7 This directory contains bunch of files to test handling of .lzma files
8 in .lzma decoder implementations. Many of the files have been created
9 by hand with a hex editor, thus there is no better "source code" than
10 the files themselves. All the test files (*.lzma) and this README have
11 been put into the public domain.
16 Good files (good-*.lzma) must decode successfully without requiring
17 a lot of CPU time or RAM. If the decoder supports only Single-Block
18 Streams, then good-multi-*.lzma won't decode, of course.
20 Bad files (bad-*.lzma) must cause the decoder to give an error. Like
21 with the good files, these files must not require a lot of CPU time
22 or RAM before they get detected to be broken.
24 Malicious files (malicious-*.lzma) are good in terms of the file format
25 specification, but try to trigger excessive CPU, RAM or disk usage in
26 the decoder. To prevent malicious files from putting the decoder in
27 inifinite loop (*), eating all available RAM or disk space, decoders
28 should have internal limitters that catch these situations.
30 (*) Strictly speaking not infinite, but if decoding of a small file
31 would take a few weeks or even years, it's an infinite loop in
35 2. Descriptions of Individual Files
39 good-single-none.lzma uses implicit Copy filter with known Uncompressed
42 good-single-none-pad.lzma is good-single-none.lzma with Footer Padding.
44 good-cat-single-none-pad.lzma is two good-single-none-pad.lzma files
45 concatenated as is. Fully decoding this file requires that the decoder
46 supports decoding concatenated files.
48 good-single-subblock_implicit.lzma uses implicit Subblock filter.
50 good-single-lzma.lzma is LZMA compressed file with EOPM.
52 good-single-subblock-lzma.lzma has basic combination of Subblock and
55 good-single-none-empty_1.lzma is an empty file with implicit Copy
56 filter and no integrity Check.
58 good-single-none-empty_2.lzma is an empty file with implicit Copy
59 filter and CRC32 as Check.
61 good-single-none-empty_3.lzma is an empty file with implicit Copy
62 filter, known Compressed Size, and no integrity Check.
64 good-single-lzma-empty.lzma is an empty file with LZMA filter and no
67 good-single-subblock_rle.lzma takes advantage of Subblock filter's
70 good-single-delta-lzma.tiff.lzma is an image file that compresses
71 better with Delta+LZMA than with plain LZMA.
73 good-single-lzma-flush_1.lzma has a flush marker in the middle of
74 the file, and no EOPM.
76 good-single-lzma-flush_2.lzma has a flush marker in the middle of
77 the file and just before EOPM.
79 good-multi-none-1.lzma is a basic Multi-Block Stream with two Data
80 Blocks and Footer Metadata Block.
82 good-multi-none-2.lzma is good-multi-none-1.lzma with Total Size and
83 Uncompressed Size added to the Footer Metadata Block.
85 good-multi-none-extra_1.lzma has the `Extra is present' flag set but
86 no actual Extra Records.
88 good-multi-none-extra_2.lzma has two non-empty Extra Records.
90 good-multi-none-extra_3.lzma has an Extra Record that has empty Data.
92 good-multi-none-header_1.lzma has very minimal Header Metadata Block
93 with only the Metadata Flags field.
95 good-multi-none-header_2.lzma has all information in both Header and
96 Footer Metadata Blocks. The Size of Header Metadata Block has wrong
97 value in Header Metadata Block, but this value must be ignored by
98 the decoder in case of Header Metadata Block.
100 good-multi-none-header_3.lzma has Index only in the Header Metadata
101 Block. Footer Metadata Block contains only Size of Header Metadata
102 Block and Total Size.
104 good-multi-none-block_1.lzma has Index in Header Metadata Block. The
105 Compressed Size and Uncompressed Size fields are present in the Data
106 Blocks. There is some Footer Padding between the Blocks.
111 bad-single-none-truncated.lzma is good-single-none.lzma without the
112 last byte of the file.
114 bad-cat-single-none-pad_garbage_1.lzma is good-cat-single-none-pad.lzma
115 with 0xFE appended to the end of the file. 0xFE doesn't begin .lzma
116 or LZMA_Alone format file.
118 bad-cat-single-none-pad_garbage_2.lzma is good-cat-single-none-pad.lzma
119 with 0xFF appended to the end of the file. 0xFF begins .lzma format
120 file, thus the decoder has to detect that the file is incomplete.
122 bad-cat-single-none-pad_garbage_3.lzma is good-cat-single-none-pad.lzma
123 with 0x5D appended to the end of the file. 0x5D is the most common
124 first byte of LZMA_Alone format file.
126 bad-single-none-footer_filter_flags.lzma has different Stream Flags
127 in Stream Footer than in Stream Header.
129 bad-single-none-too_long_vli.lzma has 10-byte variable-length integer.
131 bad-single-none-empty.lzma is like good-single-none-empty_3.lzma but
132 with non-zero value in the Compressed Size field.
134 bad-single-data_after_eopm_1.lzma has LZMA+Subblock, where the Subblock
135 filter gives one byte of data to LZMA after LZMA has detected EOPM.
