Re: [PATCH v4 2/6] util: refactor qemu_open_old to split off variadic args handling

[Daniel P . Berrangé]

On Tue, Aug 25, 2020 at 04:56:40PM +0200, Markus Armbruster wrote:
> Daniel P. Berrangé <berrange@redhat.com> writes:
> 
> > This simple refactoring prepares for future patches. The variadic args
> > handling is split from the main bulk of the open logic. The duplicated
> > calls to open() are removed in favour of updating the "flags" variable
> > to have O_CLOEXEC.
> >
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  util/osdep.c | 40 +++++++++++++++++++++++++++-------------
> >  1 file changed, 27 insertions(+), 13 deletions(-)
> >
> > diff --git a/util/osdep.c b/util/osdep.c
> > index 9df1b6adec..9ff92551e7 100644
> > --- a/util/osdep.c
> > +++ b/util/osdep.c
> > @@ -22,6 +22,7 @@
> >   * THE SOFTWARE.
> >   */
> >  #include "qemu/osdep.h"
> > +#include "qapi/error.h"
> >  
> >  /* Needed early for CONFIG_BSD etc. */
> >  
> > @@ -282,10 +283,10 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t 
> > len, bool exclusive)
> >  /*
> >   * Opens a file with FD_CLOEXEC set
> >   */
> > -int qemu_open_old(const char *name, int flags, ...)
> > +static int
> > +qemu_open_internal(const char *name, int flags, mode_t mode)
> >  {
> >      int ret;
> > -    int mode = 0;
> >  
> >  #ifndef _WIN32
> >      const char *fdset_id_str;
> > @@ -323,22 +324,35 @@ int qemu_open_old(const char *name, int flags, ...)
> >      }
> >  #endif
> >  
> > -    if (flags & O_CREAT) {
> > -        va_list ap;
> > -
> > -        va_start(ap, flags);
> > -        mode = va_arg(ap, int);
> > -        va_end(ap);
> > -    }
> > -
> >  #ifdef O_CLOEXEC
> > -    ret = open(name, flags | O_CLOEXEC, mode);
> > -#else
> > +    flags |= O_CLOEXEC;
> > +#endif /* O_CLOEXEC */
> > +
> >      ret = open(name, flags, mode);
> > +
> > +#ifndef O_CLOEXEC
> >      if (ret >= 0) {
> >          qemu_set_cloexec(ret);
> >      }
> > -#endif
> > +#endif /* ! O_CLOEXEC */
> 
> I dislike this part, to be honest.  I find
> 
>     #ifdef O_CLOEXEC
>         flags |= O_CLOEXEC;
>     #endif /* O_CLOEXEC */
> 
>         ret = open(name, flags, mode);
> 
>     #ifndef O_CLOEXEC
>         if (ret >= 0) {
>             qemu_set_cloexec(ret);
>         }
>     #endif /* ! O_CLOEXEC */
> 
> harder to read than
> 
>     #ifdef O_CLOEXEC
>         ret = open(name, flags | O_CLOEXEC, mode);
>     #else
>         ret = open(name, flags, mode);
>         if (ret >= 0) {
>             qemu_set_cloexec(ret);
>         }
>     #endif

We're re-using 'flags' variable again in a later patch and want to
have O_CLOEXEC present in it then too.

Regards,
Daniel
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