lzma_filter_flags_decode(
lzma_filter *filter, lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size)
{
lzma_vli props_size;
lzma_ret ret;
// Set the pointer to NULL so the caller can always safely free it.
filter->options = NULL;
// Filter ID
return_if_error(lzma_vli_decode(&filter->id, NULL,
in, in_pos, in_size));
if (filter->id >= LZMA_FILTER_RESERVED_START)
return LZMA_DATA_ERROR;
// Size of Properties
return_if_error(lzma_vli_decode(&props_size, NULL,
in, in_pos, in_size));
// Filter Properties
if (in_size - *in_pos < props_size)
return LZMA_DATA_ERROR;
ret = lzma_properties_decode(
filter, allocator, in + *in_pos, props_size);
*in_pos += props_size;
return ret;
}
/// Return true if the data in in_buf seems to be in the .lzma format.
static bool
is_format_lzma(void)
{
// The .lzma header is 13 bytes.
if (strm.avail_in < 13) {
return false;
}
// Decode the LZMA1 properties.
lzma_filter filter = { .id = LZMA_FILTER_LZMA1 };
if (lzma_properties_decode(&filter, NULL, in_buf.u8, 5) != LZMA_OK) {
return false;
}
// A hack to ditch tons of false positives: We allow only dictionary
// sizes that are 2^n or 2^n + 2^(n-1) or UINT32_MAX. LZMA_Alone
// created only files with 2^n, but accepts any dictionary size.
// If someone complains, this will be reconsidered.
lzma_options_lzma *opt = filter.options;
const uint32_t dict_size = opt->dict_size;
free(opt);
if (dict_size != UINT32_MAX) {
uint32_t d = dict_size - 1;
d |= d >> 2;
d |= d >> 3;
d |= d >> 4;
d |= d >> 8;
d |= d >> 16;
++d;
if (d != dict_size || dict_size == 0)
return false;
}
// refer to src/xz/coder.c in XZ Utils.
int CTarArcFile_Lzma::check_head_format(unsigned char *buf, size_t buf_size, int format_type)
{
if(buf_size>=6 && memcmp(buf, "\3757zXZ", 6) == 0){
if(format_type>=0) {
return format_type==ARCHIVETYPE_XZ;
} else {
return ARCHIVETYPE_XZ;
}
}
while(buf_size>=13){
lzma_filter filter;
filter.id = LZMA_FILTER_LZMA1;
if(lzma_properties_decode(&filter, NULL, buf, 5) != LZMA_OK){
break;
}
lzma_options_lzma *opt = (lzma_options_lzma *)(filter.options);
const uint32_t dict_size = opt->dict_size;
// free(opt);
if (dict_size != UINT32_MAX) {
uint32_t d = dict_size - 1;
d |= d >> 2;
d |= d >> 3;
d |= d >> 4;
d |= d >> 8;
d |= d >> 16;
++d;
if (d != dict_size || dict_size == 0)
break;
}
uint64_t uncompressed_size = 0;
for (size_t i = 0; i < 8; ++i)
uncompressed_size |= (uint64_t)(buf[5 + i]) << (i * 8);
if (uncompressed_size != UINT64_MAX && uncompressed_size > (UINT64_C(1) << 38)){
break;
}
if(format_type>=0) {
return format_type==ARCHIVETYPE_LZMA;
} else {
return ARCHIVETYPE_LZMA;
}
}
static PyObject *
_lzma__decode_filter_properties_impl(PyModuleDef *module, lzma_vli filter_id, Py_buffer *encoded_props)
/*[clinic end generated code: output=235f7f5345d48744 input=246410800782160c]*/
{
lzma_filter filter;
lzma_ret lzret;
PyObject *result = NULL;
filter.id = filter_id;
lzret = lzma_properties_decode(
&filter, NULL, encoded_props->buf, encoded_props->len);
if (catch_lzma_error(lzret))
return NULL;
result = build_filter_spec(&filter);
/* We use vanilla free() here instead of PyMem_Free() - filter.options was
allocated by lzma_properties_decode() using the default allocator. */
free(filter.options);
return result;
}
/// Parse the .lzma header and display information about it.
static bool
lzmainfo(const char *name, FILE *f)
{
uint8_t buf[13];
const size_t size = fread(buf, 1, sizeof(buf), f);
if (size != 13) {
fprintf(stderr, "%s: %s: %s\n", progname, name,
ferror(f) ? strerror(errno)
: _("File is too small to be a .lzma file"));
return true;
}
lzma_filter filter = { .id = LZMA_FILTER_LZMA1 };
// Parse the first five bytes.
switch (lzma_properties_decode(&filter, NULL, buf, 5)) {
case LZMA_OK:
break;
case LZMA_OPTIONS_ERROR:
fprintf(stderr, "%s: %s: %s\n", progname, name,
_("Not a .lzma file"));
return true;
case LZMA_MEM_ERROR:
fprintf(stderr, "%s: %s\n", progname, strerror(ENOMEM));
exit(EXIT_FAILURE);
default:
fprintf(stderr, "%s: %s\n", progname,
_("Internal error (bug)"));
exit(EXIT_FAILURE);
}
// Uncompressed size
uint64_t uncompressed_size = 0;
for (size_t i = 0; i < 8; ++i)
uncompressed_size |= (uint64_t)(buf[5 + i]) << (i * 8);
// Display the results. We don't want to translate these and also
// will use MB instead of MiB, because someone could be parsing
// this output and we don't want to break that when people move
// from LZMA Utils to XZ Utils.
if (f != stdin)
printf("%s\n", name);
printf("Uncompressed size: ");
if (uncompressed_size == UINT64_MAX)
printf("Unknown");
else
printf("%" PRIu64 " MB (%" PRIu64 " bytes)",
(uncompressed_size + 512 * 1024)
/ (1024 * 1024),
uncompressed_size);
lzma_options_lzma *opt = filter.options;
printf("\nDictionary size: "
"%" PRIu32 " MB (2^%" PRIu32 " bytes)\n"
"Literal context bits (lc): %" PRIu32 "\n"
"Literal pos bits (lp): %" PRIu32 "\n"
"Number of pos bits (pb): %" PRIu32 "\n",
(opt->dict_size + 512 * 1024) / (1024 * 1024),
my_log2(opt->dict_size), opt->lc, opt->lp, opt->pb);
free(opt);
return false;
}
