fix -Wconst warnings

[ew: cleaned up the dirty union hack a bit]
Signed-off-by: Eric Wong <normalperson@yhbt.net>

git-svn-id: https://svn.musicpd.org/mpd/trunk@7180 09075e82-0dd4-0310-85a5-a0d7c8717e4f

37 files changed, 223 insertions, 197 deletions

diff --git a/src/audioOutput.c b/src/audioOutput.c
index 43d073b48..d2fb2d776 100644
--- a/src/audioOutput.c
+++ b/src/audioOutput.c
@@ -67,9 +67,9 @@ void finishAudioOutputPlugins(void)
 int initAudioOutput(AudioOutput *ao, ConfigParam * param)
 {
 	void *data = NULL;
-	char *name = NULL;
+	const char *name = NULL;
 	char *format = NULL;
-	char *type = NULL;
+	const char *type = NULL;
 	BlockParam *bp = NULL;
 	AudioOutputPlugin *plugin = NULL;
 
diff --git a/src/audioOutput.h b/src/audioOutput.h
index 6c50776c2..3953d2621 100644
--- a/src/audioOutput.h
+++ b/src/audioOutput.h
@@ -54,8 +54,8 @@ typedef void (*AudioOutputSendMetadataFunc) (AudioOutput * audioOutput,
 
 struct _AudioOutput {
 	int open;
-	char *name;
-	char *type;
+	const char *name;
+	const char *type;
 
 	AudioOutputFinishDriverFunc finishDriverFunc;
 	AudioOutputOpenDeviceFunc openDeviceFunc;
@@ -77,7 +77,7 @@ struct _AudioOutput {
 };
 
 typedef struct _AudioOutputPlugin {
-	char *name;
+	const char *name;
 
 	AudioOutputTestDefaultDeviceFunc testDefaultDeviceFunc;
 	AudioOutputInitDriverFunc initDriverFunc;
diff --git a/src/audioOutputs/audioOutput_shout.c b/src/audioOutputs/audioOutput_shout.c
index 236e02b76..beacfeef9 100644
--- a/src/audioOutputs/audioOutput_shout.c
+++ b/src/audioOutputs/audioOutput_shout.c
@@ -116,7 +116,7 @@ static int myShout_initDriver(AudioOutput * audioOutput, ConfigParam * param)
 	char *host;
 	char *mount;
 	char *passwd;
-	char *user;
+	const char *user;
 	char *name;
 	BlockParam *blockParam;
 	int public;
@@ -388,8 +388,13 @@ static void myShout_closeDevice(AudioOutput * audioOutput)
 	audioOutput->open = 0;
 }
 
-#define addTag(name, value) { \
-	if(value) vorbis_comment_add_tag(&(sd->vc), name, value); \
+static void addTag(ShoutData *sd, const char *name, char *value)
+{
+	if (value) {
+		union const_hack u;
+		u.in = name;
+		vorbis_comment_add_tag(&(sd->vc), u.out, value);
+	}
 }
 
 static void copyTagToVorbisComment(ShoutData * sd)
@@ -400,13 +405,13 @@ static void copyTagToVorbisComment(ShoutData * sd)
 		for (i = 0; i < sd->tag->numOfItems; i++) {
 			switch (sd->tag->items[i].type) {
 			case TAG_ITEM_ARTIST:
-				addTag("ARTIST", sd->tag->items[i].value);
+				addTag(sd, "ARTIST", sd->tag->items[i].value);
 				break;
 			case TAG_ITEM_ALBUM:
-				addTag("ALBUM", sd->tag->items[i].value);
+				addTag(sd, "ALBUM", sd->tag->items[i].value);
 				break;
 			case TAG_ITEM_TITLE:
-				addTag("TITLE", sd->tag->items[i].value);
+				addTag(sd, "TITLE", sd->tag->items[i].value);
 				break;
 			}
 		}
diff --git a/src/charConv.c b/src/charConv.c
index 306ee9999..895a695cd 100644
--- a/src/charConv.c
+++ b/src/charConv.c
@@ -42,7 +42,7 @@ static mpd_sint8 char_conv_latin1ToUtf8;
 
 static void closeCharSetConversion(void);
 
-int setCharSetConversion(char *to, char *from)
+int setCharSetConversion(const char *to, const char *from)
 {
 	if (char_conv_to && char_conv_from) {
 		if (char_conv_latin1ToUtf8 &&
@@ -93,7 +93,7 @@ int setCharSetConversion(char *to, char *from)
 	return -1;
 }
 
-char *char_conv_str(char *dest, char *string)
+char *char_conv_str(char *dest, const char *string)
 {
 	if (!char_conv_to)
 		return NULL;
diff --git a/src/charConv.h b/src/charConv.h
index d50e84520..a416b5c8f 100644
--- a/src/charConv.h
+++ b/src/charConv.h
@@ -21,8 +21,8 @@
 
 #include "../config.h"
 
-int setCharSetConversion(char *to, char *from);
+int setCharSetConversion(const char *to, const char *from);
 
-char *char_conv_str(char *dest, char *string);
+char *char_conv_str(char *dest, const char *string);
 
 #endif
diff --git a/src/command.c b/src/command.c
index eddb49af0..78eb9a597 100644
--- a/src/command.c
+++ b/src/command.c
@@ -128,7 +128,7 @@ typedef int (*CommandListHandlerFunction)
 /* if min: -1 don't check args *
  * if max: -1 no max args      */
 struct _CommandEntry {
-	char *cmd;
+	const char *cmd;
 	int min;
 	int max;
 	int reqPermission;
@@ -136,7 +136,6 @@ struct _CommandEntry {
 	CommandListHandlerFunction listHandler;
 };
 
-
 /* this should really be "need a non-negative integer": */
 static const char need_positive[] = "need a positive integer"; /* no-op */
 
@@ -146,7 +145,7 @@ static const char need_integer[] = "need an integer";
 static const char check_boolean[] = "\"%s\" is not 0 or 1";
 static const char check_non_negative[] = "\"%s\" is not an integer >= 0";
 
-static char *current_command;
+static const char *current_command;
 static int command_listNum;
 
 static CommandEntry *getCommandEntryFromString(char *string, int *permission);
@@ -215,7 +214,7 @@ static int mpd_fprintf__ check_int(int fd, int *dst,
 	return 0;
 }
 
-static void addCommand(char *name,
+static void addCommand(const char *name,
 		       int reqPermission,
 		       int minargs,
 		       int maxargs,
@@ -291,7 +290,7 @@ static int handlePause(int fd, int *permission, int argc, char *argv[])
 
 static int commandStatus(int fd, int *permission, int argc, char *argv[])
 {
-	char *state = NULL;
+	const char *state = NULL;
 	int updateJobId;
 	int song;
 
@@ -450,7 +449,7 @@ static int handleListPlaylistInfo(int fd, int *permission,
 
 static int handleLsInfo(int fd, int *permission, int argc, char *argv[])
 {
-	char *path = "";
+	const char *path = "";
 
 	if (argc == 2)
 		path = argv[1];
diff --git a/src/conf.c b/src/conf.c
index 6b3973a1d..10d0f9d31 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -121,7 +121,7 @@ static void freeConfigEntry(ConfigEntry * entry)
 	free(entry);
 }
 
-static void registerConfigParam(char *name, int repeatable, int block)
+static void registerConfigParam(const char *name, int repeatable, int block)
 {
 	ConfigEntry *entry;
 
