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C++ getwindowtext not working
C++ getwindowtext not working












  • The condition actualTextLength > textLengthWithNullTerminator evaluates to false because actualTextLength=2 and textLengthWithNullTerminator=2.
  • GetWindowTextW() is called with nMaxCount= 3 and therefore writes "AB\0" to the buffer and returns 2.
  • Meanwhile, the control text changes to "ABC" (3 chars).
  • GetWindowTextLengthW(hWnd) returns 1, so textLengthWithNullTerminator is 2.
  • c++ getwindowtext not working

  • The control text is initially "A" (1 chars).
  • However, the condition actually doesn't work, and a truncated text is returned in that case if the text length has increased by 2 or more chars.
  • The implementation wants to handle the case when the text length increases between calling GetWindowTextLengthW and calling GetWindowTextW.
  • The issue can be fixed by changing (textLengthWithNullTerminator) to (textLengthWithNullTerminator + 1).

    c++ getwindowtext not working

  • As the text has changed to 16 characters, GetWindowTextW() writes 17 characters ( "AAAABBBBCCCCDDDx\0") to the buffer and returns the value 16, thus having written one char (2 bytes) too many.
  • This parameter specifies the maximum buffer size/characers to write, including the terminating null character.
  • GetWindowTextW() is called with nMaxCount= 17.
  • Meanwhile, the control text changes to "AAAABBBBCCCCDDDx" (16 chars).
  • (textLengthWithNullTerminator) returns an array with length 16.
  • GetWindowTextLengthW(hWnd) returns 15, so textLengthWithNullTerminator is 16.
  • The control text is initially "AAAABBBBCCCCDDD" (15 chars).
  • This can lead to too many bytes being written (out-of-bounds write) if the text changes after calling GetWindowTextLengthW.įor example, consider the following scenario:
  • When calling GetWindowTextW, the nMaxCount parameter is specified as textLengthWithNullTerminator + 1, but the call to specifies textLengthWithNullTerminator.ĪrrayPool.Rent returns a buffer that has at least the specified size, so it might return a buffer that has exact the specified size, in which case it will be 1 char too small to hold the maximum number of chars.
  • WindowTitle = new string( pWindowTitle, 0, actualTextLength) If ( actualTextLength > textLengthWithNullTerminator)ĪrrayPool. Keep looping until we get a buffer that can fit. The window text may have changed between calls. Int actualTextLength = GetWindowTextW( hWnd, pWindowTitle, textLengthWithNullTerminator + 1) Rent( textLengthWithNullTerminator) įixed ( char * pWindowTitle = windowTitleBuffer)

    c++ getwindowtext not working

    Int textLengthWithNullTerminator = GetWindowTextLengthW( hWnd) + 1 Ĭhar windowTitleBuffer = ArrayPool. GetWindowTextLengthW returns the length of the text not

    c++ getwindowtext not working

    Public static unsafe string GetWindowText( IntPtr hWnd)














    C++ getwindowtext not working