A question about ascii nulls in filenames.

Question

This code :
public class FileTest {
    public static void testFile(File f){
        try{
            System.out.println("testFile: exists[" + f.exists() + "] " +
                    "canonical[" + f.getCanonicalPath() + "] " +
                    "file[" + f + "]");
            FileReader fr = new FileReader(f);
            BufferedReader br = new BufferedReader(fr);
            String data;
            while( (data = br.readLine()) != null ){
                System.out.println("  data[" + data +"]");
            br.close();
        }catch(IOException ioe){
            System.out.println("  Error testing file : " + ioe.getMessage());
    public static void main(String[] args) {
        File f;
        f = new File("c:/test/hello_world.txt");
        testFile(f);
        f = new File("c:/test/hello_world.txt/junk");
        testFile(f);
        f = new File("c:/test/hello_world.txt" + (char)0 + "/junk");
        testFile(f);
}Produces this output:
testFile: exists[true] canonical[C:\test\hello_world.txt] file[c:\test\hello_world.txt]
  data[Hello World.]
testFile: exists[false] canonical[C:\test\hello_world.txt\junk] file[c:\test\hello_world.txt\junk]
  Error testing file : c:\test\hello_world.txt\junk (The system cannot find the path specified)
testFile: exists[true] canonical[C:\test\hello_world.txt] file[c:\test\hello_world.txt?\junk]
  data[Hello World.]The interesting point is that the code opens and reads the file with a conviently placed ascii null in the filename.
Now from a lower level I'm pretty sure what is going on here. The name is being converted to a zero terminated C string and then sent to the OS which opens the file.
My question is, does any one have any references/links that point out if this is valid behaviour. My "Java" opinion is that the file doesn't exist. My "C" opinion is it is behaving correctly, but this isn't C.
Any thoughts?
Thanks,
Michael

Answer 1

(The system cannot find the path specified)it's an illegal file name as far as the os is concerned. you wouldn't be able to do it in c either.