@@ -253,7 +253,7 @@ static ConfigParam *readConfigBlock(FILE * fp, int *count, char *string)
 	return ret;
 }
 
-void readConf(char *file)
+void readConf(const char *file)
 {
 	FILE *fp;
 	char string[MAX_STRING_SIZE + 1];
@@ -321,7 +321,7 @@ void readConf(char *file)
 	fclose(fp);
 }
 
-ConfigParam *getNextConfigParam(char *name, ConfigParam * last)
+ConfigParam *getNextConfigParam(const char *name, ConfigParam * last)
 {
 	void *voidPtr;
 	ConfigEntry *entry;
@@ -352,7 +352,7 @@ ConfigParam *getNextConfigParam(char *name, ConfigParam * last)
 	return param;
 }
 
-char *getConfigParamValue(char *name)
+char *getConfigParamValue(const char *name)
 {
 	ConfigParam *param = getConfigParam(name);
 
@@ -362,7 +362,7 @@ char *getConfigParamValue(char *name)
 	return param->value;
 }
 
-BlockParam *getBlockParam(ConfigParam * param, char *name)
+BlockParam *getBlockParam(ConfigParam * param, const char *name)
 {
 	BlockParam *ret = NULL;
 	int i;
@@ -381,7 +381,7 @@ BlockParam *getBlockParam(ConfigParam * param, char *name)
 	return ret;
 }
 
-ConfigParam *parseConfigFilePath(char *name, int force)
+ConfigParam *parseConfigFilePath(const char *name, int force)
 {
 	ConfigParam *param = getConfigParam(name);
 	char *path;
@@ -402,7 +402,7 @@ ConfigParam *parseConfigFilePath(char *name, int force)
 	return param;
 }
 
-int getBoolConfigParam(char *name, int force)
+int getBoolConfigParam(const char *name, int force)
 {
 	int ret;
 	ConfigParam *param = getConfigParam(name);
@@ -418,7 +418,7 @@ int getBoolConfigParam(char *name, int force)
 	return ret;
 }
 
-int getBoolBlockParam(ConfigParam *param, char *name, int force)
+int getBoolBlockParam(ConfigParam *param, const char *name, int force)
 {
 	int ret;
 	BlockParam *bp = getBlockParam(param, name);
diff --git a/src/conf.h b/src/conf.h
index 01337d349..79b6514c6 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -83,22 +83,22 @@ typedef struct _ConfigParam {
 void initConf(void);
 void finishConf(void);
 
-void readConf(char *file);
+void readConf(const char *file);
 
 /* don't free the returned value
    set _last_ to NULL to get first entry */
-ConfigParam *getNextConfigParam(char *name, ConfigParam * last);
+ConfigParam *getNextConfigParam(const char *name, ConfigParam * last);
 
 #define getConfigParam(name) 	getNextConfigParam(name, NULL)
 
-char *getConfigParamValue(char *name);
+char *getConfigParamValue(const char *name);
 
-BlockParam *getBlockParam(ConfigParam * param, char *name);
+BlockParam *getBlockParam(ConfigParam * param, const char *name);
 
-ConfigParam *parseConfigFilePath(char *name, int force);
+ConfigParam *parseConfigFilePath(const char *name, int force);
 
-int getBoolConfigParam(char *name, int force);
+int getBoolConfigParam(const char *name, int force);
 
-int getBoolBlockParam(ConfigParam *param, char *name, int force);
+int getBoolBlockParam(ConfigParam *param, const char *name, int force);
 
 #endif
diff --git a/src/decode.c b/src/decode.c
index 0ebdb9282..316cd34ba 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -330,7 +330,7 @@ static void decodeStart(PlayerControl * pc, OutputBuffer * cb,
 
 		/* if that fails, try suffix matching the URL: */
 		if (plugin == NULL) {
-			char *s = getSuffix(dc->utf8url);
+			const char *s = getSuffix(dc->utf8url);
 			next = 0;
 			while (ret && (plugin = getInputPluginFromSuffix(s, next++))) {
 				if (!plugin->streamDecodeFunc)
@@ -356,7 +356,7 @@ static void decodeStart(PlayerControl * pc, OutputBuffer * cb,
 		}
 	} else {
 		unsigned int next = 0;
-		char *s = getSuffix(dc->utf8url);
+		const char *s = getSuffix(dc->utf8url);
 		cb->acceptMetadata = 0;
 		while (ret && (plugin = getInputPluginFromSuffix(s, next++))) {
 			if (!plugin->streamTypes & INPUT_PLUGIN_STREAM_FILE)
diff --git a/src/directory.c b/src/directory.c
index 53b864018..3bb18bf59 100644
--- a/src/directory.c
+++ b/src/directory.c
@@ -66,7 +66,8 @@ static volatile mpd_uint16 directory_updateJobId;
 
 static DirectoryList *newDirectoryList(void);
 
-static int addToDirectory(Directory * directory, char *shortname, char *name);
+static int addToDirectory(Directory * directory,
+			  const char *shortname, const char *name);
 
 static void freeDirectoryList(DirectoryList * list);
 
@@ -78,19 +79,22 @@ static int updateDirectory(Directory * directory);
 
 static void deleteEmptyDirectoriesInDirectory(Directory * directory);
 
-static void removeSongFromDirectory(Directory * directory, char *shortname);
+static void removeSongFromDirectory(Directory * directory,
+				    const char *shortname);
 
-static int addSubDirectoryToDirectory(Directory * directory, char *shortname,
-				      char *name, struct stat *st);
+static int addSubDirectoryToDirectory(Directory * directory,
+				      const char *shortname,
+				      const char *name, struct stat *st);
 
-static Directory *getDirectoryDetails(char *name, char **shortname);
+static Directory *getDirectoryDetails(const char *name,
+				      const char **shortname);
 
-static Directory *getDirectory(char *name);
+static Directory *getDirectory(const char *name);
 
-static Song *getSongDetails(char *file, char **shortnameRet,
+static Song *getSongDetails(const char *file, const char **shortnameRet,
 			    Directory ** directoryRet);
 
-static int updatePath(char *utf8path);
+static int updatePath(const char *utf8path);
 
 static void sortDirectory(Directory * directory);
 
@@ -251,7 +255,7 @@ static DirectoryList *newDirectoryList(void)
 	return makeList((ListFreeDataFunc *) freeDirectory, 1);
 }
 
-static Directory *newDirectory(char *dirname, Directory * parent)
+static Directory *newDirectory(const char *dirname, Directory * parent)
 {
 	Directory *directory;
 
@@ -286,7 +290,7 @@ static void freeDirectoryList(DirectoryList * directoryList)
 	freeList(directoryList);
 }
 
-static void removeSongFromDirectory(Directory * directory, char *shortname)
+static void removeSongFromDirectory(Directory * directory, const char *shortname)
 {
 	void *song;
 
@@ -321,7 +325,8 @@ static void deleteEmptyDirectoriesInDirectory(Directory * directory)
     0 -> no error, but nothing updated
     1 -> no error, and stuff updated
  */
-static int updateInDirectory(Directory * directory, char *shortname, char *name)
+static int updateInDirectory(Directory * directory,
+			     const char *shortname, const char *name)
 {
 	void *song;
 	void *subDir;
@@ -415,7 +420,8 @@ static int removeDeletedFromDirectory(char *path_max_tmp, Directory * directory)
 	return ret;
 }
 
