"Operations on file descriptors performed later by one of the
parent or child processes do not affect the other."
I looked at the code for copy_files (kernel/fork.c) and when the
flag is not set, a new structure files_struct is allocated(newf)
and the pointers for the file descriptors are copied over to
the new table. From this it would appear that even though the
file descriptor table is different, the child process is still
sharing the specific fd. This means that if the child does
an lseek() on a file, f_pos will change in both the child and the
parent.
So the question I have is whether this behavior is correct
according to what the man page describes? Or is the man page
description not in synch with the implementaion? Or is it that
my understanding of an "operation performed on a file descriptor"
is incorrect?
Also, when CLONE_FILES is set, the code does:
if(clone_flags & CLONE_FILES) {
atomic_inc(&oldf->count);
goto out;
}
out:
return error;
Shouldn't tsk->files be set to oldf (which is initially set to
current->files)? Or am I confused about the behavior of clone()?
Thanks,
Deepak
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