File content as of revision 0:fd0d7bdfcdc2:

/* mbed Microcontroller Library
 * Copyright (c) 2006-2012 ARM Limited
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#ifndef MBED_FILEHANDLE_H
#define MBED_FILEHANDLE_H

typedef int FILEHANDLE;

#include <stdio.h>
#ifdef __ARMCC_VERSION
typedef int ssize_t;
typedef long off_t;
#else
#include <sys/types.h>
#endif

namespace mbed { 

/** An OO equivalent of the internal FILEHANDLE variable
 *  and associated _sys_* functions.
 *
 * FileHandle is an abstract class, needing at least sys_write and
 *  sys_read to be implmented for a simple interactive device.
 *
 * No one ever directly tals to/instanciates a FileHandle - it gets 
 *  created by FileSystem, and wrapped up by stdio.
 */
class FileHandle {

public:
    /** Write the contents of a buffer to the file
     *
     *  @param buffer the buffer to write from
     *  @param length the number of characters to write
     *
     *  @returns
     *  The number of characters written (possibly 0) on success, -1 on error.
     */
    virtual ssize_t write(const void* buffer, size_t length) = 0;

    /** Close the file
     *
     *  @returns
     *  Zero on success, -1 on error.
     */
    virtual int close() = 0;

    /** Function read
     *  Reads the contents of the file into a buffer
     *
     *  @param buffer the buffer to read in to
     *  @param length the number of characters to read
     *
     *  @returns
     *  The number of characters read (zero at end of file) on success, -1 on error.
     */
    virtual ssize_t read(void* buffer, size_t length) = 0;

    /** Check if the handle is for a interactive terminal device.
     * If so, line buffered behaviour is used by default
     *
     *  @returns
     *    1 if it is a terminal,
     *    0 otherwise
     */
    virtual int isatty() = 0;

    /** 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
     */
    virtual off_t lseek(off_t offset, int whence) = 0;

    /** 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
     */
    virtual int fsync() = 0;

    virtual off_t flen() {
        /* remember our current position */
        off_t pos = lseek(0, SEEK_CUR);
        if(pos == -1) return -1;
        /* seek to the end to get the file length */
        off_t res = lseek(0, SEEK_END);
        /* return to our old position */
        lseek(pos, SEEK_SET);
        return res;
    }
    
    virtual ~FileHandle();
};

} // namespace mbed

#endif