#include <libgen.h>
#include <string.h>

char* dirname(char* s) {
    size_t i;
    if (!s || !*s)
        return (char*)".";
    i = strlen(s) - 1;
    for (; s[i] == '/'; i--)
        if (!i)
            return (char*)"/";
    for (; s[i] != '/'; i--)
        if (!i)
            return (char*)".";
    for (; s[i] == '/'; i--)
        if (!i)
            return (char*)"/";
    s[i + 1] = 0;
    return s;
}