Dear R-Devel, I've run into an issue with a package (vcfR) that uses file.access to check a file is readable before opening it. The issue is actually in base R though. I've looked into the package code, and it calls file.access(path, mode = 4). I've created a minimal working example of the code in winAccessW from src/gnuwin32/extra.c, and the problem arises when GetFileSecurityW is called on shared files under certain circumstances.
One situation I've seen it in are when a file is shared from a non-Windows host (e.g. Linux), which is similar to the situation documented at https://social.msdn.microsoft.com/Forums/sqlserver/en-US/f57928d3-d89b-426d-a174-d06d97355afc/how-to-check-if-a-filefolder-is-writable-or-not?forum=windowssdk . The other situation arises when a file is cached offline by Windows Offline files feature. The call to GetFileSecurityW works fine when the network is up (and so the file is being accessed from the share), but fails when the network is down and the file is being accessed from the offline files cache. Is there any reason that there is a custom function here? Windows supports the use of access (as is used on other OSes), although the ISO C++ _waccess would be preferred. This seems to work well even in situations where the current code does not. BW Nick [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
