[6127] | 1 | /**********************************************************************
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| 2 | *
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| 3 | * File.cpp
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| 4 | * Copyright (C) 2003 UNESCO
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| 5 | *
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| 6 | * A component of the Greenstone digital library software
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| 7 | * from the New Zealand Digital Library Project at the
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| 8 | * University of Waikato, New Zealand.
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| 9 | *
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| 10 | * This program is free software; you can redistribute it and/or modify
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| 11 | * it under the terms of the GNU General Public License as published by
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| 12 | * the Free Software Foundation; either version 2 of the License, or
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| 13 | * (at your option) any later version.
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| 14 | *
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| 15 | * This program is distributed in the hope that it will be useful,
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| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 18 | * GNU General Public License for more details.
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| 19 | *
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| 20 | * You should have received a copy of the GNU General Public License
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| 21 | * along with this program; if not, write to the Free Software
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| 22 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 23 | *
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| 24 | *********************************************************************/
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| 25 |
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| 26 | ////////////////////////////////////////////////////////////
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| 27 | // File.cpp File object methods
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| 28 | ////////////////////////////////////////////////////////////
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| 29 | #include "stdafx.h"
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| 30 |
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| 31 |
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| 32 | #include <assert.h>
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| 33 | #include "CRC32.h"
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| 34 | #include "File.h"
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| 35 |
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| 36 |
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| 37 |
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| 38 |
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| 39 | static TCHAR closed_file_name[] = _T("closed-file");
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| 40 |
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| 41 | static const int MaxExceptionMessages = 34;
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| 42 | static const TCHAR *fileExceptionMsg[MaxExceptionMessages] =
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| 43 | {
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| 44 | _T("File exception: No exception reported"), // FILE_NO_ERROR
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| 45 | _T("File exception: Checksum error"), // FILE_CHECKSUM_ERROR
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| 46 | _T("File exception: Error closing file"), // FILE_CLOSE_ERROR
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| 47 | _T("File exception: File is corrupted"),
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| 48 | _T("File exception: Error creating file"), // FILE_CREATION_ERROR
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| 49 | _T("File exception: File already exists"), // FILE_EXISTS
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| 50 | _T("File exception: Trying to use a closed file"), // FILE_NOT_OPEN_ERROR
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| 51 | _T("File exception: File not ready for reading/writing"), // FILE_NOT_READY
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| 52 | _T("File exception: Could not write to file"), // FILE_NOT_WRITEABLE
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| 53 | _T("File exception: Error opening file"), // FILE_OPEN_ERROR
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| 54 | _T("File exception: Cannot obtain a file position"), // FILE_POSITION_ERROR
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| 55 | _T("File exception: Error reading from file"), // FILE_READ_ERROR
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| 56 | _T("File exception: Error seeking in file"), // FILE_SEEK_ERROR
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| 57 | _T("File exception: Error writing to file"), // FILE_WRITE_ERROR
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| 58 |
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| 59 | _T("Fmgr exception: No database open"), // FMGR_NO_DATABASE_OPEN
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| 60 | _T("Fmgr exception: No such file exists"), // FMGR_NO_FILE_EXISTS
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| 61 | _T("Fmgr exception: No objects exist"), // FMGR_NO_OBJECTS_EXIST
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| 62 | _T("Fmgr exception: Accessing a null pointer"), // FMGR_NULL_PTR
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| 63 | _T("Fmgr exception: Object already exists"), // FMGR_OBJECT_EXISTS
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| 64 | _T("Fmgr exception: Another object is referencing this file"), // FMGR_OBJECT_EXISTS
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| 65 | _T("Fmgr exception: Math overflow error"), // FMGR_OVERFLOW
