libs-base/config/config.printf.c

/* See if we have a broken register_printf function (e.g. an old version of glibc) */
/*
  Copyright (C) 2005 Free Software Foundation

  Copying and distribution of this file, with or without modification,
  are permitted in any medium without royalty provided the copyright
  notice and this notice are preserved.
*/
#include <stdio.h>
#include <printf.h>
#include <stdarg.h>

/* <sattler@volker.cs.Uni-Magdeburg.DE>, with libc-5.3.9 thinks this 
   flag PRINTF_ATSIGN_VA_LIST should be 0, but for me, with libc-5.0.9, 
   it crashes.  -mccallum

   Apparently GNU libc 2.xx needs this to be 0 also, along with Linux
   libc versions 5.2.xx and higher (including libc6, which is just GNU
   libc). -chung */
#define PRINTF_ATSIGN_VA_LIST			\
       (defined(_LINUX_C_LIB_VERSION_MINOR)	\
	&& _LINUX_C_LIB_VERSION_MAJOR <= 5	\
	&& _LINUX_C_LIB_VERSION_MINOR < 2)

#if ! PRINTF_ATSIGN_VA_LIST
static int
arginfo_func (const struct printf_info *info, size_t n, int *argtypes)
{
  *argtypes = PA_POINTER;
  return 1;
}
#endif /* !PRINTF_ATSIGN_VA_LIST */

static int
handle_printf_atsign (FILE *stream, 
		      const struct printf_info *info,
#if PRINTF_ATSIGN_VA_LIST
		      va_list *ap_pointer)
#elif defined(_LINUX_C_LIB_VERSION_MAJOR)       \
     && _LINUX_C_LIB_VERSION_MAJOR < 6
                      const void **const args)
#else /* GNU libc needs the following. */
                      const void *const *args)
#endif
{
#if ! PRINTF_ATSIGN_VA_LIST
  const void *ptr = *args;
#endif
  char * string_object;
  int len;

  /* xxx This implementation may not pay pay attention to as much 
     of printf_info as it should. */

#if PRINTF_ATSIGN_VA_LIST
  string_object = va_arg (*ap_pointer, char *);
#else
  string_object = *((char **) ptr);
#endif
  len = fprintf(stream, "%s", string_object);
  return len;
}

int main()
{
  char *d = "hi there";

  register_printf_function ('@', 
				    handle_printf_atsign, 
#if PRINTF_ATSIGN_VA_LIST
				    0);
#else
	                            arginfo_func);
#endif

  printf("test %s = %@\n", d, d);
  return 0;
}