fix -Wcast-qual -Wwrite-strings warnings

The previous patch enabled these warnings.  In Eric's branch, they
were worked around with a generic deconst_ptr() function.  There are
several places where we can add "const" to pointers, and in others,
libraries want non-const strings.  In the latter, convert string
literals to "static char[]" variables - this takes the same space, and
seems safer than deconsting a string literal.

src/audioOutputs/audioOutput_jack.c

@@ -31,8 +31,8 @@ static const size_t sample_size = sizeof(jack_default_audio_sample_t);
 
 typedef struct _JackData {
 	/* configuration */
-	char *name;
+	const char *name;
-	char *output_ports[2];
+	const char *output_ports[2];
 	int ringbuf_sz;
 
 	/* locks */
@@ -52,6 +52,7 @@ typedef struct _JackData {
 static JackData *newJackData(void)
 {
 	JackData *ret;
+
 	ret = xcalloc(sizeof(JackData), 1);
 
 	ret->name = "mpd";
@@ -97,12 +98,12 @@ static void freeJackData(AudioOutput *audioOutput)
 	freeJackClient(jd);
 
 	if (strcmp(jd->name, "mpd") != 0)
-		free(jd->name);
+		xfree(jd->name);
 
 	for ( i = ARRAY_SIZE(jd->output_ports); --i >= 0; ) {
 		if (!jd->output_ports[i])
 			continue;
-		free(jd->output_ports[i]);
+		xfree(jd->output_ports[i]);
 	}
 
 	free(jd);
@@ -267,7 +268,7 @@ static int jack_testDefault(void)
 static int connect_jack(AudioOutput *audioOutput)
 {
 	JackData *jd = audioOutput->data;
-	char **jports;
+	const char **jports;
 	char *port_name;
 
 	if ( (jd->client = jack_client_new(jd->name)) == NULL ) {
@@ -304,7 +305,7 @@ static int connect_jack(AudioOutput *audioOutput)
 
 	/*  hay que buscar que hay  */
 	if ( !jd->output_ports[1]
-	     && (jports = (char **)jack_get_ports(jd->client, NULL, NULL,
+	     && (jports = jack_get_ports(jd->client, NULL, NULL,
 					 JackPortIsPhysical|
 					 JackPortIsInput)) ) {
 		jd->output_ports[0] = jports[0];

src/audioOutputs/audioOutput_shout.c

@@ -637,7 +637,7 @@ static int myShout_play(AudioOutput * audioOutput,
 
 	for (i = 0; i < samples; i++) {
 		for (j = 0; j < sd->audioFormat->channels; j++) {
-			vorbbuf[j][i] = (*((mpd_sint16 *) playChunk)) / 32768.0;
+			vorbbuf[j][i] = (*((const mpd_sint16 *) playChunk)) / 32768.0;
 			playChunk += bytes;
 		}
 	}

src/inputPlugins/mod_plugin.c

@@ -48,14 +48,21 @@ static BOOL mod_mpd_IsThere(void)
 	return 1;
 }
 
+static char drv_name[] = "MPD";
+static char drv_version[] = "MPD Output Driver v0.1";
+
+#if (LIBMIKMOD_VERSION > 0x030106)
+static char drv_alias[] = "mpd";
+#endif
+
 static MDRIVER drv_mpd = {
 	NULL,
-	"MPD",
+	drv_name,
-	"MPD Output Driver v0.1",
+	drv_version,
 	0,
 	255,
 #if (LIBMIKMOD_VERSION > 0x030106)
-	"mpd", /* Alias */
+	drv_alias,
 #if (LIBMIKMOD_VERSION >= 0x030200)
 	NULL,  /* CmdLineHelp */
 #endif
@@ -92,6 +99,8 @@ static int mod_mikModInitError;
 
 static int mod_initMikMod(void)
 {
+	static char params[] = "";
+
 	if (mod_mikModInitError)
 		return -1;
 
@@ -110,7 +119,7 @@ static int mod_initMikMod(void)
 	md_mode = (DMODE_SOFT_MUSIC | DMODE_INTERP | DMODE_STEREO |
 		   DMODE_16BITS);
 
-	if (MikMod_Init("")) {
+	if (MikMod_Init(params)) {
 		ERROR("Could not init MikMod: %s\n",
 		      MikMod_strerror(MikMod_errno));
 		mod_mikModInitError = 1;

src/inputPlugins/wavpack_plugin.c

@@ -235,34 +235,38 @@ static char *wavpack_tag(WavpackContext *wpc, char *key)
 
 static ReplayGainInfo *wavpack_replaygain(WavpackContext *wpc)
 {
+	static char replaygain_track_gain[] = "replaygain_track_gain";
+	static char replaygain_album_gain[] = "replaygain_album_gain";
+	static char replaygain_track_peak[] = "replaygain_track_peak";
+	static char replaygain_album_peak[] = "replaygain_album_peak";
 	ReplayGainInfo *replayGainInfo;
 	int found = 0;
 	char *value;
 
 	replayGainInfo = newReplayGainInfo();
 
-	value = wavpack_tag(wpc, "replaygain_track_gain");
+	value = wavpack_tag(wpc, replaygain_track_gain);
 	if (value) {
 		replayGainInfo->trackGain = atof(value);
 		free(value);
 		found = 1;
 	}
 