-static Directory *addDirectoryPathToDB(char *utf8path, char **shortname)
+static Directory *addDirectoryPathToDB(const char *utf8path,
+				       const char **shortname)
 {
 	char path_max_tmp[MPD_PATH_MAX];
 	char *parent;
@@ -456,7 +462,7 @@ static Directory *addDirectoryPathToDB(char *utf8path, char **shortname)
 	return (Directory *) directory;
 }
 
-static Directory *addParentPathToDB(char *utf8path, char **shortname)
+static Directory *addParentPathToDB(const char *utf8path, const char **shortname)
 {
 	char *parent;
 	char path_max_tmp[MPD_PATH_MAX];
@@ -484,12 +490,12 @@ static Directory *addParentPathToDB(char *utf8path, char **shortname)
     0 -> no error, but nothing updated
     1 -> no error, and stuff updated
  */
-static int updatePath(char *utf8path)
+static int updatePath(const char *utf8path)
 {
 	Directory *directory;
 	Directory *parentDirectory;
 	Song *song;
-	char *shortname;
+	const char *shortname;
 	char *path = sanitizePathDup(utf8path);
 	time_t mtime;
 	int ret = 0;
@@ -575,7 +581,7 @@ static int updatePath(char *utf8path)
 	return ret;
 }
 
-static const char *opendir_path(char *path_max_tmp, char *dirname)
+static const char *opendir_path(char *path_max_tmp, const char *dirname)
 {
 	if (*dirname != '\0')
 		return rmp2amp_r(path_max_tmp,
@@ -591,7 +597,7 @@ static const char *opendir_path(char *path_max_tmp, char *dirname)
 static int updateDirectory(Directory * directory)
 {
 	DIR *dir;
-	char *dirname = getDirectoryPath(directory);
+	const char *dirname = getDirectoryPath(directory);
 	struct dirent *ent;
 	char path_max_tmp[MPD_PATH_MAX];
 	int ret = 0;
@@ -639,7 +645,7 @@ static int updateDirectory(Directory * directory)
 static int exploreDirectory(Directory * directory)
 {
 	DIR *dir;
-	char *dirname = getDirectoryPath(directory);
+	const char *dirname = getDirectoryPath(directory);
 	struct dirent *ent;
 	char path_max_tmp[MPD_PATH_MAX];
 	int ret = 0;
@@ -705,8 +711,9 @@ static int inodeFoundInParent(Directory * parent, ino_t inode, dev_t device)
 	return 0;
 }
 
-static int addSubDirectoryToDirectory(Directory * directory, char *shortname,
-				      char *name, struct stat *st)
+static int addSubDirectoryToDirectory(Directory * directory,
+				      const char *shortname,
+				      const char *name, struct stat *st)
 {
 	Directory *subDirectory;
 
@@ -726,7 +733,8 @@ static int addSubDirectoryToDirectory(Directory * directory, char *shortname,
 	return 1;
 }
 
-static int addToDirectory(Directory * directory, char *shortname, char *name)
+static int addToDirectory(Directory * directory,
+			  const char *shortname, const char *name)
 {
 	struct stat st;
 
@@ -758,7 +766,7 @@ void closeMp3Directory(void)
 	freeDirectory(mp3rootDirectory);
 }
 
-static Directory *findSubDirectory(Directory * directory, char *name)
+static Directory *findSubDirectory(Directory * directory, const char *name)
 {
 	void *subDirectory;
 	char *duplicated = xstrdup(name);
@@ -779,7 +787,7 @@ static Directory *findSubDirectory(Directory * directory, char *name)
 	return NULL;
 }
 
-int isRootDirectory(char *name)
+int isRootDirectory(const char *name)
 {
 	if (name == NULL || name[0] == '\0' || strcmp(name, "/") == 0) {
 		return 1;
@@ -787,8 +795,8 @@ int isRootDirectory(char *name)
 	return 0;
 }
 
-static Directory *getSubDirectory(Directory * directory, char *name,
-				  char **shortname)
+static Directory *getSubDirectory(Directory * directory, const char *name,
+				  const char **shortname)
 {
 	Directory *subDirectory;
 	int len;
@@ -811,16 +819,16 @@ static Directory *getSubDirectory(Directory * directory, char *name,
 	return getSubDirectory(subDirectory, &(name[len]), shortname);
 }
 
-static Directory *getDirectoryDetails(char *name, char **shortname)
+static Directory *getDirectoryDetails(const char *name, const char **shortname)
 {
 	*shortname = NULL;
 
 	return getSubDirectory(mp3rootDirectory, name, shortname);
 }
 
-static Directory *getDirectory(char *name)
+static Directory *getDirectory(const char *name)
 {
-	char *shortname;
+	const char *shortname;
 
 	return getSubDirectory(mp3rootDirectory, name, &shortname);
 }
@@ -840,7 +848,7 @@ static int printDirectoryList(int fd, DirectoryList * directoryList)
 	return 0;
 }
 
-int printDirectoryInfo(int fd, char *name)
+int printDirectoryInfo(int fd, const char *name)
 {
 	Directory *directory;
 
@@ -1258,7 +1266,7 @@ void initMp3Directory(void)
 	stats.dbPlayTime = sumSongTimesIn(STDERR_FILENO, NULL);
 }
 
-static Song *getSongDetails(char *file, char **shortnameRet,
+static Song *getSongDetails(const char *file, const char **shortnameRet,
 			    Directory ** directoryRet)
 {
 	void *song = NULL;
diff --git a/src/directory.h b/src/directory.h
index b1482988f..5782dd2cc 100644
--- a/src/directory.h
+++ b/src/directory.h
@@ -51,9 +51,9 @@ void initMp3Directory(void);
 
 void closeMp3Directory(void);
 
-int isRootDirectory(char *name);
+int isRootDirectory(const char *name);
 
-int printDirectoryInfo(int fd, char *dirname);
+int printDirectoryInfo(int fd, const char *dirname);
 
 int checkDirectoryDB(void);
 
diff --git a/src/inputPlugin.c b/src/inputPlugin.c
index e9c6d4a70..18d869268 100644
--- a/src/inputPlugin.c
+++ b/src/inputPlugin.c
@@ -44,7 +44,7 @@ void unloadInputPlugin(InputPlugin * inputPlugin)
 	deleteFromList(inputPlugin_list, inputPlugin->name);
 }
 
-static int stringFoundInStringArray(char **array, char *suffix)
+static int stringFoundInStringArray(const char *const*array, const char *suffix)
 {
 	while (array && *array) {
 		if (strcasecmp(*array, suffix) == 0)
@@ -55,7 +55,7 @@ static int stringFoundInStringArray(char **array, char *suffix)
 	return 0;
 }
 
-InputPlugin *getInputPluginFromSuffix(char *suffix, unsigned int next)
+InputPlugin *getInputPluginFromSuffix(const char *suffix, unsigned int next)
 {
 	static ListNode *pos;
 	ListNode *node;
@@ -84,7 +84,7 @@ InputPlugin *getInputPluginFromSuffix(char *suffix, unsigned int next)
 	return NULL;
 }
 
-InputPlugin *getInputPluginFromMimeType(char *mimeType, unsigned int next)
+InputPlugin *getInputPluginFromMimeType(const char *mimeType, unsigned int next)
 {
 	static ListNode *pos;
 	ListNode *node;
@@ -107,7 +107,7 @@ InputPlugin *getInputPluginFromMimeType(char *mimeType, unsigned int next)
 	return NULL;
 }
 
