X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=afs.c;h=710670255b2ec1cf67b9ab4e74823bfe19dd3a02;hp=04eed5503d18cb6d3b6e4d0cb127f98637d36b5d;hb=329bf73b72eea2c5be1bcbd9a9602c0a8994d0be;hpb=e2e1adca824585eeecd091f54955e51212927533

diff --git a/afs.c b/afs.c
index 04eed550..71067025 100644
--- a/afs.c
+++ b/afs.c
@@ -39,11 +39,10 @@ enum afs_table_num {
 	TBLNUM_AUDIO_FILES,
 	/** The table for the paraslash attributes. See \ref attribute.c. */
 	TBLNUM_ATTRIBUTES,
-	/**
-	 * Paraslash's scoring system is based on Gaussian normal
-	 * distributions, and the relevant data is stored in the rbtrees of an
-	 * osl table containing only volatile columns. See \ref score.c for
-	 * details.
+	/*
+	 * Moods and playlists organize the current set of admissible files in
+	 * an osl table which contains only volatile columns. Each row consists
+	 * of a pointer to an audio file and the score value of this file.
 	 */
 	TBLNUM_SCORES,
 	/**
@@ -91,26 +90,26 @@ static char *current_mop; /* mode or playlist specifier. NULL means dummy mood *
 extern uint32_t afs_socket_cookie;
 
 /**
- * Struct to let command handlers execute a callback in afs context.
- *
- * Commands that need to change the state of afs can't change the relevant data
- * structures directly because commands are executed in a child process, i.e.
- * they get their own virtual address space.
+ * Passed from command handlers to afs.
  *
- * This structure is used by \p send_callback_request() (executed from handler
- * context) in order to let the afs process call the specified function. An
- * instance of that structure is written to a shared memory area together with
- * the arguments to the callback function. The identifier of the shared memory
- * area is written to the command socket.
+ * Command handlers cannot change the afs database directly because they run in
+ * a separate process. The callback query structure circumvents this
+ * restriction as follows. To instruct the afs process to execute a particular
+ * function, the command hander writes an instance of this structure to a
+ * shared memory area, along with the arguments to the callback function. The
+ * identifier of the shared memory area is transferred to the afs process via
+ * the command socket.
  *
- * The afs process accepts connections on the command socket and reads the
- * shared memory id, attaches the corresponding area, calls the given handler to
- * perform the desired action and to optionally compute a result.
+ * The afs process reads the shared memory id from the command socket, attaches
+ * the corresponding area, and calls the callback function whose address is
+ * stored in the area.
  *
- * The result and a \p callback_result structure is then written to another
- * shared memory area. The identifier for that area is written to the handler's
- * command socket, so that the handler process can read the id, attach the
- * shared memory area and use the result.
+ * The command output, if any, is transferred back to the command handler in
+ * the same way: The afs process writes the output to a second shared memory
+ * area together with a fixed size metadata header whose format corresponds to
+ * the \ref callback_result structure. The identifier of this area is sent back
+ * to the command handler which attaches the area and forwards the output to
+ * the remote client.
  *
  * \sa \ref struct callback_result.
  */
@@ -418,13 +417,13 @@ static int pass_afd(int fd, char *buf, size_t size)
  */
 static int open_next_audio_file(void)
 {
-	struct audio_file_data afd;
-	int ret, shmid;
+	int ret, shmid, fd;
 	char buf[8];
 
-	ret = open_and_update_audio_file(&afd);
+	ret = open_and_update_audio_file(&fd);
 	if (ret < 0) {
-		PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+		if (ret != -OSL_ERRNO_TO_PARA_ERROR(E_OSL_RB_KEY_NOT_FOUND))
+			PARA_ERROR_LOG("%s\n", para_strerror(-ret));
 		goto no_admissible_files;
 	}
 	shmid = ret;
@@ -434,8 +433,8 @@ static int open_next_audio_file(void)
 	}
 	*(uint32_t *)buf = NEXT_AUDIO_FILE;
 	*(uint32_t *)(buf + 4) = (uint32_t)shmid;
-	ret = pass_afd(afd.fd, buf, 8);
-	close(afd.fd);
+	ret = pass_afd(fd, buf, 8);
+	close(fd);
 	if (ret >= 0)
 		return ret;
 destroy:
@@ -447,7 +446,6 @@ no_admissible_files:
 	return write_all(server_socket, buf, 8);
 }
 
-/* Never fails if arg == NULL */
 static int activate_mood_or_playlist(const char *arg, int *num_admissible,
 		char **errmsg)
 {
@@ -455,8 +453,13 @@ static int activate_mood_or_playlist(const char *arg, int *num_admissible,
 	int ret;
 
 	if (!arg) {
-		ret = change_current_mood(NULL, NULL); /* always successful */
 		mode = PLAY_MODE_MOOD;
+		ret = change_current_mood(NULL, errmsg);
+		if (ret < 0) {
+			if (num_admissible)
+				*num_admissible = 0;
+			return ret;
+		}
 	} else {
 		if (!strncmp(arg, "p/", 2)) {
 			ret = playlist_open(arg + 2);
@@ -478,6 +481,12 @@ static int activate_mood_or_playlist(const char *arg, int *num_admissible,
 	if (num_admissible)
 		*num_admissible = ret;
 	current_play_mode = mode;
+	/*
+	 * We get called with arg == current_mop from the signal dispatcher
+	 * after SIGHUP and from the error path of the select command to
+	 * re-select the current mood or playlist. In this case the assignment
+	 * to current_mop below would result in a use-after-free condition.
+	 */
 	if (arg != current_mop) {
 		free(current_mop);
 		if (arg) {
@@ -615,10 +624,10 @@ static void init_admissible_files(const char *arg)
 {
 	int ret = activate_mood_or_playlist(arg, NULL, NULL);
 	if (ret < 0) {
-		assert(arg);
 		PARA_WARNING_LOG("could not activate %s: %s\n", arg,
 			para_strerror(-ret));
-		activate_mood_or_playlist(NULL, NULL, NULL);
+		if (arg)
+			activate_mood_or_playlist(NULL, NULL, NULL);
 	}
 }
 
@@ -644,7 +653,7 @@ static char *database_dir;
 static void close_afs_tables(void)
 {
 	int i;
-	PARA_NOTICE_LOG("closing afs_tables\n");
+	PARA_NOTICE_LOG("closing afs tables\n");
 	for (i = 0; i < NUM_AFS_TABLES; i++)
 		afs_tables[i].close();
 	free(database_dir);
@@ -659,7 +668,7 @@ static void get_database_dir(void)
 		else {
 			char *home = para_homedir();
 			database_dir = make_message(
-				"%s/.paraslash/afs_database-0.4", home);
+				"%s/.paraslash/afs_database-0.7", home);
 			free(home);
 		}
 	}
@@ -981,7 +990,7 @@ __noreturn void afs_init(int socket_fd)
 	int i, ret;
 
 	register_signal_task(&s);
-	INIT_LIST_HEAD(&afs_client_list);
+	init_list_head(&afs_client_list);
 	for (i = 0; i < NUM_AFS_TABLES; i++)
 		afs_tables[i].init(&afs_tables[i]);
 	ret = open_afs_tables();
@@ -1043,7 +1052,8 @@ static int com_init_callback(struct afs_callback_arg *aca)
 	}
 	ret = open_afs_tables();
 	if (ret < 0)
-		para_printf(&aca->pbout, "cannot open afs tables\n");
+		para_printf(&aca->pbout, "cannot open afs tables: %s\n",
+			para_strerror(-ret));
 out:
 	return ret;
 }