Re: [PATCH] use xstrdup and concat more

[Trevor Saunders <tbsaunde@tbsaunde.org>]

On Wed, Apr 27, 2016 at 03:49:25PM +0930, Alan Modra wrote:
> On Tue, Apr 26, 2016 at 07:58:43PM -0400, Trevor Saunders wrote:
> > On Tue, Apr 26, 2016 at 12:26:29AM +0930, Alan Modra wrote:
> > > On Mon, Apr 25, 2016 at 09:55:50AM -0400, Trevor Saunders wrote:
> > > > On Mon, Apr 25, 2016 at 10:31:36PM +0930, Alan Modra wrote:
> > > > > On Sun, Apr 24, 2016 at 03:44:56AM -0400, tbsaunde+binutils@tbsaunde.org wrote:
> > > > > > --- a/gas/config/obj-elf.c
> > > > > > +++ b/gas/config/obj-elf.c
> > > > > > @@ -949,9 +949,7 @@ obj_elf_section_name (void)
> > > > > >  	  return NULL;
> > > > > >  	}
> > > > > >  
> > > > > > -      name = (char *) xmalloc (end - input_line_pointer + 1);
> > > > > > -      memcpy (name, input_line_pointer, end - input_line_pointer);
> > > > > > -      name[end - input_line_pointer] = '\0';
> > > > > > +      name = xstrndup (input_line_pointer, end - input_line_pointer);
> > > > > >  
> > > > > >        while (flag_sectname_subst)
> > > > > >          {
> > > > > 
> > > > > Is this a good idea, here, and in other places where the original uses
> > > > > memcpy and strlen was not called to find the string length?  I'm
> > > > > thinking that xstrndup will be needlessly calling strlen.
> > > > 
> > > > I guess that's true, I'm not sure if that really matters though?
> > > 
> > > Quite possibly not.  I wasn't rejecting the patch and didn't see
> > > anything in the patch that raised a red flag.  It was more a case
> > > of asking you to think about possible performance effects when tidying
> > > code.  Fewer lines of code is not always better.
> > 
> > Of course ;)  I think most of it is around section names which I imagine
> > isn't very hot.  What would you like to do here?
> 
> How about using a new function, called xmemdup0, say?  That way you
> can happily tidy the source without needing to worry about possible
> performance effects (and no one needs to worry when reviewing).

Sounds good with my one comment below, thanks!

> I'm about to commit the following.  inline is handled by ansidecl.h,
> and the obstack.h macros no longer used.
> 
> 	* as.h (inline): Don't define.
> 	(__PTR_TO_INT, __INT_TO_PTR): Don't define.
> 	(xmemdup0): New inline function.
> 
> diff --git a/gas/as.h b/gas/as.h
> index 9ff8bb8..f3e1cf0 100644
> --- a/gas/as.h
> +++ b/gas/as.h
> @@ -98,13 +98,6 @@
>  /* Define the standard progress macros.  */
>  #include "progress.h"
>  
> -/* This doesn't get taken care of anywhere.  */
> -#ifndef __MWERKS__  /* Metrowerks C chokes on the "defined (inline)"  */
> -#if !defined (__GNUC__) && !defined (inline)
> -#define inline
> -#endif
> -#endif /* !__MWERKS__ */
> -
>  /* Other stuff from config.h.  */
>  #ifdef NEED_DECLARATION_ENVIRON
>  extern char **environ;
> @@ -144,14 +137,6 @@ extern int vsnprintf(char *, size_t, const char *, va_list);
>  #define bcopy(src,dest,size)	memcpy (dest, src, size)
>  #endif
>  
> -/* Make Saber happier on obstack.h.  */
> -#ifdef SABER
> -#undef  __PTR_TO_INT
> -#define __PTR_TO_INT(P) ((int) (P))
> -#undef  __INT_TO_PTR
> -#define __INT_TO_PTR(P) ((char *) (P))
> -#endif
> -
>  #ifndef __LINE__
>  #define __LINE__ "unknown"
>  #endif /* __LINE__ */
> @@ -522,6 +507,14 @@ segT   subseg_get (const char *, int);
>  const char *remap_debug_filename (const char *);
>  void add_debug_prefix_map (const char *);
>  
> +static inline void *
> +xmemdup0 (const void *in, size_t len)
> +{
> +  char *out = (char *) xmalloc (len + 1);
> +  out[len] = 0;
> +  return memcpy (out, in, len);

Given we always use this with strings, and null terminating other things
with 1 zero byte doesn't seem to make a lot of sense should this return
char *?  I can make that change  with my patch if you agree.

Trev