-InputPlugin *getInputPluginFromName(char *name)
+InputPlugin *getInputPluginFromName(const char *name)
 {
 	void *plugin = NULL;
 
@@ -120,7 +120,7 @@ void printAllInputPluginSuffixes(FILE * fp)
 {
 	ListNode *node = inputPlugin_list->firstNode;
 	InputPlugin *plugin;
-	char **suffixes;
+	const char *const*suffixes;
 
 	while (node) {
 		plugin = (InputPlugin *) node->data;
diff --git a/src/inputPlugin.h b/src/inputPlugin.h
index ecb1b9801..c643cbdc2 100644
--- a/src/inputPlugin.h
+++ b/src/inputPlugin.h
@@ -60,7 +60,7 @@ typedef int (*InputPlugin_fileDecodeFunc) (OutputBuffer *, DecoderControl *,
 typedef MpdTag *(*InputPlugin_tagDupFunc) (char *file);
 
 typedef struct _InputPlugin {
-	char *name;
+	const char *name;
 	InputPlugin_initFunc initFunc;
 	InputPlugin_finishFunc finishFunc;
 	InputPlugin_tryDecodeFunc tryDecodeFunc;
@@ -72,8 +72,8 @@ typedef struct _InputPlugin {
 	unsigned char streamTypes;
 
 	/* last element in these arrays must always be a NULL: */
-	char **suffixes;
-	char **mimeTypes;
+	const char *const*suffixes;
+	const char *const*mimeTypes;
 } InputPlugin;
 
 /* individual functions to load/unload plugins */
@@ -82,11 +82,11 @@ void unloadInputPlugin(InputPlugin * inputPlugin);
 
 /* interface for using plugins */
 
-InputPlugin *getInputPluginFromSuffix(char *suffix, unsigned int next);
+InputPlugin *getInputPluginFromSuffix(const char *suffix, unsigned int next);
 
-InputPlugin *getInputPluginFromMimeType(char *mimeType, unsigned int next);
+InputPlugin *getInputPluginFromMimeType(const char *mimeType, unsigned int next);
 
-InputPlugin *getInputPluginFromName(char *name);
+InputPlugin *getInputPluginFromName(const char *name);
 
 void printAllInputPluginSuffixes(FILE * fp);
 
diff --git a/src/inputPlugins/audiofile_plugin.c b/src/inputPlugins/audiofile_plugin.c
index b5555f87d..1213d31e5 100644
--- a/src/inputPlugins/audiofile_plugin.c
+++ b/src/inputPlugins/audiofile_plugin.c
@@ -149,7 +149,7 @@ static MpdTag *audiofileTagDup(char *file)
 	return ret;
 }
 
-static char *audiofileSuffixes[] = { "wav", "au", "aiff", "aif", NULL };
+static const char *audiofileSuffixes[] = { "wav", "au", "aiff", "aif", NULL };
 
 InputPlugin audiofilePlugin = {
 	"audiofile",
diff --git a/src/inputPlugins/flac_plugin.c b/src/inputPlugins/flac_plugin.c
index 014365921..f929ef619 100644
--- a/src/inputPlugins/flac_plugin.c
+++ b/src/inputPlugins/flac_plugin.c
@@ -473,11 +473,11 @@ static unsigned int oggflac_try_decode(InputStream * inStream)
 	return (ogg_stream_type_detect(inStream) == FLAC) ? 1 : 0;
 }
 
-static char *oggflac_suffixes[] = { "ogg", "oga", NULL };
-static char *oggflac_mime_types[] = { "audio/x-flac+ogg",
-                                      "application/ogg",
-                                      "application/x-ogg",
-                                      NULL };
+static const char *oggflac_suffixes[] = { "ogg", "oga", NULL };
+static const char *oggflac_mime_types[] = { "audio/x-flac+ogg",
+					    "application/ogg",
+					    "application/x-ogg",
+					    NULL };
 
 static int flac_plugin_init(void)
 {
@@ -501,10 +501,10 @@ static int flac_plugin_init(void)
 
 #endif /* FLAC_API_VERSION_CURRENT >= 7 */
 
-static char *flacSuffixes[] = { "flac", NULL };
-static char *flac_mime_types[] = { "audio/x-flac",
-                                   "application/x-flac",
-                                   NULL };
+static const char *flacSuffixes[] = { "flac", NULL };
+static const char *flac_mime_types[] = { "audio/x-flac",
+					 "application/x-flac",
+					 NULL };
 
 InputPlugin flacPlugin = {
 	"flac",
diff --git a/src/inputPlugins/mod_plugin.c b/src/inputPlugins/mod_plugin.c
index 092d9bd55..22c364d70 100644
--- a/src/inputPlugins/mod_plugin.c
+++ b/src/inputPlugins/mod_plugin.c
@@ -249,7 +249,7 @@ static MpdTag *modTagDup(char *file)
 	return ret;
 }
 
-static char *modSuffixes[] = { "amf",
+static const char *modSuffixes[] = { "amf",
 	"dsm",
 	"far",
 	"gdm",
diff --git a/src/inputPlugins/mp3_plugin.c b/src/inputPlugins/mp3_plugin.c
index 3e5071902..b008a1dd9 100644
--- a/src/inputPlugins/mp3_plugin.c
+++ b/src/inputPlugins/mp3_plugin.c
@@ -1111,8 +1111,8 @@ static MpdTag *mp3_tagDup(char *file)
 	return ret;
 }
 
-static char *mp3_suffixes[] = { "mp3", "mp2", NULL };
-static char *mp3_mimeTypes[] = { "audio/mpeg", NULL };
+static const char *mp3_suffixes[] = { "mp3", "mp2", NULL };
+static const char *mp3_mimeTypes[] = { "audio/mpeg", NULL };
 
 InputPlugin mp3Plugin = {
 	"mp3",
diff --git a/src/inputPlugins/mpc_plugin.c b/src/inputPlugins/mpc_plugin.c
index db217f888..49142aaed 100644
--- a/src/inputPlugins/mpc_plugin.c
+++ b/src/inputPlugins/mpc_plugin.c
@@ -317,7 +317,7 @@ static MpdTag *mpcTagDup(char *file)
 	return ret;
 }
 
-static char *mpcSuffixes[] = { "mpc", NULL };
+static const char *mpcSuffixes[] = { "mpc", NULL };
 
 InputPlugin mpcPlugin = {
 	"mpc",
diff --git a/src/inputPlugins/oggflac_plugin.c b/src/inputPlugins/oggflac_plugin.c
index e980a04b2..6b8a682d5 100644
--- a/src/inputPlugins/oggflac_plugin.c
+++ b/src/inputPlugins/oggflac_plugin.c
@@ -390,11 +390,11 @@ fail:
 	return ret;
 }
 
-static char *oggflac_Suffixes[] = { "ogg", NULL };
-static char *oggflac_mime_types[] = { "audio/x-flac+ogg",
-                                      "application/ogg",
-                                      "application/x-ogg",
-                                      NULL };
+static const char *oggflac_Suffixes[] = { "ogg", NULL };
+static const char *oggflac_mime_types[] = { "audio/x-flac+ogg",
+					    "application/ogg",
+					    "application/x-ogg",
+					    NULL };
 
