1 files changed, 231 insertions, 0 deletions
diff --git a/src/svg/base64.c b/src/svg/base64.c
new file mode 100644
index 0000000..c01b130
--- /dev/null
+++ b/src/svg/base64.c
@@ -0,0 +1,231 @@
+/***********************************************************************
+===============
+BASE64 Encoding
+===============
+Available on: http://freecode-freecode.blogspot.com/2008/02/base64c.html
+Last access in: November, 10th 2009.
+************************************************************************/
+
+#include "stdio.h"
+#include "stdlib.h"
+#include "string.h"
+#include "base64.h"
+
+/**
+ * characters used for Base64 encoding
+ */  
+const char *BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/**
+ * encode three bytes using base64 (RFC 3548)
+ *
+ * @param triple three bytes that should be encoded
+ * @param result buffer of four characters where the result is stored
+ */  
+void _base64_encode_triple(unsigned char triple[3], char result[4])
+{
+	int tripleValue, i;
+	
+	tripleValue = triple[0];
+	tripleValue *= 256;
+	tripleValue += triple[1];
+	tripleValue *= 256;
+	tripleValue += triple[2];
+	
+	for (i=0; i<4; i++)
+	{
+		result[3-i] = BASE64_CHARS[tripleValue%64];
+		tripleValue /= 64;
+	}
+}
+
+/**
+ * encode an array of bytes using Base64 (RFC 3548)
+ *
+ * @param source the source buffer
+ * @param sourcelen the length of the source buffer
+ * @param target the target buffer
+ * @param targetlen the length of the target buffer
+ * @return 1 on success, 0 otherwise
+ */  
+int base64_encode(unsigned char *source, int sourcelen, char *target, int targetlen)
+{
+	/* check if the result will fit in the target buffer */
+	if ((sourcelen+2)/3*4 > targetlen-1)
+		return 0;
+	
+	/* encode all full triples */
+	while (sourcelen >= 3)
+	{
+		_base64_encode_triple(source, target);
+		sourcelen -= 3;
+		source += 3;
+		target += 4;
+	}
+	
+	/* encode the last one or two characters */
+	if (sourcelen > 0)
+	{
+		unsigned char temp[3];
+		memset(temp, 0, sizeof(temp));
+		memcpy(temp, source, sourcelen);
+		_base64_encode_triple(temp, target);
+		target[3] = '=';
+		
+		if (sourcelen == 1)
+			target[2] = '=';
+		
+		target += 4;
+	}
+	
+	/* terminate the string */
+	target[0] = 0;
+	
+	return 1;
+} 
+
+/**
+ * determine the value of a base64 encoding character
+ *
+ * @param base64char the character of which the value is searched
+ * @return the value in case of success (0-63), -1 on failure
+ */  
+int _base64_char_value(char base64char)
+{
+	if (base64char >= 'A' && base64char <= 'Z')
+		return base64char-'A';
+	
+	if (base64char >= 'a' && base64char <= 'z')
+		return base64char-'a'+26;
+	
+	if (base64char >= '0' && base64char <= '9')
+		return base64char-'0'+2*26;
+	
+	if (base64char == '+')
+		return 2*26+10;
+	
+	if (base64char == '/')
+		return 2*26+11;
+	
+	return -1;
+} 
+
+/**
+ * decode a 4 char base64 encoded byte triple
+ *
+ * @param quadruple the 4 characters that should be decoded
+ * @param result the decoded data
+ * @return lenth of the result (1, 2 or 3), 0 on failure
+ */  
+int _base64_decode_triple(char quadruple[4], unsigned char *result)
+{
+	int i, triple_value, bytes_to_decode = 3, only_equals_yet = 1;
+	int char_value[4];
+	
+	for (i=0; i<4; i++)
+		char_value[i] = _base64_char_value(quadruple[i]);
+	
+	/* check if the characters are valid */
+	for (i=3; i>=0; i--)
+	{
+		if (char_value[i]<0)
+		{
+			if (only_equals_yet && quadruple[i]=='=')
+			{
+				/* we will ignore this character anyway, make it something
+				 * that does not break our calculations */
+				 
+				char_value[i]=0;
+				bytes_to_decode--;
+				continue;
+			}
+			return 0;
+		}
+		
+		/* after we got a real character, no other '=' are allowed anymore */
+		only_equals_yet = 0;
+	}
+	
+	/* if we got "====" as input, bytes_to_decode is -1 */
+	if (bytes_to_decode < 0)
+		bytes_to_decode = 0;
+	
+	/* make one big value out of the partial values */
+	triple_value = char_value[0];
+	triple_value *= 64;
+	triple_value += char_value[1];
+	triple_value *= 64;
+	triple_value += char_value[2];
+	triple_value *= 64;
+	triple_value += char_value[3];
+	
+	/* break the big value into bytes */
+	for (i=bytes_to_decode; i<3; i++)
+		triple_value /= 256;
+	
+	for (i=bytes_to_decode-1; i>=0; i--)
+	{
+		result[i] = triple_value%256;
+		triple_value /= 256;
+	}
+	
+	return bytes_to_decode;
+} 
+
+/**
+ * decode base64 encoded data
+ *
+ * @param source the encoded data (zero terminated)
+ * @param target pointer to the target buffer
+ * @param targetlen length of the target buffer
+ * @return length of converted data on success, -1 otherwise
+ */  
+int base64_decode(char *source, unsigned char *target, int targetlen)
+{
+	char *src, *tmpptr;
+	char quadruple[4], tmpresult[3];
+	int i, tmplen = 3;
+	int converted = 0;
+	
+	/* concatenate '===' to the source to handle unpadded base64 data */
+	src = (char *)malloc(strlen(source)+5);
+	if (src == NULL)
+		return -1;
+	
+	strcpy(src, source);
+	strcat(src, "====");
+	tmpptr = src;
+	
+	/* convert as long as we get a full result */
+	while (tmplen == 3)
+	{
+		/* get 4 characters to convert */
+		for (i=0; i<4; i++)
+		{
+			/* skip invalid characters - we won't reach the end */
+			while (*tmpptr != '=' && _base64_char_value(*tmpptr)<0)
+				tmpptr++;
+			
+			quadruple[i] = *(tmpptr++);
+		}
+		
+		/* convert the characters */
+		tmplen = _base64_decode_triple(quadruple, (unsigned char*)tmpresult);
+		
+		/* check if the fit in the result buffer */
+		if (targetlen < tmplen)
+		{
+			free(src);
+			return -1;
+		}
+		
+		/* put the partial result in the result buffer */
+		memcpy(target, tmpresult, tmplen);
+		target += tmplen;
+		targetlen -= tmplen;
+		converted += tmplen;
+	}
+	
+	free(src);
+	return converted;
+}