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Checksum None is valid #27

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blacktop opened this issue Feb 23, 2020 · 4 comments
Closed

Checksum None is valid #27

blacktop opened this issue Feb 23, 2020 · 4 comments

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@blacktop
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I'm trying to decompress iOS OTA files and they are failing your flags check. They appear to have "None" checksum.

https://tukaani.org/xz/xz-file-format-1.0.4.txt

2.1.1.2. Stream Flags

        The first byte of Stream Flags is always a null byte. In the
        future, this byte may be used to indicate a new Stream version
        or other Stream properties.

        The second byte of Stream Flags is a bit field:

            Bit(s)  Mask  Description
             0-3    0x0F  Type of Check (see Section 3.4):
                              ID    Size      Check name
                              0x00   0 bytes  None
                              0x01   4 bytes  CRC32
                              0x02   4 bytes  (Reserved)
                              0x03   4 bytes  (Reserved)
                              0x04   8 bytes  CRC64
                              0x05   8 bytes  (Reserved)
                              0x06   8 bytes  (Reserved)
                              0x07  16 bytes  (Reserved)
                              0x08  16 bytes  (Reserved)
                              0x09  16 bytes  (Reserved)
                              0x0A  32 bytes  SHA-256
                              0x0B  32 bytes  (Reserved)
                              0x0C  32 bytes  (Reserved)
                              0x0D  64 bytes  (Reserved)
                              0x0E  64 bytes  (Reserved)
                              0x0F  64 bytes  (Reserved)
             4-7    0xF0  Reserved for future use; MUST be zero for now.

Thank you for a great pkg!
@ulikunitz
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Thanks for reporting. I have to look into that.

@ulikunitz
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You are right. The code doesn't support the None Check ID and the spec says it SHOULD be supported. I have to look into that.

ulikunitz added a commit that referenced this issue Feb 24, 2020
@ulikunitz
xz: add test for check-ID None
7dfc1fc 
Issue #27 reported the problem that an xz file didn't have a checksum.
This commit adds a test.
ulikunitz added a commit that referenced this issue Feb 24, 2020
@ulikunitz
xz: add support for check-ID None to Reader
ef77b79 
The check-ID None is valid and SHOULD be supported according to the
xz specification. This commit modifies the Reader to support the
check-ID None.

A new simple hash noneHash is introduced, which makes the
implementation quite elegant. For performance reasons we avoid the
writing into the hash during decompression.

Fixes issue #27 - #27
ulikunitz added a commit that referenced this issue Feb 24, 2020
@ulikunitz
xz: add support for check-ID None to Writer
2c0b983 
So far we didn't support the check-ID None for Writer. To request it I
added a NoCheckSum boolean to the configuration, because CRC64 should
still be used as a default.

The commit is related to issue #27 - #27
@ulikunitz
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I have created release v.0.5.7. Please check whether it works for you.

@blacktop
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It works great!! Thank you for such a fast response and elegant solution!!

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@blacktop @ulikunitz