xz-archive/tests/files/README

.lzma Test Files
----------------

0. Introduction

    This directory contains bunch of files to test handling of .lzma files
    in .lzma decoder implementations. Many of the files have been created
    by hand with a hex editor, thus there is no better "source code" than
    the files themselves. All the test files (*.lzma) and this README have
    been put into the public domain.


1. File Types

    Good files (good-*.lzma) must decode successfully without requiring
    a lot of CPU time or RAM.

    Unsupported files (unsupported-*.lzma) are good files, but headers
    indicate features not supported by the current file format
    specification.

    Bad files (bad-*.lzma) must cause the decoder to give an error. Like
    with the good files, these files must not require a lot of CPU time
    or RAM before they get detected to be broken.


2. Descriptions of Individual Files

2.1. Good Files

    good-0-empty.lzma has one Stream with no Blocks.

    good-0pad-empty.lzma has one Stream with no Blocks followed by
    four-byte Stream Padding.

    good-0cat-empty.lzma has two zero-Block Streams concatenated without
    Stream Padding.

    good-0catpad-empty.lzma has two zero-Block Streams concatenated with
    four-byte Stream Padding between the Streams.

    good-1-check-none.lzma has one Stream with one Block with two
    uncompressed LZMA2 chunks and no integrity check.

    good-1-check-crc32.lzma has one Stream with one Block with two
    uncompressed LZMA2 chunks and CRC32 check.

    good-1-check-crc64.lzma is like good-1-check-crc32.lzma but with CRC64.

    good-1-check-sha256.lzma is like good-1-check-crc32.lzma but with
    SHA256.

    good-2-lzma2.lzma has one Stream with two Blocks with one uncompressed
    LZMA2 chunk in each Block.

    good-1-block_header-1.lzma has both Compressed Size and Uncompressed
    Size in the Block Header. This has also four extra bytes of Header
    Padding.

    good-1-block_header-2.lzma has known Compressed Size.

    good-1-block_header-3.lzma has known Uncompressed Size.

    good-1-delta-lzma2.tiff.lzma is an image file that compresses
    better with Delta+LZMA2 than with plain LZMA2.

    good-1-x86-lzma2.lzma uses the x86 filter (BCJ) and LZMA2. The
    uncompressed file is compress_prepared_bcj_x86 found from the tests
    directory.

    good-1-sparc-lzma2.lzma uses the SPARC filter and LZMA. The
    uncompressed file is compress_prepared_bcj_sparc found from the tests
    directory.

    good-1-lzma2-1.lzma has two LZMA2 chunks, of which the second sets
    new properties.

    good-1-lzma2-2.lzma has two LZMA2 chunks, of which the second resets
    the state without specifying new properties.

    good-1-lzma2-3.lzma has two LZMA2 chunks, of which the first is
    uncompressed and the second is LZMA. The first chunk resets dictionary
    and the second sets new properties.

    good-1-3delta-lzma2.lzma has three Delta filters and LZMA2.


2.2. Unsupported Files

    unsupported-check.lzma uses Check ID 0x02 which isn't supported by
    the current version of the file format. It is implementation-defined
    how this file handled (it may reject it, or decode it possibly with
    a warning).

    unsupported-block_header.lzma has a non-nul byte in Header Padding,
    which may indicate presence of a new unsupported field.

    unsupported-filter_flags-1.lzma has unsupported Filter ID 0x7F.

    unsupported-filter_flags-2.lzma specifies only Delta filter in the
    List of Filter Flags, but Delta isn't allowed as the last filter in
    the chain. It could be a little more correct to detect this file as
    corrupt instead of unsupported, but saying it is unsupported is
    simpler in case of liblzma.

    unsupported-filter_flags-3.lzma specifies two LZMA2 filters in the
    List of Filter Flags. LZMA2 is allowed only as the last filter in the
    chain. It could be a little more correct to detect this file as
    corrupt instead of unsupported, but saying it is unsupported is
    simpler in case of liblzma.


