oc::result<void> SonyElfFormatWriter::get_entry(File &file, Entry &entry)
{
OUTCOME_TRYV(m_seg->get_entry(file, entry, m_writer));
auto swentry = m_seg->entry();
// Silently handle cmdline entry
if (swentry->type == SONY_ELF_ENTRY_CMDLINE) {
entry.clear();
entry.set_size(m_cmdline.size());
auto set_as_fatal = finally([&] {
m_writer.set_fatal();
});
OUTCOME_TRYV(write_entry(file, entry));
OUTCOME_TRYV(write_data(file, m_cmdline.data(), m_cmdline.size()));
OUTCOME_TRYV(finish_entry(file));
OUTCOME_TRYV(get_entry(file, entry));
set_as_fatal.dismiss();
}
return oc::success();
}
oc::result<void> socket_write_string_array(int fd, const std::vector<std::string> &list)
{
if (list.size() > INT32_MAX) {
return std::errc::invalid_argument;
}
OUTCOME_TRYV(socket_write_int32(fd, static_cast<int32_t>(list.size())));
for (const std::string &str : list) {
OUTCOME_TRYV(socket_write_string(fd, str));
}
return oc::success();
}
oc::result<void> AndroidFormatWriter::finish_entry(File &file)
{
OUTCOME_TRYV(m_seg->finish_entry(file, m_writer));
auto swentry = m_seg->entry();
// Update SHA1 hash
uint32_t le32_size = mb_htole32(*swentry->size);
// Include size for everything except empty DT images
if ((swentry->type != ENTRY_TYPE_DEVICE_TREE || *swentry->size > 0)
&& !SHA1_Update(&m_sha_ctx, &le32_size, sizeof(le32_size))) {
m_writer.set_fatal();
return AndroidError::Sha1UpdateError;
}
switch (swentry->type) {
case ENTRY_TYPE_KERNEL:
m_hdr.kernel_size = *swentry->size;
break;
case ENTRY_TYPE_RAMDISK:
m_hdr.ramdisk_size = *swentry->size;
break;
case ENTRY_TYPE_SECONDBOOT:
m_hdr.second_size = *swentry->size;
break;
case ENTRY_TYPE_DEVICE_TREE:
m_hdr.dt_size = *swentry->size;
break;
}
return oc::success();
}
oc::result<void> LokiFormatReader::read_header(File &file, Header &header)
{
uint64_t kernel_offset;
uint64_t ramdisk_offset;
uint64_t dt_offset = 0;
uint32_t kernel_size;
uint32_t ramdisk_size;
// New-style images record the original values of changed fields in the
// Android header
if (m_loki_hdr.orig_kernel_size != 0
&& m_loki_hdr.orig_ramdisk_size != 0
&& m_loki_hdr.ramdisk_addr != 0) {
OUTCOME_TRYV(read_header_new(m_reader, file, m_hdr, m_loki_hdr, header,
kernel_offset, kernel_size,
ramdisk_offset, ramdisk_size,
dt_offset));
} else {
OUTCOME_TRYV(read_header_old(m_reader, file, m_hdr, m_loki_hdr, header,
kernel_offset, kernel_size,
ramdisk_offset, ramdisk_size));
}
std::vector<SegmentReaderEntry> entries;
entries.push_back({
ENTRY_TYPE_KERNEL, kernel_offset, kernel_size, false
});
entries.push_back({
ENTRY_TYPE_RAMDISK, ramdisk_offset, ramdisk_size, false
});
if (m_hdr.dt_size > 0 && dt_offset != 0) {
entries.push_back({
ENTRY_TYPE_DEVICE_TREE, dt_offset, m_hdr.dt_size, false
});
}
return m_seg->set_entries(std::move(entries));
}
oc::result<ArchRegs> read_regs(pid_t tid)
{
ArchRegs ar;
iovec iov;
iov.iov_base = &ar.m_regs;
iov.iov_len = sizeof(ar.m_regs);
OUTCOME_TRYV(detail::read_raw_regs(tid, iov));
ar.m_abi = NATIVE_ARCH_ABI;
return std::move(ar);
}
oc::result<void> socket_write_string(int fd, const std::string &str)
{
