Developing Drivers with the Windows® Driver Foundation

Coding Practices that Improve PREfast Results

PREfast logs every error that it can find in your source code. If the code does not give PREfast any assurance that the code is safe, PREfast behaves as if the code is unsafe.

For example, suppose PREfast encounters a code path that dereferences a pointer. Could the pointer ever be NULL? If there is some reason to suspect that it could be—for example, if earlier code tests for NULL but subsequent code accesses the pointer in an unsafe manner, PREfast issues a warning about dereferencing a NULL pointer. If there is no reason to suspect that the pointer could ever be NULL, then PREfast does not issue a warning.

PREfast can miss some potential bugs due to faulty assumptions—these are often referred to as ...