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mbed/drivers/FileHandle.h@0:d6c9b09b4042, 2020-12-02 (annotated)

Committer:
annieluo2
Date:
Wed Dec 02 18:02:03 2020 +0000
Revision:
0:d6c9b09b4042
boo

Who changed what in which revision?

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annieluo2 0:d6c9b09b4042 1 /* mbed Microcontroller Library
annieluo2 0:d6c9b09b4042 2 * Copyright (c) 2006-2013 ARM Limited
annieluo2 0:d6c9b09b4042 3 *
annieluo2 0:d6c9b09b4042 4 * Licensed under the Apache License, Version 2.0 (the "License");
annieluo2 0:d6c9b09b4042 5 * you may not use this file except in compliance with the License.
annieluo2 0:d6c9b09b4042 6 * You may obtain a copy of the License at
annieluo2 0:d6c9b09b4042 7 *
annieluo2 0:d6c9b09b4042 8 * http://www.apache.org/licenses/LICENSE-2.0
annieluo2 0:d6c9b09b4042 9 *
annieluo2 0:d6c9b09b4042 10 * Unless required by applicable law or agreed to in writing, software
annieluo2 0:d6c9b09b4042 11 * distributed under the License is distributed on an "AS IS" BASIS,
annieluo2 0:d6c9b09b4042 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
annieluo2 0:d6c9b09b4042 13 * See the License for the specific language governing permissions and
annieluo2 0:d6c9b09b4042 14 * limitations under the License.
annieluo2 0:d6c9b09b4042 15 */
annieluo2 0:d6c9b09b4042 16 #ifndef MBED_FILEHANDLE_H
annieluo2 0:d6c9b09b4042 17 #define MBED_FILEHANDLE_H
annieluo2 0:d6c9b09b4042 18
annieluo2 0:d6c9b09b4042 19 typedef int FILEHANDLE;
annieluo2 0:d6c9b09b4042 20
annieluo2 0:d6c9b09b4042 21 #include <stdio.h>
annieluo2 0:d6c9b09b4042 22
annieluo2 0:d6c9b09b4042 23 #if defined(__ARMCC_VERSION) || defined(__ICCARM__)
annieluo2 0:d6c9b09b4042 24 typedef int ssize_t;
annieluo2 0:d6c9b09b4042 25 typedef long off_t;
annieluo2 0:d6c9b09b4042 26
annieluo2 0:d6c9b09b4042 27 #else
annieluo2 0:d6c9b09b4042 28 # include <sys/types.h>
annieluo2 0:d6c9b09b4042 29 #endif
annieluo2 0:d6c9b09b4042 30
annieluo2 0:d6c9b09b4042 31 namespace mbed {
annieluo2 0:d6c9b09b4042 32 /** \addtogroup drivers */
annieluo2 0:d6c9b09b4042 33 /** @{*/
annieluo2 0:d6c9b09b4042 34
annieluo2 0:d6c9b09b4042 35 /** An OO equivalent of the internal FILEHANDLE variable
annieluo2 0:d6c9b09b4042 36 * and associated _sys_* functions.
annieluo2 0:d6c9b09b4042 37 *
annieluo2 0:d6c9b09b4042 38 * FileHandle is an abstract class, needing at least sys_write and
annieluo2 0:d6c9b09b4042 39 * sys_read to be implmented for a simple interactive device.
annieluo2 0:d6c9b09b4042 40 *
annieluo2 0:d6c9b09b4042 41 * No one ever directly tals to/instanciates a FileHandle - it gets
annieluo2 0:d6c9b09b4042 42 * created by FileSystem, and wrapped up by stdio.
annieluo2 0:d6c9b09b4042 43 *
annieluo2 0:d6c9b09b4042 44 * @Note Synchronization level: Set by subclass
annieluo2 0:d6c9b09b4042 45 */
annieluo2 0:d6c9b09b4042 46 class FileHandle {
annieluo2 0:d6c9b09b4042 47
annieluo2 0:d6c9b09b4042 48 public:
annieluo2 0:d6c9b09b4042 49 /** Write the contents of a buffer to the file
annieluo2 0:d6c9b09b4042 50 *
annieluo2 0:d6c9b09b4042 51 * @param buffer the buffer to write from
annieluo2 0:d6c9b09b4042 52 * @param length the number of characters to write
annieluo2 0:d6c9b09b4042 53 *
annieluo2 0:d6c9b09b4042 54 * @returns
annieluo2 0:d6c9b09b4042 55 * The number of characters written (possibly 0) on success, -1 on error.
annieluo2 0:d6c9b09b4042 56 */
annieluo2 0:d6c9b09b4042 57 virtual ssize_t write(const void* buffer, size_t length) = 0;
annieluo2 0:d6c9b09b4042 58
annieluo2 0:d6c9b09b4042 59 /** Close the file
annieluo2 0:d6c9b09b4042 60 *
annieluo2 0:d6c9b09b4042 61 * @returns
annieluo2 0:d6c9b09b4042 62 * Zero on success, -1 on error.
annieluo2 0:d6c9b09b4042 63 */
annieluo2 0:d6c9b09b4042 64 virtual int close() = 0;
annieluo2 0:d6c9b09b4042 65
annieluo2 0:d6c9b09b4042 66 /** Function read