if (str.size() > INT32_MAX) {
return std::errc::invalid_argument;
}
OUTCOME_TRYV(socket_write_int32(fd, static_cast<int32_t>(str.size())));
OUTCOME_TRY(n, socket_write(fd, str.data(), str.size()));
if (n != str.size()) {
return std::errc::io_error;
}
return oc::success();
}
oc::result<void> socket_write_bytes(int fd, const void *data, size_t len)
{
if (len > INT32_MAX) {
return std::errc::invalid_argument;
}
OUTCOME_TRYV(socket_write_int32(fd, static_cast<int32_t>(len)));
OUTCOME_TRY(n, socket_write(fd, data, len));
if (n != len) {
return std::errc::io_error;
}
return oc::success();
}
oc::result<void> SonyElfFormatWriter::finish_entry(File &file)
{
OUTCOME_TRYV(m_seg->finish_entry(file, m_writer));
auto swentry = m_seg->entry();
switch (swentry->type) {
case ENTRY_TYPE_KERNEL:
m_hdr_kernel.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_kernel.p_filesz = *swentry->size;
m_hdr_kernel.p_memsz = *swentry->size;
break;
case ENTRY_TYPE_RAMDISK:
m_hdr_ramdisk.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_ramdisk.p_filesz = *swentry->size;
m_hdr_ramdisk.p_memsz = *swentry->size;
break;
case ENTRY_TYPE_SONY_IPL:
m_hdr_ipl.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_ipl.p_filesz = *swentry->size;
m_hdr_ipl.p_memsz = *swentry->size;
break;
case ENTRY_TYPE_SONY_RPM:
m_hdr_rpm.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_rpm.p_filesz = *swentry->size;
m_hdr_rpm.p_memsz = *swentry->size;
break;
case ENTRY_TYPE_SONY_APPSBL:
m_hdr_appsbl.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_appsbl.p_filesz = *swentry->size;
m_hdr_appsbl.p_memsz = *swentry->size;
break;
case SONY_ELF_ENTRY_CMDLINE:
m_hdr_cmdline.p_offset = static_cast<Elf32_Off>(swentry->offset);
m_hdr_cmdline.p_filesz = *swentry->size;
m_hdr_cmdline.p_memsz = *swentry->size;
break;
}
if (*swentry->size > 0) {
++m_hdr.e_phnum;
}
return oc::success();
}
oc::result<void> MtkFormatWriter::finish_entry(File &file)
{
OUTCOME_TRYV(m_seg->finish_entry(file, m_writer));
auto swentry = m_seg->entry();
if ((swentry->type == ENTRY_TYPE_KERNEL
|| swentry->type == ENTRY_TYPE_RAMDISK)
&& *swentry->size == UINT32_MAX - sizeof(MtkHeader)) {
m_writer.set_fatal();
return MtkError::EntryTooLargeToFitMtkHeader;
} else if ((swentry->type == ENTRY_TYPE_MTK_KERNEL_HEADER
|| swentry->type == ENTRY_TYPE_MTK_RAMDISK_HEADER)
&& *swentry->size != sizeof(MtkHeader)) {
m_writer.set_fatal();
return MtkError::InvalidEntrySizeForMtkHeader;
}
switch (swentry->type) {
case ENTRY_TYPE_KERNEL:
m_hdr.kernel_size = static_cast<uint32_t>(
*swentry->size + sizeof(MtkHeader));
break;
case ENTRY_TYPE_RAMDISK:
m_hdr.ramdisk_size = static_cast<uint32_t>(
*swentry->size + sizeof(MtkHeader));
break;
case ENTRY_TYPE_SECONDBOOT:
m_hdr.second_size = *swentry->size;
break;
case ENTRY_TYPE_DEVICE_TREE:
m_hdr.dt_size = *swentry->size;
break;
}
return oc::success();
}
oc::result<void> MtkFormatWriter::write_header(File &file, const Header &header)
{
// Construct header
m_hdr = {};
memcpy(m_hdr.magic, android::BOOT_MAGIC, android::BOOT_MAGIC_SIZE);
if (auto address = header.kernel_address()) {