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| 66 | _T("Fmgr exception: Parse error"), // FMGR_PARSE_ERROR
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| 67 | _T("Fmgr exception: Invalid path"), // FMGR_PATH_ERROR
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| 68 | _T("Fmgr exception: Trying to write to a read-only file"), // FMGR_READ_ONLY_FILE
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| 69 | _T("Fmgr exception: Stack empty"), // FMGR_STACK_EMPTY
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| 70 | _T("Fmgr exception: Stack full"), // FMGR_STACK_FULL
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| 71 | _T("Fmgr exception: Synchronization Error"), // FMGR_SYNC_ERROR
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| 72 | _T("Fmgr exception: Math under-flow error"), // FMGR_UNDERFLOW
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| 73 | _T("Fmgr exception: Wrong file type"), // FMGR_WRONG_FILE_TYPE
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| 74 |
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| 75 | // Persistent lock error messages
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| 76 | _T("Fmgr exception: Invalid lock type specified"), // FMGR_INVALID_LOCK_TYPE
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| 77 | _T("Fmgr exception: Cannot access the file lock header"), // FMGR_FILELOCK_ACCESS_ERROR
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| 78 | _T("Fmgr exception: Cannot lock the file"), // FMGR_FILELOCK_ERROR
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| 79 | _T("Fmgr exception: Cannot access the record lock header"), // FMGR_RECORDLOCK_ACCESS_ERROR
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| 80 | _T("Fmgr exception: Cannot lock the specified record") // FMGR_RECORDLOCK_ERROR
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| 81 | };
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| 82 |
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| 83 | //---------------------------------------------------------------------------
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| 84 | // CFileBase::CFileBase()
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| 85 | //
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| 86 | // Default constructor, makes a File object that isn't attached to a file
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| 87 | //---------------------------------------------------------------------------
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| 88 | CFileBase::CFileBase()
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| 89 | {
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| 90 | _tcscpy(file_name, closed_file_name); // Set the initial file name
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| 91 | fp = 0;
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| 92 |
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| 93 | // Reset the last reported error and the file status members
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| 94 | file_error = FILE_NO_ERROR;
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| 95 | is_open = 0;
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| 96 | is_ok = 0;
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| 97 | ready_for_reading = 0;
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| 98 | ready_for_writing = 0;
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| 99 | }
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| 100 |
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| 101 | //---------------------------------------------------------------------------
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| 102 | // CFileBase::~CFileBase()
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| 103 | //
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| 104 | // Destructor for CFileBase file object
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| 105 | //---------------------------------------------------------------------------
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| 106 | CFileBase::~CFileBase()
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| 107 | {
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| 108 | Close();
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| 109 | }
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| 110 |
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| 111 | //---------------------------------------------------------------------------
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| 112 | // const char* CFileBase::FileExceptionMessage()
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| 113 | //
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| 114 | // Returns a null terminated string that can / be used to log or print a
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| 115 | // file exception.
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| 116 | //---------------------------------------------------------------------------
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| 117 | const TCHAR *CFileBase::FileExceptionMessage()
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| 118 | {
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| 119 | assert(file_error<MaxExceptionMessages);
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| 120 | return fileExceptionMsg[file_error];
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| 121 | }
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| 122 |
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| 123 | //--------------------------------------------------------------------------------
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| 124 | // int Create(const char* fname)
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| 125 | //
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| 126 | // Creates a new file, truncate the file if it already exists. The file open for
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| 127 | // Read/Write access.
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| 128 | // Returns a non-zero value to indicate an error condition or zero if successful.
