UnexpectedEof encountered when decompressing data
Herschel opened this issue · comments
The following zlib-compressed data fails to decompress in libflate 1.0.2 with an UnexpectedEof error:
data.zip
(The compressed file is data.bin inside the zip file)
rustc 1.47.0 (18bf6b4f0 2020-10-07)
It successfully decompresses using flate2-rs with both the miniz-oxide and zlib backends.
Thank you for reporting this issue.
Investigating your file (data.bin), it turned out that the zlib data seems to have invalid footer bytes. ZLIB footer consists of 4-bytes ADER32 checksum, but data.bin only has 3 bytes for the footer, so an EOF error occurs during decompression.
It's easy to ignore this wrong footer but I'm not sure it's okay to do so.
I'd like to investigate this issue more when I have time.
Thank you! Sorry I don't have more info; I didn't take time to look into the issue much.
For reference, this data comes from image data inside a Flash SWF file in the wild. If it's indeed a checksum error, perhaps at least a more accurate error should be thrown (Adler32Error or similar). The user could then try to gracefully ignore this specific error.
I'm unsure if flate2 also detects a checksum error and just silently swallows it, but no error is thrown in their case.
After investigating this issue in more detail, it turned out this is a program bug rather than an input data corruption.
I'm addressing this bug on #57. Thanks a lot for reporting this bug.