m_hdr.kernel_addr = *address;
}
if (auto address = header.ramdisk_address()) {
m_hdr.ramdisk_addr = *address;
}
if (auto address = header.secondboot_address()) {
m_hdr.second_addr = *address;
}
if (auto address = header.kernel_tags_address()) {
m_hdr.tags_addr = *address;
}
if (auto page_size = header.page_size()) {
switch (*page_size) {
case 2048:
case 4096:
case 8192:
case 16384:
case 32768:
case 65536:
case 131072:
m_hdr.page_size = *page_size;
break;
default:
//DEBUG("Invalid page size: %" PRIu32, *page_size);
return android::AndroidError::InvalidPageSize;
}
} else {
return android::AndroidError::MissingPageSize;
}
if (auto board_name = header.board_name()) {
if (board_name->size() >= sizeof(m_hdr.name)) {
return android::AndroidError::BoardNameTooLong;
}
strncpy(reinterpret_cast<char *>(m_hdr.name), board_name->c_str(),
sizeof(m_hdr.name) - 1);
m_hdr.name[sizeof(m_hdr.name) - 1] = '\0';
}
if (auto cmdline = header.kernel_cmdline()) {
if (cmdline->size() >= sizeof(m_hdr.cmdline)) {
return android::AndroidError::KernelCmdlineTooLong;
}
strncpy(reinterpret_cast<char *>(m_hdr.cmdline), cmdline->c_str(),
sizeof(m_hdr.cmdline) - 1);
m_hdr.cmdline[sizeof(m_hdr.cmdline) - 1] = '\0';
}
// TODO: UNUSED
// TODO: ID
std::vector<SegmentWriterEntry> entries;
entries.push_back({ ENTRY_TYPE_MTK_KERNEL_HEADER, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_KERNEL, 0, {}, m_hdr.page_size });
entries.push_back({ ENTRY_TYPE_MTK_RAMDISK_HEADER, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_RAMDISK, 0, {}, m_hdr.page_size });
entries.push_back({ ENTRY_TYPE_SECONDBOOT, 0, {}, m_hdr.page_size });
entries.push_back({ ENTRY_TYPE_DEVICE_TREE, 0, {}, m_hdr.page_size });
OUTCOME_TRYV(m_seg->set_entries(std::move(entries)));
// Start writing after first page
auto seek_ret = file.seek(m_hdr.page_size, SEEK_SET);
if (!seek_ret) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return seek_ret.as_failure();
}
return oc::success();
}
oc::result<void> MtkFormatWriter::close(File &file)
{
auto reset_state = finally([&] {
m_hdr = {};
m_seg = {};
});
if (m_writer.is_open()) {
auto swentry = m_seg->entry();
// If successful, finish up the boot image
if (swentry == m_seg->entries().end()) {
auto file_size = file.seek(0, SEEK_CUR);
if (!file_size) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return file_size.as_failure();
}
// Truncate to set size
auto truncate_ret = file.truncate(file_size.value());
if (!truncate_ret) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return truncate_ret.as_failure();
}
// Update MTK header sizes
for (auto const &entry : m_seg->entries()) {
if (entry.type == ENTRY_TYPE_MTK_KERNEL_HEADER) {
OUTCOME_TRYV(_mtk_header_update_size(
m_writer, file, entry.offset,
static_cast<uint32_t>(
m_hdr.kernel_size - sizeof(MtkHeader))));
} else if (entry.type == ENTRY_TYPE_MTK_RAMDISK_HEADER) {
OUTCOME_TRYV(_mtk_header_update_size(
m_writer, file, entry.offset,
static_cast<uint32_t>(
m_hdr.ramdisk_size - sizeof(MtkHeader))));
}
}
// We need to take the performance hit and compute the SHA1 here.
