Gan likun / mbed-dev11

platform/FileHandle.h@0:06036f8bee2d, 2022-10-24 (annotated)

Committer:
ganlikun
Date:
Mon Oct 24 15:19:39 2022 +0000
Revision:
0:06036f8bee2d
11

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ganlikun 0:06036f8bee2d 1 /* mbed Microcontroller Library
ganlikun 0:06036f8bee2d 2 * Copyright (c) 2017 ARM Limited
ganlikun 0:06036f8bee2d 3 *
ganlikun 0:06036f8bee2d 4 * Licensed under the Apache License, Version 2.0 (the "License");
ganlikun 0:06036f8bee2d 5 * you may not use this file except in compliance with the License.
ganlikun 0:06036f8bee2d 6 * You may obtain a copy of the License at
ganlikun 0:06036f8bee2d 7 *
ganlikun 0:06036f8bee2d 8 * http://www.apache.org/licenses/LICENSE-2.0
ganlikun 0:06036f8bee2d 9 *
ganlikun 0:06036f8bee2d 10 * Unless required by applicable law or agreed to in writing, software
ganlikun 0:06036f8bee2d 11 * distributed under the License is distributed on an "AS IS" BASIS,
ganlikun 0:06036f8bee2d 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
ganlikun 0:06036f8bee2d 13 * See the License for the specific language governing permissions and
ganlikun 0:06036f8bee2d 14 * limitations under the License.
ganlikun 0:06036f8bee2d 15 */
ganlikun 0:06036f8bee2d 16 #ifndef MBED_FILEHANDLE_H
ganlikun 0:06036f8bee2d 17 #define MBED_FILEHANDLE_H
ganlikun 0:06036f8bee2d 18
ganlikun 0:06036f8bee2d 19 typedef int FILEHANDLE;
ganlikun 0:06036f8bee2d 20
ganlikun 0:06036f8bee2d 21 #include <cstdio>
ganlikun 0:06036f8bee2d 22 #include "Callback.h"
ganlikun 0:06036f8bee2d 23 #include "platform/mbed_poll.h"
ganlikun 0:06036f8bee2d 24 #include "platform/platform.h"
ganlikun 0:06036f8bee2d 25 #include "platform/NonCopyable.h"
ganlikun 0:06036f8bee2d 26
ganlikun 0:06036f8bee2d 27 namespace mbed {
ganlikun 0:06036f8bee2d 28 /** \addtogroup platform */
ganlikun 0:06036f8bee2d 29
ganlikun 0:06036f8bee2d 30
ganlikun 0:06036f8bee2d 31 /** Class FileHandle
ganlikun 0:06036f8bee2d 32 *
ganlikun 0:06036f8bee2d 33 * An abstract interface that represents operations on a file-like
ganlikun 0:06036f8bee2d 34 * object. The core functions are read, write, and seek, but only
ganlikun 0:06036f8bee2d 35 * a subset of these operations can be provided.
ganlikun 0:06036f8bee2d 36 *
ganlikun 0:06036f8bee2d 37 * @note to create a file, @see File
ganlikun 0:06036f8bee2d 38 * @note Synchronization level: Set by subclass
ganlikun 0:06036f8bee2d 39 * @ingroup platform
ganlikun 0:06036f8bee2d 40 */
ganlikun 0:06036f8bee2d 41 class FileHandle : private NonCopyable<FileHandle> {
ganlikun 0:06036f8bee2d 42 public:
ganlikun 0:06036f8bee2d 43 virtual ~FileHandle() {}
ganlikun 0:06036f8bee2d 44
ganlikun 0:06036f8bee2d 45 /** Read the contents of a file into a buffer
ganlikun 0:06036f8bee2d 46 *
ganlikun 0:06036f8bee2d 47 * Devices acting as FileHandles should follow POSIX semantics:
ganlikun 0:06036f8bee2d 48 *
ganlikun 0:06036f8bee2d 49 * * if no data is available, and non-blocking set return -EAGAIN
ganlikun 0:06036f8bee2d 50 * * if no data is available, and blocking set, wait until data is available
ganlikun 0:06036f8bee2d 51 * * If any data is available, call returns immediately
ganlikun 0:06036f8bee2d 52 *
ganlikun 0:06036f8bee2d 53 * @param buffer The buffer to read in to
ganlikun 0:06036f8bee2d 54 * @param size The number of bytes to read
ganlikun 0:06036f8bee2d 55 * @return The number of bytes read, 0 at end of file, negative error on failure
ganlikun 0:06036f8bee2d 56 */
ganlikun 0:06036f8bee2d 57 virtual ssize_t read(void *buffer, size_t size) = 0;
ganlikun 0:06036f8bee2d 58
ganlikun 0:06036f8bee2d 59 /** Write the contents of a buffer to a file
