/// \brief Parse the Index(es) from the given .xz file
///
/// \param xfi Pointer to structure where the decoded information
/// is stored.
/// \param pair Input file
///
/// \return On success, false is returned. On error, true is returned.
///
// TODO: This function is pretty big. liblzma should have a function that
// takes a callback function to parse the Index(es) from a .xz file to make
// it easy for applications.
static bool
parse_indexes(xz_file_info *xfi, file_pair *pair)
{
if (pair->src_st.st_size <= 0) {
message_error(_("%s: File is empty"), pair->src_name);
return true;
}
if (pair->src_st.st_size < 2 * LZMA_STREAM_HEADER_SIZE) {
message_error(_("%s: Too small to be a valid .xz file"),
pair->src_name);
return true;
}
io_buf buf;
lzma_stream_flags header_flags;
lzma_stream_flags footer_flags;
lzma_ret ret;
// lzma_stream for the Index decoder
lzma_stream strm = LZMA_STREAM_INIT;
// All Indexes decoded so far
lzma_index *combined_index = NULL;
// The Index currently being decoded
lzma_index *this_index = NULL;
// Current position in the file. We parse the file backwards so
// initialize it to point to the end of the file.
off_t pos = pair->src_st.st_size;
// Each loop iteration decodes one Index.
do {
// Check that there is enough data left to contain at least
// the Stream Header and Stream Footer. This check cannot
// fail in the first pass of this loop.
if (pos < 2 * LZMA_STREAM_HEADER_SIZE) {
message_error("%s: %s", pair->src_name,
message_strm(LZMA_DATA_ERROR));
goto error;
}
pos -= LZMA_STREAM_HEADER_SIZE;
lzma_vli stream_padding = 0;
// Locate the Stream Footer. There may be Stream Padding which
// we must skip when reading backwards.
while (true) {
if (pos < LZMA_STREAM_HEADER_SIZE) {
message_error("%s: %s", pair->src_name,
message_strm(
LZMA_DATA_ERROR));
goto error;
}
if (io_pread(pair, &buf,
LZMA_STREAM_HEADER_SIZE, pos))
goto error;
// Stream Padding is always a multiple of four bytes.
int i = 2;
if (buf.u32[i] != 0)
break;
// To avoid calling io_pread() for every four bytes
// of Stream Padding, take advantage that we read
// 12 bytes (LZMA_STREAM_HEADER_SIZE) already and
// check them too before calling io_pread() again.
do {
stream_padding += 4;
pos -= 4;
--i;
} while (i >= 0 && buf.u32[i] == 0);
}
// Decode the Stream Footer.
ret = lzma_stream_footer_decode(&footer_flags, buf.u8);
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
goto error;
}
// Check that the Stream Footer doesn't specify something
// that we don't support. This can only happen if the xz
// version is older than liblzma and liblzma supports
// something new.
//
// It is enough to check Stream Footer. Stream Header must
// match when it is compared against Stream Footer with
// lzma_stream_flags_compare().
if (footer_flags.version != 0) {
message_error("%s: %s", pair->src_name,
message_strm(LZMA_OPTIONS_ERROR));
goto error;
}
// Check that the size of the Index field looks sane.
lzma_vli index_size = footer_flags.backward_size;
if ((lzma_vli)(pos) < index_size + LZMA_STREAM_HEADER_SIZE) {
message_error("%s: %s", pair->src_name,
message_strm(LZMA_DATA_ERROR));
goto error;
}
// Set pos to the beginning of the Index.
pos -= index_size;
// See how much memory we can use for decoding this Index.
uint64_t memlimit = hardware_memlimit_get(MODE_LIST);
uint64_t memused = 0;
if (combined_index != NULL) {
memused = lzma_index_memused(combined_index);
if (memused > memlimit)
message_bug();
memlimit -= memused;
}
// Decode the Index.
ret = lzma_index_decoder(&strm, &this_index, memlimit);
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
goto error;
}
do {
// Don't give the decoder more input than the
// Index size.
strm.avail_in = my_min(IO_BUFFER_SIZE, index_size);
if (io_pread(pair, &buf, strm.avail_in, pos))
goto error;
pos += strm.avail_in;
index_size -= strm.avail_in;
strm.next_in = buf.u8;
ret = lzma_code(&strm, LZMA_RUN);
} while (ret == LZMA_OK);
// If the decoding seems to be successful, check also that
// the Index decoder consumed as much input as indicated
// by the Backward Size field.
if (ret == LZMA_STREAM_END)
if (index_size != 0 || strm.avail_in != 0)
ret = LZMA_DATA_ERROR;
if (ret != LZMA_STREAM_END) {
// LZMA_BUFFER_ERROR means that the Index decoder
// would have liked more input than what the Index
// size should be according to Stream Footer.
