refs.c: avoid git_path assignment in lock_ref_sha1_basic

Assigning the result of git_path is a bad pattern, because
it's not immediately obvious how long you expect the content
to stay valid (and it may be overwritten by subsequent
calls). Let's use a function-local strbuf here instead,
which we know is safe (we just have to remember to free it
in all code paths).

As a bonus, we get rid of a confusing variable-reuse
("ref_file" is used for two distinct purposes).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index 086fb1ad0275a19a13c794f53687dade0af481f8..4ed9f6b04899c0607c9e688ceb78daff3e24690b 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -2408,7 +2408,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                                            unsigned int flags, int *type_p,
                                            struct strbuf *err)
 {
-       const char *ref_file;
+       struct strbuf ref_file = STRBUF_INIT;
+       struct strbuf orig_ref_file = STRBUF_INIT;
        const char *orig_refname = refname;
        struct ref_lock *lock;
        int last_errno = 0;
@@ -2432,20 +2433,19 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        refname = resolve_ref_unsafe(refname, resolve_flags,
                                     lock->old_oid.hash, &type);
        if (!refname && errno == EISDIR) {
-               /* we are trying to lock foo but we used to
+               /*
+                * we are trying to lock foo but we used to
                 * have foo/bar which now does not exist;
                 * it is normal for the empty directory 'foo'
                 * to remain.
                 */
-               ref_file = git_path("%s", orig_refname);
-               if (remove_empty_directories(ref_file)) {
+               strbuf_git_path(&orig_ref_file, "%s", orig_refname);
+               if (remove_empty_directories(orig_ref_file.buf)) {
                        last_errno = errno;
-
                        if (!verify_refname_available(orig_refname, extras, skip,
                                                      get_loose_refs(&ref_cache), err))
                                strbuf_addf(err, "there are still refs under '%s'",
                                            orig_refname);
-
                        goto error_return;
                }
                refname = resolve_ref_unsafe(orig_refname, resolve_flags,
@@ -2485,10 +2485,10 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        }
        lock->ref_name = xstrdup(refname);
        lock->orig_ref_name = xstrdup(orig_refname);
-       ref_file = git_path("%s", refname);
+       strbuf_git_path(&ref_file, "%s", refname);
 
  retry:
-       switch (safe_create_leading_directories_const(ref_file)) {
+       switch (safe_create_leading_directories_const(ref_file.buf)) {
        case SCLD_OK:
                break; /* success */
        case SCLD_VANISHED:
@@ -2497,11 +2497,12 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                /* fall through */
        default:
                last_errno = errno;
-               strbuf_addf(err, "unable to create directory for %s", ref_file);
+               strbuf_addf(err, "unable to create directory for %s",
+                           ref_file.buf);
                goto error_return;
        }
 
-       if (hold_lock_file_for_update(lock->lk, ref_file, lflags) < 0) {
+       if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
                last_errno = errno;
                if (errno == ENOENT && --attempts_remaining > 0)
                        /*
@@ -2511,7 +2512,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                         */
                        goto retry;
                else {
-                       unable_to_lock_message(ref_file, errno, err);
+                       unable_to_lock_message(ref_file.buf, errno, err);
                        goto error_return;
                }
        }
@@ -2519,12 +2520,17 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                last_errno = errno;
                goto error_return;
        }
-       return lock;
+       goto out;
 
  error_return:
        unlock_ref(lock);
+       lock = NULL;
+
+ out:
+       strbuf_release(&ref_file);
+       strbuf_release(&orig_ref_file);
        errno = last_errno;
-       return NULL;
+       return lock;
 }
 
 /*