ganlikun 0:06036f8bee2d 60 *
ganlikun 0:06036f8bee2d 61 * @param buffer The buffer to write from
ganlikun 0:06036f8bee2d 62 * @param size The number of bytes to write
ganlikun 0:06036f8bee2d 63 * @return The number of bytes written, negative error on failure
ganlikun 0:06036f8bee2d 64 */
ganlikun 0:06036f8bee2d 65 virtual ssize_t write(const void *buffer, size_t size) = 0;
ganlikun 0:06036f8bee2d 66
ganlikun 0:06036f8bee2d 67 /** Move the file position to a given offset from from a given location
ganlikun 0:06036f8bee2d 68 *
ganlikun 0:06036f8bee2d 69 * @param offset The offset from whence to move to
ganlikun 0:06036f8bee2d 70 * @param whence The start of where to seek
ganlikun 0:06036f8bee2d 71 * SEEK_SET to start from beginning of file,
ganlikun 0:06036f8bee2d 72 * SEEK_CUR to start from current position in file,
ganlikun 0:06036f8bee2d 73 * SEEK_END to start from end of file
ganlikun 0:06036f8bee2d 74 * @return The new offset of the file, negative error code on failure
ganlikun 0:06036f8bee2d 75 */
ganlikun 0:06036f8bee2d 76 virtual off_t seek(off_t offset, int whence = SEEK_SET) = 0;
ganlikun 0:06036f8bee2d 77
ganlikun 0:06036f8bee2d 78 /** Close a file
ganlikun 0:06036f8bee2d 79 *
ganlikun 0:06036f8bee2d 80 * @return 0 on success, negative error code on failure
ganlikun 0:06036f8bee2d 81 */
ganlikun 0:06036f8bee2d 82 virtual int close() = 0;
ganlikun 0:06036f8bee2d 83
ganlikun 0:06036f8bee2d 84 /** Flush any buffers associated with the file
ganlikun 0:06036f8bee2d 85 *
ganlikun 0:06036f8bee2d 86 * @return 0 on success, negative error code on failure
ganlikun 0:06036f8bee2d 87 */
ganlikun 0:06036f8bee2d 88 virtual int sync()
ganlikun 0:06036f8bee2d 89 {
ganlikun 0:06036f8bee2d 90 return 0;
ganlikun 0:06036f8bee2d 91 }
ganlikun 0:06036f8bee2d 92
ganlikun 0:06036f8bee2d 93 /** Check if the file in an interactive terminal device
ganlikun 0:06036f8bee2d 94 *
ganlikun 0:06036f8bee2d 95 * @return True if the file is a terminal
ganlikun 0:06036f8bee2d 96 * @return False if the file is not a terminal
ganlikun 0:06036f8bee2d 97 * @return Negative error code on failure
ganlikun 0:06036f8bee2d 98 */
ganlikun 0:06036f8bee2d 99 virtual int isatty()
ganlikun 0:06036f8bee2d 100 {
ganlikun 0:06036f8bee2d 101 return false;
ganlikun 0:06036f8bee2d 102 }
ganlikun 0:06036f8bee2d 103
ganlikun 0:06036f8bee2d 104 /** Get the file position of the file
ganlikun 0:06036f8bee2d 105 *
ganlikun 0:06036f8bee2d 106 * @note This is equivalent to seek(0, SEEK_CUR)
ganlikun 0:06036f8bee2d 107 *
ganlikun 0:06036f8bee2d 108 * @return The current offset in the file, negative error code on failure
ganlikun 0:06036f8bee2d 109 */
ganlikun 0:06036f8bee2d 110 virtual off_t tell()
ganlikun 0:06036f8bee2d 111 {
ganlikun 0:06036f8bee2d 112 return seek(0, SEEK_CUR);
ganlikun 0:06036f8bee2d 113 }
ganlikun 0:06036f8bee2d 114
ganlikun 0:06036f8bee2d 115 /** Rewind the file position to the beginning of the file
ganlikun 0:06036f8bee2d 116 *
ganlikun 0:06036f8bee2d 117 * @note This is equivalent to seek(0, SEEK_SET)
ganlikun 0:06036f8bee2d 118 */
ganlikun 0:06036f8bee2d 119 virtual void rewind()
ganlikun 0:06036f8bee2d 120 {
ganlikun 0:06036f8bee2d 121 seek(0, SEEK_SET);
ganlikun 0:06036f8bee2d 122 }
ganlikun 0:06036f8bee2d 123
ganlikun 0:06036f8bee2d 124 /** Get the size of the file
ganlikun 0:06036f8bee2d 125 *
ganlikun 0:06036f8bee2d 126 * @return Size of the file in bytes
ganlikun 0:06036f8bee2d 127 */
ganlikun 0:06036f8bee2d 128 virtual off_t size();
ganlikun 0:06036f8bee2d 129
ganlikun 0:06036f8bee2d 130 /** Move the file position to a given offset from a given location.
