Opening Patch Files when Compiled for Unicode
If you want to open a .msp file with the Windows Installer APIs, you must pass MSIDBOPEN_PATCHFILE to the MsiOpenDatabase function, or ERROR_OPEN_FAILED (110) is returned. Below is the definition of both MSIDBOPEN_PATCHFILE and MSIDBOPEN_READONLY from msiquery.h in the Windows Installer SDK.


