\cat programming

int
base64encode(char *ibuf, unsigned int ilen, char **obuf, unsigned int *olen,
		int ncols)
{
	unsigned int	i, j, k, l;
	char		o[4], c, l2, l4, l6, *p;

	if(olen)
		*olen = 0;
	if(!ibuf || !ilen || !obuf)
		return 1;

	l = (ilen*8+23)/24*4+(ncols?((ilen*8+23)/24*4-1)/ncols:0);
	*obuf = p = (char *)malloc(l+1);
	if(!*obuf)
		return 1;

	l2 = (char)((1<<1)|1);
	l4 = (char)((l2<<2)|l2);
	l6 = (char)((l4<<2)|l2);

	k = 0;
	for(i=0; i<ilen; i+=3){
		o[0] = (char)((ibuf[i]>>2)&l6);
		o[1] = (char)(((ibuf[i]&l2)<<4)|
					(i+1<ilen?((ibuf[i+1]>>4)&l4):0));
		o[2] = (char)((i+1<ilen?((ibuf[i+1]&l4)<<2)|
					(i+2<ilen?(ibuf[i+2]>>6)&l2:0):64));
		o[3] = (char)((i+2<ilen?ibuf[i+2]&l6:64));
		for(j=0; j<4; j++){
			c = o[j];
			*p++ = (char)(c + (c<26?'A':
					  (c<52?'a'-26:
					  (c<62?'0'-52:
					  (c<63?'+'-c:
					  (c<64?'/'-c:'='-c))))));
			k++;
			if(ncols && !(k%ncols))
				*p++ = '\n';
		}
	}
	*p = 0;
	if(olen)
		*olen = l;

	return 0;
}

int
base64decode(char *ibuf, unsigned int ilen, char **obuf, unsigned int *olen)
{
	unsigned int	i, j, k;
	char		c[4], ch, l2, l4, l6, *p;

	if(!ibuf || !ilen || !obuf || !olen)
		return 1;

	/*
	*olen = (ilen-ilen/77)/4*3;
	for(i=0; i<3; i++){
		if(ibuf[ilen-i-1] != '=')
			break;
	}
	*olen -= i;
	*/
	*olen = ilen;
	*obuf = p = (char *)malloc(*olen+1);
	if(!*obuf){
		*olen = 0;
		return 1;
	}

	l2 = (char)((1<<1)|1);
	l4 = (char)((l2<<2)|l2);
	l6 = (char)((l4<<2)|l2);

	k = 0;
	for(i=0; i<ilen; ){
		for(j=0; j<4; j++){
			ch = 0;
			for(; i<ilen; ){
				ch = ibuf[i++];
				if((ch>='A'&&ch<='Z')||
				   (ch>='a'&&ch<='z')||
				   (ch>='0'&&ch<='9')||
				    ch=='+'||ch=='/'||ch=='=')
					break;
			}
			if(i == ilen && !j)
				break;
			c[j] = (char)(ch + (ch>='A'&&ch<='Z'?-'A':
					   (ch>='a'&&ch<='z'?-'a'+26:
					   (ch>='0'&&ch<='9'?-'0'+52:
					   (ch=='+'?-ch+62:
					   (ch=='/'?-ch+63:-ch+64))))));
		}
		if(!j)
			break;
		*p++ = (char)((c[0]<<2)|((c[1]>>4)&l2));
		if(c[2] == 64)
			break;
		*p++ = (char)(((c[1]&l4)<<4)|((c[2]>>2)&l4));
		if(c[3] == 64)
			break;
		*p++ = (char)(((c[2]&l2)<<6)|c[3]);
	}
	*p = 0;
	*olen = p-*obuf;

	return 0;
}