* ar/config-hooks: (21 commits)
  builtin/receive-pack: avoid spinning no-op sideband async threads
  hook: add -z option to "git hook list"
  hook: allow out-of-repo 'git hook' invocations
  hook: allow event = "" to overwrite previous values
  hook: allow disabling config hooks
  hook: include hooks from the config
  hook: add "git hook list" command
  hook: run a list of hooks to prepare for multihook support
  hook: add internal state alloc/free callbacks
  receive-pack: convert receive hooks to hook API
  receive-pack: convert update hooks to new API
  run-command: poll child input in addition to output
  hook: add jobs option
  reference-transaction: use hook API instead of run-command
  transport: convert pre-push to hook API
  hook: allow separate std[out|err] streams
  hook: convert 'post-rewrite' hook in sequencer.c to hook API
  hook: provide stdin via callback
  run-command: add stdin callback for parallelization
  run-command: add helper for pp child states
  ...

Move the convenience wrapper from hook to string-list since
it's a more suitable place. Add a doc comment to the header.

Also add a free_util arg to make the function more generic
and make the API similar to other functions in string-list.h.
Update the existing call-sites.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The run_receive_hook() stack-allocated `struct receive_hook_feed_state`
is a template with initial values for child states allocated on the heap
for each hook process, by calling receive_hook_feed_state_alloc() when
spinning up each hook child.

All these values are already initialized to zero, however I forgot to
properly initialize the strbuf, which I left NULL.

This is more of a code cleanup because in practice it has no effect,
the states used by the children are always initialized, however it's
good to fix in case someone ends up accidentally dereferencing the NULL
pointer in the future.

Reported-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Fix some minor style nits pointed out by Patrick, Junio and Eric:
  * Use CALLOC_ARRAY instead of xcalloc.
  * Init struct members during declaration.
  * Simplify if condition boolean logic.
  * Missing curly braces in if/else stmts.
  * Unnecessary header includes.
  * Capitalization and full-stop in error/warn messages.
  * Curly brace on separate line when defining struct.
  * Comment spelling: free'd -> freed.
  * Sort the included headers.
  * Blank line fixes to improve readability.

These contain no logic changes, the code behaves the same as before.

Suggested-by: Eric Sunshine <sunshine@sunshineco.com>
Suggested-by: Junio C Hamano <gitster@pobox.com>
Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Rename the hook callback function types to use the hook prefix.

This is a style fix with no logic changes.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Trigger a bug when an unknown hook type is encountered while
setting up hook execution.

Also issue a bug if a configured hook is enabled without a cmd.

Mostly useful for defensive coding.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Replace the custom function with string_list_clear_func() which
is a more common pattern for clearing a string_list.

To be able to do this, rework hook_clear() into hook_free(), so
it can be passed to string_list_clear_func().

A slight complication is the need to keep a copy of the internal
cb data free() pointer, however I think it's worth it since the
API becomes cleaner, e.g. no more calls with NULL function args
like hook_list_clear(hooks, NULL).

In other words, the callers don't need to keep track of hook
internal state to determine when cleanup is necessary or not
(pass NULL) because each `struct hook` now owns its data_free
callback.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Both `name` and `friendly-name` is being used. Standardize on
`friendly-name` for consistency since name is rather generic,
even when used in the hooks namespace.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

There is a documented expectation that configured hooks are
run before the hook from the hookdir. Add a test for it.

While at it, I noticed that `git hook list -h` runs twice
in the `git hook usage` test, so remove one invocation.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Replace the bare `char *command` util pointer stored in each string_list
item with a heap-allocated `struct hook_config_cache_entry` that carries
that command string.

This is just a refactoring with no behavior changes, to give the cache
entry room to grow, so it can carry the additional hook metadata we'll
be adding in the following commits.

Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Users running "git hook list" can see which hooks are configured but
have no way to tell at which config scope (local, global, system...)
each hook was defined.

Store the scope from ctx->kvi->scope in the single-pass config callback,
then carry it through the cache to the hook structs, so we can expose it
to users via the "git hook list --show-scope" flag, which mirrors the
existing git config --show-scope convention.

Without the flag the output is unchanged.

The scope is printed as a tab-separated prefix (like "git config --show-scope"),
making it unambiguously machine-parseable even when the friendly name
contains spaces.

Example usage:
$ git hook list --show-scope pre-commit
global	linter
local	no-leaks
hook from hookdir

Traditional hooks from the hookdir are unaffected by --show-scope since
the config scope concept does not apply to them.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Disabled hooks were filtered out of the cache entirely, making them
invisible to "git hook list". Keep them in the cache with a new
"disabled" flag which is propagated to the respective struct hook.

"git hook list" now shows disabled hooks as tab-separated columns,
with the status as a prefix before the name (like scope with
--show-scope). With --show-scope it looks like:

$ git hook list --show-scope pre-commit
global	linter
local	disabled	no-leaks
hook from hookdir

A disabled hook without a command issues a warning instead of the
fatal "hook.X.command must be configured" error. We could also throw
an error, however it seemd a bit excessive to me in this case.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Teach "git hook run" and "git hook list" to reject hook event names
that are not recognized by Git. This helps catch typos such as
"prereceive" when "pre-receive" was intended, since in 99% of the
cases users want known (already-existing) hook names.

The list of known hooks is derived from the generated hook-list.h
(built from Documentation/githooks.adoc). This is why the Makefile
is updated, so builtin/hook.c depends on hook-list.h. In meson the
header is already a dependency for all builtins, no change required.

The "--allow-unknown-hook-name" flag can be used to bypass this check.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>