#include "util.h"

void*
checkp(void *p)
{
	if (!p) die("pointer assertion failed, OOM?\n");
	return p;
}

void*
die(const char *fmtstr, ...)
{
	va_list ap;

	va_start(ap, fmtstr);
	vfprintf(stderr, fmtstr, ap);
	va_end(ap);

	exit(EXIT_FAILURE);
}

char*
aprintf(const char *fmtstr, ...)
{
	va_list ap, cpy;
	size_t nb;
	char *str;

	va_copy(cpy, ap);

	va_start(cpy, fmtstr);
	nb = vsnprintf(NULL, 0, fmtstr, ap);
	va_end(cpy);

	if (nb <= 0) die("encountered invalid fmtstr!\n");

	str = checkp(malloc(nb));
	va_start(ap, fmtstr);
	nb = vsnprintf(str, nb, fmtstr, ap);
	va_end(ap);

	return str;
}

const char*
mhash(const char *filename, int len)
{
	static const char *hexalph = "0123456789ABCDEF";
	static char buf[33];
	int i, k;

	if (len == -1) len = strlen(filename);

	for (i = 0; i < MIN(32, len); i++) {
		unsigned char v = 0;
		for (k = i; k < len; k += 32)
			v ^= filename[k];
		buf[i*2+0] = hexalph[(v >> 0) & 0x0f];
		buf[i*2+1] = hexalph[(v >> 4) & 0x0f];
	}

	if (i == 0) {
		memset(buf, '0', 32);
	} else if (i < 32) {
		for (k = 0; k < 32; k++)
			buf[k] = buf[k % i];
	}

	buf[32] = '\0';

	return buf;
}