mbed-os/platform/FileHandle.h

/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef MBED_FILEHANDLE_H
#define MBED_FILEHANDLE_H

typedef int FILEHANDLE;

#include <stdio.h>
#include "platform/platform.h"

namespace mbed {
/** \addtogroup drivers */
/** @{*/


/** Class FileHandle
 *
 *  An abstract interface that represents operations on a file-like
 *  object. The core functions are read, write, and seek, but only
 *  a subset of these operations can be provided.
 *
 *  @note to create a file, @see File
 *  @note Synchronization level: Set by subclass
 */
class FileHandle {
public:
    virtual ~FileHandle() {}

    /** Read the contents of a file into a buffer
     *
     *  @param buffer   The buffer to read in to
     *  @param size     The number of bytes to read
     *  @return         The number of bytes read, 0 at end of file, negative error on failure
     */
    virtual ssize_t read(void *buffer, size_t size) = 0;

    /** Write the contents of a buffer to a file
     *
     *  @param buffer   The buffer to write from
     *  @param size     The number of bytes to write 
     *  @return         The number of bytes written, negative error on failure
     */
    virtual ssize_t write(const void *buffer, size_t size) = 0;

    /** Move the file position to a given offset from from a given location
     *
     *  @param offset   The offset from whence to move to
     *  @param whence   The start of where to seek
     *      SEEK_SET to start from beginning of file,
     *      SEEK_CUR to start from current position in file,
     *      SEEK_END to start from end of file
     *  @return         The new offset of the file
     */
    virtual off_t seek(off_t offset, int whence = SEEK_SET) = 0;

    /** Close a file
     *
     *  @return         0 on success, negative error code on failure
     */
    virtual int close() = 0;

    /** Flush any buffers associated with the file
     *
     *  @return         0 on success, negative error code on failure
     */
    virtual int sync()
    {
        return 0;
    }

    /** Check if the file in an interactive terminal device
     *
     *  @return         True if the file is a terminal
     */
    virtual int isatty()
    {
        return false;
    }

    /** Get the file position of the file
     *
     *  @note This is equivalent to seek(0, SEEK_CUR)
     *
     *  @return         The current offset in the file
     */
    virtual off_t tell()
    {
        return seek(0, SEEK_CUR);
    }

    /** Rewind the file position to the beginning of the file
     *
     *  @note This is equivalent to seek(0, SEEK_SET)
     */
    virtual void rewind()
    {
        seek(0, SEEK_SET);
    }

    /** Get the size of the file
     *
     *  @return         Size of the file in bytes
     */
    virtual size_t size()
    {
        off_t off = tell();
        size_t size = seek(0, SEEK_END);
        seek(off, SEEK_SET);
        return size;
    }

    /** Move the file position to a given offset from a given location.
     *
     *  @param offset The offset from whence to move to
     *  @param whence SEEK_SET for the start of the file, SEEK_CUR for the
     *   current file position, or SEEK_END for the end of the file.
     *
     *  @returns
     *    new file position on success,
     *    -1 on failure or unsupported
     */
    MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::seek")
    virtual off_t lseek(off_t offset, int whence) { return seek(offset, whence); }

    /** Flush any buffers associated with the FileHandle, ensuring it
     *  is up to date on disk
     *
     *  @returns
     *    0 on success or un-needed,
     *   -1 on error
     */
    MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::sync")
    virtual int fsync() { return sync(); }

    /** Find the length of the file
     *
     *  @returns
     *   Length of the file
     */
    MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::size")
    virtual off_t flen() { return size(); }
};


/** @}*/
} // namespace mbed

#endif