Re: linux headers and C++
Arvind Sankar (arvinds@mit.edu)
Thu, 1 Jul 1999 20:29:31 -0400
On Thu, Jul 01, 1999 at 05:52:04PM -0400, Richard B. Johnson wrote:
> On Thu, 1 Jul 1999, Ronnie G Misra wrote:
>
> > I'm trying to build a kernel module in C++. This code includes some of
> > the linux kernel header files, and unfortunately does not compile with
> > recent versions of the kernel. The code is not my own - I have
> > inherited it from someone else - but I am assured that it used to
> > compile.
> >
> > The error I get has to do with include/linux/signal.h under the kernel
> > source tree: the functions siginitset and siginitsetinv both contain
> > switch statements which are invalid C++ syntax (and in fact, are
> > invalid in C, but which make use of a gcc extension). Specifically,
> > the last label ("case 1:") in these statements should be followed by a
> > semicolon.
> >
>
> Err Lines 137 thru 190...
>
> switch (_NSIG_WORDS) {
> default:
> memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
> break;
> case 2: set->sig[1] = -1;
> case 1:
> }
>
> ... seems okay to me.
>
> case 1: falls off the end of the switch which is legal in 'C'.
>
> To make this more clear. Observe:
>
> switch(foo)
> {
> case 0:
> case 1:
> case 2:
> default:
> }
>
> This is basically a NOP. Perfectly legal (and useless).
>
> Your code might not compile because some "include" file, necessary
> to make some macros in this header make sense, probably was not included.
>
Read the chap's mail again. He knows exactly what is wrong. IMHO, the include
file should be fixed.
-- arvind
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