[Kaffe] java.io.File(Input|Output)Stream question.

[Moses DeJong]

On Fri, 12 Feb 1999, Godmar Back wrote:

> > 
> > On Thu, 11 Feb 1999, Tony Kimball wrote:
> > 
> > > Quoth Moses DeJong on Thu, 11 February:
> > > : Is there some other kind of IOException
> > > : that could happen while opening a file for writing that would not
> > > : happen while opening a file for reading.
> > > 
> > > Paying strict attention to your 'could' and 'would' semantics,
> > > you could get EPERM in one case while you would not in the other.
> > > But, vice versa contrariwise, on the other hand.  
> > 
> > Oh, I get it now, you are saying that a file writer could hit a unix
> > file that does not have write permission. If that was the case then the
> > reader could also run into a file without read permission. So I guess
> > the problem is that there would be no way to tell if a file existed but
> > was not readable when a FileNotFoundException is thrown by a reader.
> > So, this does seem like a bug in the Sun spec after all. Does this
> > mean we should change the implementation of Kaffe's FileInputStream to
> > throw an IOException instead of a FileNotFoundException. I took a look
> > the Kaffe's impl of FileInputStream and it does throw an IOException
> > but it then catches the IOException and rethrows it as a
> > FileNotFoundException.  A less specific exception like an IOException
> > should not be rethrown as a more specific exception like a
> > FileNotFoundException. It seems like this is a bug in the Sun JDK docs
> > and implementation. Does anyone agree with me?
> > 
> 
> I think a possible way would be to write a set of simple testcases
> and run it against Sun's implementation, both 1.1 and 1.2.  I.e., test 
> non-existing, read- and write protected files.
> Then use these results and tweak Kaffe appropriately.
> 
> When the spec says a method throws such and such, then that's in their
> implementation practice not more than a rough guideline anyway.
> 
> 	- Godmar


Ok, here is a quick shot at that.


import java.io.*;

public class UnreadableFile {

    public static void main(String[] argv) throws Exception {
	
	// The file "unreadable" needs to have no read permission

	File unreadable = new File("unreadable");

	if (unreadable.exists()) {
	    FileInputStream fin = new FileInputStream(unreadable);
	} else {
	    System.out.println(unreadable + " does not exist");
	}
    }


}


/*

touch unreadable
chmod 200 unreadable
ls -la unreadable
--w-------   1 dejong   dejong          0 Feb 12 17:16 unreadable


JDK 1.1

java.io.FileNotFoundException: unreadable
        at java.io.FileInputStream.<init>(FileInputStream.java)
        at java.io.FileInputStream.<init>(FileInputStream.java)
        at UnreadableFile.main(UnreadableFile.java:12)


JDK 1.2

java UnreadableFile
exception in thread "main" java.io.FileNotFoundException: unreadable (Permission denied)
        at java.io.FileInputStream.open(Native Method)
        at java.io.FileInputStream.<init>(FileInputStream.java:68)
        at java.io.FileInputStream.<init>(FileInputStream.java:99)
        at UnreadableFile.main(UnreadableFile.java:12)