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Проблема с FILE_NOTIFY_INFORMATION   Найти похожие ветки 

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MAINUSER ©   (2004-12-05 17:11) [0]

Уважаемые мастера, помогите мне понять, как объявляется FILE_NOTIFY_INFORMATION для ReadDirectoryChangesW.
В соответствующем исходнике используется переменная PFileNotifyInformation. В статье её не объявили, а сам я не знаю как её объявить. Помогите, кто знает. Спасибо

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Morfein   (2004-12-05 19:01) [1]

кусок из хелпа по WinAPI
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The FIND_NOTIFY_INFORMATION structure describes the changes found by the ReadDirectoryChangesW function.

typedef struct _FILE_NOTIFY_INFORMATION {
  DWORD NextEntryOffset;
  DWORD Action;
  DWORD FileNameLength;
  WCHAR FileName[1];
} FILE_NOTIFY_INFORMATION;


Members

NextEntryOffset

Specifies the number of bytes that must be skipped to get to the next record. A value of zero indicates that this is the last record.

Action

Specifies the type of change that occurred.

Value Meaning
FILE_ACTION_ADDED The file was added to the directory.
FILE_ACTION_REMOVED The file was removed from the directory.
FILE_ACTION_MODIFIED The file was modified. This can be a change in the time stamp or attributes.
FILE_ACTION_RENAMED_OLD_NAME The file was renamed and this is the old name.
FILE_ACTION_RENAMED_NEW_NAME The file was renamed and this is the new name.


FileNameLength

Specifies the length, in bytes, of the filename portion of the record. Note that this length does not include the terminating null character.

FileName

This is a variable-length field that contains the filename relative to the directory handle. The filename is in the Unicode character format and is not null-terminated.



See Also: ReadDirectoryChangesW

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Игорь Шевченко ©   (2004-12-05 20:36) [2]

type
 FILE_NOTIFY_INFORMATION = packed record
   NextEntryOffset: DWORD;
   Action: DWORD;
   FileNameLength: DWORD;
   FileName: WideChar;
 end;
 PFILE_NOTIFY_INFORMATION = ^FILE_NOTIFY_INFORMATION;

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Игорь Шевченко ©   (2004-12-05 20:48) [3]

Точнее, так:

type
 FILE_NOTIFY_INFORMATION = packed record
   NextEntryOffset: DWORD;
   Action: DWORD;
   FileNameLength: DWORD;
   FileName: array[0..0] of WideChar;
 end;
 PFILE_NOTIFY_INFORMATION = ^FILE_NOTIFY_INFORMATION;

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Игорь Шевченко ©   (2004-12-05 20:50) [4]

А таким образом можно получить список добавленных в каталог файлов из буфера ReadDirectoryChangesW:


procedure ParseNotificationBuffer (Buffer: PChar; AFiles: TStrings);
var
 PEntry: PFILE_NOTIFY_INFORMATION;
 MoreEntries: Boolean;
begin
 AFiles.Clear;
 PEntry := PFILE_NOTIFY_INFORMATION(Buffer);
 MoreEntries := true;
 while MoreEntries do begin
   if PEntry^.NextEntryOffset = 0 then
     MoreEntries := false;
   if PEntry^.Action = FILE_ACTION_ADDED then
     AFiles.Add(WideCharLenToString(PEntry^.FileName,
       PEntry^.FileNameLength div SizeOf(WideChar)));
   PEntry := PFILE_NOTIFY_INFORMATION(PChar(PEntry) + PEntry^.NextEntryOffset);
 end;
end;


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