ganlikun 0:06036f8bee2d 131 *
ganlikun 0:06036f8bee2d 132 * @param offset The offset from whence to move to
ganlikun 0:06036f8bee2d 133 * @param whence SEEK_SET for the start of the file, SEEK_CUR for the
ganlikun 0:06036f8bee2d 134 * current file position, or SEEK_END for the end of the file.
ganlikun 0:06036f8bee2d 135 *
ganlikun 0:06036f8bee2d 136 * @returns
ganlikun 0:06036f8bee2d 137 * new file position on success,
ganlikun 0:06036f8bee2d 138 * -1 on failure or unsupported
ganlikun 0:06036f8bee2d 139 */
ganlikun 0:06036f8bee2d 140 MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::seek")
ganlikun 0:06036f8bee2d 141 virtual off_t lseek(off_t offset, int whence)
ganlikun 0:06036f8bee2d 142 {
ganlikun 0:06036f8bee2d 143 return seek(offset, whence);
ganlikun 0:06036f8bee2d 144 }
ganlikun 0:06036f8bee2d 145
ganlikun 0:06036f8bee2d 146 /** Flush any buffers associated with the FileHandle, ensuring it
ganlikun 0:06036f8bee2d 147 * is up to date on disk
ganlikun 0:06036f8bee2d 148 *
ganlikun 0:06036f8bee2d 149 * @returns
ganlikun 0:06036f8bee2d 150 * 0 on success or un-needed,
ganlikun 0:06036f8bee2d 151 * -1 on error
ganlikun 0:06036f8bee2d 152 */
ganlikun 0:06036f8bee2d 153 MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::sync")
ganlikun 0:06036f8bee2d 154 virtual int fsync()
ganlikun 0:06036f8bee2d 155 {
ganlikun 0:06036f8bee2d 156 return sync();
ganlikun 0:06036f8bee2d 157 }
ganlikun 0:06036f8bee2d 158
ganlikun 0:06036f8bee2d 159 /** Find the length of the file
ganlikun 0:06036f8bee2d 160 *
ganlikun 0:06036f8bee2d 161 * @returns
ganlikun 0:06036f8bee2d 162 * Length of the file
ganlikun 0:06036f8bee2d 163 */
ganlikun 0:06036f8bee2d 164 MBED_DEPRECATED_SINCE("mbed-os-5.4", "Replaced by FileHandle::size")
ganlikun 0:06036f8bee2d 165 virtual off_t flen()
ganlikun 0:06036f8bee2d 166 {
ganlikun 0:06036f8bee2d 167 return size();
ganlikun 0:06036f8bee2d 168 }
ganlikun 0:06036f8bee2d 169
ganlikun 0:06036f8bee2d 170 /** Set blocking or non-blocking mode of the file operation like read/write.
ganlikun 0:06036f8bee2d 171 * Definition depends upon the subclass implementing FileHandle.
ganlikun 0:06036f8bee2d 172 * The default is blocking.
ganlikun 0:06036f8bee2d 173 *
ganlikun 0:06036f8bee2d 174 * @param blocking true for blocking mode, false for non-blocking mode.
ganlikun 0:06036f8bee2d 175 *
ganlikun 0:06036f8bee2d 176 * @return 0 on success
ganlikun 0:06036f8bee2d 177 * @return Negative error code on failure
ganlikun 0:06036f8bee2d 178 */
ganlikun 0:06036f8bee2d 179 virtual int set_blocking(bool blocking)
ganlikun 0:06036f8bee2d 180 {
ganlikun 0:06036f8bee2d 181 return -1;
ganlikun 0:06036f8bee2d 182 }
ganlikun 0:06036f8bee2d 183
ganlikun 0:06036f8bee2d 184 /** Check for poll event flags
ganlikun 0:06036f8bee2d 185 * The input parameter can be used or ignored - the could always return all events,
ganlikun 0:06036f8bee2d 186 * or could check just the events listed in events.
ganlikun 0:06036f8bee2d 187 * Call is non-blocking - returns instantaneous state of events.
ganlikun 0:06036f8bee2d 188 * Whenever an event occurs, the derived class should call the sigio() callback).
ganlikun 0:06036f8bee2d 189 *
ganlikun 0:06036f8bee2d 190 * @param events bitmask of poll events we're interested in - POLLIN/POLLOUT etc.
ganlikun 0:06036f8bee2d 191 *
ganlikun 0:06036f8bee2d 192 * @returns bitmask of poll events that have occurred.
