#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <stddef.h>

int scandir(const char *path, struct dirent ***res,
        int (*sel)(const struct dirent *),
        int (*cmp)(const struct dirent **, const struct dirent **))
{
        DIR *d;
        struct dirent *de, **names=0, **tmp;
        size_t cnt=0, len=0;
        int old_errno = errno;
        d = opendir(path);

        if (!d) return -1;

        while ((errno=0), (de = readdir(d))) {
                if (sel && !sel(de)) continue;
                if (cnt >= len) {
                        len = 2*len+1;
                        if (len > SIZE_MAX/sizeof *names) break;
                        tmp = realloc(names, len * sizeof *names);
                        if (!tmp) break;
                        names = tmp;
                }
                names[cnt] = malloc(de->d_reclen);
                if (!names[cnt]) break;
                memcpy(names[cnt++], de, de->d_reclen);
        }

        closedir(d);

        if (errno) {
                if (names) while (cnt-->0) free(names[cnt]);
                free(names);
                return -1;
        }
        errno = old_errno;

        if (cmp) qsort(names, cnt, sizeof *names, (int (*)(const void *, const void *))cmp);
        *res = names;
        return cnt;
}