Normalize file path with WinAPI [duplicate]

Question

Possible Duplicate:
Best way to determine if two path reference to same file in C/C++

Given two file path strings with potentially different casing and slashes ('\' vs '/'), is there a quick way (that does not involve writing my own function) to normalize both paths to the same form, or at least to test them for equivalence?

I'm restricted to WinAPI and standard C++. All files are local.

Answer 1

May I suggest PathCanonicalize?

Answer 2

I found a blog posting with the most thorough, even elaborate, function I have ever seen to solve this problem. It handles anything, even horrible corner cases like V:foo.txt where you used the subst command to map V: to Z: but you already used subst to map Z: to some other drive; it loops until all subst commands are unwound. URL:

http://pdh11.blogspot.com/2009/05/pathcanonicalize-versus-what-it-says-on.html

My project is pure C code, and that function is C++. I started to translate it, but then I figured out that I could get the normalized path that I wanted with one function call: GetLongPathName(). This won't handle the horrible corner cases, but it handled my immediate needs.

I discovered that GetLongPathName("foo.txt") just returns foo.txt, but just by prepending ./ to the filename I got the expansion to normalized form:

GetLongPathName("./foo.txt"), if executed in directory C:\Users\steveha, returns C:\Users\steveha\foo.txt.

So, in pseudocode:

if the second char of the pathname is ':' or the first char is '/' or '\', just call GetLongPathName() else, copy "./" to a temp buffer, then copy the filename to temp buffer + 2, to get a copy of the filename prepended with "./" and then call GetLongPathName().

Answer 3

Depending on whether the paths could be relative, or contain "..", or junction points, or UNC paths this may be more difficult than you think. The best way might be to use the GetFileInformationByHandle() function as in this answer.

Edit: I agree with the comment by RBerteig that this may become hard to impossible to do if the paths are not pointing to a local file. Any comment on how to safely handle this case would be greatly appreciated.

Answer 4

There are odd cases. For example, "c:\windows..\data\myfile.txt" is the same as "c:\data.\myfile.txt" and "c:\data\myfile.txt". You can have any number of "\.\" and "\..\" in there. You might look into the Windows API function GetFullPathName. It might do canonicalization for you.