137 bad-single-data_after_eopm_2.lzma is like
138 bad-single-data_after_eopm_1.lzma but Subblock gives 256 MiB of data
139 to LZMA after LZMA has detected EOPM.
141 bad-single-subblock_subblock.lzma has Subblock+Subblock, where the
142 Subblock decoder is given End of Input in the middle of a Subblock.
144 bad-single-subblock-padding_loop.lzma contains huge amount of
145 consecutive Padding bytes, which isn't allowed by the Subblock filter
146 format. If it were allowed, this file would hang the decoder for very
147 long time (weeks to years).
149 bad-single-subblock1023-slow.lzma is similar to
150 malicious-single-subblock31-slow.lzma except that this uses 1023 bytes
151 of Padding in every place instead of 31 bytes. The Subblock filter
152 format specification allows only 31-byte Padings, thus this file must
153 get detected as bad without producing any output. Allowing larger
154 Padding than 31 bytes was considered (so this test file was created),
155 but it seemed to be a bad idea since it would increase worst-case CPU
158 bad-single-lzma-flush_beginning.lzma has flush marker in the beginning
161 bad-single-lzma-flush_twice.lzma has two flush markers with no data
164 bad-multi-none-1.lzma has data after the last field in the Metadata
165 Block and the `Extra is present' flag is not set.
167 bad-multi-none-2.lzma has wrong Total Size in Footer Metadata Block.
169 bad-multi-none-3.lzma has wrong Uncompressed Size in Footer Metadata
172 bad-multi-none-index_1.lzma has wrong value in the Number of Data
175 bad-multi-none-index_2.lzma has too short Metadata to contain all
178 bad-multi-none-index_3.lzma has wrong value in Total Size field in
181 bad-multi-none-index_4.lzma has wrong value in Uncompressed Size field
184 bad-multi-none-extra_1.lzma has incomplete Extra Record at the end of
187 bad-multi-none-extra_2.lzma has incomplete variable-length integer as
190 bad-multi-none-extra_3.lzma has incomplete Extra Record at the end of
193 bad-multi-none-header_1.lzma has empty Header Metadata Block (even
194 the Metadata Flags field is not present).
196 bad-multi-none-header_2.lzma has Index in the Header Metadata Block,
197 which describes only one Data Block, while the Stream actually has
198 two Data Blocks. A sophisticated decoder should give an error when
199 it detects the second Data Block; all Multi-Block decoders must
200 detect the file as corrupt at some point.
202 bad-multi-none-header_3.lzma contains too small Total Size in Header
203 Metadata Block. A sophisticated decoder should abort decoding before
204 the second Data Block, preferably before the first Data Block has
205 been finished; all Multi-Block decoders must detect the file as
206 corrupt at some point.
208 bad-multi-none-header_4.lzma is like bad-multi-none-header_3.lzma but
209 with too small Uncompressed Size.
211 bad-multi-none-header_5.lzma has Index in the Header Metadata Block,
212 but the Total Size field is missing from the Footer Metadata Block.
214 bad-multi-none-header_6.lzma has both Index and Total Size in Header
215 Metadata Block, but Total Size doesn't match the Index. A sophisticated
216 decoder should abort before decoding any Data Blocks; all Multi-Block
217 decoders must detect the file as corrupt at some point.
219 bad-multi-none-block_1.lzma has wrong Uncompressed Size in the first
220 Data Block. A sophisticated decoder should detect this error before
221 producing any output, because it can see that the Uncompressed Size
222 doesn't match with the Index in Header Metadata Block; all Multi-Block
223 decoders must detect the file as corrupt at some point.
225 bad-multi-none-block_2.lzma has too big Compressed Size in the first
226 Data Block. A sophisticated decoder may be able to detect the file as
227 corrupt before producing any output, because Comrpessed Size + size
228 of Block Header exceed the Total Size stored in Index in Header
229 Metadata Block. A sophisticated decoder should be able to detect the
230 error before the end of the first Data Block; all Multi-Block decoders
231 must detect the file as corrupt at some point.
236 malicious-single-subblock31-slow.lzma requires quite a bit of CPU time
237 per decoded byte. It contains LZMA compressed Subblock filter data that
238 has as much Padding as the specification allows. LZMA is also used as
239 a Subfilter, to further slowdown the decoder. Every Subfilter instance
240 produces only one byte of output. If you can create a file that wastes
241 notably more CPU cycles than this file, please contact Lasse Collin.
243 malicious-single-subblock-256MiB.lzma is a tiny file that produces
244 256 MiB of output. It uses Subblock filter's run-length encoding
247 malicious-single-subblock-64PiB.lzma is a tiny file that produces
248 64 PiB of output (if you have patience to wait). This is done by
249 chaining two Subblock filters and using their run-length encoders.
251 malicious-multi-metadata-64PiB.lzma is like
252 malicious-single-subblock-64PiB.lzma but the huge amount of output
253 is in a Metadata Block. Trying to decode this file may take years
254 unless the decoder catches that the Metadata has unreasonable size.