FileHandle.h

00001 /* mbed Microcontroller Library - FileHandler
00002  * Copyright (c) 2007-2009 ARM Limited. All rights reserved.
00003  */ 
00004  
00005 #ifndef MBED_FILEHANDLE_H
00006 #define MBED_FILEHANDLE_H
00007 
00008 typedef int FILEHANDLE;
00009 
00010 #include <stdio.h>
00011 #ifdef __ARMCC_VERSION
00012 typedef int ssize_t;
00013 typedef long off_t;
00014 #else
00015 #include <sys/types.h>
00016 #endif
00017 
00018 namespace mbed { 
00019 
00020 /* Class FileHandle
00021  *  An OO equivalent of the internal FILEHANDLE variable
00022  *  and associated _sys_* functions
00023  *
00024  * FileHandle is an abstract class, needing at least sys_write and
00025  * sys_read to be implmented for a simple interactive device
00026  *
00027  * No one ever directly tals to/instanciates a FileHandle - it gets 
00028  * created by FileSystem, and wrapped up by stdio
00029  */
00030 class FileHandle {
00031 
00032 public:
00033 
00034     /* Function write
00035      *  Write the contents of a buffer to the file
00036      *
00037      * Parameters
00038      *  buffer - the buffer to write from
00039      *  length - the number of characters to write
00040      *
00041      * Returns
00042      *  The number of characters written (possibly 0) on success, -1 on error.
00043      */
00044     virtual ssize_t write(const void* buffer, size_t length) = 0;
00045 
00046     /* Function close
00047      *  Close the file
00048      *
00049      * Returns
00050      *  Zero on success, -1 on error.
00051      */
00052     virtual int close() = 0;
00053 
00054     /* Function read
00055      *  Reads the contents of the file into a buffer
00056      *
00057      * Parameters
00058      *  buffer - the buffer to read in to
00059      *  length - the number of characters to read
00060      *
00061      * Returns
00062      *  The number of characters read (zero at end of file) on success, -1 on error.
00063      */
00064     virtual ssize_t read(void* buffer, size_t length) = 0;
00065 
00066     /* Function isatty
00067      *  Check if the handle is for a interactive terminal device 
00068      *
00069      * If so, line buffered behaviour is used by default
00070      *
00071      * Returns
00072      *  1 if it is a terminal, 0 otherwise
00073      */
00074     virtual int isatty() = 0 ;
00075 
00076     /* Function lseek
00077      *  Move the file position to a given offset from a given location.
00078      *
00079      * Parameters
00080      *  offset - The offset from whence to move to
00081      *  whence - SEEK_SET for the start of the file, SEEK_CUR for the
00082      *   current file position, or SEEK_END for the end of the file.
00083      *
00084      * Returns
00085      *  New file position on success, -1 on failure or unsupported
00086      */
00087     virtual off_t lseek(off_t offset, int whence) = 0;
00088 
00089     /* Function fsync
00090      *  Flush any buffers associated with the FileHandle, ensuring it
00091      *  is up to date on disk
00092      *
00093      * Returns
00094      *  0 on success or un-needed, -1 on error
00095      */
00096     virtual int fsync() = 0;
00097 
00098     virtual off_t flen() {
00099         /* remember our current position */
00100         off_t pos = lseek(0, SEEK_CUR);
00101         if(pos == -1) return -1;
00102         /* seek to the end to get the file length */
00103         off_t res = lseek(0, SEEK_END);
00104         /* return to our old position */
00105         lseek(pos, SEEK_SET);
00106         return res;
00107     }
00108 
00109 };
00110 
00111 } // namespace mbed
00112 
00113 #endif
00114