FileHandle.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #ifndef MBED_FILEHANDLE_H
00017 #define MBED_FILEHANDLE_H
00018 
00019 typedef int FILEHANDLE;
00020 
00021 #include <stdio.h>
00022 #include "platform/platform.h"
00023 
00024 namespace mbed {
00025 /** \addtogroup drivers */
00026 /** @{*/
00027 
00028 /** An OO equivalent of the internal FILEHANDLE variable
00029  *  and associated _sys_* functions.
00030  *
00031  * FileHandle is an abstract class, needing at least sys_write and
00032  *  sys_read to be implmented for a simple interactive device.
00033  *
00034  * No one ever directly tals to/instanciates a FileHandle - it gets
00035  *  created by FileSystem, and wrapped up by stdio.
00036  *
00037  * @Note Synchronization level: Set by subclass
00038  */
00039 class FileHandle {
00040 
00041 public:
00042     MBED_DEPRECATED_SINCE("mbed-os-5.4",
00043         "The mbed 2 filesystem classes have been superseeded by the FileSystem api, "
00044         "Replaced by File")
00045     FileHandle() {}
00046 
00047     /** Write the contents of a buffer to the file
00048      *
00049      *  @param buffer the buffer to write from
00050      *  @param length the number of characters to write
00051      *
00052      *  @returns
00053      *  The number of characters written (possibly 0) on success, -1 on error.
00054      */
00055     virtual ssize_t write(const void* buffer, size_t length) = 0;
00056 
00057     /** Close the file
00058      *
00059      *  @returns
00060      *  Zero on success, -1 on error.
00061      */
00062     virtual int close() = 0;
00063 
00064     /** Function read
00065      *  Reads the contents of the file into a buffer
00066      *
00067      *  @param buffer the buffer to read in to
00068      *  @param length the number of characters to read
00069      *
00070      *  @returns
00071      *  The number of characters read (zero at end of file) on success, -1 on error.
00072      */
00073     virtual ssize_t read(void* buffer, size_t length) = 0;
00074 
00075     /** Check if the handle is for a interactive terminal device.
00076      * If so, line buffered behaviour is used by default
00077      *
00078      *  @returns
00079      *    1 if it is a terminal,
00080      *    0 otherwise
00081      */
00082     virtual int isatty() = 0;
00083 
00084     /** Move the file position to a given offset from a given location.
00085      *
00086      *  @param offset The offset from whence to move to
00087      *  @param whence SEEK_SET for the start of the file, SEEK_CUR for the
00088      *   current file position, or SEEK_END for the end of the file.
00089      *
00090      *  @returns
00091      *    new file position on success,
00092      *    -1 on failure or unsupported
00093      */
00094     virtual off_t lseek(off_t offset, int whence) = 0;
00095 
00096     /** Flush any buffers associated with the FileHandle, ensuring it
00097      *  is up to date on disk
00098      *
00099      *  @returns
00100      *    0 on success or un-needed,
00101      *   -1 on error
00102      */
00103     virtual int fsync() = 0;
00104 
00105     virtual off_t flen() {
00106         lock();
00107         /* remember our current position */
00108         off_t pos = lseek(0, SEEK_CUR);
00109         if(pos == -1) {
00110             unlock();
00111             return -1;
00112         }
00113         /* seek to the end to get the file length */
00114         off_t res = lseek(0, SEEK_END);
00115         /* return to our old position */
00116         lseek(pos, SEEK_SET);
00117         unlock();
00118         return res;
00119     }
00120 
00121     virtual ~FileHandle() {};
00122 
00123 protected:
00124 
00125     /** Acquire exclusive access to this object.
00126      */
00127     virtual void lock() {
00128         // Stub
00129     }
00130 
00131     /** Release exclusive access to this object.
00132      */
00133     virtual void unlock() {
00134         // Stub
00135     }
00136 };
00137 
00138 } // namespace mbed
00139 
00140 #endif
00141 
00142 /** @}*/