refs.c: rename log_ref_setup to create_reflog

log_ref_setup is used to do several semi-related things :
* sometimes it will create a new reflog including missing parent directories
  and cleaning up any conflicting stale directories in the path.
* fill in a filename buffer for the full path to the reflog.
* unconditionally re-adjust the permissions for the file.

This function is only called from two places: checkout.c where it is always
used to create a reflog and refs.c:log_ref_write where it sometimes are
used to create a reflog and sometimes just used to fill in the filename.

Rename log_ref_setup to create_reflog and change it to only take the
refname as argument to make its signature similar to delete_reflog and
reflog_exists. Change create_reflog to ignore log_all_ref_updates and
"unconditionally" create the reflog when called. Since checkout.c always
wants to create a reflog we can call create_reflog directly and avoid the
temp-and-log_all_ref_update dance.

In log_ref_write, only call create_reflog iff we want to create a reflog
and if the reflog does not yet exist. This means that for the common case
where the log already exists we now only need to perform a single lstat()
instead of a open(O_CREAT)+lstat()+close().

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 17 insertions, 21 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5410dacea0..8550b6d94e 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -587,19 +587,13 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 	if (opts->new_branch) {
 		if (opts->new_orphan_branch) {
 			if (opts->new_branch_log && !log_all_ref_updates) {
-				int temp;
-				char log_file[PATH_MAX];
 				char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 
-				temp = log_all_ref_updates;
-				log_all_ref_updates = 1;
-				if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
+				if (create_reflog(ref_name)) {
 					fprintf(stderr, _("Can not do reflog for '%s'\n"),
 					    opts->new_orphan_branch);
-					log_all_ref_updates = temp;
 					return;
 				}
-				log_all_ref_updates = temp;
 			}
 		}
 		else
diff --git a/refs.c b/refs.c
index a4bdfaf010..0b46bd9bf7 100644
--- a/refs.c
+++ b/refs.c
@@ -2947,16 +2947,16 @@ static int copy_msg(char *buf, const char *msg)
 }
 
 /* This function must set a meaningful errno on failure */
-int log_ref_setup(const char *refname, char *logfile, int bufsize)
+int create_reflog(const char *refname)
 {
 	int logfd, oflags = O_APPEND | O_WRONLY;
+	char logfile[PATH_MAX];
 
-	git_snpath(logfile, bufsize, "logs/%s", refname);
-	if (log_all_ref_updates &&
-	    (starts_with(refname, "refs/heads/") ||
-	     starts_with(refname, "refs/remotes/") ||
-	     starts_with(refname, "refs/notes/") ||
-	     !strcmp(refname, "HEAD"))) {
+	git_snpath(logfile, sizeof(logfile), "logs/%s", refname);
+	if (starts_with(refname, "refs/heads/") ||
+	    starts_with(refname, "refs/remotes/") ||
+	    starts_with(refname, "refs/notes/") ||
+	    !strcmp(refname, "HEAD")) {
 		if (safe_create_leading_directories(logfile) < 0) {
 			int save_errno = errno;
 			error("unable to create directory for %s", logfile);
@@ -3025,16 +3025,20 @@ static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
 			 const unsigned char *new_sha1, const char *msg)
 {
-	int logfd, result, oflags = O_APPEND | O_WRONLY;
+	int logfd, result = 0, oflags = O_APPEND | O_WRONLY;
 	char log_file[PATH_MAX];
 
 	if (log_all_ref_updates < 0)
 		log_all_ref_updates = !is_bare_repository();
 
-	result = log_ref_setup(refname, log_file, sizeof(log_file));
+	if (log_all_ref_updates && !reflog_exists(refname))
+		result = create_reflog(refname);
+
 	if (result)
 		return result;
 
+	git_snpath(log_file, sizeof(log_file), "logs/%s", refname);
+
 	logfd = open(log_file, oflags);
 	if (logfd < 0)
 		return 0;
diff --git a/refs.h b/refs.h
index 9f70b8977a..17e3a3c6f2 100644
--- a/refs.h
+++ b/refs.h
@@ -207,11 +207,6 @@ extern int commit_ref(struct ref_lock *lock);
 /** Release any lock taken but not written. **/
 extern void unlock_ref(struct ref_lock *lock);
 
-/*
- * Setup reflog before using. Set errno to something meaningful on failure.
- */
-int log_ref_setup(const char *refname, char *logfile, int bufsize);
-
 /** Reads log for the value of ref during at_time. **/
 extern int read_ref_at(const char *refname, unsigned int flags,
 		       unsigned long at_time, int cnt,
@@ -221,6 +216,9 @@ extern int read_ref_at(const char *refname, unsigned int flags,
 /** Check if a particular reflog exists */
 extern int reflog_exists(const char *refname);
 
+/** Create reflog. Set errno to something meaningful on failure. */
+extern int create_reflog(const char *refname);
+
 /** Delete a reflog */
 extern int delete_reflog(const char *refname);