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Re: [PATCH] http: cast result to FILE *




Hi Duy,

On Sat, 2 Feb 2019, Duy Nguyen wrote:

> On Sat, Feb 2, 2019 at 4:21 AM Junio C Hamano <gitster@xxxxxxxxx> wrote:
> >
> > Dan McGregor <dan.mcgregor@xxxxxxxx> writes:
> >
> > > Commit 8dd2e88a92 ("http: support file handles for HTTP_KEEP_ERROR",
> > > 2019-01-10) introduced an implicit assumption that rewind, fileno, and
> > > fflush are functions. At least on FreeBSD fileno is not, and as such
> > > passing a void * failed.
> >
> > I am not strongly opposed to this patch,
> 
> Even if this is needed, should it be done behind git-compat-util.h
> instead? That way if fileno(void*) is used elsewhere, we don't have to
> do the casting again.

The disadvantage, of course, would be that other call sites would not
benefit from a manual auditing whether the argument has side effects (and
thus, whether a macro using the argument multiple times would result in
very unexpected multiple side effects).

I'd rather not paper over this issue and thereby open even larger
problems.

Ciao,
Dscho

> 
> > but shouldn't you be filing
> > a bug report against FreeBSD instead?  The implementation is free to
> > define fileno(fh) as a macro, but it shouldn't force such a change
> > to conformant programs.
> >
> > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206146
> >
> > > Explicitly cast result to a FILE * when using standard functions that
> > > may ultimately be macros.
> > >
> > > Signed-off-by: Dan McGregor <dan.mcgregor@xxxxxxxx>
> > > ---
> > >  http.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/http.c b/http.c
> > > index 954bebf684..8b9476b151 100644
> > > --- a/http.c
> > > +++ b/http.c
> > > @@ -1996,12 +1996,12 @@ static int http_request_reauth(const char *url,
> > >               strbuf_reset(result);
> > >               break;
> > >       case HTTP_REQUEST_FILE:
> > > -             if (fflush(result)) {
> > > +             if (fflush((FILE *)result)) {
> > >                       error_errno("unable to flush a file");
> > >                       return HTTP_START_FAILED;
> > >               }
> > > -             rewind(result);
> > > -             if (ftruncate(fileno(result), 0) < 0) {
> > > +             rewind((FILE *)result);
> > > +             if (ftruncate(fileno((FILE *)result), 0) < 0) {
> > >                       error_errno("unable to truncate a file");
> > >                       return HTTP_START_FAILED;
> > >               }
> 
> 
> 
> -- 
> Duy
>