// The message for LZMA_DATA_ERROR makes more
// sense in that case.
if (ret == LZMA_BUF_ERROR)
ret = LZMA_DATA_ERROR;
message_error("%s: %s", pair->src_name,
message_strm(ret));
// If the error was too low memory usage limit,
// show also how much memory would have been needed.
if (ret == LZMA_MEMLIMIT_ERROR) {
uint64_t needed = lzma_memusage(&strm);
if (UINT64_MAX - needed < memused)
needed = UINT64_MAX;
else
needed += memused;
message_mem_needed(V_ERROR, needed);
}
goto error;
}
// Decode the Stream Header and check that its Stream Flags
// match the Stream Footer.
pos -= footer_flags.backward_size + LZMA_STREAM_HEADER_SIZE;
if ((lzma_vli)(pos) < lzma_index_total_size(this_index)) {
message_error("%s: %s", pair->src_name,
message_strm(LZMA_DATA_ERROR));
goto error;
}
pos -= lzma_index_total_size(this_index);
if (io_pread(pair, &buf, LZMA_STREAM_HEADER_SIZE, pos))
goto error;
ret = lzma_stream_header_decode(&header_flags, buf.u8);
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
goto error;
}
ret = lzma_stream_flags_compare(&header_flags, &footer_flags);
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
goto error;
}
// Store the decoded Stream Flags into this_index. This is
// needed so that we can print which Check is used in each
// Stream.
ret = lzma_index_stream_flags(this_index, &footer_flags);
if (ret != LZMA_OK)
message_bug();
// Store also the size of the Stream Padding field. It is
// needed to show the offsets of the Streams correctly.
ret = lzma_index_stream_padding(this_index, stream_padding);
if (ret != LZMA_OK)
message_bug();
if (combined_index != NULL) {
// Append the earlier decoded Indexes
// after this_index.
ret = lzma_index_cat(
this_index, combined_index, NULL);
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
goto error;
}
}
combined_index = this_index;
this_index = NULL;
xfi->stream_padding += stream_padding;
} while (pos > 0);
lzma_end(&strm);
// All OK. Make combined_index available to the caller.
xfi->idx = combined_index;
return false;
error:
// Something went wrong, free the allocated memory.
lzma_end(&strm);
lzma_index_end(combined_index, NULL);
lzma_index_end(this_index, NULL);
return true;
}
/// \brief Parse the Block Header
///
/// The result is stored into *bhi. The caller takes care of initializing it.
///
/// \return False on success, true on error.
static bool
parse_block_header(file_pair *pair, const lzma_index_iter *iter,
block_header_info *bhi, xz_file_info *xfi)
{
#if IO_BUFFER_SIZE < LZMA_BLOCK_HEADER_SIZE_MAX
# error IO_BUFFER_SIZE < LZMA_BLOCK_HEADER_SIZE_MAX
#endif
// Get the whole Block Header with one read, but don't read past
// the end of the Block (or even its Check field).
const uint32_t size = my_min(iter->block.total_size
- lzma_check_size(iter->stream.flags->check),
LZMA_BLOCK_HEADER_SIZE_MAX);
io_buf buf;
if (io_pread(pair, &buf, size, iter->block.compressed_file_offset))
return true;
// Zero would mean Index Indicator and thus not a valid Block.
if (buf.u8[0] == 0)
goto data_error;
// Initialize the block structure and decode Block Header Size.
lzma_filter filters[LZMA_FILTERS_MAX + 1];
lzma_block block;
block.version = 0;
block.check = iter->stream.flags->check;
block.filters = filters;
block.header_size = lzma_block_header_size_decode(buf.u8[0]);
if (block.header_size > size)
goto data_error;
// Decode the Block Header.
switch (lzma_block_header_decode(&block, NULL, buf.u8)) {
case LZMA_OK:
break;
case LZMA_OPTIONS_ERROR:
message_error("%s: %s", pair->src_name,
message_strm(LZMA_OPTIONS_ERROR));
return true;
case LZMA_DATA_ERROR:
goto data_error;
default:
message_bug();
}
// Check the Block Flags. These must be done before calling
// lzma_block_compressed_size(), because it overwrites
// block.compressed_size.
bhi->flags[0] = block.compressed_size != LZMA_VLI_UNKNOWN
? 'c' : '-';
bhi->flags[1] = block.uncompressed_size != LZMA_VLI_UNKNOWN
? 'u' : '-';
bhi->flags[2] = '\0';
// Collect information if all Blocks have both Compressed Size
// and Uncompressed Size fields. They can be useful e.g. for
// multi-threaded decompression so it can be useful to know it.
xfi->all_have_sizes &= block.compressed_size != LZMA_VLI_UNKNOWN
&& block.uncompressed_size != LZMA_VLI_UNKNOWN;
// Validate or set block.compressed_size.
switch (lzma_block_compressed_size(&block,
iter->block.unpadded_size)) {
case LZMA_OK:
// Validate also block.uncompressed_size if it is present.
// If it isn't present, there's no need to set it since
// we aren't going to actually decompress the Block; if
// we were decompressing, then we should set it so that
// the Block decoder could validate the Uncompressed Size
// that was stored in the Index.
if (block.uncompressed_size == LZMA_VLI_UNKNOWN
|| block.uncompressed_size
== iter->block.uncompressed_size)
break;
// If the above fails, the file is corrupt so
// LZMA_DATA_ERROR is a good error code.
