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68 lines
1.9 KiB
C
68 lines
1.9 KiB
C
#ifndef STDARGX_H_INCLUDED
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#define STDARGX_H_INCLUDED
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#include "xmlrpc_config.h"
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#include <stdarg.h>
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#include <string.h>
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/*----------------------------------------------------------------------------
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We need a special version of va_list in order to pass around the
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variable argument heap by reference, thus allowing a subroutine to
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advance the heap's pointer.
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On some systems (e.g. Gcc for PPC or AMD64), va_list is an array.
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That invites the scourge of array-to-pointer degeneration if you try
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to take its address. Burying it inside a struct as we do with out
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va_listx type makes it immune.
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Example of what would happen if we used va_list instead of va_listx,
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on a system where va_list is an array:
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void sub2(va_list * argsP) [
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...
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}
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void sub1(va_list args) {
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sub2(&args);
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}
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This doesn't work. '&args' is the same thing as 'args', so is
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va_list, not va_list *. The compiler will even warn you about the
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pointer type mismatch.
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To use va_listx:
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void sub1_va(char * format, va_list args) {
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va_listx argsx;
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init_va_listx(&argsx, args);
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sub2(format, &argsx);
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}
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-----------------------------------------------------------------------------*/
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typedef struct {
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/*----------------------------------------------------------------------------
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Same thing as va_list, but in a form that works everywhere. See above.
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-----------------------------------------------------------------------------*/
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va_list v;
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} va_listx;
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static __inline__ void
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init_va_listx(va_listx * const argsxP,
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va_list const args) {
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#if VA_LIST_IS_ARRAY
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/* 'args' is NOT a va_list. It is a pointer to the first element of a
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'va_list', which is the same address as a pointer to the va_list
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itself.
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*/
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memcpy(&argsxP->v, args, sizeof(argsxP->v));
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#else
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argsxP->v = args;
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#endif
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}
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#endif
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