/* 3. RecordAccess. */
/* : RecordAccess [ ]
(nrec) , . (nrec) , ( , ). (nrec) . */
/* :
1. .
2. LARGE_INTEGER 64- .
3. .
4. ( NTFS).
*/
#include "EvryThng.h"
#define STRING_SIZE 256
typedef struct _RECORD { /* */
DWORD ReferenceCount; /* 0 . */
SYSTEMTIME RecordCreationTime;
SYSTEMTIME RecordLastReferenceTime;
SYSTEMTIME RecordUpdateTime;
TCHAR DataString[STRING_SIZE];
} RECORD;
typedef struct _HEADER { /* */
DWORD NumRecords;
DWORD NumNonEmptyRecords;
} HEADER;
int _tmain(int argc, LPTSTR argv[]) {
HANDLE hFile;
LARGE_INTEGER CurPtr;
DWORD FPos, OpenOption, nXfer, RecNo;
RECORD Record;
TCHAR String[STRING_SIZE], Command, Extra;
OVERLAPPED ov = {0, 0, 0, 0, NULL}, ovZero = {0, 0, 0, 0, NULL};
HEADER Header = {0, 0};
SYSTEMTIME CurrentTime;
BOOLEAN HeaderChange, RecordChange;
OpenOption = (argc == 2)? OPEN_EXISTING: CREATE_ALWAYS;
hFile = CreateFile(argv[1], GENERIC_READ | GENERIC_WRITE, 0, NULL, OpenOption, FILE_ATTRIBUTE_NORMAL, NULL);
if (argc >= 3) { /* */
Header.NumRecords = atoi(argv[2]);
WriteFile(hFile, &Header, sizeof(Header), &nXfer, &ovZero);
CurPtr.QuadPart = sizeof(RECORD)*atoi(argv[2])+sizeof(HEADER);
FPos = SetFilePointer(hFile, CurPtr.LowPart, &CurPtr.HighPart, FILE_BEGIN);
if (FPos == 0xFFFFFFFF && GetLastError()!= NO_ERROR) ReportError(_T(" ."), 4, TRUE);
SetEndOfFile(hFile);
}
/* : . */
ReadFile(hFile, &Header, sizeof(HEADER), &nXfer, &ovZero);
/* . */
while(TRUE) {
HeaderChange = FALSE;
RecordChange = FALSE;
_tprintf(_(" r(ead)/w(rite)/d(elete)/q #\n"));
_tscanf(_T("%c" "%d" "%c"), &Command, &RecNo, &Extra);
if (Command == 'q') break;
CurPtr.QuadPart = RecNo * sizeof(RECORD) + sizeof(HEADER);
ov.Offset = CurPtr.LowPart;
ov.OffsetHigh = CurPtr.HighPart;
ReadFile(hFile, &Record, sizeof(RECORD), &nXfer, &ov);
GetSystemTime(&CurrentTime); /* . */
Record.RecordLastRefernceTime = CurrentTime;
if (Command == 'r' || Command == 'd') { /* .*/
|
|
|
if (Record.ReferenceCount == 0) {
_tprintf(_T(" %d .\n"), RecNo);
continue;
} else {
_tprintf(_(" %d. : %d \n"), RecNo, Record.ReferenceCount);
_tprintf(_(": %s\n"), Record.DataString);
/* : . . . */
RecordChange = TRUE;
}
if (Command == 'd') { /* . */
Record.ReferenceCount = 0;
Header.NumNonEmptyRecords--;
HeaderChange = TRUE;
RecordChange = TRUE;
}
} else if (Command == 'w') { /* . ? */
_tprintf(_(" .\n"));
_getts(String);
if (Record.ReferenceCount == 0) {
Record.RecordCreationTime = CurrentTime;
Header.NumNonEmptyRecords++;
HeaderChange = TRUE;
}
Record.RecordUpdateTime = CurrentTime;
Record.ReferenceCount++;
_tcsncpy(Record.DataString, String, STRING_SIZE-1);
RecordChange = TRUE;
} else {
_tprintf(_T(" : r, w d. .\n"));
}
/* , . */
if (RecordChange) WriteFile(hFile, &Record, sizeof(RECORD), &nXfer, &ov);
/* . */
if (HeaderChange) WriteFile(hFile, &Header, sizeof(Header), &nXfer, &ovZero);
}
_tprintf(_T(" : %d\n"), Header.NumNonEmptyRecords);
CloseHandle(hFile);
return 0;
}
