/* adapted from official xz source: xz/src/xz/list.c */
static lzma_index* read_index(File file, uint64_t memlimit, std::string &error) {
union {
unsigned char buf[4096];
unsigned char u8[LZMA_STREAM_HEADER_SIZE];
uint32_t u32[LZMA_STREAM_HEADER_SIZE/4];
} buf;
lzma_stream strm = LZMA_STREAM_INIT;
lzma_index *cur_index = nullptr;
lzma_index *col_index = nullptr;
FileReaderState *filestate = nullptr;
lzma_stream_flags header_flags;
lzma_stream_flags footer_flags;
lzma_ret ret;
// Current position in the file. We parse the file backwards so
// initialize it to point to the end of the file.
int64_t pos = file->filesize();;
// Each loop iteration decodes one Index.
do {
lzma_vli stream_padding, index_size;
uint64_t memused;
// 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) {
error.assign("file too small for xz archive");
goto failed;
}
pos -= LZMA_STREAM_HEADER_SIZE;
stream_padding = 0;
// Locate the Stream Footer. There may be Stream Padding which
// we must skip when reading backwards.
for (;;) {
if (pos < LZMA_STREAM_HEADER_SIZE) {
error.assign("file too small for xz archive");
goto failed;
}
if (!file->readInto(filestate, pos, LZMA_STREAM_HEADER_SIZE, buf.buf, error)) goto failed;
/* padding must be a multiple of 4 */
if (buf.u32[2] != 0) break;
pos -= 4; stream_padding += 4;
if (buf.u32[1] != 0) break;
pos -= 4; stream_padding += 4;
if (buf.u32[0] != 0) break;
pos -= 4; stream_padding += 4;
}
// Decode the Stream Footer.
ret = lzma_stream_footer_decode(&footer_flags, buf.u8);
if (LZMA_OK != ret) {
errnoLzmaToStr("invalid footer", ret, error);
goto failed;
}
// Check that the size of the Index field looks sane.
index_size = footer_flags.backward_size;
if ((lzma_vli)(pos) < index_size + LZMA_STREAM_HEADER_SIZE) {
error.assign("invalid index size");
goto failed;
}
// Set pos to the beginning of the Index.
pos -= index_size;
// See how much memory we can use for decoding this Index.
memused = nullptr != col_index ? lzma_index_memused(col_index) : 0;
if (memused > memlimit) {
error.assign("mem limit hit");
goto failed;
}
// Decode the Index.
ret = lzma_index_decoder(&strm, &cur_index, memlimit - memused);
if (ret != LZMA_OK) {
errnoLzmaToStr("couldn't allocate new index", ret, error);
goto failed;
}
do {
ssize_t want = (index_size < sizeof(buf.buf) ? index_size : sizeof(buf.buf));
if (want < 0) { ret = LZMA_DATA_ERROR; break; }
if (!file->readInto(filestate, pos, want, buf.buf, error)) goto failed;
strm.avail_in = want;
strm.next_in = buf.buf;
pos += want;
index_size -= want;
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;
errnoLzmaToStr("decoding index failed", ret, error);
goto failed;
}
// 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(cur_index)) {
error.assign("invalid archive - index large than available data");
goto failed;
}
pos -= lzma_index_total_size(cur_index);
if (!file->readInto(filestate, pos, LZMA_STREAM_HEADER_SIZE, buf.buf, error)) goto failed;
ret = lzma_stream_header_decode(&header_flags, buf.u8);
if (ret != LZMA_OK) {
errnoLzmaToStr("invalid header", ret, error);
goto failed;
}
ret = lzma_stream_flags_compare(&header_flags, &footer_flags);
if (ret != LZMA_OK) {
errnoLzmaToStr("invalid stream: footer doesn't match header", ret, error);
goto failed;
}
// 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(cur_index, &footer_flags);
if (ret != LZMA_OK) {
errnoLzmaToStr("decoding stream flags failed", ret, error);
goto failed;
}
// 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(cur_index, stream_padding);
if (ret != LZMA_OK) {
errnoLzmaToStr("storing stream padding failed", ret, error);
goto failed;
}
if (nullptr != col_index) {
// Append the earlier decoded Indexes
// after this_index.
ret = lzma_index_cat(cur_index, col_index, NULL);
col_index = nullptr;
if (ret != LZMA_OK) {
errnoLzmaToStr("failed to concatenate indexes", ret, error);
goto failed;
}
}
col_index = cur_index;
cur_index = nullptr;
} while (pos > 0);
lzma_end(&strm);
file->finish(filestate);
return col_index;
failed:
lzma_end(&strm);
if (nullptr != cur_index) lzma_index_end(cur_index, NULL);
if (nullptr != col_index) lzma_index_end(col_index, NULL);
file->finish(filestate);
return nullptr;
}
/// \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, int src_fd)
{
struct stat st;
fstat(src_fd, &st);
if (st.st_size <= 0) {
return true;
}
if (st.st_size < 2 * LZMA_STREAM_HEADER_SIZE) {
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 = 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) {
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) {
goto error;
}
if (io_pread(src_fd, &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) {
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) {
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) {
goto error;
}
// Set pos to the beginning of the Index.
pos -= index_size;
// Decode the Index.
ret = lzma_index_decoder(&strm, &this_index, UINT64_MAX);
if (ret != LZMA_OK) {
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(src_fd, &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;
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)) {
goto error;
}
pos -= lzma_index_total_size(this_index);
if (io_pread(src_fd, &buf, LZMA_STREAM_HEADER_SIZE, pos))
goto error;
ret = lzma_stream_header_decode(&header_flags, buf.u8);
if (ret != LZMA_OK) {
goto error;
}
ret = lzma_stream_flags_compare(&header_flags, &footer_flags);
if (ret != LZMA_OK) {
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)
goto error;
// 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)
goto error;
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) {
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 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 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;
}
