Extract ForFan Android HU update files

forfan_upd_extractor.c

#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>

static void *mmap_file(const char *file_path) {
    int fd = open(file_path, O_RDONLY);
    if (fd == -1) {
        printf("open failed: %s\n", strerror(errno));
        return NULL;
    }

    struct stat st;
    if (fstat(fd, &st) == -1) {
        printf("fstat failed: %s\n", strerror(errno));
        close(fd);
        return NULL;
    }

    void *addr = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (addr == MAP_FAILED) {
        printf("mmap failed: %s\n", strerror(errno));
        close(fd);
        return NULL;
    }

    close(fd);

    return addr;
}

static void munmap_file(const char *file_path, void *addr) {
    int fd = open(file_path, O_RDONLY);
    if (fd == -1) {
        printf("open failed: %s\n", strerror(errno));
        return;
    }

    struct stat st;
    if (fstat(fd, &st) == -1) {
        printf("fstat failed: %s\n", strerror(errno));
        close(fd);
        return;
    }

    if (munmap(addr, st.st_size) == -1) {
        printf("munmap failed: %s\n", strerror(errno));
        close(fd);
        return;
    }

    close(fd);
}

static void write_to_file(uint8_t *buf, size_t len, const char *file_path) {
    int fd = open(file_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd == -1) {
        printf("open failed: %s\n", strerror(errno));
        return;
    }

    if (write(fd, buf, len) == -1) {
        printf("write failed: %s\n", strerror(errno));
        close(fd);
        return;
    }

    close(fd);
}

int main() {
    printf("ForFan .upd extractor v1.0 by Iscle\n");

    char *file_path = "/mnt/d/Users/Iscle/Downloads/8667Q军灿UI02-国外-VHD720x1280_v11_20211207/8667.bin";

    uint8_t *addr = mmap_file(file_path);
    if (addr == NULL) {
        return 1;
    }

    uint64_t total_size = (uint64_t) addr[7] << 56 |
                          (uint64_t) addr[6] << 48 |
                          (uint64_t) addr[5] << 40 |
                          (uint64_t) addr[4] << 32 |
                          (uint64_t) addr[3] << 24 |
                          (uint64_t) addr[2] << 16 |
                          (uint64_t) addr[1] << 8 |
                          (uint64_t) addr[0];
    printf("Total size: %lu bytes\n", total_size);

    printf("\nPartitions:\n");

    uint64_t current_offset = 0x908;

    for (size_t i = 0; i < 15; i++) {
        uint8_t *base = addr + 0x08 + (i * 0x48);
        char fileName[0x30];
        memcpy(fileName, base, sizeof(fileName));
        char name[0x10];
        memcpy(name, base + 0x30, sizeof(name));
        uint32_t size = (uint32_t) base[0x43] << 24 |
                        (uint32_t) base[0x42] << 16 |
                        (uint32_t) base[0x41] << 8 |
                        (uint32_t) base[0x40];

        uint32_t flags = (uint32_t) base[0x47] << 24 |
                         (uint32_t) base[0x46] << 16 |
                         (uint32_t) base[0x45] << 8 |
                         (uint32_t) base[0x44];

        printf("%s: %s (%u bytes), flags: 0x%08X, offset: 0x%lX\n", name, fileName, size, flags, current_offset);

        if (size == 0) continue;

        char out_file_path[0x100];
        sprintf(out_file_path, "/mnt/d/Users/Iscle/Downloads/8667Q军灿UI02-国外-VHD720x1280_v11_20211207/out/%s", fileName);
        write_to_file(addr + current_offset, size, out_file_path);

        current_offset += size;
    }

    munmap_file(file_path, addr);

    return 0;
}