 InputPlugin oggflacPlugin = {
 	"oggflac",
diff --git a/src/inputPlugins/oggvorbis_plugin.c b/src/inputPlugins/oggvorbis_plugin.c
index 2e9342526..a2648ce62 100644
--- a/src/inputPlugins/oggvorbis_plugin.c
+++ b/src/inputPlugins/oggvorbis_plugin.c
@@ -80,7 +80,7 @@ static size_t ogg_read_cb(void *ptr, size_t size, size_t nmemb, void *vdata)
 
 static int ogg_seek_cb(void *vdata, ogg_int64_t offset, int whence)
 {
-	OggCallbackData *data = (OggCallbackData *) vdata;
+	const OggCallbackData *data = (const OggCallbackData *) vdata;
 	if(data->dc->stop)
 		return -1;
 	return seekInputStream(data->inStream, offset, whence);
@@ -94,12 +94,12 @@ static int ogg_close_cb(void *vdata)
 
 static long ogg_tell_cb(void *vdata)
 {
-	OggCallbackData *data = (OggCallbackData *) vdata;
+	const OggCallbackData *data = (const OggCallbackData *) vdata;
 
 	return (long)(data->inStream->offset);
 }
 
-static char *ogg_parseComment(char *comment, char *needle)
+static const char *ogg_parseComment(const char *comment, const char *needle)
 {
 	int len = strlen(needle);
 
@@ -112,7 +112,7 @@ static char *ogg_parseComment(char *comment, char *needle)
 
 static void ogg_getReplayGainInfo(char **comments, ReplayGainInfo ** infoPtr)
 {
-	char *temp;
+	const char *temp;
 	int found = 0;
 
 	if (*infoPtr)
@@ -236,7 +236,7 @@ static int oggvorbis_decode(OutputBuffer * cb, DecoderControl * dc,
 	long test;
 	ReplayGainInfo *replayGainInfo = NULL;
 	char **comments;
-	char *errorStr;
+	const char *errorStr;
 
 	data.inStream = inStream;
 	data.dc = dc;
@@ -383,11 +383,11 @@ static unsigned int oggvorbis_try_decode(InputStream * inStream)
 	return (ogg_stream_type_detect(inStream) == VORBIS) ? 1 : 0;
 }
 
-static char *oggvorbis_Suffixes[] = { "ogg", NULL };
-static char *oggvorbis_MimeTypes[] = { "application/ogg",
-                                       "audio/x-vorbis+ogg",
-                                       "application/x-ogg",
-                                       NULL };
+static const char *oggvorbis_Suffixes[] = { "ogg", NULL };
+static const char *oggvorbis_MimeTypes[] = { "application/ogg",
+					     "audio/x-vorbis+ogg",
+					     "application/x-ogg",
+					     NULL };
 
 InputPlugin oggvorbisPlugin = {
 	"oggvorbis",
diff --git a/src/inputStream_http.c b/src/inputStream_http.c
index db8b3062a..c5dccf9dd 100644
--- a/src/inputStream_http.c
+++ b/src/inputStream_http.c
@@ -187,7 +187,8 @@ static char *base64Dup(char *s)
 	return ret;
 }
 
-static char *authString(char *header, char *user, char *password)
+static char *authString(const char *header,
+			const char *user, const char *password)
 {
 	char *ret = NULL;
 	int templen;
diff --git a/src/list.c b/src/list.c
index 6a54d8a5f..65ad4ec98 100644
--- a/src/list.c
+++ b/src/list.c
@@ -63,7 +63,7 @@ List *makeList(ListFreeDataFunc * freeDataFunc, int strdupKeys)
 }
 
 ListNode *insertInListBeforeNode(List * list, ListNode * beforeNode, int pos,
-				 char *key, void *data)
+				 const char *key, void *data)
 {
 	ListNode *node;
 
@@ -126,7 +126,7 @@ ListNode *insertInListBeforeNode(List * list, ListNode * beforeNode, int pos,
 	return node;
 }
 
-ListNode *insertInList(List * list, char *key, void *data)
+ListNode *insertInList(List * list, const char *key, void *data)
 {
 	ListNode *node;
 
@@ -201,7 +201,7 @@ int insertInListWithoutKey(List * list, void *data)
 
 /* if _key_ is not found, *_node_ is assigned to the node before which
 	the info would be found */
-int findNodeInList(List * list, char *key, ListNode ** node, int *pos)
+int findNodeInList(List * list, const char *key, ListNode ** node, int *pos)
 {
 	long high;
 	long low;
@@ -268,7 +268,7 @@ int findNodeInList(List * list, char *key, ListNode ** node, int *pos)
 	return 0;
 }
 
-int findInList(List * list, char *key, void **data)
+int findInList(List * list, const char *key, void **data)
 {
 	ListNode *node;
 	int pos;
@@ -282,7 +282,7 @@ int findInList(List * list, char *key, void **data)
 	return 0;
 }
 
-int deleteFromList(List * list, char *key)
+int deleteFromList(List * list, const char *key)
 {
 	ListNode *tmpNode;
 
@@ -302,6 +302,11 @@ int deleteFromList(List * list, char *key)
 	return 1;
 }
 
+static void free_const_string(const char *p)
+{
+	free((char *)p);
+}
+
 void deleteNodeFromList(List * list, ListNode * node)
 {
 	assert(list != NULL);
@@ -322,7 +327,7 @@ void deleteNodeFromList(List * list, ListNode * node)
 	}
 
 	if (list->strdupKeys)
-		free(node->key);
+		free_const_string(node->key);
 	free(node);
 	list->numberOfNodes--;
 
@@ -349,7 +354,7 @@ void freeList(void *list)
 	while (tmpNode != NULL) {
 		tmpNode2 = tmpNode->nextNode;
 		if (((List *) list)->strdupKeys)
-			free(tmpNode->key);
+			free_const_string(tmpNode->key);
 		if (((List *) list)->freeDataFunc) {
 			((List *) list)->freeDataFunc(tmpNode->data);
 		}
@@ -362,7 +367,7 @@ void freeList(void *list)
 
 static void swapNodes(ListNode * nodeA, ListNode * nodeB)
 {
-	char *key;
+	const char *key;
 	void *data;
 
 	assert(nodeA != NULL);
@@ -408,7 +413,7 @@ static void quickSort(ListNode ** nodesArray, long start, long end)
 		ListNode *node;
 		long pivot;
 		ListNode *pivotNode;
-		char *pivotKey;
+		const char *pivotKey;
 
 		List *startList = makeList(free, 0);
 		List *endList = makeList(free, 0);
diff --git a/src/list.h b/src/list.h
index 62c40aef7..6aca5f503 100644
--- a/src/list.h
+++ b/src/list.h
@@ -30,7 +30,7 @@ typedef void ListFreeDataFunc(void *);
 
 typedef struct _ListNode {
 	/* used to identify node (ie. when using findInList) */
-	char *key;
+	const char *key;
 	/* data store in node */
 	void *data;
 	/* next node in list */
@@ -69,10 +69,10 @@ List *makeList(ListFreeDataFunc * freeDataFunc, int strdupKeys);
  *  _data_ -> data to be inserted in list
  * returns 1 if successful, 0 otherwise
  */
-ListNode *insertInList(List * list, char *key, void *data);
+ListNode *insertInList(List * list, const char *key, void *data);
 
