This program was developed when we noticed some of our in-house Windows applications stopped functioning properly when accessing files via NFS instead of SMB. Using the Sysinternals tool "ProcMon.exe", we discovered that one of these programs was suffering Windows error 50, "The request is not supported" when issuing the LockFile function.

FileLock.exe simply opens a file and then issues a few variations of LockFile, reporting the results after each test. The program requires a single command-line argument: the fully-qualified path name to the input file to be tested. For example:

FileLock.exe P:\Viking\PCPASWRD\register.dbf

FileLock.exe is a 32-bit Windows application that requires only the standard C and Windows runtime libraries. It was built using Visual Studio 2019.