IsBadWritePtr

The IsBadWritePtr function verifies that the calling process has write access to the specified range of memory.

BOOL IsBadWritePtr(
  LPVOID lp,     // memory address
  UINT_PTR ucb   // size of memory block
);

Parameters

lp

[in] Pointer to the first byte of the memory block.

ucb

[in] Specifies the size, in bytes, of the memory block. If this parameter is zero, the return value is zero.

Return Values

If the calling process has write access to all bytes in the specified memory range, the return value is zero.

If the calling process does not have write access to all bytes in the specified memory range, the return value is nonzero.

If the application is compiled as a debugging version, and the process does not have write access to all bytes in the specified memory range, the function causes an assertion and breaks into the debugger. Leaving the debugger, the function continues as usual, and returns a nonzero value This behavior is by design, as a debugging aid.

Remarks

If the calling process has write access to some, but not all, of the bytes in the specified memory range, the return value is nonzero.

In a preemptive multitasking environment, it is possible for some other thread to change the process's access to the memory being tested. Even when the function indicates that the process has write access to the specified memory, you should use structured exception handling when attempting to access the memory. Use of structured exception handling enables the system to notify the process if an access violation exception occurs, giving the process an opportunity to handle the exception.

IsBadWritePtr is not multithread safe. To use it properly on a pointer shared by multiple threads, call it inside a critical region of code that allows only one thread to access the memory being checked. Use operating system–level objects such as critical sections or mutexes or the interlocked functions to create the critical region of code.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Winbase.h; include Windows.h.
  Library: Use Kernel32.lib.

See Also

Memory Management Overview, Memory Management Functions, IsBadCodePtr, IsBadHugeReadPtr, IsBadHugeWritePtr, IsBadReadPtr