Re: Re: c/s 23253:a3db6b91f32d causes build failure with gcc 4.4.3-4ubuntu5

[Shriram Rajagopalan <rshriram@cs.ubc.ca>]

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On Fri, May 6, 2011 at 7:58 AM, Ian Campbell <Ian.Campbell@eu.citrix.com>wrote:

> On Fri, 2011-05-06 at 13:50 +0100, George Dunlap wrote:
> > Unfortunately not.
> >
> > Looks like we could either make libxl__domain_bios() a #define (not
> > tested), or make the argument "%s" (which seems to work, patch
> > attached).
> >
> > Adding a format string of just a string seems kind of dumb, but I
> > don't think this is a really hot path...
>
> It's actually sensible to use "%s" when the string might be untrusted
> but in this case it's really just a string literal, I guess the
> laundering through a function is enough to hide that from gcc. Using %s
> is the best fix, I think.
>
> Is this going to go in as a patch? I havent seen any so far (or probably
missed it).

shriram

>  Ian.
>
> >
> >  -George
> >
> >
> > On Fri, May 6, 2011 at 1:33 PM, Ian Campbell <Ian.Campbell@eu.citrix.com>
> wrote:
> > > On Fri, 2011-05-06 at 12:14 +0100, George Dunlap wrote:
> > >
> > >> The line in question is:
> > >>     libxl__xs_write(gc, XBT_NULL, libxl__sprintf(gc, "%s/bios", path),
> > >>                     libxl__domain_bios(gc, info));
> > >>
> > >> Looks like libxl__xs_write() is expecting the 4th argument to be a
> > >> format string...?
> > >
> > > Yes, and hence it needs to be a const char * not a char *, so we should
> > > change both libxl__domain_bios and libxl__xs_write I think.
> > >
> > > Does this help? It works for me, but my compiler doesn't appear to
> > > complain in this way...
> > >
> > > Ian.
> > >
> > > 8<-------------------------------------------
> > >
> > > # HG changeset patch
> > > # User Ian Campbell <ian.campbell@citrix.com>
> > > # Date 1304685175 -3600
> > > # Node ID 4e5487962178e7affd7d7d0341a90dde8c60915e
> > > # Parent  faca1c90188e536eb0f02992c766d06759be376f
> > > libxl: libxl__xs_write format string should be const.
> > >
> > > George Dunlap reports that gcc 4.4.3 complains:
> > >        libxl_dm.c: In function libxl__create_device_mode:
> > >        libxl_dm.c:776: error: format not a string literal and no format
> arguments
> > > And indeed the format argument here is a char * from
> libxl__domain_bios().
> > >
> > > Make the argument to libxl__xs_write a const char * and change
> > > libxl__domain_bios to return a const char too.
> > >
> > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> > >
> > > diff -r faca1c90188e -r 4e5487962178 tools/libxl/libxl_dm.c
> > > --- a/tools/libxl/libxl_dm.c    Fri May 06 13:14:24 2011 +0100
> > > +++ b/tools/libxl/libxl_dm.c    Fri May 06 13:32:55 2011 +0100
> > > @@ -68,12 +68,12 @@ const char *libxl__domain_device_model(l
> > >     return dm;
> > >  }
> > >
> > > -static char *libxl__domain_bios(libxl__gc *gc,
> > > +static const char *libxl__domain_bios(libxl__gc *gc,
> > >                                 libxl_device_model_info *info)
> > >  {
> > >     switch (info->device_model_version) {
> > > -    case 1: return libxl__strdup(gc, "rombios");
> > > -    case 2: return libxl__strdup(gc, "seabios");
> > > +    case 1: return "rombios";
> > > +    case 2: return "seabios";
> > >     default:return NULL;
> > >     }
> > >  }
> > > diff -r faca1c90188e -r 4e5487962178 tools/libxl/libxl_internal.h
> > > --- a/tools/libxl/libxl_internal.h      Fri May 06 13:14:24 2011 +0100
> > > +++ b/tools/libxl/libxl_internal.h      Fri May 06 13:32:55 2011 +0100
> > > @@ -153,7 +153,7 @@ _hidden char **libxl__xs_kvs_of_flexarra
> > >  _hidden int libxl__xs_writev(libxl__gc *gc, xs_transaction_t t,
> > >                     char *dir, char **kvs);
> > >  _hidden int libxl__xs_write(libxl__gc *gc, xs_transaction_t t,
> > > -                   char *path, char *fmt, ...) PRINTF_ATTRIBUTE(4, 5);
> > > +                   char *path, const char *fmt, ...)
> PRINTF_ATTRIBUTE(4, 5);
> > >    /* Each fn returns 0 on success.
> > >     * On error: returns -1, sets errno (no logging) */
> > >
> > > diff -r faca1c90188e -r 4e5487962178 tools/libxl/libxl_xshelp.c
> > > --- a/tools/libxl/libxl_xshelp.c        Fri May 06 13:14:24 2011 +0100
> > > +++ b/tools/libxl/libxl_xshelp.c        Fri May 06 13:32:55 2011 +0100
> > > @@ -69,7 +69,7 @@ int libxl__xs_writev(libxl__gc *gc, xs_t
> > >  }
> > >
> > >  int libxl__xs_write(libxl__gc *gc, xs_transaction_t t,
> > > -                   char *path, char *fmt, ...)
> > > +                   char *path, const char *fmt, ...)
> > >  {
> > >     libxl_ctx *ctx = libxl__gc_owner(gc);
> > >     char *s;
> > >
> > >
> > >
> > > _______________________________________________
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> > > Xen-devel@lists.xensource.com
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> > >
>
>
>
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