RPM

Prefer file extension for detecting file compression.

Registered by Jeff Johnson

     Change: extension-based-compression-detection
     Purpose: Prefer file extension for detecting file compression.
     Reason: RPM tries to detect file compression by inspecting
                     "magic" bytes at the front of a file. This works for
                     formats with known "magic" bytes just fine, but fails
                     horribly for formats like LZMA where no such "magic"
                     bytes exist. For Mandriva we prefer to first use file
                     extension based determination (if someone is mis-names
                     his distribution files we have to take action anyway)
                     and fall back to "magic" byte based determination only
                     if no well known extension is found. Additionally,
                     detecting LZMA we want to do via file extension only.

Blueprint information

Status:
Started
Approver:
Jeff Johnson
Priority:
Medium
Drafter:
None
Direction:
Needs approval
Assignee:
None
Definition:
Review
Series goal:
Accepted for 5.4
Implementation:
Needs Code Review
Milestone target:
None
Started by
Jeff Johnson

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This (and similar for other vendors) can be fixed by
recompressing LZMA archives using XZ (which has
internal magic).

recompressing an LZMA archive isn't hard and should suffice.

=== A comment from Per √ėyvind about current state of affairs in MDV (but the same is definitely true for ROSA):
As you don't really encounter much stuff compressed with lzma around, this one isn't really that relevant anymore and I think we can just drop it and the mandriva #ifdef carried upstream to make code simpler to maintain.

There's LZMA compressed archives and there are LZMA payloads (widely
used in SLES). Theses are separate and coupled issues.

I'm still in favor of dropping LZMA: I see no reason why RPM needs to
carry around LZMA because SuSE made the wrong business decision
several years ago (heck its ~5y now maybe half-way through whatever
SLES support promise is current)

(?)

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