// We can't fill in the sizes in the MTK headers when we're writing
// them. Thus, if we calculated the SHA1sum during write, it would
// be incorrect.
OUTCOME_TRYV(_mtk_compute_sha1(
m_writer, *m_seg, file,
reinterpret_cast<unsigned char *>(m_hdr.id)));
// Convert fields back to little-endian
android_fix_header_byte_order(m_hdr);
// Seek back to beginning to write header
auto seek_ret = file.seek(0, SEEK_SET);
if (!seek_ret) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return seek_ret.as_failure();
}
// Write header
auto ret = file_write_exact(file, &m_hdr, sizeof(m_hdr));
if (!ret) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return ret.as_failure();
}
}
}
return oc::success();
}
oc::result<void> SonyElfFormatWriter::write_header(File &file,
const Header &header)
{
m_cmdline.clear();
m_hdr = {};
m_hdr_kernel = {};
m_hdr_ramdisk = {};
m_hdr_cmdline = {};
m_hdr_ipl = {};
m_hdr_rpm = {};
m_hdr_appsbl = {};
// Construct ELF header
memcpy(&m_hdr.e_ident, SONY_E_IDENT, SONY_EI_NIDENT);
m_hdr.e_type = 2;
m_hdr.e_machine = 40;
m_hdr.e_version = 1;
m_hdr.e_phoff = 52;
m_hdr.e_shoff = 0;
m_hdr.e_flags = 0;
m_hdr.e_ehsize = sizeof(Sony_Elf32_Ehdr);
m_hdr.e_phentsize = sizeof(Sony_Elf32_Phdr);
m_hdr.e_shentsize = 0;
m_hdr.e_shnum = 0;
m_hdr.e_shstrndx = 0;
if (auto entrypoint_address = header.entrypoint_address()) {
m_hdr.e_entry = *entrypoint_address;
} else if (auto kernel_address = header.kernel_address()) {
m_hdr.e_entry = *kernel_address;
}
// Construct kernel program header
m_hdr_kernel.p_type = SONY_E_TYPE_KERNEL;
m_hdr_kernel.p_flags = SONY_E_FLAGS_KERNEL;
m_hdr_kernel.p_align = 0;
if (auto address = header.kernel_address()) {
m_hdr_kernel.p_vaddr = *address;
m_hdr_kernel.p_paddr = *address;
}
// Construct ramdisk program header
m_hdr_ramdisk.p_type = SONY_E_TYPE_RAMDISK;
m_hdr_ramdisk.p_flags = SONY_E_FLAGS_RAMDISK;
m_hdr_ramdisk.p_align = 0;
if (auto address = header.ramdisk_address()) {
m_hdr_ramdisk.p_vaddr = *address;
m_hdr_ramdisk.p_paddr = *address;
}
// Construct cmdline program header
m_hdr_cmdline.p_type = SONY_E_TYPE_CMDLINE;
m_hdr_cmdline.p_vaddr = 0;
m_hdr_cmdline.p_paddr = 0;
m_hdr_cmdline.p_flags = SONY_E_FLAGS_CMDLINE;
m_hdr_cmdline.p_align = 0;
if (auto cmdline = header.kernel_cmdline()) {
m_cmdline = *cmdline;
}
// Construct IPL program header
m_hdr_ipl.p_type = SONY_E_TYPE_IPL;
m_hdr_ipl.p_flags = SONY_E_FLAGS_IPL;
m_hdr_ipl.p_align = 0;
if (auto address = header.sony_ipl_address()) {
m_hdr_ipl.p_vaddr = *address;
m_hdr_ipl.p_paddr = *address;
}
// Construct RPM program header
m_hdr_rpm.p_type = SONY_E_TYPE_RPM;
m_hdr_rpm.p_flags = SONY_E_FLAGS_RPM;
m_hdr_rpm.p_align = 0;
if (auto address = header.sony_rpm_address()) {
m_hdr_rpm.p_vaddr = *address;
m_hdr_rpm.p_paddr = *address;
}
// Construct APPSBL program header
m_hdr_appsbl.p_type = SONY_E_TYPE_APPSBL;
m_hdr_appsbl.p_flags = SONY_E_FLAGS_APPSBL;
m_hdr_appsbl.p_align = 0;
if (auto address = header.sony_appsbl_address()) {