annieluo2 0:d6c9b09b4042 67 * Reads the contents of the file into a buffer
annieluo2 0:d6c9b09b4042 68 *
annieluo2 0:d6c9b09b4042 69 * @param buffer the buffer to read in to
annieluo2 0:d6c9b09b4042 70 * @param length the number of characters to read
annieluo2 0:d6c9b09b4042 71 *
annieluo2 0:d6c9b09b4042 72 * @returns
annieluo2 0:d6c9b09b4042 73 * The number of characters read (zero at end of file) on success, -1 on error.
annieluo2 0:d6c9b09b4042 74 */
annieluo2 0:d6c9b09b4042 75 virtual ssize_t read(void* buffer, size_t length) = 0;
annieluo2 0:d6c9b09b4042 76
annieluo2 0:d6c9b09b4042 77 /** Check if the handle is for a interactive terminal device.
annieluo2 0:d6c9b09b4042 78 * If so, line buffered behaviour is used by default
annieluo2 0:d6c9b09b4042 79 *
annieluo2 0:d6c9b09b4042 80 * @returns
annieluo2 0:d6c9b09b4042 81 * 1 if it is a terminal,
annieluo2 0:d6c9b09b4042 82 * 0 otherwise
annieluo2 0:d6c9b09b4042 83 */
annieluo2 0:d6c9b09b4042 84 virtual int isatty() = 0;
annieluo2 0:d6c9b09b4042 85
annieluo2 0:d6c9b09b4042 86 /** Move the file position to a given offset from a given location.
annieluo2 0:d6c9b09b4042 87 *
annieluo2 0:d6c9b09b4042 88 * @param offset The offset from whence to move to
annieluo2 0:d6c9b09b4042 89 * @param whence SEEK_SET for the start of the file, SEEK_CUR for the
annieluo2 0:d6c9b09b4042 90 * current file position, or SEEK_END for the end of the file.
annieluo2 0:d6c9b09b4042 91 *
annieluo2 0:d6c9b09b4042 92 * @returns
annieluo2 0:d6c9b09b4042 93 * new file position on success,
annieluo2 0:d6c9b09b4042 94 * -1 on failure or unsupported
annieluo2 0:d6c9b09b4042 95 */
annieluo2 0:d6c9b09b4042 96 virtual off_t lseek(off_t offset, int whence) = 0;
annieluo2 0:d6c9b09b4042 97
annieluo2 0:d6c9b09b4042 98 /** Flush any buffers associated with the FileHandle, ensuring it
annieluo2 0:d6c9b09b4042 99 * is up to date on disk
annieluo2 0:d6c9b09b4042 100 *
annieluo2 0:d6c9b09b4042 101 * @returns
annieluo2 0:d6c9b09b4042 102 * 0 on success or un-needed,
annieluo2 0:d6c9b09b4042 103 * -1 on error
annieluo2 0:d6c9b09b4042 104 */
annieluo2 0:d6c9b09b4042 105 virtual int fsync() = 0;
annieluo2 0:d6c9b09b4042 106
annieluo2 0:d6c9b09b4042 107 virtual off_t flen() {
annieluo2 0:d6c9b09b4042 108 lock();
annieluo2 0:d6c9b09b4042 109 /* remember our current position */
annieluo2 0:d6c9b09b4042 110 off_t pos = lseek(0, SEEK_CUR);
annieluo2 0:d6c9b09b4042 111 if(pos == -1) {
annieluo2 0:d6c9b09b4042 112 unlock();
annieluo2 0:d6c9b09b4042 113 return -1;
annieluo2 0:d6c9b09b4042 114 }
annieluo2 0:d6c9b09b4042 115 /* seek to the end to get the file length */
annieluo2 0:d6c9b09b4042 116 off_t res = lseek(0, SEEK_END);
annieluo2 0:d6c9b09b4042 117 /* return to our old position */
annieluo2 0:d6c9b09b4042 118 lseek(pos, SEEK_SET);
annieluo2 0:d6c9b09b4042 119 unlock();
annieluo2 0:d6c9b09b4042 120 return res;
annieluo2 0:d6c9b09b4042 121 }
annieluo2 0:d6c9b09b4042 122
annieluo2 0:d6c9b09b4042 123 virtual ~FileHandle();
annieluo2 0:d6c9b09b4042 124
annieluo2 0:d6c9b09b4042 125 protected:
annieluo2 0:d6c9b09b4042 126
annieluo2 0:d6c9b09b4042 127 /** Acquire exclusive access to this object.
annieluo2 0:d6c9b09b4042 128 */
annieluo2 0:d6c9b09b4042 129 virtual void lock() {
annieluo2 0:d6c9b09b4042 130 // Stub
annieluo2 0:d6c9b09b4042 131 }
annieluo2 0:d6c9b09b4042 132
annieluo2 0:d6c9b09b4042 133 /** Release exclusive access to this object.
annieluo2 0:d6c9b09b4042 134 */
annieluo2 0:d6c9b09b4042 135 virtual void unlock() {
annieluo2 0:d6c9b09b4042 136 // Stub
annieluo2 0:d6c9b09b4042 137 }
annieluo2 0:d6c9b09b4042 138 };
annieluo2 0:d6c9b09b4042 139
annieluo2 0:d6c9b09b4042 140 } // namespace mbed
annieluo2 0:d6c9b09b4042 141
annieluo2 0:d6c9b09b4042 142 #endif
annieluo2 0:d6c9b09b4042 143
annieluo2 0:d6c9b09b4042 144 /** @}*/