tmk_core/tool/mbed/mbed-sdk/libraries/mbed/api/FileHandle.h

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #ifndef MBED_FILEHANDLE_H
  17 #define MBED_FILEHANDLE_H
  18
  19 typedef int FILEHANDLE;
  20
  21 #include <stdio.h>
  22
  23 #if defined(__ARMCC_VERSION) || defined(__ICCARM__)
  24 typedef int ssize_t;
  25 typedef long off_t;
  26
  27 #else
  28 #   include <sys/types.h>
  29 #endif
  30
  31 namespace mbed {
  32
  33 /** An OO equivalent of the internal FILEHANDLE variable
  34  *  and associated _sys_* functions.
  35  *
  36  * FileHandle is an abstract class, needing at least sys_write and
  37  *  sys_read to be implmented for a simple interactive device.
  38  *
  39  * No one ever directly tals to/instanciates a FileHandle - it gets
  40  *  created by FileSystem, and wrapped up by stdio.
  41  */
  42 class FileHandle {
  43
  44 public:
  45     /** Write the contents of a buffer to the file
  46      *
  47      *  @param buffer the buffer to write from
  48      *  @param length the number of characters to write
  49      *
  50      *  @returns
  51      *  The number of characters written (possibly 0) on success, -1 on error.
  52      */
  53     virtual ssize_t write(const void* buffer, size_t length) = 0;
  54
  55     /** Close the file
  56      *
  57      *  @returns
  58      *  Zero on success, -1 on error.
  59      */
  60     virtual int close() = 0;
  61
  62     /** Function read
  63      *  Reads the contents of the file into a buffer
  64      *
  65      *  @param buffer the buffer to read in to
  66      *  @param length the number of characters to read
  67      *
  68      *  @returns
  69      *  The number of characters read (zero at end of file) on success, -1 on error.
  70      */
  71     virtual ssize_t read(void* buffer, size_t length) = 0;
  72
  73     /** Check if the handle is for a interactive terminal device.
  74      * If so, line buffered behaviour is used by default
  75      *
  76      *  @returns
  77      *    1 if it is a terminal,
  78      *    0 otherwise
  79      */
  80     virtual int isatty() = 0;
  81
  82     /** Move the file position to a given offset from a given location.
  83      *
  84      *  @param offset The offset from whence to move to
  85      *  @param whence SEEK_SET for the start of the file, SEEK_CUR for the
  86      *   current file position, or SEEK_END for the end of the file.
  87      *
  88      *  @returns
  89      *    new file position on success,
  90      *    -1 on failure or unsupported
  91      */
  92     virtual off_t lseek(off_t offset, int whence) = 0;
  93
  94     /** Flush any buffers associated with the FileHandle, ensuring it
  95      *  is up to date on disk
  96      *
  97      *  @returns
  98      *    0 on success or un-needed,
  99      *   -1 on error
 100      */
 101     virtual int fsync() = 0;
 102
 103     virtual off_t flen() {
 104         /* remember our current position */
 105         off_t pos = lseek(0, SEEK_CUR);
 106         if(pos == -1) return -1;
 107         /* seek to the end to get the file length */
 108         off_t res = lseek(0, SEEK_END);
 109         /* return to our old position */
 110         lseek(pos, SEEK_SET);
 111         return res;
 112     }
 113
 114     virtual ~FileHandle();
 115 };
 116
 117 } // namespace mbed
 118
 119 #endif