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.
108 good-multi-none-block_2.lzma has Index in Header Metadata Block. The
109 Uncompressed Size field is present in Data Blocks and no EOPM is used.
114 bad-single-none-truncated.lzma is good-single-none.lzma without the
115 last byte of the file.
117 bad-cat-single-none-pad_garbage_1.lzma is good-cat-single-none-pad.lzma
118 with 0xFE appended to the end of the file. 0xFE doesn't begin .lzma
119 or LZMA_Alone format file.
121 bad-cat-single-none-pad_garbage_2.lzma is good-cat-single-none-pad.lzma
122 with 0xFF appended to the end of the file. 0xFF begins .lzma format
123 file, thus the decoder has to detect that the file is incomplete.
125 bad-cat-single-none-pad_garbage_3.lzma is good-cat-single-none-pad.lzma
126 with 0x5D appended to the end of the file. 0x5D is the most common
127 first byte of LZMA_Alone format file.
129 bad-single-none-footer_filter_flags.lzma has different Stream Flags
130 in Stream Footer than in Stream Header.
132 bad-single-none-too_long_vli.lzma has 10-byte variable-length integer.
134 bad-single-none-empty.lzma is like good-single-none-empty_3.lzma but
135 with non-zero value in the Compressed Size field.
137 bad-single-data_after_eopm_1.lzma has LZMA+Subblock, where the Subblock
138 filter gives one byte of data to LZMA after LZMA has detected EOPM.
140 bad-single-data_after_eopm_2.lzma is like
141 bad-single-data_after_eopm_1.lzma but Subblock gives 256 MiB of data
142 to LZMA after LZMA has detected EOPM.
144 bad-single-subblock_subblock.lzma has Subblock+Subblock, where the
145 Subblock decoder is given End of Input in the middle of a Subblock.
147 bad-single-subblock-padding_loop.lzma contains huge amount of
148 consecutive Padding bytes, which isn't allowed by the Subblock filter
149 format. If it were allowed, this file would hang the decoder for very
150 long time (weeks to years).
152 bad-single-subblock1023-slow.lzma is similar to
153 malicious-single-subblock31-slow.lzma except that this uses 1023 bytes
154 of Padding in every place instead of 31 bytes. The Subblock filter
155 format specification allows only 31-byte Padings, thus this file must
156 get detected as bad without producing any output. Allowing larger
157 Padding than 31 bytes was considered (so this test file was created),
158 but it seemed to be a bad idea since it would increase worst-case CPU
161 bad-single-lzma-flush_beginning.lzma has flush marker in the beginning
164 bad-single-lzma-flush_twice.lzma has two flush markers with no data
167 bad-multi-none-1.lzma has data after the last field in the Metadata
168 Block and the `Extra is present' flag is not set.
170 bad-multi-none-2.lzma has wrong Total Size in Footer Metadata Block.
172 bad-multi-none-3.lzma has wrong Uncompressed Size in Footer Metadata
175 bad-multi-none-index_1.lzma has wrong value in the Number of Data
178 bad-multi-none-index_2.lzma has too short Metadata to contain all
181 bad-multi-none-index_3.lzma has wrong value in Total Size field in
184 bad-multi-none-index_4.lzma has wrong value in Uncompressed Size field
187 bad-multi-none-extra_1.lzma has incomplete Extra Record at the end of
190 bad-multi-none-extra_2.lzma has incomplete variable-length integer as
193 bad-multi-none-extra_3.lzma has incomplete Extra Record at the end of
196 bad-multi-none-header_1.lzma has empty Header Metadata Block (even
197 the Metadata Flags field is not present).
199 bad-multi-none-header_2.lzma has Index in the Header Metadata Block,
200 which describes only one Data Block, while the Stream actually has
201 two Data Blocks. A sophisticated decoder should give an error when
202 it detects the second Data Block; all Multi-Block decoders must
203 detect the file as corrupt at some point.
205 bad-multi-none-header_3.lzma contains too small Total Size in Header
206 Metadata Block. A sophisticated decoder should abort decoding before
207 the second Data Block, preferably before the first Data Block has
208 been finished; all Multi-Block decoders must detect the file as
209 corrupt at some point.
211 bad-multi-none-header_4.lzma is like bad-multi-none-header_3.lzma but
212 with too small Uncompressed Size.
214 bad-multi-none-header_5.lzma has Index in the Header Metadata Block,
215 but the Total Size field is missing from the Footer Metadata Block.
217 bad-multi-none-header_6.lzma has both Index and Total Size in Header
218 Metadata Block, but Total Size doesn't match the Index. A sophisticated
219 decoder should abort before decoding any Data Blocks; all Multi-Block
220 decoders must detect the file as corrupt at some point.
222 bad-multi-none-block_1.lzma has wrong Uncompressed Size in the first
223 Data Block. A sophisticated decoder should detect this error before
224 producing any output, because it can see that the Uncompressed Size
225 doesn't match with the Index in Header Metadata Block; all Multi-Block
226 decoders must detect the file as corrupt at some point.
228 bad-multi-none-block_2.lzma has too big Compressed Size in the first
229 Data Block. A sophisticated decoder may be able to detect the file as
230 corrupt before producing any output, because Comrpessed Size + size
231 of Block Header exceed the Total Size stored in Index in Header
232 Metadata Block. A sophisticated decoder should be able to detect the
233 error before the end of the first Data Block; all Multi-Block decoders
234 must detect the file as corrupt at some point.
236 bad-multi-none-block_3.lzma has only the Compressed Size field in the
237 Block Header of the second Data Block and EOPM isn't used.
242 malicious-single-subblock31-slow.lzma requires quite a bit of CPU time
243 per decoded byte. It contains LZMA compressed Subblock filter data that
244 has as much Padding as the specification allows. LZMA is also used as
245 a Subfilter, to further slowdown the decoder. Every Subfilter instance
246 produces only one byte of output. If you can create a file that wastes
247 notably more CPU cycles than this file, please contact Lasse Collin.
249 malicious-single-subblock-256MiB.lzma is a tiny file that produces
250 256 MiB of output. It uses Subblock filter's run-length encoding
253 malicious-single-subblock-64PiB.lzma is a tiny file that produces
254 64 PiB of output (if you have patience to wait). This is done by
255 chaining two Subblock filters and using their run-length encoders.
257 malicious-multi-metadata-64PiB.lzma is like
258 malicious-single-subblock-64PiB.lzma but the huge amount of output
259 is in a Metadata Block. Trying to decode this file may take years
260 unless the decoder catches that the Metadata has unreasonable size.