tools/missing-macros/src/m4/va_copy.m4

   1 # va_copy.m4 serial 1 (js-1.6.20070208)
   2
   3 dnl ##
   4 dnl ##  Check for C99 va_copy() implementation
   5 dnl ##  (and provide fallback implementation if neccessary)
   6 dnl ##
   7 dnl ##  configure.in:
   8 dnl ##    AC_CHECK_VA_COPY
   9 dnl ##  foo.c:
  10 dnl ##    #include "config.h"
  11 dnl ##    [...]
  12 dnl ##    va_copy(d,s)
  13 dnl ##
  14 dnl ##  This check is rather complex: first because we really have to
  15 dnl ##  try various possible implementations in sequence and second, we
  16 dnl ##  cannot define a macro in config.h with parameters directly.
  17 dnl ##
  18
  19 dnl #   test program for va_copy() implementation
  20 changequote(<<,>>)
  21 m4_define(__va_copy_test, <<[
  22 #include <stdlib.h>
  23 #include <stdarg.h>
  24 #include <string.h>
  25 #define DO_VA_COPY(d, s) $1
  26 void test(char *str, ...)
  27 {
  28     va_list ap, ap2;
  29     int i;
  30     va_start(ap, str);
  31     DO_VA_COPY(ap2, ap);
  32     for (i = 1; i <= 9; i++) {
  33         int k = (int)va_arg(ap, int);
  34         if (k != i)
  35             abort();
  36     }
  37     DO_VA_COPY(ap, ap2);
  38     for (i = 1; i <= 9; i++) {
  39         int k = (int)va_arg(ap, int);
  40         if (k != i)
  41             abort();
  42     }
  43     va_end(ap);
  44 }
  45 int main(int argc, char *argv[])
  46 {
  47     test("test", 1, 2, 3, 4, 5, 6, 7, 8, 9);
  48     exit(0);
  49 }
  50 ]>>)
  51 changequote([,])
  52
  53 dnl #   test driver for va_copy() implementation
  54 m4_define(__va_copy_check, [
  55     AH_VERBATIM($1,
  56 [/* Predefined possible va_copy() implementation (id: $1) */
  57 #define __VA_COPY_USE_$1(d, s) $2])
  58     if test ".$ac_cv_va_copy" = .; then
  59         AC_TRY_RUN(__va_copy_test($2), [ac_cv_va_copy="$1"])
  60     fi
  61 ])
  62
  63 dnl #   Autoconf check for va_copy() implementation checking
  64 AC_DEFUN([AC_CHECK_VA_COPY],[
  65   dnl #   provide Autoconf display check message
  66   AC_MSG_CHECKING(for va_copy() function)
  67   dnl #   check for various implementations in priorized sequence
  68   AC_CACHE_VAL(ac_cv_va_copy, [
  69     ac_cv_va_copy=""
  70     dnl #   1. check for standardized C99 macro
  71     __va_copy_check(C99, [va_copy((d), (s))])
  72     dnl #   2. check for alternative/deprecated GCC macro
  73     __va_copy_check(GCM, [VA_COPY((d), (s))])
  74     dnl #   3. check for internal GCC macro (high-level define)
  75     __va_copy_check(GCH, [__va_copy((d), (s))])
  76     dnl #   4. check for internal GCC macro (built-in function)
  77     __va_copy_check(GCB, [__builtin_va_copy((d), (s))])
  78     dnl #   5. check for assignment approach (assuming va_list is a struct)
  79     __va_copy_check(ASS, [do { (d) = (s); } while (0)])
  80     dnl #   6. check for assignment approach (assuming va_list is a pointer)
  81     __va_copy_check(ASP, [do { *(d) = *(s); } while (0)])
  82     dnl #   7. check for memory copying approach (assuming va_list is a struct)
  83     __va_copy_check(CPS, [memcpy((void *)&(d), (void *)&(s)), sizeof((s))])
  84     dnl #   8. check for memory copying approach (assuming va_list is a pointer)
  85     __va_copy_check(CPP, [memcpy((void *)(d), (void *)(s)), sizeof(*(s))])
  86     if test ".$ac_cv_va_copy" = .; then
  87         AC_ERROR([no working implementation found])
  88     fi
  89   ])
  90   dnl #   optionally activate the fallback implementation
  91   if test ".$ac_cv_va_copy" = ".C99"; then
  92       AC_DEFINE(HAVE_VA_COPY, 1, [Define if va_copy() macro exists (and no fallback implementation is required)])
  93   fi
  94   dnl #   declare which fallback implementation to actually use
  95   AC_DEFINE_UNQUOTED([__VA_COPY_USE], [__VA_COPY_USE_$ac_cv_va_copy],
  96       [Define to id of used va_copy() implementation])
  97   dnl #   provide activation hook for fallback implementation
  98   AH_VERBATIM([__VA_COPY_ACTIVATION],
  99 [/* Optional va_copy() implementation activation */
 100 #ifndef HAVE_VA_COPY
 101 #define va_copy(d, s) __VA_COPY_USE(d, s)
 102 #endif
 103 ])
 104   dnl #   provide Autoconf display result message
 105   if test ".$ac_cv_va_copy" = ".C99"; then
 106       AC_MSG_RESULT([yes])
 107   else
 108       AC_MSG_RESULT([no (using fallback implementation)])
 109   fi
 110 ])
 111