/* SPDX-License-Identifier: BSD-3-Clause */
/* Copyright (c) 2026 Open-IOV contributors */
/* scan3.c - scan all writable memory of a process for qwords equal to any
   of the given 64-bit needles; print every hit address.
   usage: scan3 PID 0xNEEDLE [0xNEEDLE ...] */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <fcntl.h>
#include <unistd.h>

#define MAXR 4096
#define MAXN 64
static struct { uint64_t lo, hi; } wr[MAXR];
static int nwr;
static uint64_t needle[MAXN];
static int nn;

static void load_maps(int pid)
{
    char path[64], line[1024];
    snprintf(path, sizeof path, "/proc/%d/maps", pid);
    FILE *f = fopen(path, "r");
    if (!f) { perror("maps"); exit(1); }
    while (fgets(line, sizeof line, f)) {
        uint64_t lo, hi;
        char perms[16];
        if (sscanf(line, "%lx-%lx %15s", &lo, &hi, perms) < 3) continue;
        if (strchr(perms, 'w') && nwr < MAXR) { wr[nwr].lo = lo; wr[nwr].hi = hi; nwr++; }
    }
    fclose(f);
}

int main(int argc, char **argv)
{
    if (argc < 3) { fprintf(stderr, "usage: scan3 PID 0xNEEDLE [...]\n"); return 1; }
    int pid = atoi(argv[1]);
    for (int i = 2; i < argc && nn < MAXN; i++)
        needle[nn++] = strtoull(argv[i], 0, 16);
    load_maps(pid);
    printf("writable=%d needles=%d\n", nwr, nn);

    char mp[64];
    snprintf(mp, sizeof mp, "/proc/%d/mem", pid);
    int fd = open(mp, O_RDONLY);
    if (fd < 0) { perror("mem"); return 1; }

    size_t CH = 4 << 20;
    uint8_t *buf = malloc(CH + 64);
    int hits = 0;
    for (int r = 0; r < nwr; r++) {
        uint64_t a = wr[r].lo;
        while (a < wr[r].hi) {
            size_t n = (size_t)((wr[r].hi - a) < CH ? (wr[r].hi - a) : CH);
            ssize_t got = pread(fd, buf, n, (off_t)a);
            if (got <= 0) {
                if (n > (256u << 10)) { n = 256u << 10; continue; }
                a += 4096; continue;
            }
            if ((size_t)got < n) n = got;
            n -= n % 8;
            uint64_t *w = (uint64_t *)buf;
            for (size_t i = 0; i < n / 8; i++) {
                uint64_t v = w[i];
                for (int k = 0; k < nn; k++) {
                    if (v == needle[k]) {
                        printf("hit 0x%lx = 0x%lx\n", a + i * 8, v);
                        hits++;
                    }
                }
            }
            a += n;
        }
    }
    printf("hits=%d\n", hits);
    return 0;
}