* stdio-common/printf.h (struct printf_info): Add user element.

New types printf_arginfo_size_function, printf_va_arg_function.
	Declare register_printf_specifier, register_printf_modifier,
	register_printf_type.
	* stdio-common/printf-parse.h (struct printf_spec): Add size element.
	(union printf_arg): Add pa_user element.
	Adjust __printf_arginfo_table type.
	Add __printf_va_arg_table, __printf_modifier_table,
	__handle_registered_modifier_mb, and __handle_registered_modifier_wc
	declarations.
	* stdio-common/printf-parsemb.c: Recognize registered modifiers.
	If registered arginfo call failed try normal specifier.
	* stdio-common/printf-prs.c: Pass additional parameter to arginfo
	function.
	* stdio-common/Makefile (routines): Add reg-modifier and reg-type.
	* stdio-common/Versions: Export register_printf_modifier,
	register_printf_type, and register_printf_specifier for GLIBC_2.10.
	* stdio-common/reg-modifier.c: New file.
	* stdio-common/reg-type.c: New file.
	* stdio-common/reg-printf.c (__register_printf_specifier): New
	function.  Mostly the old __register_printf_function function but
	uses locking and type of third parameter changed.
	(__register_printf_function): Implement using
	__register_printf_specifier.
	* stdio-common/vfprintf.c (vfprintf): Collect argument sizes in
	calls to arginfo functions.  Allocate enough memory for user-defined
	types.  Call new va_arg functions to get user-defined types.
	Try installed handlers even for existing format specifiers first.

stdio-common/vfprintf.c

@@ -238,7 +238,7 @@ vfprintf (FILE *s, const CHAR_T *format, va_list ap)
   /* This table maps a character into a number representing a
      class.  In each step there is a destination label for each
      class.  */
-  static const int jump_table[] =
+  static const uint8_t jump_table[] =
   {
     /* ' ' */  1,            0,            0, /* '#' */  4,
 	       0, /* '%' */ 14,            0, /* '\''*/  6,
@@ -1630,6 +1630,7 @@ do_positional:
     size_t nargs = 0;
     int *args_type;
     union printf_arg *args_value = NULL;
+    int *args_size;
 
     /* Positional parameters refer to arguments directly.  This could
        also determine the maximum number of arguments.  Track the
@@ -1684,6 +1685,7 @@ do_positional:
     memset (args_type, s->_flags2 & _IO_FLAGS2_FORTIFY ? '\xff' : '\0',
 	    nargs * sizeof (int));
     args_value = alloca (nargs * sizeof (union printf_arg));
+    args_size = alloca (nargs * sizeof (int));
 
     /* XXX Could do sanity check here: If any element in ARGS_TYPE is
        still zero after this loop, format is invalid.  For now we
@@ -1704,8 +1706,10 @@ do_positional:
 	  {
 	  case 0:		/* No arguments.  */
 	    break;
-	  case 1:		/* One argument; we already have the type.  */
+	  case 1:		/* One argument; we already have the
+				   type and size.  */
 	    args_type[specs[cnt].data_arg] = specs[cnt].data_arg_type;
+	    args_size[specs[cnt].data_arg] = specs[cnt].size;
 	    break;
 	  default:
 	    /* We have more than one argument for this format spec.
@@ -1713,7 +1717,8 @@ do_positional:
 	       all the types.  */
 	    (void) (*__printf_arginfo_table[specs[cnt].info.spec])
 	      (&specs[cnt].info,
-	       specs[cnt].ndata_args, &args_type[specs[cnt].data_arg]);
+	       specs[cnt].ndata_args, &args_type[specs[cnt].data_arg],
+	       &args_size[specs[cnt].data_arg]);
 	    break;
 	  }
       }
@@ -1760,6 +1765,13 @@ do_positional:
 	default:
 	  if ((args_type[cnt] & PA_FLAG_PTR) != 0)
 	    args_value[cnt].pa_pointer = va_arg (ap_save, void *);
+	  else if (__builtin_expect (__printf_va_arg_table != NULL, 0)
+		   && __printf_va_arg_table[args_type[cnt] - PA_LAST] != NULL)
+	    {
+	      args_value[cnt].pa_user = alloca (args_size[cnt]);
+	      (*__printf_va_arg_table[args_type[cnt] - PA_LAST])
+		(args_value[cnt].pa_user, &ap_save);
+	    }
 	  else
 	    args_value[cnt].pa_long_double = 0.0;
 	  break;
@@ -1863,6 +1875,40 @@ do_positional:
 	/* Process format specifiers.  */
 	while (1)
 	  {
+	    extern printf_function **__printf_function_table;
+	    int function_done;
+
+	    if (spec <= UCHAR_MAX
+		&& __printf_function_table != NULL
+		&& __printf_function_table[(size_t) spec] != NULL)
+	      {
+		const void **ptr = alloca (specs[nspecs_done].ndata_args
+					   * sizeof (const void *));
+
+		/* Fill in an array of pointers to the argument values.  */
+		for (unsigned int i = 0; i < specs[nspecs_done].ndata_args;
+		     ++i)
+		  ptr[i] = &args_value[specs[nspecs_done].data_arg + i];
+
+		/* Call the function.  */
+		function_done = __printf_function_table[(size_t) spec]
+		  (s, &specs[nspecs_done].info, ptr);
+
+		if (function_done != -2)
+		  {
+		    /* If an error occurred we don't have information
+		       about # of chars.  */
+		    if (function_done < 0)
+		      {
+			done = -1;
+			goto all_done;
+		      }
+
+		    done_add (function_done);
+		    break;
+		  }
+	      }
+
 	    JUMP (spec, step4_jumps);
 
 	    process_arg ((&specs[nspecs_done]));
@@ -1870,19 +1916,9 @@ do_positional:
 
 	  LABEL (form_unknown):
 	    {
-	      extern printf_function **__printf_function_table;
-	      int function_done;
-	      printf_function *function;
 	      unsigned int i;
 	      const void **ptr;
 
-	      function =
-		(__printf_function_table == NULL ? NULL :
-		 __printf_function_table[specs[nspecs_done].info.spec]);
-
-	      if (function == NULL)
-		function = &printf_unknown;
-
 	      ptr = alloca (specs[nspecs_done].ndata_args
 			    * sizeof (const void *));
 
@@ -1891,7 +1927,8 @@ do_positional:
 		ptr[i] = &args_value[specs[nspecs_done].data_arg + i];
 
 	      /* Call the function.  */
-	      function_done = (*function) (s, &specs[nspecs_done].info, ptr);
+	      function_done = printf_unknown (s, &specs[nspecs_done].info,
+					      ptr);
 
 	      /* If an error occurred we don't have information about #
 		 of chars.  */