hook: add 'run' subcommand

In order to enable hooks to be run as an external process, by a
standalone Git command, or by tools which wrap Git, provide an external
means to run all configured hook commands for a given hook event.

Most of our hooks require more complex functionality than this, but
let's start with the bare minimum required to support our simplest
hooks.

In terms of implementation the usage_with_options() and "goto usage"
pattern here mirrors that of
builtin/{commit-graph,multi-pack-index}.c.

Some of the implementation here, such as a function being named
run_hooks_opt() when it's tasked with running one hook, to using the
run_processes_parallel_tr2() API to run with jobs=1 is somewhere
between a bit odd and and an overkill for the current features of this
"hook run" command and the hook.[ch] API.

This code will eventually be able to run multiple hooks declared in
config in parallel, by starting out with these names and APIs we
reduce the later churn of renaming functions, switching from the
run_command() to run_processes_parallel_tr2() API etc.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/command-list.txt b/command-list.txt
index 675c28f..9bd6f3c 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -103,6 +103,7 @@ git-grep                                mainporcelain           info
 git-gui                                 mainporcelain
 git-hash-object                         plumbingmanipulators
 git-help                                ancillaryinterrogators          complete
+git-hook                                purehelpers
 git-http-backend                        synchingrepositories
 git-http-fetch                          synchelpers
 git-http-push                           synchelpers