refs/files-backend: fix memory leak in lock_ref_for_update

After the previous patch, none of the functions we call hold on to
`referent.buf`, so we can safely release the string buffer before
returning.

Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs/files-backend.c b/refs/files-backend.c
index baceef3..3d63639 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2756,7 +2756,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
        struct strbuf referent = STRBUF_INIT;
        int mustexist = (update->flags & REF_HAVE_OLD) &&
                !is_null_oid(&update->old_oid);
-       int ret;
+       int ret = 0;
        struct ref_lock *lock;
 
        files_assert_main_repository(refs, "lock_ref_for_update");
@@ -2768,7 +2768,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                ret = split_head_update(update, transaction, head_ref,
                                        affected_refnames, err);
                if (ret)
-                       return ret;
+                       goto out;
        }
 
        ret = lock_raw_ref(refs, update->refname, mustexist,
@@ -2782,7 +2782,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                strbuf_addf(err, "cannot lock ref '%s': %s",
                            original_update_refname(update), reason);
                free(reason);
-               return ret;
+               goto out;
        }
 
        update->backend_data = lock;
@@ -2801,10 +2801,12 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                                        strbuf_addf(err, "cannot lock ref '%s': "
                                                    "error reading reference",
                                                    original_update_refname(update));
-                                       return -1;
+                                       ret = -1;
+                                       goto out;
                                }
                        } else if (check_old_oid(update, &lock->old_oid, err)) {
-                               return TRANSACTION_GENERIC_ERROR;
+                               ret = TRANSACTION_GENERIC_ERROR;
+                               goto out;
                        }
                } else {
                        /*
@@ -2818,13 +2820,15 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                                                  referent.buf, transaction,
                                                  affected_refnames, err);
                        if (ret)
-                               return ret;
+                               goto out;
                }
        } else {
                struct ref_update *parent_update;
 
-               if (check_old_oid(update, &lock->old_oid, err))
-                       return TRANSACTION_GENERIC_ERROR;
+               if (check_old_oid(update, &lock->old_oid, err)) {
+                       ret = TRANSACTION_GENERIC_ERROR;
+                       goto out;
+               }
 
                /*
                 * If this update is happening indirectly because of a
@@ -2861,7 +2865,8 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                                    "cannot update ref '%s': %s",
                                    update->refname, write_err);
                        free(write_err);
-                       return TRANSACTION_GENERIC_ERROR;
+                       ret = TRANSACTION_GENERIC_ERROR;
+                       goto out;
                } else {
                        update->flags |= REF_NEEDS_COMMIT;
                }
@@ -2875,10 +2880,14 @@ static int lock_ref_for_update(struct files_ref_store *refs,
                if (close_ref(lock)) {
                        strbuf_addf(err, "couldn't close '%s.lock'",
                                    update->refname);
-                       return TRANSACTION_GENERIC_ERROR;
+                       ret = TRANSACTION_GENERIC_ERROR;
+                       goto out;
                }
        }
-       return 0;
+
+out:
+       strbuf_release(&referent);
+       return ret;
 }
 
 /*