github.com/afumu/libc@v0.0.6/musl/src/network/dn_expand.c (about)

     1  #include <resolv.h>
     2  
     3  int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
     4  {
     5  	const unsigned char *p = src;
     6  	char *dend, *dbegin = dest;
     7  	int len = -1, i, j;
     8  	if (p==end || space <= 0) return -1;
     9  	dend = dest + (space > 254 ? 254 : space);
    10  	/* detect reference loop using an iteration counter */
    11  	for (i=0; i < end-base; i+=2) {
    12  		/* loop invariants: p<end, dest<dend */
    13  		if (*p & 0xc0) {
    14  			if (p+1==end) return -1;
    15  			j = ((p[0] & 0x3f) << 8) | p[1];
    16  			if (len < 0) len = p+2-src;
    17  			if (j >= end-base) return -1;
    18  			p = base+j;
    19  		} else if (*p) {
    20  			if (dest != dbegin) *dest++ = '.';
    21  			j = *p++;
    22  			if (j >= end-p || j >= dend-dest) return -1;
    23  			while (j--) *dest++ = *p++;
    24  		} else {
    25  			*dest = 0;
    26  			if (len < 0) len = p+1-src;
    27  			return len;
    28  		}
    29  	}
    30  	return -1;
    31  }
    32  
    33  weak_alias(__dn_expand, dn_expand);