2.3. Bad Files

    bad-0pad-empty.lzma has one Stream with no Blocks followed by
    five-byte Stream Padding. Stream Padding must be a multiple of four
    bytes, thus this file is corrupt.

    bad-0catpad-empty.lzma has two zero-Block Streams concatenated with
    five-byte Stream Padding between the Streams.

    bad-0cat-alone.lzma is good-0-empty.lzma concatenated with an empty
    LZMA_Alone file.

    bad-0-empty-truncated.lzma is good-0-empty.lzma without the last byte
    of the file.

    bad-0-nonempty_index.lzma has no Blocks but Index claims that there is
    one Block.

    bad-0-backward_size.lzma has wrong Backward Size in Stream Footer.

    bad-1-stream_flags-1.lzma has different Stream Flags in Stream Header
    and Stream Footer.

    bad-1-stream_flags-2.lzma has wrong CRC32 in Stream Header.

    bad-1-stream_flags-3.lzma has wrong CRC32 in Stream Footer.

    bad-1-vli-1.lzma has two-byte variable-length integer in the
    Uncompressed Size field in Block Header while one-byte would be enough
    for that value. It's important that the file gets rejected due to too
    big integer encoding instead of due to Uncompressed Size not matching
    the value stored in the Block Header. That is, the decoder must not
    try to decode the Compressed Data field.

    bad-1-vli-2.lzma has ten-byte variable-length integer as Uncompressed
    Size in Block Header. It's important that the file gets rejected due
    to too big integer encoding instead of due to Uncompressed Size not
    matching the value stored in the Block Header. That is, the decoder
    must not try to decode the Compressed Data field.

    bad-1-block_header-1.lzma has Block Header that ends in the middle of
    the Filter Flags field.

    bad-1-block_header-2.lzma has Block Header that has Compressed Size and
    Uncompressed Size but no List of Filter Flags field.

    bad-1-block_header-3.lzma has wrong CRC32 in Block Header.

    bad-1-block_header-4.lzma has too big Compressed Size (2^63 bytes while
    maximum is 2^63 - 4 bytes) in Block Header. It's important that the
    file gets rejected due to invalid Compressed Size value; the decoder
    must not try decoding the Compressed Data field.

    bad-2-index-1.lzma has wrong Total Sizes in Index.

    bad-2-index-2.lzma has wrong Uncompressed Sizes in Index.

    bad-2-index-3.lzma has non-nul byte in Index Padding.

    bad-2-index-4.lzma wrong CRC32 in Index.

    bad-2-compressed_data_padding.lzma has non-nul byte in the padding of
    the Compressed Data field of the first Block.

    bad-1-check-crc32.lzma has wrong Check (CRC32).

    bad-1-check-crc64.lzma has wrong Check (CRC64).

    bad-1-check-sha256.lzma has wrong Check (SHA-256).

    bad-1-lzma2-1.lzma has LZMA2 stream whose first chunk (uncompressed)
    doesn't reset the dictionary.

    bad-1-lzma2-2.lzma has two LZMA2 chunks, of which the second chunk
    indicates dictionary reset, but the LZMA compressed data tries to
    repeat data from the previous chunk.

    bad-1-lzma2-3.lzma sets new invalid properties (lc=8, lp=0, pb=0) in
    the middle of Block.

    bad-1-lzma2-4.lzma has two LZMA2 chunks, of which the first is
    uncompressed and the second is LZMA. The first chunk resets dictionary
    as it should, but the second chunk tries to reset state without
    specifying properties for LZMA.

    bad-1-lzma2-5.lzma is like bad-1-lzma2-4.lzma but doesn't try to reset
    anything in the header of the second chunk.

    bad-1-lzma2-6.lzma has reserved LZMA2 control byte value (0x03).

    bad-1-lzma2-7.lzma has EOPM at LZMA level.