-	value = wavpack_tag(wpc, "replaygain_album_gain");
+	value = wavpack_tag(wpc, replaygain_album_gain);
 	if (value) {
 		replayGainInfo->albumGain = atof(value);
 		free(value);
 		found = 1;
 	}
 
-	value = wavpack_tag(wpc, "replaygain_track_peak");
+	value = wavpack_tag(wpc, replaygain_track_peak);
 	if (value) {
 		replayGainInfo->trackPeak = atof(value);
 		free(value);
 		found = 1;
 	}
 
-	value = wavpack_tag(wpc, "replaygain_album_peak");
+	value = wavpack_tag(wpc, replaygain_album_peak);
 	if (value) {
 		replayGainInfo->albumPeak = atof(value);
 		free(value);

src/list.c

@@ -301,11 +301,6 @@ int deleteFromList(List * list, const char *key)
 	return 1;
 }
 
-static void free_const_string(const char *p)
-{
-	free((char *)p);
-}
-
 void deleteNodeFromList(List * list, ListNode * node)
 {
 	assert(list != NULL);
@@ -326,7 +321,7 @@ void deleteNodeFromList(List * list, ListNode * node)
 	}
 
 	if (list->strdupKeys)
-		free_const_string(node->key);
+		xfree(node->key);
 	free(node);
 	list->numberOfNodes--;
 
@@ -353,7 +348,7 @@ void freeList(void *list)
 	while (tmpNode != NULL) {
 		tmpNode2 = tmpNode->nextNode;
 		if (((List *) list)->strdupKeys)
-			free_const_string(tmpNode->key);
+			xfree(tmpNode->key);
 		if (((List *) list)->freeDataFunc) {
 			((List *) list)->freeDataFunc(tmpNode->data);
 		}

src/pcm_utils.c

@@ -149,6 +149,7 @@ static int pcm_getSampleRateConverter(void)
 	const char *conf = getConfigParamValue(CONF_SAMPLERATE_CONVERTER);
 	long convalgo;
 	char *test;
+	const char *test2;
 	size_t len;
 
 	if (!conf) {
@@ -162,12 +163,12 @@ static int pcm_getSampleRateConverter(void)
 
 	len = strlen(conf);
 	for (convalgo = 0 ; ; convalgo++) {
-		test = (char *)src_get_name(convalgo);
+		test2 = src_get_name(convalgo);
-		if (!test) {
+		if (!test2) {
 			convalgo = SRC_SINC_FASTEST;
 			break;
 		}
-		if (strncasecmp(test, conf, len) == 0)
+		if (strncasecmp(test2, conf, len) == 0)
 			goto out;
 	}
 
@@ -239,7 +240,7 @@ static size_t pcm_convertSampleRate(mpd_sint8 channels, mpd_uint32 inSampleRate,
 		data->data_out = xrealloc(data->data_out, dataOutSize);
 	}
 
-	src_short_to_float_array((short *)inBuffer, data->data_in,
+	src_short_to_float_array((const short *)inBuffer, data->data_in,
 	                         data->input_frames * channels);
 
 	error = src_process(convState->state, data);
@@ -305,7 +306,7 @@ static char *pcm_convertChannels(mpd_sint8 channels, const char *inBuffer,
 	static char *buf;
 	static size_t len;
 	char *outBuffer = NULL;
-	mpd_sint16 *in;
+	const mpd_sint16 *in;
 	mpd_sint16 *out;
 	int inSamples, i;
 
@@ -320,7 +321,7 @@ static char *pcm_convertChannels(mpd_sint8 channels, const char *inBuffer,
 		outBuffer = buf;
 
 		inSamples = inSize >> 1;
-		in = (mpd_sint16 *)inBuffer;
+		in = (const mpd_sint16 *)inBuffer;
 		out = (mpd_sint16 *)outBuffer;
 		for (i = 0; i < inSamples; i++) {
 			*out++ = *in;
@@ -338,7 +339,7 @@ static char *pcm_convertChannels(mpd_sint8 channels, const char *inBuffer,
 		outBuffer = buf;
 
 		inSamples = inSize >> 2;
-		in = (mpd_sint16 *)inBuffer;
+		in = (const mpd_sint16 *)inBuffer;
 		out = (mpd_sint16 *)outBuffer;
 		for (i = 0; i < inSamples; i++) {
 			*out = (*in++) / 2;
@@ -359,7 +360,7 @@ static const char *pcm_convertTo16bit(mpd_sint8 bits, const char *inBuffer,
 	static char *buf;
 	static size_t len;
 	char *outBuffer = NULL;
-	mpd_sint8 *in;
+	const mpd_sint8 *in;
 	mpd_sint16 *out;
 	size_t i;
 
@@ -372,7 +373,7 @@ static const char *pcm_convertTo16bit(mpd_sint8 bits, const char *inBuffer,
 		}
 		outBuffer = buf;
 
-		in = (mpd_sint8 *)inBuffer;
+		in = (const mpd_sint8 *)inBuffer;
 		out = (mpd_sint16 *)outBuffer;
 		for (i = 0; i < inSize; i++)
 			*out++ = (*in++) << 8;