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| 129 | //--------------------------------------------------------------------------------
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| 130 | FileError CFileBase::Create(const TCHAR *fname)
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| 131 | {
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| 132 | // Close any open files
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| 133 | if (Close() != FILE_NO_ERROR)
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| 134 | return file_error;
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| 135 |
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| 136 | // Create and truncate existing files
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| 137 | fp = FileSystem::Create(fname);
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| 138 |
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| 139 | if (fp == 0)
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| 140 | {
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| 141 | is_ok = 0;
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| 142 | is_open = 0;
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| 143 | ready_for_writing = 0;
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| 144 | ready_for_reading = 0;
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| 145 | file_error = FILE_CREATION_ERROR;
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| 146 | #ifdef __CPP_EXCEPTIONS__
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| 147 | throw CFileBaseException(file_error);
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| 148 | #else
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| 149 | return file_error;
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| 150 | #endif
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| 151 | }
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| 152 | else
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| 153 | {
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| 154 | is_open = 1;
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| 155 | is_ok = 1;
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| 156 | ready_for_writing = 1;
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| 157 | ready_for_reading = 1;
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| 158 | last_operation = IO_READ;
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| 159 | _tcscpy(file_name, fname);
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| 160 | }
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| 161 |
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| 162 | // Returns 0 if the file was successfully created and opened.
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| 163 | return file_error = FILE_NO_ERROR;
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| 164 | }
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| 165 |
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| 166 | //----------------------------------------------------------------------------------------
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| 167 | // FileError CFileBase::Open(const TCHAR *fname, FileSystem::AccessMode mode
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| 168 | // /* = FileSystem::FILE_READWRITE */ )
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| 169 | //
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| 170 | // Open an existing file. The "mode" variable determines if the file is opened for
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| 171 | // read only or read/write access. Returns a non-zero value to indicate an error
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| 172 | // condition or zero if successful.
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| 173 | // NOTE: This version of the open functions will only accept:
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| 174 | // FILE_READONLY and FILE_READWRITE access modes.
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| 175 | //---------------------------------------------------------------------------------------
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| 176 | FileError CFileBase::Open(const TCHAR *fname, FileSystem::AccessMode mode /* = FileSystem::FILE_READWRITE */)
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| 177 | {
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| 178 | // Close any open files
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| 179 | if (Close() != FILE_NO_ERROR)
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| 180 | return file_error;
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| 181 |
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| 182 | if (mode == FileSystem::FILE_READONLY)
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| 183 | { // Open with read only access
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| 184 | ready_for_reading = 1;
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| 185 | ready_for_writing = 0;
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| 186 | fp = FileSystem::Open(fname, FileSystem::FILE_READONLY);
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| 187 | }
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| 188 | else
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| 189 | { // Open with read/write access
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| 190 | ready_for_reading = 1;
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| 191 | ready_for_writing = 1;
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| 192 | fp = FileSystem::Open(fname, FileSystem::FILE_READWRITE);
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| 193 | }
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| 194 |
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| 195 | if (fp == 0)
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| 196 | {
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| 197 | ready_for_reading = 0;
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| 198 | ready_for_writing = 0;
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| 199 | file_error = FILE_OPEN_ERROR;
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| 200 | #ifdef __CPP_EXCEPTIONS__
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| 201 | throw CFileBaseException(file_error);
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| 202 | #else
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| 203 | return file_error;
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| 204 | #endif
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| 205 | }
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| 206 | else
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| 207 | {
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| 208 | is_open = 1;
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| 209 | is_ok = 1;
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| 210 | last_operation = IO_WRITE;
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| 211 | _tcscpy(file_name, fname);
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| 212 | }
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| 213 | return file_error = FILE_NO_ERROR;
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| 214 | }
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| 215 |
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| 216 | //--------------------------------------------------------------------------------
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| 217 | // void CFileBase::Close()
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| 218 | //
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| 219 | // Close the open database file. Returns a non-zero value
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| 220 | // to indicate an error condition or zero if successful.
