environment: move access to "core.hooksPath" into repo settings

The "core.hooksPath" setting is stored in a global variable and
populated via the `git_default_core_config`. This may cause issues in
the case where one is handling multiple different repositories in a
single process with different values for that config key, as we may or
may not see the correct value in that case. Furthermore, global state
blocks our path towards libification.

Refactor the code so that we instead store the value in `struct
repo_settings`. The value is computed as-needed and cached. The result
should be functionally the same as there aren't ever any code paths
where we'd execute hooks outside the context of a repository.

Note that this requires us to change the passed-in repository in the
`repo_git_path()` family of functions to be non-constant, as we call
`adjust_git_path()` there.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -1436,11 +1436,6 @@ static int git_default_core_config(const char *var, const char *value,
 		return git_config_pathname(&git_attributes_file, var, value);
 	}
 
-	if (!strcmp(var, "core.hookspath")) {
-		FREE_AND_NULL(git_hooks_path);
-		return git_config_pathname(&git_hooks_path, var, value);
-	}
-
 	if (!strcmp(var, "core.bare")) {
 		is_bare_repository_cfg = git_config_bool(var, value);
 		return 0;

environment.c

@@ -42,7 +42,6 @@ char *git_log_output_encoding;
 char *apply_default_whitespace;
 char *apply_default_ignorewhitespace;
 char *git_attributes_file;
-char *git_hooks_path;
 int zlib_compression_level = Z_BEST_SPEED;
 int pack_compression_level = Z_DEFAULT_COMPRESSION;
 int fsync_object_files = -1;

environment.h

@@ -160,7 +160,6 @@ extern int warn_on_object_refname_ambiguity;
 extern char *apply_default_whitespace;
 extern char *apply_default_ignorewhitespace;
 extern char *git_attributes_file;
-extern char *git_hooks_path;
 extern int zlib_compression_level;
 extern int pack_compression_level;
 extern size_t packed_git_window_size;

path.c

@@ -387,10 +387,11 @@ void report_linked_checkout_garbage(struct repository *r)
 	strbuf_release(&sb);
 }
 
-static void adjust_git_path(const struct repository *repo,
+static void adjust_git_path(struct repository *repo,
 			    struct strbuf *buf, int git_dir_len)
 {
 	const char *base = buf->buf + git_dir_len;
+
 	if (is_dir_file(base, "info", "grafts"))
 		strbuf_splice(buf, 0, buf->len,
 			      repo->graft_file, strlen(repo->graft_file));
@@ -399,8 +400,8 @@ static void adjust_git_path(const struct repository *repo,
 			      repo->index_file, strlen(repo->index_file));
 	else if (dir_prefix(base, "objects"))
 		replace_dir(buf, git_dir_len + 7, repo->objects->odb->path);
-	else if (git_hooks_path && dir_prefix(base, "hooks"))
-		replace_dir(buf, git_dir_len + 5, git_hooks_path);
+	else if (repo_settings_get_hooks_path(repo) && dir_prefix(base, "hooks"))
+		replace_dir(buf, git_dir_len + 5, repo_settings_get_hooks_path(repo));
 	else if (repo->different_commondir)
 		update_common_dir(buf, git_dir_len, repo->commondir);
 }
@@ -417,7 +418,7 @@ static void strbuf_worktree_gitdir(struct strbuf *buf,
 		repo_common_path_append(repo, buf, "worktrees/%s", wt->id);
 }
 
-static void repo_git_pathv(const struct repository *repo,
+static void repo_git_pathv(struct repository *repo,
 			   const struct worktree *wt, struct strbuf *buf,
 			   const char *fmt, va_list args)
 {
@@ -432,7 +433,7 @@ static void repo_git_pathv(const struct repository *repo,
 	strbuf_cleanup_path(buf);
 }
 
-char *repo_git_path(const struct repository *repo,
+char *repo_git_path(struct repository *repo,
 		    const char *fmt, ...)
 {
 	struct strbuf path = STRBUF_INIT;
@@ -443,7 +444,7 @@ char *repo_git_path(const struct repository *repo,
 	return strbuf_detach(&path, NULL);
 }
 
-const char *repo_git_path_append(const struct repository *repo,
+const char *repo_git_path_append(struct repository *repo,
 				 struct strbuf *sb,
 				 const char *fmt, ...)
 {
@@ -454,7 +455,7 @@ const char *repo_git_path_append(const struct repository *repo,
 	return sb->buf;
 }
 
-const char *repo_git_path_replace(const struct repository *repo,
+const char *repo_git_path_replace(struct repository *repo,
 				  struct strbuf *sb,
 				  const char *fmt, ...)
 {

path.h

@@ -52,14 +52,14 @@ const char *repo_common_path_replace(const struct repository *repo,
  * For an exhaustive list of the adjustments made look at `common_list` and
  * `adjust_git_path` in path.c.
  */
-char *repo_git_path(const struct repository *repo,
+char *repo_git_path(struct repository *repo,
 		    const char *fmt, ...)
 	__attribute__((format (printf, 2, 3)));
-const char *repo_git_path_append(const struct repository *repo,
+const char *repo_git_path_append(struct repository *repo,
 				 struct strbuf *sb,
 				 const char *fmt, ...)
 	__attribute__((format (printf, 3, 4)));
-const char *repo_git_path_replace(const struct repository *repo,
+const char *repo_git_path_replace(struct repository *repo,
 				  struct strbuf *sb,
 				  const char *fmt, ...)
 	__attribute__((format (printf, 3, 4)));

repo-settings.c

@@ -146,6 +146,7 @@ void repo_settings_clear(struct repository *r)
 {
 	struct repo_settings empty = REPO_SETTINGS_INIT;
 	FREE_AND_NULL(r->settings.fsmonitor);
+	FREE_AND_NULL(r->settings.hooks_path);
 	r->settings = empty;
 }
 
@@ -173,3 +174,10 @@ int repo_settings_get_warn_ambiguous_refs(struct repository *repo)
 			      &repo->settings.warn_ambiguous_refs, 1);
 	return repo->settings.warn_ambiguous_refs;
 }
+
+const char *repo_settings_get_hooks_path(struct repository *repo)
+{
+	if (!repo->settings.hooks_path)
+		repo_config_get_pathname(repo, "core.hookspath", &repo->settings.hooks_path);
+	return repo->settings.hooks_path;
+}

repo-settings.h

@@ -61,6 +61,8 @@ struct repo_settings {
 	size_t delta_base_cache_limit;
 	size_t packed_git_window_size;
 	size_t packed_git_limit;
+
+	char *hooks_path;
 };
 #define REPO_SETTINGS_INIT { \
 	.index_version = -1, \
@@ -79,5 +81,7 @@ void repo_settings_clear(struct repository *r);
 enum log_refs_config repo_settings_get_log_all_ref_updates(struct repository *repo);
 /* Read the value for "core.warnAmbiguousRefs". */
 int repo_settings_get_warn_ambiguous_refs(struct repository *repo);
+/* Read the value for "core.hooksPath". */
+const char *repo_settings_get_hooks_path(struct repository *repo);
 
 #endif /* REPO_SETTINGS_H */