1 /*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "host/commands/launch/boot_image_unpacker.h"
18
19 #include <string.h>
20 #include <unistd.h>
21
22 #include <sstream>
23
24 #include <glog/logging.h>
25
26 #include "common/libs/utils/subprocess.h"
27 #include "host/commands/launch/bootimg.h"
28
29 namespace cvd {
30
31 namespace {
32
33 // Extracts size bytes from file, starting at offset bytes from the beginning to
34 // path.
ExtractFile(SharedFD source,off_t offset,size_t size,const std::string & path)35 bool ExtractFile(SharedFD source, off_t offset, size_t size,
36 const std::string& path) {
37 auto dest = SharedFD::Open(path.c_str(), O_CREAT | O_RDWR, 0755);
38 if (!dest->IsOpen()) {
39 LOG(ERROR) << "Unable to open " << path;
40 return false;
41 }
42 auto off = source->LSeek(offset, SEEK_SET);
43 if (off != offset) {
44 LOG(ERROR) << "Failed to lseek: " << source->StrError();
45 return false;
46 }
47 return dest->CopyFrom(*source, size);
48 }
49 } // namespace
50
FromImage(const std::string & path)51 std::unique_ptr<BootImageUnpacker> BootImageUnpacker::FromImage(
52 const std::string& path) {
53 auto boot_img = SharedFD::Open(path.c_str(), O_RDONLY);
54 if (!boot_img->IsOpen()) {
55 LOG(ERROR) << "Unable to open boot image (" << path
56 << "): " << boot_img->StrError();
57 return nullptr;
58 }
59 boot_img_hdr header;
60 auto bytes_read = boot_img->Read(&header, sizeof(header));
61 if (bytes_read != sizeof(header)) {
62 LOG(ERROR) << "Error reading boot image header";
63 return nullptr;
64 }
65
66 std::ostringstream cmdline;
67 cmdline << reinterpret_cast<char*>(&header.cmdline[0]);
68 if (header.extra_cmdline[0] != '\0') {
69 cmdline << " ";
70 cmdline << reinterpret_cast<char*>(&header.extra_cmdline[0]);
71 }
72
73 uint32_t page_size = header.page_size;
74 // See system/core/mkbootimg/include/mkbootimg/bootimg.h for the origin of
75 // these offset calculations
76 uint32_t kernel_offset = page_size;
77 uint32_t ramdisk_offset =
78 kernel_offset +
79 ((header.kernel_size + page_size - 1) / page_size) * page_size;
80
81 std::unique_ptr<BootImageUnpacker> ret(new BootImageUnpacker(
82 boot_img, cmdline.str(), header.kernel_size, kernel_offset,
83 header.ramdisk_size, ramdisk_offset));
84
85 return ret;
86 }
87
kernel_cmdline() const88 std::string BootImageUnpacker::kernel_cmdline() const {
89 return kernel_cmdline_;
90 }
91
ExtractKernelImage(const std::string & path) const92 bool BootImageUnpacker::ExtractKernelImage(const std::string& path) const {
93 if (kernel_image_size_ == 0) return false;
94 return ExtractFile(boot_image_, kernel_image_offset_, kernel_image_size_,
95 path);
96 }
ExtractRamdiskImage(const std::string & path) const97 bool BootImageUnpacker::ExtractRamdiskImage(const std::string& path) const {
98 if (ramdisk_image_size_ == 0) return false;
99 return ExtractFile(boot_image_, ramdisk_image_offset_, ramdisk_image_size_,
100 path);
101 }
102
Unpack(const std::string & ramdisk_image_path,const std::string & kernel_image_path)103 bool BootImageUnpacker::Unpack(const std::string& ramdisk_image_path,
104 const std::string& kernel_image_path) {
105 if (HasRamdiskImage()) {
106 if (!ExtractRamdiskImage(ramdisk_image_path)) {
107 LOG(ERROR) << "Error extracting ramdisk from boot image";
108 return false;
109 }
110 }
111 if (!kernel_image_path.empty()) {
112 if (HasKernelImage()) {
113 if (!ExtractKernelImage(kernel_image_path)) {
114 LOG(ERROR) << "Error extracting kernel from boot image";
115 return false;
116 }
117 } else {
118 LOG(ERROR) << "No kernel found on boot image";
119 return false;
120 }
121 }
122 return true;
123 }
124
125 } // namespace cvd
126