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| 221 | //--------------------------------------------------------------------------------
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| 222 | FileError CFileBase::Close()
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| 223 | {
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| 224 | if (IsOpen())
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| 225 | {
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| 226 | if (FileSystem::Close(fp) != 0)
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| 227 | {
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| 228 | file_error = FILE_CLOSE_ERROR;
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| 229 | #ifdef __CPP_EXCEPTIONS__
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| 230 | throw CFileBaseException(file_error);
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| 231 | #else
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| 232 | return file_error;
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| 233 | #endif
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| 234 | }
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| 235 | _tcscpy(file_name, closed_file_name); // Set the initial file name
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| 236 | }
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| 237 |
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| 238 | is_open = 0;
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| 239 | is_ok = 0;
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| 240 | ready_for_reading = 0;
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| 241 | ready_for_writing = 0;
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| 242 | fp = 0; // Reset the file pointer to zero after the file is closed
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| 243 |
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| 244 | return file_error = FILE_NO_ERROR;
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| 245 | }
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| 246 |
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| 247 | //----------------------------------------------------------------------------------
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| 248 | // FileError CFileBase::Seek(FAU offset, FileSystem::SeekMode mode)
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| 249 | //
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| 250 | // Seek to the specified offset starting at the beginning (SEEK_SET), end (SEEK_END)
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| 251 | // or current offset (SEEK_CUR). Returns a non-zero value to indicate an error
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| 252 | // condition or zero if successful.
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| 253 | //----------------------------------------------------------------------------------
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| 254 | FileError CFileBase::Seek(FileSystem::FAU_t offset, FileSystem::SeekMode mode)
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| 255 | {
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| 256 | if (IsOK())
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| 257 | {
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| 258 | if (FileSystem::Seek(fp, offset, mode) == (isis::int32_t) - 1)
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| 259 | {
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| 260 | file_error = FILE_SEEK_ERROR;
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| 261 | #ifdef __CPP_EXCEPTIONS__
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| 262 | throw CFileBaseException(file_error);
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| 263 | #else
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| 264 | return file_error;
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| 265 | #endif
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| 266 | }
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| 267 | last_operation = IO_SEEK;
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| 268 | }
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| 269 | else
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| 270 | {
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| 271 | file_error = FILE_NOT_READY;
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| 272 | #ifdef __CPP_EXCEPTIONS__
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| 273 | throw CFileBaseException(file_error);
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| 274 | #else
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| 275 | return file_error;
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| 276 | #endif
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| 277 | }
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| 278 | return file_error = FILE_NO_ERROR;
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| 279 | }
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| 280 |
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| 281 | //----------------------------------------------------------------------------------
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| 282 | // FAU CFileBase::SeekTo(FileSystem::FAU_t file_address)
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| 283 | //
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| 284 | // Seek to the specified address, optimizing the seek operation by moving the
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| 285 | // file position indicator based on the current stream position. Returns the
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| 286 | // current file position after performing the seek operation.
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| 287 | //----------------------------------------------------------------------------------
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| 288 | FileSystem::FAU_t CFileBase::SeekTo(FileSystem::FAU_t file_address)
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| 289 | {
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| 290 | // Get the current stream position
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| 291 | FileSystem::StreamPos pos = FilePosition();
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| 292 |
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| 293 | if (file_address == CURRADDR)
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| 294 | { // Do not perform a seek operation
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| 295 | return pos;
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| 296 | }
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| 297 | else if (file_address > pos)
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| 298 | { // Seek forward to the specified address
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| 299 | FileSystem::StreamPos offset = file_address - pos;
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| 300 | Seek(offset, FileSystem::FILE_SEEK_CUR);
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| 301 | }
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| 302 | else if (file_address < pos)
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| 303 | { // Seek backward to the specified address
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| 304 | Seek(file_address, FileSystem::FILE_SEEK_BEG);
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| 305 | }
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| 306 | else
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| 307 | { // Current file position equals the specified address
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| 308 | // Find current the position
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| 309 | Seek((FileSystem::FAU_t)0, FileSystem::FILE_SEEK_CUR);
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| 310 | }
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| 311 |
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| 312 | return FilePosition(); // Return current file position after seeking
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| 313 | }
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| 314 |
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| 315 | //-------------------------------------------------------------------------------
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| 316 | // FileError Store(const void* buf, isis::uint32_t nBytes,
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| 317 | // FAU file_addres = CFileBase::CURRADDR,
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| 318 | // int flush = 1, int bit_test = 1);
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| 319 | //
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| 320 | // Write a specific number of bytes from a memory buffer to a specified file
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| 321 | // offset. If the "flush" variable is true, the file buffers will be flushed to
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| 322 | // disk with each write operation. If the bit_test variable if true, the CRC of
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| 323 | // the buffer will be compared to the CRC of the actual bytes written to disk.
