0) {
                         ERROR("problems fork'ing for daemon!\n");
                         exit(EXIT_FAILURE);
-                }
+		}
+
+		DEBUG("daemonized!\n");
         }
+
+	DEBUG("writing pid file\n");
+	fprintf(fp, "%lu\n", (unsigned long)getpid());
+	fclose(fp);
 }
 
 void setupLogOutput(Options * options, FILE * out, FILE * err) {
@@ -349,6 +376,58 @@ void setupLogOutput(Options * options, FILE * out, FILE * err) {
         }
 }
 
+void cleanUpPidFile() {
+	ConfigParam * pidFileParam = parseConfigFilePath(CONF_PID_FILE, 1);
+
+	DEBUG("cleaning up pid file\n");
+	
+	unlink(pidFileParam->value);
+}
+
+void killMpdFromPidFile(char * cmd) {
+	struct stat st_cmd;
+	struct stat st_exe;
+	ConfigParam * pidFileParam = parseConfigFilePath(CONF_PID_FILE, 1);
+	int pid;
+	char buf[32];
+
+	FILE * fp = fopen(pidFileParam->value,"r");
+	if(!fp) {
+		ERROR("unable to open %s \"%s\" (config line %i): %s\n", 
+				CONF_PID_FILE, pidFileParam->value,
+				pidFileParam->line);
+		exit(EXIT_FAILURE);
+	}
+	if(fscanf(fp, "%i",  &pid) != 1) {
+		ERROR("unable to read the pid from file \"%s\"\n",
+				pidFileParam->value);
+		exit(EXIT_FAILURE);
+	}
+	fclose(fp);
+
+	memset(buf, 0, 32);
+	snprintf(buf, 31, "/proc/%i/exe", pid);
+
+	if(stat(cmd, &st_cmd)) {
+		ERROR("unable to stat file \"%s\"\n", cmd);
+		exit(EXIT_FAILURE);
+	}
+	if(stat(buf, &st_exe)) {
+		ERROR("unable to kill proccess %i (%s: %s)\n", pid, buf,
+				strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	if(st_exe.st_dev != st_cmd.st_dev || st_exe.st_ino != st_cmd.st_ino) {
+		ERROR("%s doesn't appear to be running as pid %i\n",
+				cmd, pid);
+		exit(EXIT_FAILURE);
+	}
+
+	kill(pid, SIGTERM);
+	exit(EXIT_SUCCESS);
+}
+
 int main(int argc, char * argv[]) {
         FILE * out;
         FILE * err;
@@ -360,6 +439,8 @@ int main(int argc, char * argv[]) {
 
         parseOptions(argc, argv, &options);
 
+	if(options.kill) killMpdFromPidFile(argv[0]);
+
         initStats();
 	initTagConfig();
         initLog();
@@ -421,6 +502,7 @@ int main(int argc, char * argv[]) {
 	finishPermissions();
         finishCommands();
         finishInputPlugins();
+	cleanUpPidFile();
 
         return EXIT_SUCCESS;
 }