What does \\?\ mean when prepended to a file path

Question

I found a reference to a file in a log that had the following format:

\\\\?\\C:\\Path\\path\\file.log

I cannot find a reference to what the

Answer 1

The Windows API parses input strings for file I/O. Among other things, it translates / to \ as part of converting the name to an NT-style name, or interpreting the . and .. pseudo directories. With few exceptions, the Windows API also limits path names to 260 characters.

The documented purpose of the \\?\ prefix is:

For file I/O, the "\\?\" prefix to a path string tells the Windows APIs to disable all string parsing and to send the string that follows it straight to the file system.

This allows the use of . or .. in path names, as well as relaxing the 260 character path name limit, if the underlying file system supports long paths and file names.