85 lines
2.9 KiB
C++
85 lines
2.9 KiB
C++
/*
|
|
* Copyright (C) 2009 Apple, Inc. All rights reserved.
|
|
*
|
|
* This document is the property of Apple Inc.
|
|
* It is considered confidential and proprietary.
|
|
*
|
|
* This document may not be reproduced or transmitted in any form,
|
|
* in whole or in part, without the express written permission of
|
|
* Apple Inc.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
|
|
#include "sys.h"
|
|
#include "Buffer.h"
|
|
#include "Kernelcache.h"
|
|
#include "lib/cksum.h"
|
|
#include "lib/lzss.h"
|
|
|
|
/* Constant for the magic field of the mach_header (32-bit architectures) */
|
|
#define MH_MAGIC 0xfeedface /* the mach magic number */
|
|
#define MH_MAGIC_64 0xfeedfacf /* the 64-bit mach magic number */
|
|
|
|
struct compressed_kernel_header {
|
|
uint32_t signature;
|
|
uint32_t compress_type;
|
|
uint32_t adler32;
|
|
uint32_t uncompressed_size;
|
|
uint32_t compressed_size;
|
|
uint32_t reserved[11];
|
|
uint8_t platform_name[64];
|
|
uint8_t root_path[256];
|
|
uint8_t data[];
|
|
} __attribute__((packed));
|
|
|
|
bool DecompressKernelcache(const Buffer &kernelcache, Buffer *ret_macho) {
|
|
if (kernelcache.size() < sizeof(compressed_kernel_header)) {
|
|
fprintf(stderr, "Runt image (only %u bytes)\n",
|
|
(unsigned) kernelcache.size());
|
|
return false;
|
|
}
|
|
compressed_kernel_header *header =
|
|
(compressed_kernel_header *) kernelcache.buf();
|
|
if (ntohl(header->signature) != 'comp' ||
|
|
ntohl(header->compress_type) != 'lzss') {
|
|
fprintf(stderr, "File does not contain a compressed kernelcache\n");
|
|
return false;
|
|
}
|
|
fprintf(stderr, "Found compressed kernelcache header\n");
|
|
uint32_t decompressed_size = ntohl(header->uncompressed_size);
|
|
uint32_t compressed_size = ntohl(header->compressed_size);
|
|
if (compressed_size + sizeof(compressed_kernel_header) > kernelcache.size()) {
|
|
fprintf(stderr, "Compressed image size (%u) greater than image (%u)\n",
|
|
(unsigned) compressed_size,
|
|
(unsigned) (kernelcache.size() - sizeof(compressed_kernel_header)));
|
|
return false;
|
|
}
|
|
fprintf(stderr, "Decompress %u -> %u\n", compressed_size, decompressed_size);
|
|
Buffer decompressed;
|
|
decompressed.alloc(decompressed_size);
|
|
uint32_t actual_size = decompress_lzss((uint8_t *) decompressed.buf(),
|
|
decompressed.size(),
|
|
(uint8_t *) &header->data[0],
|
|
compressed_size);
|
|
if (actual_size != decompressed.size()) {
|
|
fprintf(stderr, "Decompressed size mismatch, expected %u got %u\n",
|
|
(unsigned) decompressed.size(), (unsigned) actual_size);
|
|
return false;
|
|
}
|
|
if (adler32((const uint8_t *) decompressed.buf(),
|
|
decompressed_size) != ntohl(header->adler32)) {
|
|
fprintf(stderr, "Adler32 mismatch\n");
|
|
return false;
|
|
}
|
|
uint32_t macho_got_magic;
|
|
memcpy(&macho_got_magic, decompressed.buf(), 4);
|
|
if (macho_got_magic != MH_MAGIC && macho_got_magic != MH_MAGIC_64) {
|
|
fprintf(stderr, "Decompressed kernelcache not in Mach-O format\n");
|
|
return false;
|
|
}
|
|
decompressed.swap(ret_macho);
|
|
return true;
|
|
}
|