Re: Infinite Loop In "rm -fr" When Busy File Encountered

[Randall R Schulz <rrschulz at cris dot com>]

Chris,

OK. Here's more information. Possibly even interesting information.


I tried this as a test:

% mkdir tstdir
% cd tstdir
% cat >tstdir &
[1]+  Stopped                 cat >target

% rm target
# No complaint!
% ls -l
ls: target: Permission denied
% rm target
rm: cannot remove `target': Permission denied


That was not quite what I expected, and, ignorant as I am about the Windows APIs, I cannot explain it.


Now as it turns out, the case where I encountered this problem was when an errant non-Cygwin program (specifically, a Java program) was the culprit keeping the file open. I happened, presumably, due to incomplete clean-up by a tool plug-in executing within an IDE (jEdit).

So, I wrote a little Java program to open a file for writing and then just pause, keeping the file open:


import      java.io.*;

public
class       Writer
{
    public
    static
    void
    main(String args[])
    {
        if (args.length < 2) {
            System.err.println("Usage: Writer <outputFile> <string> [ ... ]");
            System.exit(1);
        }

        PrintWriter pw = null;

        try {
            pw = new PrintWriter(new FileWriter(args[0]));
        }
        catch (IOException ioEx) {
            System.err.println("Error opening \"" + args[0] + "\"");
            System.exit(2);
        }

        for (int argN = 1; argN < args.length; argN++) {
            pw.print(args[argN]);
        }

        Thread thisThread = Thread.currentThread();

        for (;;) {
            try {
                thisThread.sleep(100 * 1000);
            }
            catch (InterruptedException iEx) {
            }
        }
    }
}


Now I do this:

% mkdir subdir
% java Writer subdir/target Now is the time


In a separate Cygwin window:

% cd tstdir
% rm -fr subdir


And the symptom is manifest: rm sits there, churning away, awaiting its death at the hands of a merciless signal.


Randall Schulz
Mountain View, CA USA



At 09:26 2002-04-06, Chris January wrote:
>> Greetings,
>>
>> I have encountered a problem in "rm" when used with the "-f" and "-r"
>> options and a busy and hence unremovable file is encountered.
>>
>> When "rm -fr" encounters a busy and hence unremovable file, it goes into an
>> infinite loop consuming as much CPU time as it can get until it is forcibly
>> terminated. The error is completely repeatable as long as the file remains
>> busy by virtue of being open in another program.
>>
>> The file system is NTFS and the mount is binmode. The system is Windows
>> 2000 Pro with SP2 and security patches installed.
>>
>> This is an up-to-date Cygwin installation that is exhibiting no other
>> anomalous behavior.
>>
>> In reference to the attached "cygcheck -rs" output, this happened on "C:"
>> "/cygdrive/c" (reached via a symlink "/c -> /cygdrive/c").
>
>I tried exhaustively to reproduce this (cygwin1.dll v1.3.10), but failed.
>
>Chris


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