Re: Sanitize file name

From:
Philipp <sicsicsic@freesurf.ch>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 25 Oct 2007 14:36:42 +0200
Message-ID:
<1193315771_2710@sicinfo3.epfl.ch>
Andrew Thompson wrote:

Philipp wrote:
..

Is there a way to test if a filename is valid on a certain platform?


This E.G. makes for some interesting results, though I
am not sure if it really helps with the problem. The
programmer would need to specially account for the
'last situation' where the user puts a character in the
name that is used as (or is generally understood to be)
a path separator.

Irritatingly, although Win's path separator is '\', '/'
will apparently also work (here, on this Win XP pro
box).

<sscce>
import java.io.File;
import java.io.IOException;

class TestFileName {

  static void testFileName(String name) {
    try {
      File f = new File(name);
      System.out.println( f.getCanonicalPath() );
    } catch(IOException ioe) {
      System.err.println( ioe.getMessage() + " '" + name + "'");
    }
  }

  public static void main(String[] args) {
    testFileName("123.txt");
    testFileName("12?3.txt");
    testFileName("12[3.txt");
    testFileName("12{3.txt");
    testFileName("12!3.txt");
    testFileName("12/3.txt");
  }
}
</sscce>

[OP]
D:\projects\123.txt
Invalid argument '12?3.txt'
D:\projects\12[3.txt
D:\projects\12{3.txt
D:\projects\12!3.txt
D:\projects\12\3.txt
Press any key to continue . . .
[\OP]


As far as I know the invalid characters for filenames are:
On Windows \ / : * ? " < > |
On UNIX :

Running your SSCCE with these signs (although in a different order)
gives (on WinXP):

[OP]
Invalid argument '12?3.txt'
D:\workspace\test\123.txt
Syntaxe du nom de fichier, de r?pertoire ou de volume incorrecte '12:3.txt'
D:\workspace\test\12[3.txt
D:\workspace\test\12{3.txt
D:\workspace\test\12!3.txt
D:\workspace\test\12\3.txt
D:\workspace\test\12;3.txt
D:\workspace\test\12<3.txt
D:\workspace\test\12>3.txt
Invalid argument '12*3.txt'
D:\workspace\test\12"3.txt
Syntaxe du nom de fichier, de r?pertoire ou de volume incorrecte '12|3.txt'
[/OP]

Note that the getCanonicalPath() method throws IOException for only some
of them. So this does not seem a good method to identify bad chars.

The method described in
http://forum.java.sun.com/thread.jspa?threadID=629458&start=0&tstart=0
(thanks Sabine for the link) actually creates the file. Well, that
definitely works, but it's really ugly (IMHO).

Best regards
Phil

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