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| 324 | // Returns a non-zero value to indicate an error condition or zero if successful.
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| 325 | //
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| 326 | // void* buf - Pointer to the user-supplied buffer that is to receive
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| 327 | // the data read from the file.
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| 328 | // isis::uint32_t nBytes - The maximum number of bytes to be read from the
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| 329 | // file. Note that an CFileBase is always a binary file,
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| 330 | // so a CR/LF pair will always be read or written as two bytes.
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| 331 | // FAU file_address - The file byte address. The address is always interpreted to
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| 332 | // be from the beginning of the file, unless dwAddr is equal
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| 333 | // to CURRADDR, which means from the current position.
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| 334 | //-------------------------------------------------------------------------------
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| 335 | FileError CFileBase::Store(const void* buf, isis::uint32_t nBytes,
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| 336 | FileSystem::FAU_t file_address /*= CURRADDR */,
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| 337 | int flush_flag /* = 1 */,
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| 338 | int bit_test /* = 1 */)
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| 339 | {
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| 340 | FileSystem::FAU_t buf_address;
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| 341 |
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| 342 | if (ReadyForWriting())
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| 343 | {
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| 344 | if (file_address == CURRADDR)
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| 345 | {
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| 346 | if (last_operation == IO_READ)
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| 347 | {
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| 348 | if (Seek(0, FileSystem::FILE_SEEK_CUR) != FILE_NO_ERROR)
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| 349 | return file_error;
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| 350 | }
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| 351 | }
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| 352 | else
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| 353 | {
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| 354 | if (Seek(file_address, FileSystem::FILE_SEEK_BEG) != FILE_NO_ERROR)
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| 355 | return file_error;
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| 356 | }
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| 357 |
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| 358 | buf_address = FilePosition();
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| 359 |
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| 360 | if (file_error != FILE_NO_ERROR)
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| 361 | return file_error;
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| 362 |
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| 363 | if (FileSystem::Write(fp, buf, nBytes) != nBytes)
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| 364 | {
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| 365 | file_error = FILE_WRITE_ERROR;
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| 366 | #ifdef __CPP_EXCEPTIONS__
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| 367 | throw CFileBaseException(file_error);
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| 368 | #else
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| 369 | return file_error;
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| 370 | #endif
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| 371 | }
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| 372 | last_operation = IO_WRITE;
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| 373 | }
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| 374 | else
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| 375 | {
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| 376 | file_error = FILE_NOT_WRITEABLE;
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| 377 | #ifdef __CPP_EXCEPTIONS__
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| 378 | throw CFileBaseException(file_error);
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| 379 | #else
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| 380 | return file_error;
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| 381 | #endif
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| 382 | }
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| 383 |
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| 384 | // Allow application to flush disk buffers after each write
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| 385 | // operation to ensure the file data stays in sync during multiple
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| 386 | // file access.