 ListNode *insertInListBeforeNode(List * list, ListNode * beforeNode,
-				 int pos, char *key, void *data);
+				 int pos, const char *key, void *data);
 
 int insertInListWithoutKey(List * list, void *data);
 
@@ -81,7 +81,7 @@ int insertInListWithoutKey(List * list, void *data);
  *  _key_ -> key used to identify node to delete
  *  returns 1 if node is found and deleted, 0 otherwise
  */
-int deleteFromList(List * list, char *key);
+int deleteFromList(List * list, const char *key);
 
 void deleteNodeFromList(List * list, ListNode * node);
 
@@ -93,11 +93,11 @@ void deleteNodeFromList(List * list, ListNode * node);
  *      _data_ can be NULL
  * returns 1 if successful, 0 otherwise
  */
-int findInList(List * list, char *key, void **data);
+int findInList(List * list, const char *key, void **data);
 
 /* if _key_ is not found, *_node_ is assigned to the node before which
 	the info would be found */
-int findNodeInList(List * list, char *key, ListNode ** node, int *pos);
+int findNodeInList(List * list, const char *key, ListNode ** node, int *pos);
 
 /* frees memory malloc'd for list and its nodes
  *  _list_ -> List to be free'd
diff --git a/src/locate.c b/src/locate.c
index 3a4e35b84..f459d2769 100644
--- a/src/locate.c
+++ b/src/locate.c
@@ -24,7 +24,7 @@
 #define LOCATE_TAG_FILE_KEY_OLD "filename"
 #define LOCATE_TAG_ANY_KEY      "any"
 
-int getLocateTagItemType(char *str)
+int getLocateTagItemType(const char *str)
 {
 	int i;
 
@@ -48,7 +48,8 @@ int getLocateTagItemType(char *str)
 	return -1;
 }
 
-static int initLocateTagItem(LocateTagItem * item, char *typeStr, char *needle)
+static int initLocateTagItem(LocateTagItem * item,
+			     const char *typeStr, const char *needle)
 {
 	item->tagType = getLocateTagItemType(typeStr);
 
@@ -60,7 +61,7 @@ static int initLocateTagItem(LocateTagItem * item, char *typeStr, char *needle)
 	return 0;
 }
 
-LocateTagItem *newLocateTagItem(char *typeStr, char *needle)
+LocateTagItem *newLocateTagItem(const char *typeStr, const char *needle)
 {
 	LocateTagItem *ret = xmalloc(sizeof(LocateTagItem));
 
diff --git a/src/locate.h b/src/locate.h
index c165a310a..28b2782b0 100644
--- a/src/locate.h
+++ b/src/locate.h
@@ -28,10 +28,10 @@ typedef struct _LocateTagItem {
 	char *needle;
 } LocateTagItem;
 
-int getLocateTagItemType(char *str);
+int getLocateTagItemType(const char *str);
 
 /* returns NULL if not a known type */
-LocateTagItem *newLocateTagItem(char *typeString, char *needle);
+LocateTagItem *newLocateTagItem(const char *typeString, const char *needle);
 
 /* return number of items or -1 on error */
 int newLocateTagItemArrayFromArgArray(char *argArray[], int numArgs,
diff --git a/src/ls.c b/src/ls.c
index d06ae350d..a858057c3 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -25,14 +25,14 @@
 #include "utils.h"
 #include "os_compat.h"
 
-static char *remoteUrlPrefixes[] = {
+static const char *remoteUrlPrefixes[] = {
 	"http://",
 	NULL
 };
 
 int printRemoteUrlHandlers(int fd)
 {
-	char **prefixes = remoteUrlPrefixes;
+	const char **prefixes = remoteUrlPrefixes;
 
 	while (*prefixes) {
 		fdprintf(fd, "handler: %s\n", *prefixes);
@@ -85,7 +85,7 @@ int isValidRemoteUtf8Url(char *utf8url)
 int isRemoteUrl(char *url)
 {
 	int count = 0;
-	char **urlPrefixes = remoteUrlPrefixes;
+	const char **urlPrefixes = remoteUrlPrefixes;
 
 	while (*urlPrefixes) {
 		count++;
@@ -98,7 +98,7 @@ int isRemoteUrl(char *url)
 	return 0;
 }
 
-int lsPlaylists(int fd, char *utf8path)
+int lsPlaylists(int fd, const char *utf8path)
 {
 	DIR *dir;
 	struct stat st;
@@ -181,11 +181,11 @@ int lsPlaylists(int fd, char *utf8path)
 	return 0;
 }
 
-int myStat(char *utf8file, struct stat *st)
+int myStat(const char *utf8file, struct stat *st)
 {
 	char path_max_tmp[MPD_PATH_MAX];
-	char *file = utf8_to_fs_charset(path_max_tmp, utf8file);
-	char *actualFile = file;
+	const char *file = utf8_to_fs_charset(path_max_tmp, utf8file);
+	const char *actualFile = file;
 
 	if (actualFile[0] != '/')
 		actualFile = rmp2amp_r(path_max_tmp, file);
@@ -193,7 +193,7 @@ int myStat(char *utf8file, struct stat *st)
 	return stat(actualFile, st);
 }
 
-int isFile(char *utf8file, time_t * mtime)
+int isFile(const char *utf8file, time_t * mtime)
 {
 	struct stat st;
 
@@ -215,9 +215,9 @@ int isFile(char *utf8file, time_t * mtime)
 }
 
 /* suffixes should be ascii only characters */
-char *getSuffix(char *utf8file)
+const char *getSuffix(const char *utf8file)
 {
-	char *ret = NULL;
+	const char *ret = NULL;
 
 	while (*utf8file) {
 		if (*utf8file == '.')
@@ -228,15 +228,15 @@ char *getSuffix(char *utf8file)
 	return ret;
 }
 
-static int hasSuffix(char *utf8file, char *suffix)
+static int hasSuffix(const char *utf8file, const char *suffix)
 {
-	char *s = getSuffix(utf8file);
+	const char *s = getSuffix(utf8file);
 	if (s && 0 == strcmp(s, suffix))
 		return 1;
 	return 0;
 }
 
-int isPlaylist(char *utf8file)
+int isPlaylist(const char *utf8file)
 {
 	if (isFile(utf8file, NULL)) {
 		return hasSuffix(utf8file, PLAYLIST_FILE_SUFFIX);
@@ -244,7 +244,7 @@ int isPlaylist(char *utf8file)
 	return 0;
 }
 
-int isDir(char *utf8name)
+int isDir(const char *utf8name)
 {
 	struct stat st;
 
@@ -257,11 +257,11 @@ int isDir(char *utf8name)
 	return 0;
 }
 
-InputPlugin *hasMusicSuffix(char *utf8file, unsigned int next)
+InputPlugin *hasMusicSuffix(const char *utf8file, unsigned int next)
 {
 	InputPlugin *ret = NULL;
 
-	char *s = getSuffix(utf8file);
+	const char *s = getSuffix(utf8file);
 	if (s) {
 		ret = getInputPluginFromSuffix(s, next);
 	} else {
@@ -272,7 +272,7 @@ InputPlugin *hasMusicSuffix(char *utf8file, unsigned int next)
 	return ret;
 }
 
