Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

archive-tar.c and archive-zip.c now perform conversion check, with
help of sha1_file_to_archive() from archive.c

This gives backends more freedom in dealing with (streaming) large
blobs.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Some tar filters may be very expensive to run, so sites do
not want to expose them via upload-archive. This patch lets
users configure tar.<filter>.remote to turn them off.

By default, gzip filters are left on, as they are about as
expensive as creating zip archives.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The process for guessing an archive output format based on
the filename is something like this:

  a. parse --output in cmd_archive; check the filename
     against a static set of mapping heuristics (right now
     it just matches ".zip" for zip files).

  b. if found, stick a fake "--format=zip" at the beginning
     of the arguments list (if the user did specify a
     --format manually, the later option will override our
     fake one)

  c. if it's a remote call, ship the arguments to the remote
     (including the fake), which will call write_archive on
     their end

  d. if it's local, ship the arguments to write_archive
     locally

There are two problems:

  1. The set of mappings is static and at too high a level.
     The write_archive level is going to check config for
     user-defined formats, some of which will specify
     extensions. We need to delay lookup until those are
     parsed, so we can match against them.

  2. For a remote archive call, our set of mappings (or
     formats) may not match the remote side's. This is OK in
     practice right now, because all versions of git
     understand "zip" and "tar". But as new formats are
     added, there is going to be a mismatch between what the
     client can do and what the remote server can do.

To fix (1), this patch refactors the location guessing to
happen at the write_archive level, instead of the
cmd_archive level. So instead of sticking a fake --format
field in the argv list, we actually pass a "name hint" down
the callchain; this hint is used at the appropriate time to
guess the format (if one hasn't been given already).

This patch leaves (2) unfixed. The name_hint is converted to
a "--format" option as before, and passed to the remote.
This means the local side's idea of how extensions map to
formats will take precedence.

Another option would be to pass the name hint to the remote
side and let the remote choose. This isn't a good idea for
two reasons:

  1. There's no room in the protocol for passing that
     information. We can pass a new argument, but older
     versions of git on the server will choke on it.

  2. Letting the remote side decide creates a silent
     inconsistency in user experience. Consider the case
     that the locally installed git knows about the "tar.gz"
     format, but a remote server doesn't.

     Running "git archive -o foo.tar.gz" will use the tar.gz
     format. If we use --remote, and the local side chooses
     the format, then we send "--format=tar.gz" to the
     remote, which will complain about the unknown format.
     But if we let the remote side choose the format, then
     it will realize that it doesn't know about "tar.gz" and
     output uncompressed tar without even issuing a warning.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The current archivers are very static; when you are in the
write_tar_archive function, you know you are writing a tar.
However, to facilitate runtime-configurable archivers
that will share a common write function we need to tell the
function which archiver was used.

As a convenience, we also provide an opaque data pointer in
the archiver struct so that individual archivers can put
something useful there when they register themselves.
Technically they could just use the "name" field to look in
an internal map of names to data, but this is much simpler.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Most of the tar and zip code was nicely split out into two
abstracted files which knew only about their specific
formats. The entry point to this code was a single "write
archive" function.

However, as these basic formats grow more complex (e.g., by
handling multiple file extensions and format names), a
static list of the entry point functions won't be enough.
Instead, let's provide a way for the tar and zip code to
tell the main archive code what they support by registering
archiver names and functions.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The old behaviour still remains with --worktree-attributes, and it is
always on for the legacy "git tar-tree".

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Move the declaration of struct archiver to archive.c, as this is the only
file left where it is used.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

MAX_EXTRA_ARGS is not used anymore, so remove it.  MAX_ARGS is used only
in builtin-upload-archive.c, so define it there.  Also report the actual
value we're comparing against when the number of args is too big.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

write_archive() in archive.c is the only callsite for the command line
parsing functions located in builtin-archive.c.  Move them to the place
where they are used, un-export them and make them static, as hinted at
by Stephan.

Cc: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>