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| 387 | if (flush_flag)
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| 388 | {
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| 389 | if (FileSystem::Flush(fp) != FILE_NO_ERROR)
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| 390 | {
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| 391 | file_error = FILE_WRITE_ERROR;
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| 392 | #ifdef __CPP_EXCEPTIONS__
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| 393 | throw CFileBaseException(file_error);
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| 394 | #else
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| 395 | return file_error;
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| 396 | #endif
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| 397 | }
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| 398 | if (Seek(0, FileSystem::FILE_SEEK_CUR) != FILE_NO_ERROR)
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| 399 | return file_error;
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| 400 | }
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| 401 |
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| 402 | if (bit_test)
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| 403 | {
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| 404 | isis::uint32_t w_csum = CalcCRC32((char* ) buf, nBytes);
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| 405 | isis::uint32_t r_csum = CalcChecksum(nBytes, buf_address);
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| 406 |
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| 407 | // Check for file errors
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| 408 |
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| 409 | if (file_error != FILE_NO_ERROR)
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| 410 | return file_error;
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| 411 |
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| 412 | if (w_csum ^ r_csum)
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| 413 | {
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| 414 | file_error = FILE_CHECKSUM_ERROR;
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| 415 | #ifdef __CPP_EXCEPTIONS__
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| 416 | throw CFileBaseException(file_error);
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| 417 | #else
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| 418 | return file_error;
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| 419 | #endif
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| 420 | }
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| 421 | }
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| 422 | return file_error = FILE_NO_ERROR;
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| 423 | }
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| 424 |
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| 425 | //-------------------------------------------------------------------------------
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| 426 | // FileError CFileBase::Fetch(void* buf, isis::uint32_t nBytes, FAU file_addres
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| 427 | // /* = CFileBase::CURRADDR */)
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| 428 | //
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| 429 | // Read a specified number of bytes from the specified file offset into a memory
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| 430 | // buffer. Returns a non-zero value to indicate an error condition or zero if
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| 431 | // successful.
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| 432 | // void* buf - Pointer to the user-supplied buffer that is to receive
|
---|
| 433 | // the data read from the file.
|
---|
| 434 | // isis::uint32_t nBytes - The maximum number of bytes to be read from the file.
|
---|
| 435 | // Note that an CFileBase is always a binary file, so a
|
---|
| 436 | // CR/LF pair will always be read or written as two bytes.
|
---|
| 437 | // FAU file_addres - The file byte address. The address is always interpreted
|
---|
| 438 | // to be from the beginning of the file, unless dwAddr is
|
---|
| 439 | // equal to CURRADDR, which means from the current position.
|
---|
| 440 | //-------------------------------------------------------------------------------
|
---|
| 441 | FileError CFileBase::Fetch(void* buf, isis::uint32_t nBytes,
|
---|
| 442 | FileSystem::FAU_t file_address /* = CFileBase::CURRADDR */)
|
---|
| 443 | {
|
---|
| 444 | if (IsOK())
|
---|
| 445 | {
|
---|
| 446 | if (file_address == CURRADDR)
|
---|
| 447 | {
|
---|
| 448 | if (last_operation == IO_WRITE)
|
---|
| 449 | {
|
---|
| 450 | if (Seek(0, FileSystem::FILE_SEEK_CUR) != FILE_NO_ERROR)
|
---|
| 451 | return file_error;
|
---|
| 452 | }
|
---|
| 453 | }
|
---|
| 454 | else
|
---|
| 455 | {
|
---|
| 456 | if (Seek(file_address, FileSystem::FILE_SEEK_BEG) != FILE_NO_ERROR)
|
---|
| 457 | return file_error;
|
---|
| 458 | }
|
---|
| 459 |
|
---|
| 460 | //TRACE("\nFetchfile_address=%ld nBytes=%u",file_address, nBytes);
|
---|
| 461 | if (FileSystem::Read(fp, buf, nBytes) != nBytes)
|
---|
| 462 | {
|
---|
| 463 | file_error = FILE_READ_ERROR;
|
---|
| 464 | #ifdef __CPP_EXCEPTIONS__
|
---|
| 465 | throw CFileBaseException(file_error);
|
---|
| 466 | #else
|
---|
| 467 | return file_error;
|
---|
| 468 | #endif
|
---|
| 469 | }
|
---|
| 470 | last_operation = IO_READ;
|
---|
| 471 | }
|
---|
| 472 | else
|
---|
| 473 | {
|
---|
| 474 | file_error = FILE_NOT_READY;
|
---|
| 475 | #ifdef __CPP_EXCEPTIONS__
|
---|
| 476 | throw CFileBaseException(file_error);
|
---|
| 477 | #else
|
---|
| 478 | return file_error;
|
---|
| 479 | #endif
|
---|
| 480 | }
|
---|
| 481 |
|
---|
| 482 | return file_error = FILE_NO_ERROR;
|
---|
| 483 | }
|
---|
| 484 | //-------------------------------------------------------------------------------
|
---|
| 485 | // FileError Flush()
|
---|
| 486 | //
|
---|
| 487 | // Flush any open disk buffers. Returns a non-zero value to indicate an error
|
---|
| 488 | // condition or zero if successful.
