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/* Copyright 2013 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
#define _BSD_SOURCE
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#include <endian.h>
#include <fcntl.h>
#include <unistd.h>
#include <zlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#define RG_MAGIC 0xFEEDBABE
#define HEADER_SIZE ( sizeof(uint32_t) * 5 + 0x80 )
struct File {
uint32_t magic; /* FEEDBABE */
uint32_t size; /* Length of file excluding header */
uint32_t checksum; /* 32-bit sum of all bytes in file and header, excluding checksum */
uint32_t counter; /* Unknown */
uint32_t start_offset; /* Unknown */
char name[0x80]; /* Filename */
uint8_t *data; /* Pointer to mmap'd or allocated data of file */
uint32_t decompressed_size; /* Decompressed length of file */
uint8_t *decompressed_data; /* Pointer to allocated decompressed data */
};
uint8_t* decompress_data(uint8_t *data, uint32_t compressed_length, uint32_t decompressed_length)
{
uint8_t *decompressed_data;
z_stream strm;
decompressed_data = malloc(decompressed_length);
if (!decompressed_data)
return NULL;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.avail_in = compressed_length;
strm.next_in = data;
strm.avail_out = decompressed_length;
strm.next_out = decompressed_data;
if (inflateInit(&strm) != Z_OK) {
fprintf(stderr, "inflateInit: %s\n", strm.msg);
goto error;
}
if (inflate(&strm, Z_SYNC_FLUSH) != Z_STREAM_END) {
fprintf(stderr, "inflate: %s\n", strm.msg);
goto error;
}
goto out;
error:
free(decompressed_data);
decompressed_data = NULL;
out:
inflateEnd(&strm);
return decompressed_data;
}
void free_file(struct File *file)
{
if (file->decompressed_data)
free(file->decompressed_data);
}
uint32_t checksum(uint8_t *data, uint32_t length)
{
uint32_t sum = 0;
while (length--) {
/* The checksum does not include itself, so we skip that field. */
if (length >= 8 && length < 12)
continue;
sum += data[length];
}
return sum;
}
bool read_file(uint8_t *data, struct File *file)
{
uint32_t *packed_integers = (uint32_t *)data;
file->magic = be32toh(packed_integers[0]);
file->size = be32toh(packed_integers[1]);
file->checksum = be32toh(packed_integers[2]);
file->counter = be32toh(packed_integers[3]);
file->start_offset = be32toh(packed_integers[4]);
memcpy(&file->name, &packed_integers[5], sizeof(file->name));
file->name[0x7f] = '\0';
file->data = data + HEADER_SIZE;
file->decompressed_data = NULL;
file->decompressed_size = 0;
if (!strcmp(file->name, "rg_conf")) {
/* When the file is gzipped, the length of the decompressed file is
* the first four bytes in big endian. */
file->decompressed_size = be32toh(*((uint32_t *)file->data));
file->decompressed_data = decompress_data(file->data + sizeof(uint32_t), file->size - sizeof(uint32_t), file->decompressed_size);
if (!file->decompressed_data)
file->decompressed_size = 0;
}
return file->magic == RG_MAGIC && file->checksum == checksum(data, HEADER_SIZE + file->size);
}
void print_file(struct File *file, bool valid)
{
printf("==== %s (%s) ====\n", file->name, valid ? "Valid Checksum" : "INVALID CHECKSUM");
printf("Length: %u bytes\n", file->size);
if (file->decompressed_size)
printf("Decompressed Length: %u bytes\n", file->decompressed_size);
}
void save_file(struct File *file, bool valid, uint32_t offset)
{
char filename[0x100];
char *slash;
int fd;
sprintf(filename, "%#.8x-%s%s", offset, file->name, valid ? "" : ".corrupt");
for (slash = filename; (slash = strchr(slash, '/')) != NULL; ++slash)
*slash = '_';
printf("Saving to: %s\n", filename);
fd = creat(filename, S_IRUSR | S_IWUSR);
if (fd < 0) {
perror("creat");
exit(EXIT_FAILURE);
}
if (file->decompressed_size) {
if (write(fd, file->decompressed_data, file->decompressed_size) < 0) {
perror("write");
exit(EXIT_FAILURE);
}
} else {
if (write(fd, file->data, file->size) < 0) {
perror("write");
exit(EXIT_FAILURE);
}
}
close(fd);
}
int main(int argc, char *argv[])
{
int fd;
bool valid;
uint8_t *data, *next;
struct stat sbuf;
uint32_t needle;
struct File file;
if (argc != 2) {
fprintf(stderr, "Usage: %s image_filename\n", argv[0]);
return EXIT_FAILURE;
}
fd = open(argv[1], 0, O_RDONLY);
if (fd < 0) {
perror("open");
return EXIT_FAILURE;
}
if (fstat(fd, &sbuf)) {
perror("fstat");
return EXIT_FAILURE;
}
data = mmap(NULL, sbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (data == MAP_FAILED) {
perror("mmap");
return EXIT_FAILURE;
}
needle = htobe32(RG_MAGIC);
next = data;
for (;;) {
next = memmem(next, sbuf.st_size - (next - data), &needle, sizeof(needle));
if (!next)
break;
valid = read_file(next, &file);
print_file(&file, valid);
save_file(&file, valid, (uint32_t)(next - data));
free_file(&file);
printf("\n");
++next;
}
munmap(data, sbuf.st_size);
close(fd);
return EXIT_SUCCESS;
}
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