From: Karthik Nayak Date: Tue, 01 Sep 2026 15:19:22 GMT Subject: [PATCH v5 0/3] hook: introduce the receive-report hook Message-ID: <20260901-758-introduce-hook-v5-0-35cdc6be3cc1@gmail.com> In-Reply-To: <20260818-758-introduce-hook-v1-1-8a8d89e65838@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 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 (3): doc: add proc-receive hook info in 'git-receive-pack.adoc' receive-pack: move message generation to separate function hook: introduce the receive-report hook Documentation/git-receive-pack.adoc | 17 +++ Documentation/githooks.adoc | 47 ++++++++ builtin/receive-pack.c | 132 +++++++++++++++------ t/meson.build | 1 + t/t5412-receive-report-hook.sh | 224 ++++++++++++++++++++++++++++++++++++ 5 files changed, 384 insertions(+), 37 deletions(-) Range-diff versus v4: 1: 6b173f391d < -: ---------- doc: add proc-receive hook info in 'git-receive-pack.adoc' -: ---------- > 1: cb32302829 doc: add proc-receive hook info in 'git-receive-pack.adoc' 2: 24e3e651ff ! 2: ad3394490e receive-pack: move message generation to separate function @@ Metadata ## Commit message ## receive-pack: move message generation to separate function - Post the reference transaction, both `report()` and `report_v2()` - generate the message to be sent to the client. In v2, we also add - reports for each reference if available. Since they share common code, - move them to a common function. This will also help the following - commit, where we will need to regenerate the message during hook - failure. + After git-receive-pack(1) has committed the reference updates, we call + either `report()` or `report_v2()` to report to the client which of the + references we have updated successfully and which updates have failed. + The only difference between those two functions is that the latter also + knows to provide a more detailed report about how exactly a given + reference was updated. + In the next commit we're about to add another site that wants to + generate these reports. Refactor the logic into a shared function that + can easily be reused. + + Helped-by: Patrick Steinhardt Signed-off-by: Karthik Nayak ## builtin/receive-pack.c ## @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands -static void report(struct command *commands, const char *unpack_status) +/* + * Generate the response to be sent to the client invoking 'git-receive-pack(1)'. -+ * For v2 protocol, set `add_reports` to true, which will also add additional ++ * For v2 protocol, set `detailed_report` to true, which will also add detailed + * report per reference update. + */ -+static void generate_response(struct strbuf *buf, struct command *commands, -+ const char *unpack_status, bool add_reports) ++static void generate_report(struct strbuf *buf, struct command *commands, ++ const char *unpack_status, bool detailed_report) { struct command *cmd; - struct strbuf buf = STRBUF_INIT; @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands + else + packet_buf_write(buf, "ok %s\n", cmd->ref_name); + -+ if (!add_reports || cmd->error_string) ++ if (!detailed_report || cmd->error_string) continue; - } - packet_buf_write(&buf, "ok %s\n", @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands +{ + struct strbuf buf = STRBUF_INIT; + -+ generate_response(&buf, commands, unpack_status, false); ++ generate_report(&buf, commands, unpack_status, false); + + if (use_sideband) + send_sideband(1, 1, buf.buf, buf.len, use_sideband); @@ builtin/receive-pack.c: static void update_shallow_info(struct command *commands +{ + struct strbuf buf = STRBUF_INIT; + -+ generate_response(&buf, commands, unpack_status, true); ++ generate_report(&buf, commands, unpack_status, true); if (use_sideband) send_sideband(1, 1, buf.buf, buf.len, use_sideband); 3: d6c98d2693 ! 3: a24ca1141d hook: introduce the receive-report hook @@ Commit message Signed-off-by: Karthik Nayak ## Documentation/git-receive-pack.adoc ## -@@ Documentation/git-receive-pack.adoc: requests. It handles refs whose names match the patterns defined by - `receive.procReceiveRefs` and executes the actual ref updates. See - linkgit:githooks[5] for the full protocol description. +@@ Documentation/git-receive-pack.adoc: commands will be executed by this hook, instead of by the internal + `execute_commands()` function. This hook is responsible for updating + the relevant references and reporting the results back to 'receive-pack'. +RECEIVE-REPORT HOOK +------------------- +This hook is invoked by 'git-receive-pack' after all the ref updates +have been applied but before the report is sent to the client. The hook +receives the complete report in pkt-line format on stdin and its stdout -+replaces the report sent to the client. Allowing the hook to rewrite ++replaces the report sent to the client, which allows the hook to rewrite +the outcomes or abort the push completely. See linkgit:githooks[5] for +the full protocol