m_hdr_appsbl.p_vaddr = *address;
m_hdr_appsbl.p_paddr = *address;
}
std::vector<SegmentWriterEntry> entries;
entries.push_back({ ENTRY_TYPE_KERNEL, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_RAMDISK, 0, {}, 0 });
entries.push_back({ SONY_ELF_ENTRY_CMDLINE, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_SONY_IPL, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_SONY_RPM, 0, {}, 0 });
entries.push_back({ ENTRY_TYPE_SONY_APPSBL, 0, {}, 0 });
OUTCOME_TRYV(m_seg->set_entries(std::move(entries)));
// Start writing at offset 4096
auto seek_ret = file.seek(4096, SEEK_SET);
if (!seek_ret) {
if (file.is_fatal()) { m_writer.set_fatal(); }
return seek_ret.as_failure();
}
return oc::success();
}
/*!
* \brief Read header for new-style Loki image
*
* \param[in] reader Reader to set error message
* \param[in] file File handle
* \param[in] hdr Android header for image
* \param[in] loki_hdr Loki header for image
* \param[out] header Header instance to store header values
* \param[out] kernel_offset_out Pointer to store kernel offset
* \param[out] kernel_size_out Pointer to store kernel size
* \param[out] ramdisk_offset_out Pointer to store ramdisk offset
* \param[out] ramdisk_size_out Pointer to store ramdisk size
* \param[out] dt_offset_out Pointer to store device tree offset
*
* \return Nothing if the header is successfully read. Otherwise, a specific
* error code.
*/
oc::result<void>
LokiFormatReader::read_header_new(Reader &reader, File &file,
const android::AndroidHeader &hdr,
const LokiHeader &loki_hdr,
Header &header,
uint64_t &kernel_offset_out,
uint32_t &kernel_size_out,
uint64_t &ramdisk_offset_out,
uint32_t &ramdisk_size_out,
uint64_t &dt_offset_out)
{
uint32_t fake_size;
uint32_t ramdisk_addr;
if (hdr.page_size == 0) {
return LokiError::PageSizeCannotBeZero;
}
if (is_lg_ramdisk_address(hdr.ramdisk_addr)) {
fake_size = hdr.page_size;
} else {
fake_size = 0x200;
}
// Find original ramdisk address
OUTCOME_TRYV(find_ramdisk_address(reader, file, hdr, loki_hdr,
ramdisk_addr));
// Restore original values in boot image header
kernel_size_out = loki_hdr.orig_kernel_size;
ramdisk_size_out = loki_hdr.orig_ramdisk_size;
auto *name_ptr = reinterpret_cast<const char *>(hdr.name);
auto name_size = strnlen(name_ptr, sizeof(hdr.name));
auto *cmdline_ptr = reinterpret_cast<const char *>(hdr.cmdline);
auto cmdline_size = strnlen(cmdline_ptr, sizeof(hdr.cmdline));
header.set_supported_fields(NEW_SUPPORTED_FIELDS);
header.set_board_name({{name_ptr, name_size}});
header.set_kernel_cmdline({{cmdline_ptr, cmdline_size}});
header.set_page_size(hdr.page_size);
header.set_kernel_address(hdr.kernel_addr);
header.set_ramdisk_address(ramdisk_addr);
header.set_secondboot_address(hdr.second_addr);
header.set_kernel_tags_address(hdr.tags_addr);
uint64_t pos = 0;
// pos cannot overflow due to the nature of the operands (adding UINT32_MAX
// a few times can't overflow a uint64_t). File length overflow is checked
// during read.
