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

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