Re: [PATCH v7 03/17] hook: add list command

[Jonathan Tan <jonathantanmy@google.com>]

> Teach 'git hook list <hookname>', which checks the known configs in
> order to create an ordered list of hooks to run on a given hook event.
> 
> Multiple commands can be specified for a given hook by providing
> multiple "hook.<hookname>.command = <path-to-hook>" lines. Hooks will be
> run in config order. If more properties need to be set on a given hook
> in the future, commands can also be specified by providing
> "hook.<hookname>.command = <hookcmd-name>", as well as a "[hookcmd
> <hookcmd-name>]" subsection; at minimum, this subsection must contain a
> "hookcmd.<hookcmd-name>.command = <path-to-hook>" line.

I learned later that this isn't true - in patch 6, the commit message
and one of the tests therein describe being able to skip a previously
inline command by making a hookcmd section of the same name and just
specifying "skip = true" there (without any command).

Maybe just delete the "at minimum" part.

> +static int list(int argc, const char **argv, const char *prefix)
>  {
> -	struct option builtin_hook_options[] = {
> +	struct list_head *head, *pos;
> +	struct hook *item;

You asked for review on nits too so here's one: "item" should be
declared in the list_for_each block. (That also makes it easier to see
that we don't need to free it.)

> diff --git a/hook.c b/hook.c
> new file mode 100644
> index 0000000000..937dc768c8
> --- /dev/null
> +++ b/hook.c
> @@ -0,0 +1,115 @@
> +#include "cache.h"
> +
> +#include "hook.h"
> +#include "config.h"

Usually we put all the includes together without any intervening blank
lines.

> +static void append_or_move_hook(struct list_head *head, const char *command)
> +{
> +	struct list_head *pos = NULL, *tmp = NULL;
> +	struct hook *to_add = NULL;
> +
> +	/*
> +	 * remove the prior entry with this command; we'll replace it at the
> +	 * end.
> +	 */
> +	list_for_each_safe(pos, tmp, head) {
> +		struct hook *it = list_entry(pos, struct hook, list);
> +		if (!strcmp(it->command.buf, command)) {
> +		    list_del(pos);
> +		    /* we'll simply move the hook to the end */
> +		    to_add = it;

"break" here?

> +		}
> +	}
> +
> +	if (!to_add) {
> +		/* adding a new hook, not moving an old one */
> +		to_add = xmalloc(sizeof(struct hook));

Style is to write sizeof(*to_add), I think.

[snip]

> +struct hook_config_cb
> +{
> +	struct strbuf *hookname;

struct declarations have "{" not on a line on its own.

Also, "hookname" could just be a char *?
	
> +	struct list_head *list;
> +};
> +
> +static int hook_config_lookup(const char *key, const char *value, void *cb_data)
> +{
> +	struct hook_config_cb *data = cb_data;
> +	const char *hook_key = data->hookname->buf;
> +	struct list_head *head = data->list;
> +
> +	if (!strcmp(key, hook_key)) {
> +		const char *command = value;
> +		struct strbuf hookcmd_name = STRBUF_INIT;
> +
> +		/* Check if a hookcmd with that name exists. */
> +		strbuf_addf(&hookcmd_name, "hookcmd.%s.command", command);
> +		git_config_get_value(hookcmd_name.buf, &command);

So we don't really care whether git_config_get_value returns 0 or 1 as
long as it doesn't touch "command" if there is no such hookcmd. That
fits with how git_config_get_value() is documented, so that's great.
Perhaps better to document as:

  If a hookcmd.%s.command config exists, replace the command with the
  value of that config. (If not, do nothing - git_config_get_value() is
  documented to not overwrite the value argument in this case.)

> +
> +		if (!command) {
> +			strbuf_release(&hookcmd_name);
> +			BUG("git_config_get_value overwrote a string it shouldn't have");
> +		}
> +
> +		/*
> +		 * TODO: implement an option-getting callback, e.g.
> +		 *   get configs by pattern hookcmd.$value.*
> +		 *   for each key+value, do_callback(key, value, cb_data)
> +		 */
> +
> +		append_or_move_hook(head, command);
> +
> +		strbuf_release(&hookcmd_name);
> +	}
> +
> +	return 0;
> +}
> +
> +struct list_head* hook_list(const struct strbuf* hookname)

"const char *hookname" should suffice?

Also, search for "* " and replace with " *" where applicable (also in
the .h file).

> +{
> +	struct strbuf hook_key = STRBUF_INIT;
> +	struct list_head *hook_head = xmalloc(sizeof(struct list_head));
> +	struct hook_config_cb cb_data = { &hook_key, hook_head };
> +
> +	INIT_LIST_HEAD(hook_head);
> +
> +	if (!hookname)
> +		return NULL;
> +
> +	strbuf_addf(&hook_key, "hook.%s.command", hookname->buf);
> +
> +	git_config(hook_config_lookup, (void*)&cb_data);

Do we need this void* cast?

> +
> +	strbuf_release(&hook_key);
> +	return hook_head;
> +}
> diff --git a/hook.h b/hook.h
> new file mode 100644
> index 0000000000..8ffc4f14b6
> --- /dev/null
> +++ b/hook.h
> @@ -0,0 +1,26 @@
> +#include "config.h"
> +#include "list.h"
> +#include "strbuf.h"
> +
> +struct hook
> +{
> +	struct list_head list;
> +	/*
> +	 * Config file which holds the hook.*.command definition.
> +	 * (This has nothing to do with the hookcmd.<name>.* configs.)
> +	 */
> +	enum config_scope origin;
> +	/* The literal command to run. */
> +	struct strbuf command;

"char *" would suffice?

The tests look fine.