[PATCH v8 0/4] hook: introduce the receive-report hook

[Karthik Nayak <karthik.188@gmail.com>]

Introduce a new receive-report hook which kicks in after the reference
transaction is complete, but before the report is sent to the client.
The hook receives the pkt-line encoded report in its stdin and its
stdout replaces the report transferred to the user. If the hook exits
with a non-zero exit code, all references are marked as rejected.

The first patch, adds missing documentation to 'git-receive-pack.adoc'.
The second patch refactors code and the third patch contains the new
hook.

---
Changes in v8:
- Fix spelling mistake s/UNKOWN/UNKNOWN
- Remove a stale comment from previous version.
- Fix an argument which wasn't changed with the previous version's
  changes.
- Link to v7: https://patch.msgid.link/20260904-758-introduce-hook-v7-0-6c66f0a3a572@gmail.com

Changes in v7:
- Removed report_v2() since it is the same as report() with the new
  changes.
- Used a switch statement instead of an if/else for the enum.
- Removed an unnecessary curly brace.
- Also rebased on top of latest master (3cb9185f65 (The 22nd batch,
  2026-09-02) as there were conflicts.
- Link to v6: https://patch.msgid.link/20260903-758-introduce-hook-v6-0-6283b1fb9b1c@gmail.com

Changes in v6:
- Introduce a new commit which introduces `enum report_status_version`,
  use that and drop static variables in the codebase.
- Reword the commit message and documentation to:
  - State further why reference-transaction cannot be used.
  - State the responsibility of the hook owner to undo and reference
    changes if needed.
- Link to v5: https://patch.msgid.link/20260901-758-introduce-hook-v5-0-35cdc6be3cc1@gmail.com

Changes in v5:
- Rewrote some of the commit messages and documentation.
- Renamed the function `generate_response` to `generate_report` to avoid
  ambiguity.
- We now override the cmd's error_strings, this avoids the whole
  precedence issue with the earlier series.
- Also add information about how we can override the unpack status to
  fail the push and add a corresponding test.
- Thanks to Patrick for the review!
- Junio: This causes conflict with next ('jt/receive-pack-pluggable-writes')
  similar to before, please let me know if its better for me to add that
  dependency.
- Link to v4: https://patch.msgid.link/20260826-758-introduce-hook-v4-0-6b14975ad957@gmail.com

Changes in v4:
- Change the name of the hook to be 'receive-report' to avoid ambiguity.
- Link to v3: https://patch.msgid.link/20260824-758-introduce-hook-v3-0-499526f0a062@gmail.com

Changes in v3:
- Move out addition of proc-receive hook doc to 'git-receive-pack.adoc'
  into a new commit.
- Add a new commit to move out the response generation in receive-pack
  to a new function.
- Instead of die-ing on non-zero exit code, we modify each reference to
  indicate that the hook failed.
- Instead of correctly listing out the protocol, link to
  linkgit:gitprotocol-pack[5], as the protocol also differs between v1
  and v2.
- Link to v2: https://patch.msgid.link/20260821-758-introduce-hook-v2-1-e90e2f7ac2cf@gmail.com

Changes in v2:
- Modify the documentation and commit message to be more verbose.
- Add documentation to 'git-receive-pack.adoc'
- Use 'ret' as the variable name for the return code.
- Modify the test to also check for the 'remote:'.
- Link to v1: https://patch.msgid.link/20260818-758-introduce-hook-v1-1-8a8d89e65838@gmail.com

 To: git@vger.kernel.org
 CC: ps@pks.im
 CC: gitster@pobox.com
 CC: jltobler@gmail.com
 CC: kristofferhaugsbakk@fastmail.com
 CC: phillip.wood123@gmail.com

---
Karthik Nayak (4):
      doc: add proc-receive hook info in 'git-receive-pack.adoc'
      receive-pack: drop static variables to track report status version
      receive-pack: move message generation to separate function
      hook: introduce the receive-report hook

 Documentation/git-receive-pack.adoc |  17 +++
 Documentation/githooks.adoc         |  61 ++++++++++
 builtin/receive-pack.c              | 146 +++++++++++++++--------
 t/meson.build                       |   1 +
 t/t5412-receive-report-hook.sh      | 224 ++++++++++++++++++++++++++++++++++++
 5 files changed, 401 insertions(+), 48 deletions(-)

Range-diff versus v7:

1:  a80b77f284 = 1:  55f08ef482 doc: add proc-receive hook info in 'git-receive-pack.adoc'
2:  116699bd30 ! 2:  df5840c4fa receive-pack: drop static variables to track report status version
    @@ builtin/receive-pack.c: enum deny_action {
      };
      
     +enum report_status_version {
    -+	REPORT_STATUS_UNKOWN = 0,
    ++	REPORT_STATUS_UNKNOWN = 0,
     +	REPORT_STATUS_V0,
     +	REPORT_STATUS_V2,
     +};
    @@ builtin/receive-pack.c: int cmd_receive_pack(int argc,
      	struct shallow_info si;
      	struct packet_reader reader;
      	struct odb_transaction *transaction = NULL;
    -+	enum report_status_version version = REPORT_STATUS_UNKOWN;
    ++	enum report_status_version version = REPORT_STATUS_UNKNOWN;
      
      	struct option options[] = {
      		OPT__QUIET(&quiet, N_("quiet")),
3:  e36b4e7a21 ! 3:  d7c3b7ed55 receive-pack: move message generation to separate function
    @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands
     -static void report(struct command *commands, const struct strbuf *unpack_status)
     +/*
     + * Generate the response to be sent to the client invoking 'git-receive-pack(1)'.
    -+ * For v2 protocol, set `detailed_report` to true, which will also add detailed
    -+ * report per reference update.
     + */
     +static void generate_report(struct strbuf *buf, struct command *commands,
     +			    const struct strbuf *unpack_status,
4:  e7c1c0d196 ! 4:  d0e632235a hook: introduce the receive-report hook
    @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands
     +
      /*
       * Generate the response to be sent to the client invoking 'git-receive-pack(1)'.
    -  * For v2 protocol, set `detailed_report` to true, which will also add detailed
    +  */
     @@ builtin/receive-pack.c: static void report(struct command *commands, const struct strbuf *unpack_status,
      
      	generate_report(&buf, commands, unpack_status, version);
    @@ builtin/receive-pack.c: static void report(struct command *commands, const struc
     +	if (run_receive_report_hook(&buf)) {
     +		strbuf_reset(&buf);
     +		override_cmds_error(commands, "receive-report hook failed");
    -+		generate_report(&buf, commands, unpack_status, false);
    ++		generate_report(&buf, commands, unpack_status, version);
     +	}
     +
      	if (use_sideband)

---
base-commit: 3cb9185f65410273787f74333cc027d2ea5daada
change-id: 20260812-758-introduce-hook-5b3af9f1a7e8


Thanks
- Karthik