[Bug 194293] New: FUSE program freezes when seeking pos > file size

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194293

            Bug ID: 194293
           Summary: FUSE program freezes when seeking pos > file size
           Product: Base System
           Version: 10.1-BETA3
          Hardware: amd64
                OS: Any
            Status: Needs Triage
          Severity: Affects Many People
          Priority: ---
         Component: kern
          Assignee: freebsd-bugs at FreeBSD.org
          Reporter: nishida at asusa.net

This happens with both 10.1-RC1 and 9.3-Release.

I wrote a simple and straight forward file system program with FUSE.
It just does like:

open: open a file with the same name in a different directory
read: read a file with the same name in a different directory
write: write a file with the same name in a different directory
etc.

However, the program always freezes when saving a xcf file (Gimp's native
format) with Gimp.
Once it freezes, it cannot be killed even by shutdown.
Therefore, I always have to reset my PC after shutdown.

After investigating Gimp's source code, I found that this happened when Gimp
tried to fseek() a position greater than the file size.

In /usr/ports/graphics/gimp-app/work/gimp-2.8.10/app/xcf/xcf-seek.c, there is
xcf_seek_pos().

Adding

fstat(fd, &sb);
if (pos > sb.st_size) {
    ftruncate(fd, pos);
}

to it solved the problem.

This is not only a FUSE's problem, but I guess it will be better to deal with
it.

Sincerely,

-- 
You are receiving this mail because:
You are the assignee for the bug.