add my own utf8/ascii converters and utf8 validator

validate all mpd tags on import, if they are invalid, assume they are ascii
and convert to utf8

git-svn-id: https://svn.musicpd.org/mpd/trunk@707 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/utf8.c

@@ -0,0 +1,87 @@
+#include "utf8.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+unsigned char * asciiToUtf8(unsigned char c) {
+	static unsigned char utf8[3];
+
+	memset(utf8,0,3);
+
+	if(c < 128) utf8[0] = c;
+	else if(c<192) {
+		utf8[0] = 194;
+		utf8[1] = c;
+	}
+	else {
+		utf8[0] = 195;
+		utf8[1] = c-64;
+	}
+
+	return utf8;
+}
+
+unsigned char * asciiStrToUtf8Dup(unsigned char * ascii) {
+	/* utf8 should have at most two char's per ascii char */
+	int len = strlen(ascii)*2+1;
+	unsigned char * ret = malloc(len);
+	unsigned char * cp = ret;
+	unsigned char * utf8;
+
+	memset(ret,0,len);
+
+	len = 0;
+
+	while(*ascii) {
+		utf8 = asciiToUtf8(*ascii);
+		while(*utf8) {
+			*(cp++) = *(utf8++);
+			len++;
+		}
+		ascii++;
+	}
+
+	return realloc(ret,len+1);
+}
+
+unsigned char utf8ToAscii(unsigned char * utf8) {
+	unsigned char c = 0;
+
+	if(utf8[0]<128) return utf8[0];
+	else if(utf8[0]==195) c+=64;
+	else if(utf8[0]!=194) return '?';
+	return c+utf8[1];
+}
+
+int validateUtf8Char(unsigned char * utf8Char) {
+	if(utf8Char[0]<0x80) return 1;
+	
+	if(utf8Char[0]>=0xC0 && utf8Char[0]<=0xFD) {
+		int count = 1;
+		unsigned char t = 0x20;
+		int i;
+		while(count < 6 && (t & utf8Char[0])) {
+			t = (t >> 1);
+			count++;
+		}
+		if(count > 5) return 0;
+		for(i=1;i<=count;i++) {
+			if(utf8Char[i] < 0x80 || utf8Char[i] > 0xBF) return 0;
+		}
+		return count;
+	}
+	else return 0;
+}
+
+int validUtf8String(unsigned char * string) {
+	int ret;
+
+	while(*string) {
+		ret = validateUtf8Char(string);
+		if(!ret) return 0;
+		string+= ret;
+	}
+
+	return 1;
+}