|
---|
| 489 | //-------------------------------------------------------------------------------
|
---|
| 490 | FileError CFileBase::Flush()
|
---|
| 491 | {
|
---|
| 492 | PRECONDITION(ReadyForWriting());
|
---|
| 493 | if (FileSystem::Flush(fp) != FILE_NO_ERROR)
|
---|
| 494 | {
|
---|
| 495 | file_error = FILE_WRITE_ERROR;
|
---|
| 496 | #ifdef __CPP_EXCEPTIONS__
|
---|
| 497 | throw CFileBaseException(file_error);
|
---|
| 498 | #else
|
---|
| 499 | return file_error;
|
---|
| 500 | #endif
|
---|
| 501 | }
|
---|
| 502 | Seek((FileSystem::FAU_t)0, FileSystem::FILE_SEEK_CUR);
|
---|
| 503 | return file_error = FILE_NO_ERROR;
|
---|
| 504 | }
|
---|
| 505 |
|
---|
| 506 |
|
---|
| 507 | //-------------------------------------------------------------------------------
|
---|
| 508 | // StreamPos CFileBase::FilePosition()
|
---|
| 509 | //
|
---|
| 510 | // Returns the current file position or -1 to indicate an error condition.
|
---|
| 511 | //-------------------------------------------------------------------------------
|
---|
| 512 | FileSystem::StreamPos CFileBase::FilePosition()
|
---|
| 513 | {
|
---|
| 514 | if (!IsOK())
|
---|
| 515 | {
|
---|
| 516 | file_error = FILE_NOT_READY;
|
---|
| 517 | #ifdef __CPP_EXCEPTIONS__
|
---|
| 518 | throw CFileBase();
|
---|
| 519 | #else
|
---|
| 520 | return (StreamPos) - 1;
|
---|
| 521 | #endif
|
---|
| 522 | }
|
---|
| 523 |
|
---|
| 524 | FileSystem::StreamPos pos = FileSystem::Tell(fp);
|
---|
| 525 | if (pos < 0)
|
---|
| 526 | {
|
---|
| 527 | file_error = FILE_POSITION_ERROR;
|
---|
| 528 | #ifdef __CPP_EXCEPTIONS__
|
---|
| 529 | throw CFileBaseException(file_error);
|
---|
| 530 | #else
|
---|
| 531 | return (StreamPos) - 1;
|
---|
| 532 | #endif
|
---|
| 533 | }
|
---|
| 534 | return pos;
|
---|
| 535 | }
|
---|
| 536 |
|
---|
| 537 | //-------------------------------------------------------------------------------
|
---|
| 538 | // isis::uint32_t CFileBase::CalcChecksum(isis::uint32_t bytes, FAU file_address,
|
---|
| 539 | // int mem_alloc)
|
---|
| 540 | //
|
---|
| 541 | // Calculate a 32-bit CRC checksum for a given number of bytes starting at the
|
---|
| 542 | // specified address. Returns a 32-bit CRC value. If the mem_alloc variable is
|
---|
| 543 | // true, a buffer equal to the specified number of bytes will be created in
|
---|
| 544 | // memory. If the mem_alloc variable is false or memory allocation fails, the CRC
|
---|
| 545 | // will be calculated byte by byte starting at the specified address.
