#include <str_util.h>


const char* str_util_strnstr(const char* haystack, const char* needle, os_size_t needle_len) {
    if (needle_len == 0) return (char*)haystack;
    if (!haystack || !needle || haystack[0]=='\0') return NULL;

    os_size_t haystack_len = strlen(haystack);
    if (haystack_len < needle_len) return NULL;

    for (os_size_t i = 0; i <= haystack_len - needle_len; i++) {
        if (memcmp(haystack + i, needle, needle_len) == 0) {
            return haystack + i;
        }
    }
    return NULL;
}

const char* str_util_strstr(const char* haystack, const char* needle) {
    if (!haystack || !needle || haystack[0]=='\0' || needle[0]=='\0') return NULL;

    os_size_t needle_len = strlen(needle);
    os_size_t haystack_len = strlen(haystack);
    if (haystack_len < needle_len) return NULL;

    for (os_size_t i = 0; i <= haystack_len - needle_len; i++) {
        if (memcmp(haystack + i, needle, needle_len) == 0) {
            return haystack + i;
        }
    }
    return NULL;
}