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Re: [PATCH] import-tars: ignore the global PAX header

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Mar 23, 2020, 21:05 UTC
Message-ID
<nycvar.QRO.7.76.6.2003232158160.46@tvgsbejvaqbjf.bet>
In-Reply-To
<fce519db-5ad4-270f-abcf-0e26549486cb@web.de>
Hi René,
On Mon, 23 Mar 2020, René Scharfe wrote:
Show 14 quoted lines
> Am 23.03.20 um 14:08 schrieb Johannes Schindelin via GitGitGadget:
> > From: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> > Git's own `git archive` inserts that header, but it often gets into the
> > way of `import-tars.perl` e.g. when a prefix was specified (for example
> > via `--prefix=my-project-1.0.0/`, or when downloading a `.tar.gz` from
> > GitHub releases): this prefix _should_ be stripped.
> >
> > Let's just skip it.
>
> git archive uses a global pax header to pass the ID of the archived
> commit as a comment, and for mtime values after 2242-03-16.  Ignoring it
> in a simple importer seems reasonable for now, but I don't understand
> how this relates to prefixes.

The tar importer in `contrib/fast-import/import-tars.perl` has a very convenient feature that I took for public knowledge: if _all_ paths stored in the imported `.tar` start with a common prefix, e.g. `my-project-1.0.0/` as indicated in the commit message (or `git-2.26.0/` in the tar at https://github.com/git/git/archive/v2.26.0.tar.gz), then this prefix is stripped.

This feature makes a ton of sense because it is relatively common to import two or more revisions of the same project into Git, and obviously we don't want all files to live in a tree whose name changes from revision to revision.

Now, the problem with that feature is that it breaks down if there is a `pax_global_header` "file" located outside of said prefix.

> Is it because the header is treated as a regular file with the full path
> "pax_global_header" (independently from any prefix for actual files) and
> can thus be placed outside the expected destination directory?
Exactly.

Thanks, Dscho

Show 5 quoted lines
>
> Thanks,
> René
>
>
Previous: Junio C HamanoNext: Junio C Hamano
Message 6 of 13 in “import-tars: ignore the global PAX header”
  1. import-tars: ignore the global PAX headerJohannes Schindelin via GitGitGadget, Mar 23, 2020
  2. René ScharfeMar 23, 2020
  3. Junio C HamanoMar 23, 2020
  4. Johannes SchindelinMar 23, 2020
  5. Junio C HamanoMar 23, 2020
  6. Johannes SchindelinMar 23, 2020
  7. Junio C HamanoMar 23, 2020
  8. brian m. carlsonMar 23, 2020
  9. Johannes SchindelinMar 24, 2020
  10. import-tars: ignore the global PAX headerJohannes Schindelin via GitGitGadget, Mar 24, 2020
  11. Junio C HamanoMar 24, 2020
  12. Johannes SchindelinMar 25, 2020
  13. Junio C HamanoMar 25, 2020

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