// Header
pos += hdr.page_size;
// Kernel
kernel_offset_out = pos;
pos += loki_hdr.orig_kernel_size;
pos += align_page_size<uint64_t>(pos, hdr.page_size);
// Ramdisk
ramdisk_offset_out = pos;
pos += loki_hdr.orig_ramdisk_size;
pos += align_page_size<uint64_t>(pos, hdr.page_size);
// Device tree
if (hdr.dt_size != 0) {
pos += fake_size;
}
dt_offset_out = pos;
pos += hdr.dt_size;
pos += align_page_size<uint64_t>(pos, hdr.page_size);
return oc::success();
}
/*!
* \brief Read header for old-style Loki image
*
* \param[in] reader Reader to set error message
* \param[in] file File handle
* \param[in] hdr Android header for image
* \param[in] loki_hdr Loki header for image
* \param[out] header Header instance to store header values
* \param[out] kernel_offset_out Pointer to store kernel offset
* \param[out] kernel_size_out Pointer to store kernel size
* \param[out] ramdisk_offset_out Pointer to store ramdisk offset
* \param[out] ramdisk_size_out Pointer to store ramdisk size
*
* \return Nothing if the header is successfully read. Otherwise, a specific
* error code.
*/
oc::result<void>
LokiFormatReader::read_header_old(Reader &reader, File &file,
const android::AndroidHeader &hdr,
const LokiHeader &loki_hdr,
Header &header,
uint64_t &kernel_offset_out,
uint32_t &kernel_size_out,
uint64_t &ramdisk_offset_out,
uint32_t &ramdisk_size_out)
{
uint32_t tags_addr;
uint32_t kernel_size;
uint32_t ramdisk_size;
uint32_t ramdisk_addr;
uint64_t gzip_offset;
if (hdr.page_size == 0) {
return LokiError::PageSizeCannotBeZero;
}
// The kernel tags address is invalid in the old loki images, so use the
// default for jflte
tags_addr = hdr.kernel_addr - android::DEFAULT_KERNEL_OFFSET
+ android::DEFAULT_TAGS_OFFSET;
// Try to guess kernel size
OUTCOME_TRYV(find_linux_kernel_size(reader, file, hdr.page_size,
kernel_size));
// Look for gzip offset for the ramdisk
OUTCOME_TRYV(find_gzip_offset_old(
reader, file, hdr.page_size + kernel_size
+ align_page_size<uint32_t>(kernel_size, hdr.page_size),
gzip_offset));
// Try to guess ramdisk size
OUTCOME_TRYV(find_ramdisk_size_old(reader, file, hdr,
static_cast<uint32_t>(gzip_offset),
ramdisk_size));
// Guess original ramdisk address
OUTCOME_TRYV(find_ramdisk_address(reader, file, hdr, loki_hdr,
ramdisk_addr));
kernel_size_out = kernel_size;
ramdisk_size_out = ramdisk_size;
auto *name_ptr = reinterpret_cast<const char *>(hdr.name);
auto name_size = strnlen(name_ptr, sizeof(hdr.name));
auto *cmdline_ptr = reinterpret_cast<const char *>(hdr.cmdline);
auto cmdline_size = strnlen(cmdline_ptr, sizeof(hdr.cmdline));
header.set_supported_fields(OLD_SUPPORTED_FIELDS);
header.set_board_name({{name_ptr, name_size}});
header.set_kernel_cmdline({{cmdline_ptr, cmdline_size}});
header.set_page_size(hdr.page_size);
header.set_kernel_address(hdr.kernel_addr);
header.set_ramdisk_address(ramdisk_addr);
header.set_secondboot_address(hdr.second_addr);
header.set_kernel_tags_address(tags_addr);
uint64_t pos = 0;
// pos cannot overflow due to the nature of the operands (adding UINT32_MAX
// a few times can't overflow a uint64_t). File length overflow is checked
// during read.
