lint: Use early exit/continue

src/history.cpp

@@ -939,24 +939,28 @@ void history_t::populate_from_mmap(void) {
 /// if successful. Returns the mapped memory region by reference.
 bool history_t::map_file(const wcstring &name, const char **out_map_start, size_t *out_map_len,
                          file_id_t *file_id) {
-    bool result = false;
     wcstring filename = history_filename(name, L"");
-    if (!filename.empty()) {
+    if (filename.empty()) {
+        return false;
+    }
+
     int fd = wopen_cloexec(filename, O_RDONLY);
-        if (fd >= 0) {
+    if (fd == -1) {
+        return false;
+    }
+
+    bool result = false;
     // Get the file ID if requested.
     if (file_id != NULL) *file_id = file_id_for_fd(fd);
 
-            // Take a read lock to guard against someone else appending. This is released when the
+    // Take a read lock to guard against someone else appending. This is released when the file
-            // file is closed (below). We will read the file after releasing the lock, but that's
+    // is closed (below). We will read the file after releasing the lock, but that's not a
-            // not a problem, because we never modify already written data. In short, the purpose of
+    // problem, because we never modify already written data. In short, the purpose of this lock
-            // this lock is to ensure we don't see the file size change mid-update.
+    // is to ensure we don't see the file size change mid-update.
     //
-            //    We may fail to lock (e.g. on lockless NFS - see
+    // We may fail to lock (e.g. on lockless NFS - see issue #685. In that case, we proceed as
-            //    https://github.com/fish-shell/fish-shell/issues/685 ). In that case, we proceed as
+    // if it did not fail. The risk is that we may get an incomplete history item; this is
-            //    if it did not fail. The risk is that we may get an incomplete history item; this
+    // unlikely because we only treat an item as valid if it has a terminating newline.
-            //    is unlikely because we only treat an item as valid if it has a terminating
-            //    newline.
     //
     // Simulate a failing lock in chaos_mode.
     if (!chaos_mode) history_file_lock(fd, F_RDLCK);
@@ -974,8 +978,6 @@ bool history_t::map_file(const wcstring &name, const char **out_map_start, size_
         }
     }
     close(fd);
-        }
-    }
     return result;
 }