kern/src/strstr.c

//INFERNO
#include <string.h>

/*
 * Return pointer to first occurrence of s2 in s1,
 * 0 if none
 */
char *strstr(char *s1, char *s2)
{
	char *p;
	int f, n;

	f = s2[0];
	if (f == 0)
		return s1;
	n = strlen(s2);
	for (p = strchr(s1, f); p; p = strchr(p + 1, f))
		if (strncmp(p, s2, n) == 0)
			return p;
	return 0;
}

/* Case insensitive strcmp */
int cistrcmp(char *s1, char *s2)
{
	int c1, c2;

	while (*s1) {
		c1 = *(uint8_t *) s1++;
		c2 = *(uint8_t *) s2++;

		if (c1 == c2)
			continue;

		if (c1 >= 'A' && c1 <= 'Z')
			c1 -= 'A' - 'a';

		if (c2 >= 'A' && c2 <= 'Z')
			c2 -= 'A' - 'a';

		if (c1 != c2)
			return c1 - c2;
	}
	return -*s2;
}