Re: [PATCH] kern: fix mig_strncpy

[Justus Winter]

Quoting Samuel Thibault (2014-02-22 16:53:11)
> Justus Winter, le Sat 22 Feb 2014 16:17:13 +0100, a écrit :
> > Quoting Samuel Thibault (2014-02-22 15:37:29)
> > > Justus Winter, le Sat 22 Feb 2014 11:25:14 +0100, a écrit :
> > > > * kern/ipc_mig.c (mig_strncpy): Do not zero-terminate the destination
> > > > string.  Return length of destination string.
> > > 
> > > Well, that calls for some rationale :)
> > > 
> > > I guess this is related with the other, MIG change?  I.e. that this
> > > modified version of kernel mig_strncpy depends on the fixed MIG
> > > behavior?
> > 
> > No.  It's just that the version in mach did not return anything (and
> > thus I believe that sending such a string from the kernel would never
> > have worked).
> 
> > The change in semantics is to make it behave like the version in the
> > glibc (and like strncpy in general).
> 
> Ok, but that contradicts the previous "OUGHT" comment :) And changing
> the behavior means callers would get potentially broken.  AIUI, the only
> callers are the ones from mig-generated stubs ?

Yes.  And furthermore, since mig_strncpy is supposed to return the
string length (and it didn't), any use within the kernel was probably
not working before.

Justus