Re: [Xen-devel] [PATCH 14/22] libelf: use C99 bool for booleans

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Andrew Cooper writes ("Re: [PATCH 14/22] libelf: use C99 bool for booleans"):
> On 07/06/13 19:27, Ian Jackson wrote:
> > @@ -46,7 +46,7 @@ static void log_callback(struct elf_binary *elf, void 
> > *caller_data,
> >  
> >  void xc_elf_set_logfile(xc_interface *xch, struct elf_binary *elf,
> >                          int verbose) {
> > -    elf_set_log(elf, log_callback, xch, verbose);
> > +    elf_set_log(elf, log_callback, xch, verbose /* convert to bool */);
> 
> Change the function prototype from int verbose to bool verbose ?
> 
> If not, for API reasons, then use !!verbose to correctly convert an
> integer to a boolean.

Not, for API reasons, as you surmise.  As I write in the commit
message:
  For the one visible libelf boolean in libxc's public interface we
  retain the use of int to avoid changing the ABI; libxc converts it to
  a bool for consumption by libelf.

It is not necessary to use !!verbose.  See C99 6.3.1.2.  Any
conversion of a scalar to a _Bool is equivalent to a comparison !=0
(which is the same test as for ?: (6.5.15(4)) and "if" (6.8.4.1(2)).

Some of this is explained in the commit message.

Ian.

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