[Devel] Re: [PATCH 1/1] cr: uts: don't pass an unsigned var as a signed int

[Serge E. Hallyn]

Quoting Nathan Lynch (ntl at pobox.com):
> "Serge E. Hallyn" <serue at us.ibm.com> writes:
> 
> > Else my checkpoing image gets reeeaallly huge.  Just passing the
> > result of sizeof() however does the right thing.
> >
> > Signed-off-by: Serge E. Hallyn <serue at us.ibm.com>
> > ---
> >  checkpoint/namespace.c |   12 ++++++------
> >  1 files changed, 6 insertions(+), 6 deletions(-)
> 
> But right above the code you're changing we have:
> 
> 	h->sysname_len = sizeof(name->sysname);
> 	h->nodename_len = sizeof(name->nodename);
> 	h->release_len = sizeof(name->release);
> 	h->version_len = sizeof(name->version);
> 	h->machine_len = sizeof(name->machine);
> 	h->domainname_len = sizeof(name->domainname);
> 
> Your patch shouldn't change any behavior.  What gives?

"Shouldn't", perhaps, but does.

I assumed the compiler guessed that i wanted an int in the
second case and gave me a different result for that sizeof.

> (PS: ckpt_write_string and friends should take a size_t or some other
> unsigned type for len.)

There I agree, but then we need to check that no callers are
passing in potentially negative signed ints coming from userspace,
so I thought this patch would spur discussion about best path
forward (plus make checkpoint work for me again :)

-serge
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