* new gnulib m4 macros

1 files changed, 59 insertions, 0 deletions

diff --git a/m4/size_max.m4 b/m4/size_max.m4
new file mode 100644
index 0000000..0336f3a
--- /dev/null
+++ b/m4/size_max.m4
@@ -0,0 +1,59 @@
+# size_max.m4 serial 3
+dnl Copyright (C) 2003, 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_SIZE_MAX],
+[
+  AC_CHECK_HEADERS(stdint.h)
+  dnl First test whether the system already has SIZE_MAX.
+  AC_MSG_CHECKING([for SIZE_MAX])
+  result=
+  AC_EGREP_CPP([Found it], [
+#include <limits.h>
+#if HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#ifdef SIZE_MAX
+Found it
+#endif
+], result=yes)
+  if test -z "$result"; then
+    dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
+    dnl than the type 'unsigned long'.
+    dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr',
+    dnl which is guaranteed to work from LONG_MIN to LONG_MAX.
+    _AC_COMPUTE_INT([(size_t)~(size_t)0 / 10], res_hi,
+      [#include <stddef.h>], result=?)
+    _AC_COMPUTE_INT([(size_t)~(size_t)0 % 10], res_lo,
+      [#include <stddef.h>], result=?)
+    _AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
+      [#include <stddef.h>], result=?)
+    if test "$fits_in_uint" = 1; then
+      dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
+      dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
+      AC_TRY_COMPILE([#include <stddef.h>
+        extern size_t foo;
+        extern unsigned long foo;
+        ], [], fits_in_uint=0)
+    fi
+    if test -z "$result"; then
+      if test "$fits_in_uint" = 1; then
+        result="$res_hi$res_lo"U
+      else
+        result="$res_hi$res_lo"UL
+      fi
+    else
+      dnl Shouldn't happen, but who knows...
+      result='((size_t)~(size_t)0)'
+    fi
+  fi
+  AC_MSG_RESULT([$result])
+  if test "$result" != yes; then
+    AC_DEFINE_UNQUOTED([SIZE_MAX], [$result],
+      [Define as the maximum value of type 'size_t', if the system doesn't define it.])
+  fi
+])