it seems to me that the following code from userprog/file.c is wrong: if((err = filetable_findfile(fd, &file)) != 0) return err; lock_acquire(file->lock); /* if this is the last close of this file, free it up */ if((--file->refcount) == 0) { /* if vfs_closing the file fails, we fail. this isn't exactly " fair", * since if it wasn't the last fd to be closed for this file, it * wouldn't know about this, but it's the best we can do. */ if((err = vfs_close(file->vnode)) != 0) { file->refcount++; lock_release(file->lock); return err; } -> curthread->filetable->openfiles[fd] = NULL; lock_release(file->lock); lock_destroy(file->lock); kfree(file); } else { lock_release(file->lock); } shouldn't the line at the -> be unconditional if there's no error, as otherwise you could open fd 3, fork 4 times, then have one process close 3 four times, leaving all the others with garbage pointers? have i, as usual, missed something? brady _______________________________________________ cs161-list mailing list cs161-list(a)fas.harvard.edu http://www.fas.harvard.edu/mailman/listinfo/cs161-list