description. + @@ Documentation/githooks.adoc: The exit status of the hook is ignored for any stat +fully buffered by `receive-pack` before any data is sent to the client, +so the hook's exit status is known before the client receives anything. + -+There are two distinct ways the hook can affect the push outcome: ++There are three distinct ways the hook can affect the push outcome: ++ ++* To reject the push, modify the unpack status from `ok` to the required ++ error message. While `git-push` will fail, individual references may ++ still show success messages unless modified. + +* To reject individual ref updates while keeping `receive-pack` alive, + rewrite the corresponding `ok ` lines to -+ `ng ` lines in the output and exit with status 0. ++ `ng [ ]` lines in the output and exit with status 0. + The client will then mark those specific refs as rejected while + treating any `ok` refs as successful. The push as a whole is + considered failed if any ref is `ng`, and `git push` will exit with @@ builtin/receive-pack.c: static int run_update_hook(struct command *cmd) const char *refname) { @@ 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 `add_reports` to true, which will also add additional - * report per reference update. -+ * If `ref_error` is set, then all references will be rejected with the given -+ * error message. - */ - static void generate_response(struct strbuf *buf, struct command *commands, -- const char *unpack_status, bool add_reports) -+ const char *unpack_status, bool add_reports, -+ const char *ref_error) - { - struct command *cmd; - -@@ builtin/receive-pack.c: static void generate_response(struct strbuf *buf, struct command *commands, - if (cmd->error_string) - packet_buf_write(buf, "ng %s %s\n", - cmd->ref_name, cmd->error_string); -+ else if (ref_error) -+ packet_buf_write(buf, "ng %s %s\n", -+ cmd->ref_name, ref_error); - else - packet_buf_write(buf, "ok %s\n", cmd->ref_name); - -- if (!add_reports || cmd->error_string) -+ if (!add_reports || cmd->error_string || ref_error) - continue; + free(ref_status); + } - for (report = cmd->report; report; report = report->next) { ++static void override_cmds_error(struct command *commands, const char *err) ++{ ++ for (struct command *cmd = commands; cmd; cmd = cmd->next) { ++ cmd->error_string = err; ++ } ++} ++ + /* + * 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 char *unpack_status) - { - struct strbuf buf = STRBUF_INIT; -- generate_response(&buf, commands, unpack_status, false); -+ generate_response(&buf, commands, unpack_status, false, NULL); -+ + generate_report(&buf, commands, unpack_status, false); + + if (run_receive_report_hook(&buf)) { + strbuf_reset(&buf); -+ generate_response(&buf, commands, unpack_status, false, -+ "receive-report hook failed"); ++ override_cmds_error(commands, "receive-report hook failed"); ++ generate_report(&buf, commands, unpack_status, false); + } - ++ if (use_sideband) send_sideband(1, 1, buf.buf, buf.len, use_sideband); + else @@ builtin/receive-pack.c: static void report_v2(struct command *commands, const char *unpack_status) - { - struct strbuf buf = STRBUF_INIT; -- generate_response(&buf, commands, unpack_status, true); -+ generate_response(&buf, commands, unpack_status, true, NULL); -+ + generate_report(&buf, commands, unpack_status, true); + + if (run_receive_report_hook(&buf)) { + strbuf_reset(&buf); -+ generate_response(&buf, commands, unpack_status, true, -+ "receive-report hook failed"); ++ override_cmds_error(commands, "receive-report hook failed"); ++ generate_report(&buf, commands, unpack_status, true); + } - ++ if (use_sideband) send_sideband(1, 1, buf.buf, buf.len, use_sideband); + else ## t/meson.build ## @@ t/meson.build: integration_tests = [ @@ t/t5412-receive-report-hook.sh (new) + test_cmp expect actual +' + ++test_expect_success "hook can modify the unpack status" ' ++ test_when_finished "rm -rf upstream" && ++ test_when_finished "git -C workbench remote remove origin" && ++ ++ git init --bare upstream && ++ git -C workbench remote add origin ../upstream && ++ git -C workbench push origin $A:refs/heads/main && ++ ++ test_hook -C upstream --setup receive-report <<-\EOF && ++ test-tool pkt-line unpack | ++ sed "s/^unpack ok$/unpack push failed due to server error/" | ++ test-tool pkt-line pack ++ EOF ++ ++ test_must_fail git -C workbench push origin $B:refs/heads/main >out 2>&1 && ++ test_grep "error: remote unpack failed: push failed due to server error" out && ++ make_user_friendly_and_stable_output actual && ++ cat >expect <<-\EOF && ++ To ../upstream ++ .. -> main ++ EOF ++ test_cmp expect actual ++' ++ +test_expect_success "hook can report a custom failure message" ' + test_when_finished "rm -rf upstream" && + test_when_finished "git -C workbench remote remove origin" && --- base-commit: 11c6700f10234578d10523faf35656ca491425c9 change-id: 20260812-758-introduce-hook-5b3af9f1a7e8 Thanks - Karthik