Lee Kai Xuan / mbed-os

mbed-os

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drivers/FileHandle.h@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2013 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #ifndef MBED_FILEHANDLE_H
elessair 0:f269e3021894 17 #define MBED_FILEHANDLE_H
elessair 0:f269e3021894 18
elessair 0:f269e3021894 19 typedef int FILEHANDLE;
elessair 0:f269e3021894 20
elessair 0:f269e3021894 21 #include <stdio.h>
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 #if defined(__ARMCC_VERSION) || defined(__ICCARM__)
elessair 0:f269e3021894 24 typedef int ssize_t;
elessair 0:f269e3021894 25 typedef long off_t;
elessair 0:f269e3021894 26
elessair 0:f269e3021894 27 #else
elessair 0:f269e3021894 28 # include <sys/types.h>
elessair 0:f269e3021894 29 #endif
elessair 0:f269e3021894 30
elessair 0:f269e3021894 31 namespace mbed {
elessair 0:f269e3021894 32 /** \addtogroup drivers */
elessair 0:f269e3021894 33 /** @{*/
elessair 0:f269e3021894 34
elessair 0:f269e3021894 35 /** An OO equivalent of the internal FILEHANDLE variable
elessair 0:f269e3021894 36 * and associated _sys_* functions.
elessair 0:f269e3021894 37 *
elessair 0:f269e3021894 38 * FileHandle is an abstract class, needing at least sys_write and
elessair 0:f269e3021894 39 * sys_read to be implmented for a simple interactive device.
elessair 0:f269e3021894 40 *
elessair 0:f269e3021894 41 * No one ever directly tals to/instanciates a FileHandle - it gets
elessair 0:f269e3021894 42 * created by FileSystem, and wrapped up by stdio.
elessair 0:f269e3021894 43 *
elessair 0:f269e3021894 44 * @Note Synchronization level: Set by subclass
elessair 0:f269e3021894 45 */
elessair 0:f269e3021894 46 class FileHandle {
elessair 0:f269e3021894 47
elessair 0:f269e3021894 48 public:
elessair 0:f269e3021894 49 /** Write the contents of a buffer to the file
elessair 0:f269e3021894 50 *
elessair 0:f269e3021894 51 * @param buffer the buffer to write from
elessair 0:f269e3021894 52 * @param length the number of characters to write
elessair 0:f269e3021894 53 *
elessair 0:f269e3021894 54 * @returns
elessair 0:f269e3021894 55 * The number of characters written (possibly 0) on success, -1 on error.
elessair 0:f269e3021894 56 */
elessair 0:f269e3021894 57 virtual ssize_t write(const void* buffer, size_t length) = 0;
elessair 0:f269e3021894 58
elessair 0:f269e3021894 59 /** Close the file
elessair 0:f269e3021894 60 *
elessair 0:f269e3021894 61 * @returns
elessair 0:f269e3021894 62 * Zero on success, -1 on error.
elessair 0:f269e3021894 63 */
elessair 0:f269e3021894 64 virtual int close() = 0;
elessair 0:f269e3021894 65
elessair 0:f269e3021894 66 /** Function read
elessair 0:f269e3021894 67 * Reads the contents of the file into a buffer
elessair 0:f269e3021894 68 *
elessair 0:f269e3021894 69 * @param buffer the buffer to read in to
elessair 0:f269e3021894 70 * @param length the number of characters to read
elessair 0:f269e3021894 71 *
elessair 0:f269e3021894 72 * @returns
elessair 0:f269e3021894 73 * The number of characters read (zero at end of file) on success, -1 on error.
elessair 0:f269e3021894 74 */
elessair 0:f269e3021894 75 virtual ssize_t read(void* buffer, size_t length) = 0;
elessair 0:f269e3021894 76
elessair 0:f269e3021894 77 /** Check if the handle is for a interactive terminal device.
elessair 0:f269e3021894 78 * If so, line buffered behaviour is used by default
elessair 0:f269e3021894 79 *
elessair 0:f269e3021894 80 * @returns
elessair 0:f269e3021894 81 * 1 if it is a terminal,
elessair 0:f269e3021894 82 * 0 otherwise
elessair 0:f269e3021894 83 */
elessair 0:f269e3021894 84 virtual int isatty() = 0;
elessair 0:f269e3021894 85
elessair 0:f269e3021894 86 /** Move the file position to a given offset from a given location.
elessair 0:f269e3021894 87 *
elessair 0:f269e3021894 88 * @param offset The offset from whence to move to
elessair 0:f269e3021894 89 * @param whence SEEK_SET for the start of the file, SEEK_CUR for the
elessair 0:f269e3021894 90 * current file position, or SEEK_END for the end of the file.
elessair 0:f269e3021894 91 *
elessair 0:f269e3021894 92 * @returns
elessair 0:f269e3021894 93 * new file position on success,
elessair 0:f269e3021894 94 * -1 on failure or unsupported
elessair 0:f269e3021894 95 */
elessair 0:f269e3021894 96 virtual off_t lseek(off_t offset, int whence) = 0;
elessair 0:f269e3021894 97
elessair 0:f269e3021894 98 /** Flush any buffers associated with the FileHandle, ensuring it
elessair 0:f269e3021894 99 * is up to date on disk
elessair 0:f269e3021894 100 *
elessair 0:f269e3021894 101 * @returns
elessair 0:f269e3021894 102 * 0 on success or un-needed,
elessair 0:f269e3021894 103 * -1 on error
elessair 0:f269e3021894 104 */
elessair 0:f269e3021894 105 virtual int fsync() = 0;
elessair 0:f269e3021894 106
elessair 0:f269e3021894 107 virtual off_t flen() {
elessair 0:f269e3021894 108 lock();
elessair 0:f269e3021894 109 /* remember our current position */
elessair 0:f269e3021894 110 off_t pos = lseek(0, SEEK_CUR);
elessair 0:f269e3021894 111 if(pos == -1) {
elessair 0:f269e3021894 112 unlock();
elessair 0:f269e3021894 113 return -1;
elessair 0:f269e3021894 114 }
elessair 0:f269e3021894 115 /* seek to the end to get the file length */
elessair 0:f269e3021894 116 off_t res = lseek(0, SEEK_END);
elessair 0:f269e3021894 117 /* return to our old position */
elessair 0:f269e3021894 118 lseek(pos, SEEK_SET);
elessair 0:f269e3021894 119 unlock();
elessair 0:f269e3021894 120 return res;
elessair 0:f269e3021894 121 }
elessair 0:f269e3021894 122
elessair 0:f269e3021894 123 virtual ~FileHandle();
elessair 0:f269e3021894 124
elessair 0:f269e3021894 125 protected:
elessair 0:f269e3021894 126
elessair 0:f269e3021894 127 /** Acquire exclusive access to this object.
elessair 0:f269e3021894 128 */
elessair 0:f269e3021894 129 virtual void lock() {
elessair 0:f269e3021894 130 // Stub
elessair 0:f269e3021894 131 }
elessair 0:f269e3021894 132
elessair 0:f269e3021894 133 /** Release exclusive access to this object.
elessair 0:f269e3021894 134 */
elessair 0:f269e3021894 135 virtual void unlock() {
elessair 0:f269e3021894 136 // Stub
elessair 0:f269e3021894 137 }
elessair 0:f269e3021894 138 };
elessair 0:f269e3021894 139
elessair 0:f269e3021894 140 } // namespace mbed
elessair 0:f269e3021894 141
elessair 0:f269e3021894 142 #endif
elessair 0:f269e3021894 143
elessair 0:f269e3021894 144 /** @}*/