[PATCH GSoC v18 00/13] cat-file: add remote-object-info to batch-command

This patch series is a continuation of Eric Ju's (eric.peijian@gmail.com) and Calvin Wan's (calvinwan@google.com) patch series [1] and [2] respectively.

Sometimes it is beneficial to retrieve information about an object without having to download it completely. The server logic for retrieving size has already been implemented and merged in a2ba162cda (object-info: support for retrieving object info, 2021-04-20) [3]. This patch series implement the client option for it.

Eric's series adds the remote-object-info command to cat-file --batch-command. This command allows the client to make an object-info command request to a server that supports protocol v2.

If the server uses protocol v2 but does not support the object-info capability, cat-file --batch-command will die.

If a user attempts to use remote-object-info with protocol v1, cat-file --batch-command will die.

Currently, only the size (%(objectsize)) is supported end to end in this implementation. The type (%(objecttype)) is known by the client's allow-list and request path but is not supported on the server side nor the response parsing. A follow up series will add full end-to-end support for %(objecttype).

The default format for remote-object-info is set to "%(objectname) %(objectsize)". Once %(objecttype) is supported, the default format will be unified accordingly.

If the batch command format includes unsupported fields such as %(objecttype), %(objectsize:disk), or %(deltabase), the command will return empty strings for each unsupported field.

This series completes Eric's work mainly with the refactor of the validation of the placeholder with an allow-list that filters what the client asks with what the server is capable of provide following Jeff King's idea [4].

GitHub CI: https://github.com/pabloosabaterr/git/actions/runs/29404390713

[1]: https://lore.kernel.org/git/20250221190451.12536-1-eric.peijian@gmail.com/ [2]: https://lore.kernel.org/git/20220728230210.2952731-1-calvinwan@google.com/#t [3]: https://git.kernel.org/pub/scm/git/git.git/commit/?id=a2ba162cda2acc171c3e36acbbc854792b093cb7 [4]: https://lore.kernel.org/git/20250313060250.GH94015@coredump.intra.peff.net/

Changes since v17:

At 10th commit: transport: add client support for object-info
- style
- enforced the server response handling, not allowing bare "<oid>" or
  responses with a different number of attributes different from the
  number asked.

Signed-off-by: Pablo Sabater <pabloosabaterr@gmail.com>

---
Calvin Wan (3):
      fetch-pack: move fetch initialization
      serve: advertise object-info feature
      transport: add client support for object-info

Eric Ju (3):
      cat-file: declare loop counter inside for()
      t1006: split test utility functions into new 'lib-cat-file.sh'
      cat-file: add remote-object-info to batch-command

Pablo Sabater (7):
      transport-helper: fix memory leak of helper on disconnect
      fetch-pack: fix hash_algo variable type
      fetch-pack: drop static advertise_sid variable
      fetch-pack: move write_fetch_command_and_capabilities() to connect.c
      connect: make write_fetch_command_and_capabilities() more generic
      cat-file: validate remote atoms with an allow-list
      cat-file: make remote-object-info allow-list dynamic

 Documentation/git-cat-file.adoc        |  29 +-
 Documentation/gitprotocol-v2.adoc      |  11 +-
 Makefile                               |   1 +
 builtin/cat-file.c                     | 221 ++++++++++-
 connect.c                              |  34 ++
 connect.h                              |   8 +
 fetch-object-info.c                    | 141 +++++++
 fetch-object-info.h                    |  22 ++
 fetch-pack.c                           |  58 +--
 fetch-pack.h                           |   1 +
 meson.build                            |   1 +
 object-file.c                          |  10 +
 odb.h                                  |   3 +
 serve.c                                |   5 +-
 t/lib-cat-file.sh                      |  16 +
 t/meson.build                          |   1 +
 t/t1006-cat-file.sh                    |  13 +-
 t/t1017-cat-file-remote-object-info.sh | 699 +++++++++++++++++++++++++++++++++
 transport-helper.c                     |  12 +-
 transport-internal.h                   |   8 +
 transport.c                            |  45 +++
 transport.h                            |  10 +
 22 files changed, 1265 insertions(+), 84 deletions(-)

--- base-commit: f60db8d575adb79761d363e026fb49bddf330c73