-InputPlugin *isMusic(char *utf8file, time_t * mtime, unsigned int next)
+InputPlugin *isMusic(const char *utf8file, time_t * mtime, unsigned int next)
 {
 	if (isFile(utf8file, mtime)) {
 		InputPlugin *plugin = hasMusicSuffix(utf8file, next);
diff --git a/src/ls.h b/src/ls.h
index e14966ca7..4eee3ca26 100644
--- a/src/ls.h
+++ b/src/ls.h
@@ -24,26 +24,26 @@
 #include "inputPlugin.h"
 #include "os_compat.h"
 
-int lsPlaylists(int fd, char *utf8path);
+int lsPlaylists(int fd, const char *utf8path);
 
-char *getSuffix(char *utf8file);
+const char *getSuffix(const char *utf8file);
 
 int isValidRemoteUtf8Url(char *utf8url);
 
 int isRemoteUrl(char *url);
 
-int myStat(char *utf8file, struct stat *st);
+int myStat(const char *utf8file, struct stat *st);
 
-int isDir(char *utf8name);
+int isDir(const char *utf8name);
 
-int isPlaylist(char *utf8file);
+int isPlaylist(const char *utf8file);
 
-InputPlugin *hasMusicSuffix(char *utf8file, unsigned int next);
+InputPlugin *hasMusicSuffix(const char *utf8file, unsigned int next);
 
-InputPlugin *isMusic(char *utf8file, time_t * mtime, unsigned int next);
+InputPlugin *isMusic(const char *utf8file, time_t * mtime, unsigned int next);
 
 int printRemoteUrlHandlers(int fd);
 
-int isFile(char *utf8file, time_t * mtime);
+int isFile(const char *utf8file, time_t * mtime);
 
 #endif
diff --git a/src/mpd_types.h b/src/mpd_types.h
index 765d0d001..35ff3604f 100644
--- a/src/mpd_types.h
+++ b/src/mpd_types.h
@@ -41,4 +41,9 @@ typedef unsigned long mpd_uint32;
 typedef signed long mpd_sint32;
 #endif
 
+union const_hack {
+	const char *in;
+	char *out;
+};
+
 #endif
diff --git a/src/path.c b/src/path.c
index 258363036..6aaff84cf 100644
--- a/src/path.c
+++ b/src/path.c
@@ -38,24 +38,25 @@ static size_t music_dir_len;
 static size_t playlist_dir_len;
 static char *fsCharset;
 
-static char *path_conv_charset(char *dest, char *to, char *from, char *str)
+static char *path_conv_charset(char *dest, const char *to,
+			       const char *from, const char *str)
 {
 	return setCharSetConversion(to, from) ? NULL : char_conv_str(dest, str);
 }
 
-char *fs_charset_to_utf8(char *dst, char *str)
+char *fs_charset_to_utf8(char *dst, const char *str)
 {
 	char *ret = path_conv_charset(dst, "UTF-8", fsCharset, str);
 	return (ret && !validUtf8String(ret)) ? NULL : ret;
 }
 
-char *utf8_to_fs_charset(char *dst, char *str)
+char *utf8_to_fs_charset(char *dst, const char *str)
 {
 	char *ret = path_conv_charset(dst, fsCharset, "UTF-8", str);
 	return ret ? ret : strcpy(dst, str);
 }
 
-void setFsCharset(char *charset)
+void setFsCharset(const char *charset)
 {
 	int error = 0;
 
@@ -86,7 +87,7 @@ void setFsCharset(char *charset)
 	}
 }
 
-char *getFsCharset(void)
+const char *getFsCharset(void)
 {
 	return fsCharset;
 }
@@ -243,7 +244,7 @@ char *parent_path(char *path_max_tmp, const char *path)
 	return path_max_tmp;
 }
 
-char *sanitizePathDup(char *path)
+char *sanitizePathDup(const char *path)
 {
 	int len = strlen(path) + 1;
 	char *ret = xmalloc(len);
@@ -285,7 +286,7 @@ char *sanitizePathDup(char *path)
 
 void utf8_to_fs_playlist_path(char *path_max_tmp, const char *utf8path)
 {
-	utf8_to_fs_charset(path_max_tmp, (char *)utf8path);
+	utf8_to_fs_charset(path_max_tmp, utf8path);
 	rpp2app_r(path_max_tmp, path_max_tmp);
 	strncat(path_max_tmp, "." PLAYLIST_FILE_SUFFIX, MPD_PATH_MAX - 1);
 }
diff --git a/src/path.h b/src/path.h
index 560cf6073..d29354523 100644
--- a/src/path.h
+++ b/src/path.h
@@ -38,13 +38,13 @@ void initPaths(void);
 
 void finishPaths(void);
 
-char *fs_charset_to_utf8(char *dst, char *str);
+char *fs_charset_to_utf8(char *dst, const char *str);
 
-char *utf8_to_fs_charset(char *dst, char *str);
+char *utf8_to_fs_charset(char *dst, const char *str);
 
-void setFsCharset(char *charset);
+void setFsCharset(const char *charset);
 
-char *getFsCharset(void);
+const char *getFsCharset(void);
 
 /*
  * pfx_dir - sets dst="$pfx/$path" and returns a pointer to path inside * dst
@@ -75,7 +75,7 @@ char *rpp2app_r(char *dst, const char *rel_path);
 char *parent_path(char *path_max_tmp, const char *path);
 
 /* strips extra "///" and leading "/" and trailing "/" */
-char *sanitizePathDup(char *path);
+char *sanitizePathDup(const char *path);
 
 /* this is actually like strlcpy (OpenBSD), but we don't actually want to
  * blindly use it everywhere, only for paths that are OK to truncate (for
diff --git a/src/song.c b/src/song.c
index d8d4251dd..83781efb8 100644
--- a/src/song.c
+++ b/src/song.c
@@ -44,7 +44,7 @@ Song *newNullSong(void)
 	return song;
 }
 
-Song *newSong(char *url, int type, Directory * parentDir)
+Song *newSong(const char *url, int type, Directory * parentDir)
 {
 	Song *song = NULL;
 
@@ -101,7 +101,7 @@ SongList *newSongList(void)
 	return makeList((ListFreeDataFunc *) freeSong, 0);
 }
 
-Song *addSongToList(SongList * list, char *url, char *utf8path,
+Song *addSongToList(SongList * list, const char *url, const char *utf8path,
 		    int songType, Directory * parentDirectory)
 {
 	Song *song = NULL;
diff --git a/src/song.h b/src/song.h
index ccf87e348..6f06101bf 100644
--- a/src/song.h
+++ b/src/song.h
@@ -45,7 +45,7 @@ typedef List SongList;
 
 Song *newNullSong(void);
 
-Song *newSong(char *url, int songType, struct _Directory *parentDir);
+Song *newSong(const char *url, int songType, struct _Directory *parentDir);
 
 void freeSong(Song *);
 
@@ -55,7 +55,7 @@ SongList *newSongList(void);
 
 void freeSongList(SongList * list);
 
-Song *addSongToList(SongList * list, char *url, char *utf8path,
+Song *addSongToList(SongList * list, const char *url, const char *utf8path,
 		    int songType, struct _Directory *parentDir);
 
 int printSongInfo(int fd, Song * song);
diff --git a/src/tag.c b/src/tag.c
index bacc2cb16..cfda3add1 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -44,7 +44,7 @@
 #  endif
 #endif
 
