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Re: RFC: fixing the 32-bit size and time limits in gzip file format
From: |
Greg Roelofs |
Subject: |
Re: RFC: fixing the 32-bit size and time limits in gzip file format |
Date: |
Mon, 16 Aug 2010 13:19:05 -0700 |
Mark wrote:
> Eventually new versions of gzip that don't issue that warning in
> that case would replace the old ones. We could stick in a small
> extra field that simply indicates that those extra four bytes
> are there. (We'd have to always accept that hit in the streaming
> case, since you wouldn't know until too late that you needed
> the longer length. The total hit would be eight bytes -- four
> for the extra field and four for the extended length at the end.)
The extra field is a minimum of six bytes (assuming there are no other
subfields already present).
> Concatenated gzip streams with older gzips unaware of the extra
> field would still be supported by preventing the two-byte magic
> header (1f 8b) in the appended length extension. Simply shift
> the 32-bit value up one bit, forcing the low bit to be zero.
> Then it can't match 8b1f on the bottom. That limits the total
> length to 63 bits, but that's not really a loss since the off_t
> type is signed anyway.
Concatenated gzip streams made by newer gzips fail on older gzips,
though. I'm not sure I believe that's a worthwhile tradeoff.
Greg
- RFC: fixing the 32-bit size and time limits in gzip file format, Paul Eggert, 2010/08/15
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Greg Roelofs, 2010/08/15
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/15
- Re: RFC: fixing the 32-bit size and time limits in gzip file format,
Greg Roelofs <=
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Paul Eggert, 2010/08/16
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/17
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/17
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Paul Eggert, 2010/08/19
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/20
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Greg Roelofs, 2010/08/20
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/20
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/20
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/21
- Re: RFC: fixing the 32-bit size and time limits in gzip file format, Mark Adler, 2010/08/16