// Fall through
case LZMA_DATA_ERROR:
// Free the memory allocated by lzma_block_header_decode().
for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)
free(filters[i].options);
goto data_error;
default:
message_bug();
}
// Copy the known sizes.
bhi->header_size = block.header_size;
bhi->compressed_size = block.compressed_size;
// Calculate the decoder memory usage and update the maximum
// memory usage of this Block.
bhi->memusage = lzma_raw_decoder_memusage(filters);
if (xfi->memusage_max < bhi->memusage)
xfi->memusage_max = bhi->memusage;
// Determine the minimum XZ Utils version that supports this Block.
//
// Currently the only thing that 5.0.0 doesn't support is empty
// LZMA2 Block. This decoder bug was fixed in 5.0.2.
{
size_t i = 0;
while (filters[i + 1].id != LZMA_VLI_UNKNOWN)
++i;
if (filters[i].id == LZMA_FILTER_LZMA2
&& iter->block.uncompressed_size == 0
&& xfi->min_version < 50000022U)
xfi->min_version = 50000022U;
}
// Convert the filter chain to human readable form.
message_filters_to_str(bhi->filter_chain, filters, false);
// Free the memory allocated by lzma_block_header_decode().
for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)
free(filters[i].options);
return false;
data_error:
// Show the error message.
message_error("%s: %s", pair->src_name,
message_strm(LZMA_DATA_ERROR));
return true;
}
/// \brief Parse the Block Header
///
/// The result is stored into *bhi. The caller takes care of initializing it.
///
/// \return False on success, true on error.
static bool
parse_block_header(file_pair *pair, const lzma_index_iter *iter,
block_header_info *bhi, xz_file_info *xfi)
{
#if IO_BUFFER_SIZE < LZMA_BLOCK_HEADER_SIZE_MAX
# error IO_BUFFER_SIZE < LZMA_BLOCK_HEADER_SIZE_MAX
#endif
// Get the whole Block Header with one read, but don't read past
// the end of the Block (or even its Check field).
const uint32_t size = my_min(iter->block.total_size
- lzma_check_size(iter->stream.flags->check),
LZMA_BLOCK_HEADER_SIZE_MAX);
io_buf buf;
if (io_pread(pair, &buf, size, iter->block.compressed_file_offset))
return true;
// Zero would mean Index Indicator and thus not a valid Block.
if (buf.u8[0] == 0)
goto data_error;
lzma_block block;
lzma_filter filters[LZMA_FILTERS_MAX + 1];
// Initialize the pointers so that they can be passed to free().
for (size_t i = 0; i < ARRAY_SIZE(filters); ++i)
filters[i].options = NULL;
// Initialize the block structure and decode Block Header Size.
block.version = 0;
block.check = iter->stream.flags->check;
block.filters = filters;
block.header_size = lzma_block_header_size_decode(buf.u8[0]);
if (block.header_size > size)
goto data_error;
// Decode the Block Header.
switch (lzma_block_header_decode(&block, NULL, buf.u8)) {
case LZMA_OK:
break;
case LZMA_OPTIONS_ERROR:
message_error("%s: %s", pair->src_name,
message_strm(LZMA_OPTIONS_ERROR));
return true;
case LZMA_DATA_ERROR:
goto data_error;
default:
message_bug();
}
// Check the Block Flags. These must be done before calling
// lzma_block_compressed_size(), because it overwrites
// block.compressed_size.
bhi->flags[0] = block.compressed_size != LZMA_VLI_UNKNOWN
? 'c' : '-';
bhi->flags[1] = block.uncompressed_size != LZMA_VLI_UNKNOWN
? 'u' : '-';
bhi->flags[2] = '\0';
// Collect information if all Blocks have both Compressed Size
// and Uncompressed Size fields. They can be useful e.g. for
// multi-threaded decompression so it can be useful to know it.
xfi->all_have_sizes &= block.compressed_size != LZMA_VLI_UNKNOWN
&& block.uncompressed_size != LZMA_VLI_UNKNOWN;
// Validate or set block.compressed_size.
switch (lzma_block_compressed_size(&block,
iter->block.unpadded_size)) {
case LZMA_OK:
break;
case LZMA_DATA_ERROR:
goto data_error;
default:
message_bug();
}
// Copy the known sizes.
bhi->header_size = block.header_size;
bhi->compressed_size = block.compressed_size;
// Calculate the decoder memory usage and update the maximum
// memory usage of this Block.
bhi->memusage = lzma_raw_decoder_memusage(filters);
if (xfi->memusage_max < bhi->memusage)
xfi->memusage_max = bhi->memusage;
// Convert the filter chain to human readable form.
message_filters_to_str(bhi->filter_chain, filters, false);
// Free the memory allocated by lzma_block_header_decode().
for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)
free(filters[i].options);
return false;
data_error:
// Show the error message.
message_error("%s: %s", pair->src_name,
message_strm(LZMA_DATA_ERROR));
// Free the memory allocated by lzma_block_header_decode().
// This is truly needed only if we get here after a succcessful
// call to lzma_block_header_decode() but it doesn't hurt to
// always do it.
for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)
free(filters[i].options);
return true;
}
