lib/lzo: fix bugs for very short or empty input

For very short input data (0 - 1 bytes), lzo-rle was not behaving
correctly.  Fix this behaviour and update documentation accordingly.

For zero-length input, lzo v0 outputs an end-of-stream marker only,
which was misinterpreted by lzo-rle as a bitstream version number.
Ensure bitstream versions > 0 require a minimum stream length of 5.

Also fixes a bug in handling the tail for very short inputs when a
bitstream version is present.

Link: http://lkml.kernel.org/r/20190326165857.34613-1-dave.rodgman@arm.com
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Rodgman
2019-04-05 18:38:58 -07:00
committed by Linus Torvalds
parent 6147e136ff
commit b11ed18efa
3 changed files with 12 additions and 9 deletions

View File

@@ -102,9 +102,11 @@ Byte sequences
dictionary which is empty, and that it will always be
invalid at this place.
17 : bitstream version. If the first byte is 17, the next byte
gives the bitstream version (version 1 only). If the first byte
is not 17, the bitstream version is 0.
17 : bitstream version. If the first byte is 17, and compressed
stream length is at least 5 bytes (length of shortest possible
versioned bitstream), the next byte gives the bitstream version
(version 1 only).
Otherwise, the bitstream version is 0.
18..21 : copy 0..3 literals
state = (byte - 17) = 0..3 [ copy <state> literals ]