// Header
pos += hdr.page_size;
// Kernel
kernel_offset_out = pos;
pos += kernel_size;
pos += align_page_size<uint64_t>(pos, hdr.page_size);
// Ramdisk
ramdisk_offset_out = pos = gzip_offset;
pos += ramdisk_size;
pos += align_page_size<uint64_t>(pos, hdr.page_size);
return oc::success();
}
/*!
* \brief Find gzip ramdisk offset in old-style Loki image
*
* This function will search for gzip headers (`0x1f8b08`) with a flags byte of
* `0x00` or `0x08`. It will find the first occurrence of either magic string.
* If both are found, the one with the flags byte set to `0x08` takes precedence
* as it indiciates that the original filename field is set. This is usually the
* case for ramdisks packed via the `gzip` command line tool.
*
* \pre The file position can be at any offset prior to calling this function.
*
* \post The file pointer position is undefined after this function returns.
* Use File::seek() to return to a known position.
*
* \param[in] reader Reader to set error message
* \param[in] file File handle
* \param[in] start_offset Starting offset for search
* \param[out] gzip_offset_out Pointer to store gzip ramdisk offset
*
* \return
* * Nothing if a gzip offset is found
* * A LokiError if no gzip offsets are found
* * A specific error if any file operation fails
*/
oc::result<void>
LokiFormatReader::find_gzip_offset_old(Reader &reader, File &file,
uint32_t start_offset,
uint64_t &gzip_offset_out)
{
struct SearchResult
{
std::optional<uint64_t> flag0_offset;
std::optional<uint64_t> flag8_offset;
};
// gzip header:
// byte 0-1 : magic bytes 0x1f, 0x8b
// byte 2 : compression (0x08 = deflate)
// byte 3 : flags
// byte 4-7 : modification timestamp
// byte 8 : compression flags
// byte 9 : operating system
static const unsigned char gzip_deflate_magic[] = { 0x1f, 0x8b, 0x08 };
SearchResult result = {};
// Find first result with flags == 0x00 and flags == 0x08
auto result_cb = [&](File &file_, uint64_t offset)
-> oc::result<FileSearchAction> {
unsigned char flags;
// Stop early if possible
if (result.flag0_offset && result.flag8_offset) {
return FileSearchAction::Stop;
}
// Save original position
OUTCOME_TRY(orig_offset, file_.seek(0, SEEK_CUR));
// Seek to flags byte
OUTCOME_TRYV(file_.seek(static_cast<int64_t>(offset + 3), SEEK_SET));
// Read next bytes for flags
auto ret = file_read_exact(file_, &flags, sizeof(flags));
if (!ret) {
if (ret.error() == FileError::UnexpectedEof) {
return FileSearchAction::Stop;
} else {
return ret.as_failure();
}
}
if (!result.flag0_offset && flags == 0x00) {
result.flag0_offset = offset;
} else if (!result.flag8_offset && flags == 0x08) {
result.flag8_offset = offset;
}
// Restore original position as per contract
OUTCOME_TRYV(file_.seek(static_cast<int64_t>(orig_offset), SEEK_SET));
return FileSearchAction::Continue;
};
auto ret = file_search(file, start_offset, {}, 0, gzip_deflate_magic,
sizeof(gzip_deflate_magic), {}, result_cb);
if (!ret) {
if (file.is_fatal()) { reader.set_fatal(); }
return ret.as_failure();
}
// Prefer gzip header with original filename flag since most loki'd boot
// images will have been compressed manually with the gzip tool
if (result.flag8_offset) {
gzip_offset_out = *result.flag8_offset;
} else if (result.flag0_offset) {
gzip_offset_out = *result.flag0_offset;
} else {
return LokiError::NoRamdiskGzipHeaderFound;
}
return oc::success();
}
