you probably mean if a path is syntactically correct. Well, that's sometimes hard to tell as on Windows you have the backslash as a separator and certain other characters are not allowed whereas under Unix you use the forward slash (aka slash ;-)) as the delimiter while at the same time the backslash is a widely used character used to mask the next character (e.g. a space).
This leaves you with the problem of how to know if a backslash is used to mask the next character or if it is a Windows path.
But there are ways to translate Windows paths to Unix and vv.