#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char **argv) {
    const char *path = argc > 1 ? argv[1] : "/boot";
    int fd = open(path, O_RDONLY);
    if (fd < 0) { perror("open"); return 1; }
    static char buf[262144];
    ssize_t tot = 0, n;
    while (tot < (ssize_t)sizeof(buf) && (n = read(fd, buf + tot, sizeof(buf) - tot)) > 0) tot += n;
    printf("total read = %zd\n", tot);
    int hits = 0;
    for (ssize_t i = 0; i + 12 <= tot; i++)
        if (memcmp(buf + i, "ZZsecretsalt", 12) == 0) { hits++; printf("RESIDUE 'ZZsecretsalt' at raw offset %zd\n", i); }
    printf("residue hits = %d\n", hits);
    /* parse dirents: fileno u32, reclen u16, namlen u8, type u8, name */
    long off = 0; int cnt = 0;
    while (off + 8 <= tot && cnt < 400) {
        unsigned char *d = (unsigned char*)buf + off;
        unsigned short reclen = d[4] | (d[5] << 8);
        unsigned char namlen = d[6];
        if (reclen < 8 || (reclen & 3) || off + reclen > tot) break;
        char name[300]; int cp = namlen < 299 ? namlen : 299;
        memcpy(name, d + 8, cp); name[cp] = 0;
        int used = 8 + ((cp + 1 + 3) & ~3);
        if (reclen > used + 3) {
            int nz = 0; for (int j = used; j < reclen; j++) if (d[j]) nz++;
            if (nz) printf("dirent off=%ld name='%s' reclen=%u slack_nz_bytes=%d:", off, name, reclen, nz);
            else printf("dirent off=%ld name='%s' reclen=%u slack=zero\n", off, name, reclen);
            if (nz) { for (int j = used; j < reclen && j < used + 28; j++) printf(" %02x", d[j]); printf("\n"); }
        } else
            printf("dirent off=%ld name='%s' reclen=%u\n", off, name, reclen);
        off += reclen; cnt++;
    }
    close(fd); return 0;
}