[PATCH 4/2] setup: cache normalized safe.directory configuration

[Junio C Hamano <gitster@pobox.com>]

[Do not use. For illustration purposes only]

The current check performed in ensure_valid_ownership() reads each
safe.directory configuration item and normalizes it before checking
against the path to the repository.

This is OK as long as we are checking just a single directory, like
in die_upon_dubious_ownership() and setup_git_directory_gently_1().
But let's pretend that the latter calls ensure_valid_ownership()
many times in the loop, and demonstrate how we would avoid having to
normalize the same safe.directory configuration item over and over.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 setup.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 67 insertions(+), 12 deletions(-)

diff --git a/setup.c b/setup.c
index 29e23a905c..75bcce0368 100644
--- a/setup.c
+++ b/setup.c
@@ -20,6 +20,7 @@
 #include "trace2.h"
 #include "worktree.h"
 #include "exec-cmd.h"
+#include "strvec.h"
 
 static int inside_git_dir = -1;
 static int inside_work_tree = -1;
@@ -1217,6 +1218,7 @@ static int canonicalize_ceiling_entry(struct string_list_item *item,
 struct safe_directory_data {
 	char *path;
 	int is_safe;
+	int prenormalized;
 };
 
 static int safe_directory_cb(const char *key, const char *value,
@@ -1236,14 +1238,20 @@ static int safe_directory_cb(const char *key, const char *value,
 
 		if (!git_config_pathname(&allowed, key, value)) {
 			const char *check = allowed ? allowed : value;
-			char *to_free = real_pathdup(check, 0);
-
-			if (!to_free) {
-				warning(_("safe.directory '%s' cannot be normalized"),
-					check);
-				goto next;
-			} else {
+			char *to_free = NULL;
+
+			if (!data->prenormalized) {
+				to_free = real_pathdup(check, 0);
+				if (!to_free) {
+					warning(_("safe.directory '%s' "
+						  "cannot be normalized"),
+						check);
+					goto next;
+				}
 				check = to_free;
+			} else {
+				to_free = NULL;
+				check = value;
 			}
 
 			if (ends_with(check, "/*")) {
@@ -1263,6 +1271,39 @@ static int safe_directory_cb(const char *key, const char *value,
 	return 0;
 }
 
+static int prenorm_cb(const char *key, const char *value,
+		      const struct config_context *ctx UNUSED, void *v_)
+{
+	struct strvec *v = v_;
+
+	if (strcmp(key, "safe.directory"))
+		return 0;
+	if (!value || !*value) {
+		strvec_clear(v);
+	} else if (!strcmp(value, "*")) {
+		strvec_push(v, value);
+	} else {
+		char *allowed = NULL;
+		if (!git_config_pathname(&allowed, key, value)) {
+			const char *ccheck = allowed ? allowed : value;
+			char *check = real_pathdup(ccheck, 0);
+			if (check)
+				strvec_push_nodup(v, check);
+			else
+				warning(_("safe.directory '%s' cannot be normalized"),
+					ccheck);
+		}
+		if (allowed != value)
+			free(allowed);
+	}
+	return 0;
+}
+
+static void prenormalize_safe_directory(struct strvec *v)
+{
+	git_protected_config(prenorm_cb, v);
+}
+
 /*
  * Check if a repository is safe, by verifying the ownership of the
  * worktree (if any), the git directory, and the gitfile (if any).
@@ -1273,6 +1314,7 @@ static int safe_directory_cb(const char *key, const char *value,
  */
 static int ensure_valid_ownership(const char *gitfile,
 				  const char *worktree, const char *gitdir,
+				  struct strvec *safe_cache,
 				  struct strbuf *report)
 {
 	struct safe_directory_data data = { 0 };
@@ -1297,8 +1339,15 @@ static int ensure_valid_ownership(const char *gitfile,
 	 * constant regardless of what failed above. data.is_safe should be
 	 * initialized to false, and might be changed by the callback.
 	 */
-	git_protected_config(safe_directory_cb, &data);
-
+	if (!safe_cache) {
+		git_protected_config(safe_directory_cb, &data);
+	} else {
+		data.prenormalized = 1;
+		for (size_t i = 0; i < safe_cache->nr; i++) {
+			safe_directory_cb("safe.directory", safe_cache->v[i],
+					  NULL, &data);
+		}
+	}
 	free(data.path);
 	return data.is_safe;
 }
@@ -1309,7 +1358,7 @@ void die_upon_dubious_ownership(const char *gitfile, const char *worktree,
 	struct strbuf report = STRBUF_INIT, quoted = STRBUF_INIT;
 	const char *path;
 
-	if (ensure_valid_ownership(gitfile, worktree, gitdir, &report))
+	if (ensure_valid_ownership(gitfile, worktree, gitdir, NULL, &report))
 		return;
 
 	strbuf_complete(&report, '\n');
@@ -1416,6 +1465,7 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 	int ceil_offset = -1, min_offset = offset_1st_component(dir->buf);
 	dev_t current_device = 0;
 	int one_filesystem = 1;
+	struct strvec safe_cache = STRVEC_INIT;
 	enum discovery_result result;
 
 	/*
@@ -1463,6 +1513,8 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 	one_filesystem = !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0);
 	if (one_filesystem)
 		current_device = get_device_or_die(dir->buf, NULL, 0);
+
+	prenormalize_safe_directory(&safe_cache);
 	for (;;) {
 		int offset = dir->len, error_code = 0;
 		char *gitdir_path = NULL;
@@ -1499,7 +1551,8 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 				gitdir_path ? gitdir_path : gitdirenv;
 
 			if (ensure_valid_ownership(gitfile, dir->buf,
-						   gitdir_candidate, report)) {
+						   gitdir_candidate,
+						   &safe_cache, report)) {
 				strbuf_addstr(gitdir, gitdirenv);
 				result = GIT_DIR_DISCOVERED;
 			} else
@@ -1525,7 +1578,8 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 			if (get_allowed_bare_repo() == ALLOWED_BARE_REPO_EXPLICIT &&
 			    !is_implicit_bare_repo(dir->buf))
 				return GIT_DIR_DISALLOWED_BARE;
-			if (!ensure_valid_ownership(NULL, NULL, dir->buf, report)) {
+			if (!ensure_valid_ownership(NULL, NULL, dir->buf,
+						    &safe_cache, report)) {
 				result = GIT_DIR_INVALID_OWNERSHIP;
 			} else {
 				strbuf_addstr(gitdir, ".");
@@ -1555,6 +1609,7 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 	}
 
 cleanup_and_return:
+	strvec_clear(&safe_cache);
 	return result;
 }
 
-- 
2.46.0-rc1-48-g0900f1888e