Factor out read_firmware_device()

include/chromeos/firmware_storage.h

 /*
  * Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  */
 
@@ skipping 54 matching lines @@
         uint8_t *firmware_body[2];
 } firmware_storage_t;
 
 /* Initialize fields for talking to GetFirmwareBody(). */
 void GetFirmwareBody_setup(firmware_storage_t *f,
                 off_t firmware_data_offset_0, off_t firmware_data_offset_1);
 
 /* Dispose fields that are used for communicating with GetFirmwareBody(). */
 void GetFirmwareBody_dispose(firmware_storage_t *f);
 
+/*
+ * Read <count> bytes, starting from <offset>, from firmware storage
+ * device <file> into buffer <buf>.
+ *
+ * Return 0 on success, non-zero on error.
+ */
+int read_firmware_device(firmware_storage_t *file, off_t offset, void *buf,
+                size_t count);
+
 #endif /* __FIRMWARE_STORAGE_H_ */