376 lines
7.3 KiB
C
376 lines
7.3 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#define IMG_SIZE 0x3e0000
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#define KERNEL_START 0x020000
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#define KERNEL_SIZE 0x0b0000
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#define ROOTFS_START 0x0d0000
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#define ROOTFS_SIZE 0x30ffb2
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char* app_name;
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void print_usage(void)
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{
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fprintf(stderr, "usage: dgfirmware [<opts>] <img>\n");
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fprintf(stderr, " <img> firmware image filename\n");
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fprintf(stderr, " <opts> -h print this message\n");
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fprintf(stderr, " -f fix the checksum\n");
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fprintf(stderr, " -x <file> extract the rootfs file to <file>\n");
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fprintf(stderr, " -xk <file> extract the kernel to <file>\n");
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fprintf(stderr, " -m <file> merge in rootfs fil\e from <file>\n");
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fprintf(stderr, " -k <file> merge in kernel from <file>\n");
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fprintf(stderr, " -w <file> write back the modified firmware\n");
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}
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unsigned char* read_img(const char *fname)
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{
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FILE *fp;
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int size;
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unsigned char *img;
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fp = fopen(fname, "rb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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fseek(fp, 0, SEEK_END);
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size = ftell(fp);
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if (size != IMG_SIZE) {
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fprintf(stderr, "%s: image file has wrong size\n", app_name);
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fclose(fp);
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exit(-1);
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}
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rewind(fp);
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img = malloc(IMG_SIZE);
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if (img == NULL) {
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perror(app_name);
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fclose(fp);
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exit(-1);
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}
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if (fread(img, 1, IMG_SIZE, fp) != IMG_SIZE) {
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fprintf(stderr, "%s: can't read image file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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fclose(fp);
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return img;
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}
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void write_img(unsigned char* img, const char *fname)
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{
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FILE *fp;
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fp = fopen(fname, "wb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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if (fwrite(img, 1, IMG_SIZE, fp) != IMG_SIZE) {
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fprintf(stderr, "%s: can't write image file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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}
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void write_rootfs(unsigned char* img, const char *fname)
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{
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FILE *fp;
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fp = fopen(fname, "wb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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if (fwrite(img+ROOTFS_START, 1, ROOTFS_SIZE, fp) != ROOTFS_SIZE) {
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fprintf(stderr, "%s: can't write image file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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}
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void write_kernel(unsigned char* img, const char *fname)
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{
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FILE *fp;
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fp = fopen(fname, "wb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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if (fwrite(img+KERNEL_START, 1, KERNEL_SIZE, fp) != KERNEL_SIZE) {
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fprintf(stderr, "%s: can't write kernel file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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}
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unsigned char* read_rootfs(unsigned char* img, const char *fname)
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{
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FILE *fp;
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int size;
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int i;
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for (i=ROOTFS_START; i<ROOTFS_START+ROOTFS_SIZE; i++)
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img[i] = 0xff;
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fp = fopen(fname, "rb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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fseek(fp, 0, SEEK_END);
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size = ftell(fp);
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if (size > ROOTFS_SIZE) {
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fprintf(stderr, "%s: rootfs image file is too big\n", app_name);
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fclose(fp);
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exit(-1);
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}
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rewind(fp);
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if (fread(img+ROOTFS_START, 1, size, fp) != size) {
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fprintf(stderr, "%s: can't read rootfs image file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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fclose(fp);
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return img;
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}
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unsigned char* read_kernel(unsigned char* img, const char *fname)
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{
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FILE *fp;
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int size;
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int i;
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for (i=KERNEL_START; i<KERNEL_START+KERNEL_SIZE; i++)
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img[i] = 0xff;
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fp = fopen(fname, "rb");
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if (fp == NULL) {
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perror(app_name);
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exit(-1);
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}
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fseek(fp, 0, SEEK_END);
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size = ftell(fp);
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if (size > KERNEL_SIZE) {
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fprintf(stderr, "%s: kernel binary file is too big\n", app_name);
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fclose(fp);
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exit(-1);
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}
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rewind(fp);
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if (fread(img+KERNEL_START, 1, size, fp) != size) {
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fprintf(stderr, "%s: can't read kernel file\n", app_name);
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fclose(fp);
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exit(-1);
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}
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fclose(fp);
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return img;
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}
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int get_checksum(unsigned char* img)
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{
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short unsigned s;
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s = img[0x3dfffc] + (img[0x3dfffd]<<8);
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return s;
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}