ganlikun 0:06036f8bee2d 193 */
ganlikun 0:06036f8bee2d 194 virtual short poll(short events) const
ganlikun 0:06036f8bee2d 195 {
ganlikun 0:06036f8bee2d 196 // Possible default for real files
ganlikun 0:06036f8bee2d 197 return POLLIN | POLLOUT;
ganlikun 0:06036f8bee2d 198 }
ganlikun 0:06036f8bee2d 199
ganlikun 0:06036f8bee2d 200 /** Definition depends upon the subclass implementing FileHandle.
ganlikun 0:06036f8bee2d 201 * For example, if the FileHandle is of type Stream, writable() could return
ganlikun 0:06036f8bee2d 202 * true when there is ample buffer space available for write() calls.
ganlikun 0:06036f8bee2d 203 *
ganlikun 0:06036f8bee2d 204 * @returns true if the FileHandle is writable.
ganlikun 0:06036f8bee2d 205 */
ganlikun 0:06036f8bee2d 206 bool writable() const
ganlikun 0:06036f8bee2d 207 {
ganlikun 0:06036f8bee2d 208 return poll(POLLOUT) & POLLOUT;
ganlikun 0:06036f8bee2d 209 }
ganlikun 0:06036f8bee2d 210
ganlikun 0:06036f8bee2d 211 /** Definition depends upon the subclass implementing FileHandle.
ganlikun 0:06036f8bee2d 212 * For example, if the FileHandle is of type Stream, readable() could return
ganlikun 0:06036f8bee2d 213 * true when there is something available to read.
ganlikun 0:06036f8bee2d 214 *
ganlikun 0:06036f8bee2d 215 * @returns true when there is something available to read.
ganlikun 0:06036f8bee2d 216 */
ganlikun 0:06036f8bee2d 217 bool readable() const
ganlikun 0:06036f8bee2d 218 {
ganlikun 0:06036f8bee2d 219 return poll(POLLIN) & POLLIN;
ganlikun 0:06036f8bee2d 220 }
ganlikun 0:06036f8bee2d 221
ganlikun 0:06036f8bee2d 222 /** Register a callback on state change of the file.
ganlikun 0:06036f8bee2d 223 *
ganlikun 0:06036f8bee2d 224 * The specified callback will be called on state changes such as when
ganlikun 0:06036f8bee2d 225 * the file can be written to or read from.
ganlikun 0:06036f8bee2d 226 *
ganlikun 0:06036f8bee2d 227 * The callback may be called in an interrupt context and should not
ganlikun 0:06036f8bee2d 228 * perform expensive operations.
ganlikun 0:06036f8bee2d 229 *
ganlikun 0:06036f8bee2d 230 * Note! This is not intended as an attach-like asynchronous api, but rather
ganlikun 0:06036f8bee2d 231 * as a building block for constructing such functionality.
ganlikun 0:06036f8bee2d 232 *
ganlikun 0:06036f8bee2d 233 * The exact timing of when the registered function
ganlikun 0:06036f8bee2d 234 * is called is not guaranteed and susceptible to change. It should be used
ganlikun 0:06036f8bee2d 235 * as a cue to make read/write/poll calls to find the current state.
ganlikun 0:06036f8bee2d 236 *
ganlikun 0:06036f8bee2d 237 * @param func Function to call on state change
ganlikun 0:06036f8bee2d 238 */
ganlikun 0:06036f8bee2d 239 virtual void sigio(Callback<void()> func)
ganlikun 0:06036f8bee2d 240 {
ganlikun 0:06036f8bee2d 241 //Default for real files. Do nothing for real files.
ganlikun 0:06036f8bee2d 242 }
ganlikun 0:06036f8bee2d 243 };
ganlikun 0:06036f8bee2d 244
ganlikun 0:06036f8bee2d 245 /** Not a member function
ganlikun 0:06036f8bee2d 246 * This call is equivalent to posix fdopen().
ganlikun 0:06036f8bee2d 247 * It associates a Stream to an already opened file descriptor (FileHandle)
ganlikun 0:06036f8bee2d 248 *
ganlikun 0:06036f8bee2d 249 * @param fh a pointer to an opened file descriptor
ganlikun 0:06036f8bee2d 250 * @param mode operation upon the file descriptor, e.g., 'wb+'
ganlikun 0:06036f8bee2d 251 *
ganlikun 0:06036f8bee2d 252 * @returns a pointer to std::FILE
ganlikun 0:06036f8bee2d 253 */
ganlikun 0:06036f8bee2d 254
ganlikun 0:06036f8bee2d 255 std::FILE *fdopen(FileHandle *fh, const char *mode);
ganlikun 0:06036f8bee2d 256
ganlikun 0:06036f8bee2d 257 } // namespace mbed
ganlikun 0:06036f8bee2d 258
ganlikun 0:06036f8bee2d 259 #endif
ganlikun 0:06036f8bee2d 260