Re: [PATCH] gdb/objc: make objc_demangle a member function of objc_language

[Lancelot SIX <lsix@lancelotsix.com>]

Le Tue, Mar 16, 2021 at 07:02:04PM +0000, Andrew Burgess a écrit :
> Makes the objc_demangle helper function a member function of
> objc_language (by renaming it to be the demangle_symbol member
> function).
> 
> I also fixed some of the obvious coding standard violations in
> obj_demangle, so the '&&' operators are now at the start of the line,
> not the end.  Comparison to nullptr are now made explicit, as are
> comparisons to the null character.
> 
> There should be no user visible changes after this commit.
> 
> gdb/ChangeLog:
> 
> 	* objc-lang.c (objc_demangle): Renamed to
> 	objc_language::demangle_symbol, and moved later in the file.
> 	(objc_language::sniff_from_mangled_name): Call demangle_symbol
> 	member function.
> 	(objc_language::demangle_symbol): Defined outside of class
> 	declaration.  The definition is the old objc_demangle with NULL
> 	changed to nullptr, and if conditions relating to nullptr pointers
> 	or null character checks made explicit.
> 	* objc-lang.h (objc_demangle): Delete declaration.
> ---
>  gdb/ChangeLog   |  12 +++++
>  gdb/objc-lang.c | 139 +++++++++++++++++++++++-------------------------
>  gdb/objc-lang.h |   2 -
>  3 files changed, 80 insertions(+), 73 deletions(-)
> 
> diff --git a/gdb/objc-lang.c b/gdb/objc-lang.c
> index 8e8cc053531..7e53124e4be 100644
> --- a/gdb/objc-lang.c
> +++ b/gdb/objc-lang.c
> @@ -216,72 +216,6 @@ value_nsstring (struct gdbarch *gdbarch, const char *ptr, int len)
>    return nsstringValue;
>  }
>  
> -/* Objective-C name demangling.  */
> -
> -char *
> -objc_demangle (const char *mangled, int options)
> -{
> -  char *demangled, *cp;
> -
> -  if (mangled[0] == '_' &&
> -     (mangled[1] == 'i' || mangled[1] == 'c') &&
> -      mangled[2] == '_')
> -    {
> -      cp = demangled = (char *) xmalloc (strlen (mangled) + 2);
> -
> -      if (mangled[1] == 'i')
> -	*cp++ = '-';		/* for instance method */
> -      else
> -	*cp++ = '+';		/* for class    method */
> -
> -      *cp++ = '[';		/* opening left brace  */
> -      strcpy(cp, mangled+3);	/* Tack on the rest of the mangled name.  */
> -
> -      while (*cp && *cp == '_')
> -	cp++;			/* Skip any initial underbars in class
> -				   name.  */
> -
> -      cp = strchr(cp, '_');
> -      if (!cp)	                /* Find first non-initial underbar.  */
> -	{
> -	  xfree(demangled);	/* not mangled name */
> -	  return NULL;
> -	}
> -      if (cp[1] == '_')		/* Easy case: no category name.    */
> -	{
> -	  *cp++ = ' ';		/* Replace two '_' with one ' '.   */
> -	  strcpy(cp, mangled + (cp - demangled) + 2);
> -	}
> -      else
> -	{
> -	  *cp++ = '(';		/* Less easy case: category name.  */
> -	  cp = strchr(cp, '_');
> -	  if (!cp)
> -	    {
> -	      xfree(demangled);	/* not mangled name */
> -	      return NULL;
> -	    }
> -	  *cp++ = ')';
> -	  *cp++ = ' ';		/* Overwriting 1st char of method name...  */
> -	  strcpy(cp, mangled + (cp - demangled));	/* Get it back.  */
> -	}
> -
> -      while (*cp && *cp == '_')
> -	cp++;			/* Skip any initial underbars in
> -				   method name.  */
> -
> -      for (; *cp; cp++)
> -	if (*cp == '_')
> -	  *cp = ':';		/* Replace remaining '_' with ':'.  */
> -
> -      *cp++ = ']';		/* closing right brace */
> -      *cp++ = 0;		/* string terminator */
> -      return demangled;
> -    }
> -  else
> -    return NULL;	/* Not an objc mangled name.  */
> -}
> -
>  /* Class representing the Objective-C language.  */
>  
>  class objc_language : public language_defn
> @@ -320,16 +254,13 @@ class objc_language : public language_defn
>    bool sniff_from_mangled_name (const char *mangled,
>  				char **demangled) const override
>    {
> -    *demangled = objc_demangle (mangled, 0);
> +    *demangled = demangle_symbol (mangled, 0);
>      return *demangled != NULL;
>    }
>  
>    /* See language.h.  */
>  
> -  char *demangle_symbol (const char *mangled, int options) const override
> -  {
> -    return objc_demangle (mangled, options);
> -  }
> +  char *demangle_symbol (const char *mangled, int options) const override;
>  
>    /* See language.h.  */
>  
> @@ -385,6 +316,72 @@ class objc_language : public language_defn
>    { return macro_expansion_c; }
>  };
>  
> +/* See declaration of objc_language::demangle_symbol above.  */
> +
> +char *
> +objc_language::demangle_symbol (const char *mangled, int options) const
> +{
> +  char *demangled, *cp;
> +
> +  if (mangled[0] == '_'
> +      && (mangled[1] == 'i' || mangled[1] == 'c')
> +      && mangled[2] == '_')
> +    {
> +      cp = demangled = (char *) xmalloc (strlen (mangled) + 2);
> +
> +      if (mangled[1] == 'i')
> +	*cp++ = '-';		/* for instance method */
> +      else
> +	*cp++ = '+';		/* for class    method */
> +
> +      *cp++ = '[';		/* opening left brace  */
> +      strcpy(cp, mangled+3);	/* Tack on the rest of the mangled name.  */
> +
> +      while (*cp && *cp == '_')