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void set_checksum(unsigned char*img, unsigned short sum)
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{
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img[0x3dfffc] = sum & 0xff;
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img[0x3dfffd] = (sum>>8) & 0xff;
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}
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int compute_checksum(unsigned char* img)
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{
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int i;
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short s=0;
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for (i=0; i<0x3dfffc; i++)
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s += img[i];
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return s;
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}
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int main(int argc, char* argv[])
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{
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char *img_fname = NULL;
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char *rootfs_fname = NULL;
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char *kernel_fname = NULL;
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char *new_img_fname = NULL;
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int do_fix_checksum = 0;
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int do_write = 0;
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int do_write_rootfs = 0;
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int do_read_rootfs = 0;
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int do_write_kernel = 0;
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int do_read_kernel = 0;
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int i;
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unsigned char *img;
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unsigned short img_checksum;
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unsigned short real_checksum;
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app_name = argv[0];
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for (i=1; i<argc; i++) {
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if (!strcmp(argv[i], "-h")) {
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print_usage();
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return 0;
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}
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else if (!strcmp(argv[i], "-f")) {
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do_fix_checksum = 1;
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}
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else if (!strcmp(argv[i], "-x")) {
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if (i+1 >= argc) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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do_write_rootfs = 1;
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rootfs_fname = argv[i+1];
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i++;
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}
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else if (!strcmp(argv[i], "-xk")) {
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if (i+1 >= argc) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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do_write_kernel = 1;
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kernel_fname = argv[i+1];
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i++;
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}
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else if (!strcmp(argv[i], "-m")) {
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if (i+1 >= argc) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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do_read_rootfs = 1;
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rootfs_fname = argv[i+1];
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i++;
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}
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else if (!strcmp(argv[i], "-k")) {
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if (i+1 >= argc) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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do_read_kernel = 1;
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kernel_fname = argv[i+1];
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i++;
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}
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else if (!strcmp(argv[i], "-w")) {
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if (i+1 >= argc) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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do_write = 1;
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new_img_fname = argv[i+1];
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i++;
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}
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else if (img_fname != 0) {
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fprintf(stderr, "%s: too many arguments\n", app_name);
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return -1;
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}
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else {
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img_fname = argv[i];
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}
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}
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if (img_fname == NULL) {
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fprintf(stderr, "%s: missing argument\n", app_name);
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return -1;
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}
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if ((do_read_rootfs && do_write_rootfs) ||
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(do_read_kernel && do_write_kernel)) {
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fprintf(stderr, "%s: conflictuous options\n", app_name);
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return -1;
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}
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printf ("** Read firmware file\n");
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img = read_img(img_fname);
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printf ("Firmware product: %s\n", img+0x3dffbd);
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printf ("Firmware version: 1.%02d.%02d\n", (img[0x3dffeb] & 0x7f), img[0x3dffec]);
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if (do_write_rootfs) {
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printf ("** Write rootfs file\n");
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write_rootfs(img, rootfs_fname);
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}
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if (do_write_kernel) {
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printf ("** Write kernel file\n");
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write_kernel(img, kernel_fname);
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}
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if (do_read_rootfs) {
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printf ("** Read rootfs file\n");
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read_rootfs(img, rootfs_fname);
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do_fix_checksum = 1;
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}
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if (do_read_kernel) {
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printf ("** Read kernel file\n");
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read_kernel(img, kernel_fname);
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do_fix_checksum = 1;
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}
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img_checksum = get_checksum(img);
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real_checksum = compute_checksum(img);
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printf ("image checksum = %04x\n", img_checksum);
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printf ("real checksum = %04x\n", real_checksum);
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if (do_fix_checksum) {
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if (img_checksum != real_checksum) {
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printf ("** Bad Checksum, fix it\n");
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set_checksum(img, real_checksum);
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}
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else {
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printf ("** Checksum is correct, good\n");
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}
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}
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if (do_write) {
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printf ("** Write image file\n");
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write_img(img, new_img_fname);
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}
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free(img);
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return 0;
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}
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