|
---|
| 546 | // NOTE: the calling function must check for disk file errors.
|
---|
| 547 | // Returns the CRC value.
|
---|
| 548 | //-------------------------------------------------------------------------------
|
---|
| 549 |
|
---|
| 550 | isis::uint32_t CFileBase::CalcChecksum(isis::uint32_t bytes, FileSystem::FAU_t file_address, int mem_alloc)
|
---|
| 551 | {
|
---|
| 552 | isis::uint32_t CRC;
|
---|
| 553 | isis::uint32_t len = bytes;
|
---|
| 554 | unsigned char data;
|
---|
| 555 | char *buf = 0;
|
---|
| 556 |
|
---|
| 557 | // Create a buffer equal to the object length
|
---|
| 558 | if (mem_alloc)
|
---|
| 559 | buf = new char[bytes];
|
---|
| 560 |
|
---|
| 561 | if (buf)
|
---|
| 562 | {
|
---|
| 563 | if (IsOK())
|
---|
| 564 | {
|
---|
| 565 | if (Fetch(buf, bytes, file_address) != FILE_NO_ERROR) return 0;
|
---|
| 566 | CRC = CalcCRC32(buf, bytes);
|
---|
| 567 | delete[] buf;
|
---|
| 568 | }
|
---|
| 569 | }
|
---|
| 570 | else
|
---|
| 571 | {
|
---|
| 572 | if (IsOK())
|
---|
| 573 | {
|
---|
| 574 | // Seek to the specified file address
|
---|
| 575 | SeekTo(file_address);
|
---|
| 576 | if (file_error != FILE_NO_ERROR) return 0;
|
---|
| 577 | CRC = 0xffffffffL;
|
---|
| 578 | while (len--)
|
---|
| 579 | {
|
---|
| 580 | if (Fetch(&data, sizeof(data)) != FILE_NO_ERROR) return 0;
|
---|
| 581 | CRC = CalcCRC32(data, CRC);
|
---|
| 582 | }
|
---|
| 583 | CRC ^= 0xffffffffL;
|
---|
| 584 | }
|
---|
| 585 | }
|
---|
| 586 |
|
---|
| 587 | return CRC;
|
---|
| 588 | }
|
---|
| 589 | ///////////////////////////////////////////////////////////////////////////
|
---|
| 590 | // General purpose file utilites
|
---|
| 591 | //
|
---|
| 592 | int CFileBase::Exists(const TCHAR *fname)
|
---|
| 593 | // Returns true if the file exists
|
---|
| 594 | {
|
---|
| 595 | return FileSystem::Exists(fname);
|
---|
| 596 | }
|
---|
| 597 |
|
---|
| 598 | FileSystem::FAU_t CFileBase::FileSize(const TCHAR *fname)
|
---|
| 599 | // Returns the file size. Use after file has been closed
|
---|
| 600 | // and re-opened to ensure that all the buffers are flushed
|
---|
| 601 | // to disk. Returns -1 to indicate an error condition.
|
---|
| 602 | {
|
---|
| 603 | return (FileSystem::FAU_t) FileSystem::FileSize(fname);
|
---|
| 604 | }
|
---|
| 605 |
|
---|
| 606 | int CFileBase::CanOpenForWriting(const TCHAR *fname)
|
---|
| 607 | // Returns true if the file is opened
|
---|
| 608 | {
|
---|
| 609 | return 1;
|
---|
| 610 | //return FileSystem::CanOpenForWriting(fname);
|
---|
| 611 | }
|
---|
| 612 |
|
---|
| 613 | int CFileBase::CanOpenReadOnly(const TCHAR *fname)
|
---|
| 614 | // Returns true if the file is opened
|
---|
| 615 | {
|
---|
| 616 | return 1;
|
---|
| 617 | //return FileSystem::CanOpenReadOnly(fname);
|
---|
| 618 | }
|
---|