Hi,

You forgot one explicit comparison to null char here.

Lancelot.

> +	cp++;			/* Skip any initial underbars in class
> +				   name.  */
> +
> +      cp = strchr(cp, '_');
> +      if (cp == nullptr)	/* Find first non-initial underbar.  */
> +	{
> +	  xfree(demangled);	/* not mangled name */
> +	  return nullptr;
> +	}
> +      if (cp[1] == '_')		/* Easy case: no category name.    */
> +	{
> +	  *cp++ = ' ';		/* Replace two '_' with one ' '.   */
> +	  strcpy(cp, mangled + (cp - demangled) + 2);
> +	}
> +      else
> +	{
> +	  *cp++ = '(';		/* Less easy case: category name.  */
> +	  cp = strchr(cp, '_');
> +	  if (cp == nullptr)
> +	    {
> +	      xfree(demangled);	/* not mangled name */
> +	      return nullptr;
> +	    }
> +	  *cp++ = ')';
> +	  *cp++ = ' ';		/* Overwriting 1st char of method name...  */
> +	  strcpy(cp, mangled + (cp - demangled));	/* Get it back.  */
> +	}
> +
> +      while (*cp != '\0' && *cp == '_')
> +	cp++;			/* Skip any initial underbars in
> +				   method name.  */
> +
> +      for (; *cp != '\0'; cp++)
> +	if (*cp == '_')
> +	  *cp = ':';		/* Replace remaining '_' with ':'.  */
> +
> +      *cp++ = ']';		/* closing right brace */
> +      *cp++ = 0;		/* string terminator */
> +      return demangled;
> +    }
> +  else
> +    return nullptr;	/* Not an objc mangled name.  */
> +}
> +
>  /* Single instance of the class representing the Objective-C language.  */
>  
>  static objc_language objc_language_defn;
> diff --git a/gdb/objc-lang.h b/gdb/objc-lang.h
> index f58335e62cd..9d3e26d18a0 100644
> --- a/gdb/objc-lang.h
> +++ b/gdb/objc-lang.h
> @@ -31,8 +31,6 @@ extern CORE_ADDR lookup_objc_class     (struct gdbarch *gdbarch,
>  extern CORE_ADDR lookup_child_selector (struct gdbarch *gdbarch,
>  					const char *methodname);
>  
> -extern char *objc_demangle (const char *mangled, int options);
> -
>  extern int find_objc_msgcall (CORE_ADDR pc, CORE_ADDR *new_pc);
>  
>  extern const char *find_imps (const char *method,
> -- 
> 2.25.4
> 

-- 
Lancelot SIX