-char *mpdTagItemKeys[TAG_NUM_OF_ITEM_TYPES] = {
+const char *mpdTagItemKeys[TAG_NUM_OF_ITEM_TYPES] = {
 	"Artist",
 	"Album",
 	"Title",
@@ -169,7 +169,8 @@ static id3_utf8_t * processID3FieldString (int is_id3v1, const id3_ucs4_t *ucs4,
     return utf8;
 }
 
-static MpdTag *getID3Info(struct id3_tag *tag, char *id, int type, MpdTag * mpdTag)
+static MpdTag *getID3Info(
+	struct id3_tag *tag, const char *id, int type, MpdTag * mpdTag)
 {
 	struct id3_frame const *frame;
 	id3_ucs4_t const *ucs4;
@@ -480,7 +481,7 @@ MpdTag *apeDup(char *file)
 		unsigned char reserved[8];
 	} footer;
 
-	char *apeItems[7] = {
+	const char *apeItems[7] = {
 		"title",
 		"artist",
 		"album",
diff --git a/src/tag.h b/src/tag.h
index a554ee1cc..363ad98aa 100644
--- a/src/tag.h
+++ b/src/tag.h
@@ -41,7 +41,7 @@
 
 #define TAG_NUM_OF_ITEM_TYPES	11
 
-extern char *mpdTagItemKeys[];
+extern const char *mpdTagItemKeys[];
 
 typedef struct _MpdTagItem {
 	mpd_sint8 type;
diff --git a/src/utf8.c b/src/utf8.c
index d7b1503c3..f0d6b3b11 100644
--- a/src/utf8.c
+++ b/src/utf8.c
@@ -20,10 +20,10 @@
 #include "utils.h"
 #include "os_compat.h"
 
-char *latin1_to_utf8(char *dest, char *in_latin1)
+char *latin1_to_utf8(char *dest, const char *in_latin1)
 {
 	unsigned char *cp = (unsigned char *)dest;
-	unsigned char *latin1 = (unsigned char *)in_latin1;
+	const unsigned char *latin1 = (const unsigned char *)in_latin1;
 
 	while (*latin1) {
 		if (*latin1 < 128)
@@ -45,7 +45,7 @@ char *latin1_to_utf8(char *dest, char *in_latin1)
 	return dest;
 }
 
-char *latin1StrToUtf8Dup(char *latin1)
+char *latin1StrToUtf8Dup(const char *latin1)
 {
 	/* utf8 should have at most two char's per latin1 char */
 	char *ret = xmalloc(strlen(latin1) * 2 + 1);
@@ -55,10 +55,10 @@ char *latin1StrToUtf8Dup(char *latin1)
 	return ((ret) ? xrealloc(ret, strlen((char *)ret) + 1) : NULL);
 }
 
-static char utf8_to_latin1_char(char *inUtf8)
+static char utf8_to_latin1_char(const char *inUtf8)
 {
 	unsigned char c = 0;
-	unsigned char *utf8 = (unsigned char *)inUtf8;
+	const unsigned char *utf8 = (const unsigned char *)inUtf8;
 
 	if (utf8[0] < 128)
 		return utf8[0];
@@ -69,9 +69,9 @@ static char utf8_to_latin1_char(char *inUtf8)
 	return (char)(c + utf8[1]);
 }
 
-static int validateUtf8Char(char *inUtf8Char)
+static int validateUtf8Char(const char *inUtf8Char)
 {
-	unsigned char *utf8Char = (unsigned char *)inUtf8Char;
+	const unsigned char *utf8Char = (const unsigned char *)inUtf8Char;
 
 	if (utf8Char[0] < 0x80)
 		return 1;
@@ -95,7 +95,7 @@ static int validateUtf8Char(char *inUtf8Char)
 		return 0;
 }
 
-int validUtf8String(char *string)
+int validUtf8String(const char *string)
 {
 	int ret;
 
@@ -109,7 +109,7 @@ int validUtf8String(char *string)
 	return 1;
 }
 
-char *utf8StrToLatin1Dup(char *utf8)
+char *utf8StrToLatin1Dup(const char *utf8)
 {
 	/* utf8 should have at most two char's per latin1 char */
 	char *ret = xmalloc(strlen(utf8) + 1);
@@ -133,7 +133,7 @@ char *utf8StrToLatin1Dup(char *utf8)
 	return xrealloc(ret, len + 1);
 }
 
-char *utf8_to_latin1(char *dest, char *utf8)
+char *utf8_to_latin1(char *dest, const char *utf8)
 {
 	char *cp = dest;
 	int count;
diff --git a/src/utf8.h b/src/utf8.h
index 05e1a4a31..4a4983064 100644
--- a/src/utf8.h
+++ b/src/utf8.h
@@ -19,15 +19,15 @@
 #ifndef UTF_8_H
 #define UTF_8_H
 
-char *latin1StrToUtf8Dup(char *latin1);
+char *latin1StrToUtf8Dup(const char *latin1);
 
-char *utf8StrToLatin1Dup(char *utf8);
+char *utf8StrToLatin1Dup(const char *utf8);
 
-int validUtf8String(char *string);
+int validUtf8String(const char *string);
 
-char *utf8_to_latin1(char *dest, char *utf8);
+char *utf8_to_latin1(char *dest, const char *utf8);
 
-char *latin1_to_utf8(char *dest, char *utf8);
+char *latin1_to_utf8(char *dest, const char *utf8);
 
 
 #endif
diff --git a/src/volume.c b/src/volume.c
index 736838139..846a76eaa 100644
--- a/src/volume.c
+++ b/src/volume.c
@@ -57,7 +57,7 @@
 #endif
 
 static int volume_mixerType = VOLUME_MIXER_TYPE_DEFAULT;
-static char *volume_mixerDevice = VOLUME_MIXER_DEVICE_DEFAULT;
+static const char *volume_mixerDevice = VOLUME_MIXER_DEVICE_DEFAULT;
 
 static int volume_softwareSet = 100;
 
@@ -82,7 +82,7 @@ static void closeOssMixer(void)
 	volume_ossFd = -1;
 }
 
-static int prepOssMixer(char *device)
+static int prepOssMixer(const char *device)
 {
 	ConfigParam *param;
 
@@ -94,7 +94,7 @@ static int prepOssMixer(char *device)
 	param = getConfigParam(CONF_MIXER_CONTROL);
 
 	if (param) {
-		char *labels[SOUND_MIXER_NRDEVICES] = SOUND_DEVICE_LABELS;
+		const char *labels[SOUND_MIXER_NRDEVICES] = SOUND_DEVICE_LABELS;
 		char *duplicated;
 		int i, j;
 		int devmask = 0;
@@ -211,11 +211,11 @@ static void closeAlsaMixer(void)
 	volume_alsaMixerHandle = NULL;
 }
 
-static int prepAlsaMixer(char *card)
+static int prepAlsaMixer(const char *card)
 {
 	int err;
 	snd_mixer_elem_t *elem;
-	char *controlName = VOLUME_MIXER_ALSA_CONTROL_DEFAULT;
+	const char *controlName = VOLUME_MIXER_ALSA_CONTROL_DEFAULT;
 	ConfigParam *param;
 
 	err = snd_mixer_open(&volume_alsaMixerHandle, 0);
@@ -370,7 +370,7 @@ static int changeAlsaVolumeLevel(int fd, int change, int rel)
 }
 #endif
 
-static int prepMixer(char *device)
+static int prepMixer(const char *device)
 {
 	switch (volume_mixerType) {
 #ifdef HAVE_ALSA