add RC_FUNC_GETGROUPS configure magic

1 files changed, 19 insertions, 1 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index c8913a0..60ec318 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1,3 +1,19 @@
+dnl This macro sets HAVE_POSIX_GETGROUPS if the
+dnl getgroups() function accepts a zero first argument.
+AC_DEFUN(RC_FUNC_GETGROUPS, [
+	AC_CACHE_CHECK(for POSIX getgroups, rc_cv_func_posix_getgroups, AC_TRY_RUN([
+#include <sys/types.h>
+#include <unistd.h>
+int main(void) {
+	return getgroups(0, (void *)0) == -1;
+}
+	], rc_cv_func_posix_getgroups=yes, rc_cv_func_posix_getgroups=no, rc_cv_func_posix_getgroups=yes))
+	case "$rc_cv_func_posix_getgroups" in
+	yes) AC_DEFINE(HAVE_POSIX_GETGROUPS) ;;
+	esac
+])
+
+
 dnl The AC_FUNC_SETPGRP macro doesn't
 dnl #include <unistd.h>, so it fails on OSF-1, where setpgrp
 dnl will happily accept arguments, but the protoype doesn't
@@ -7,7 +23,9 @@ AC_DEFUN(RC_FUNC_SETPGRP, [
 	AC_CACHE_CHECK(for setpgrp that takes no arguments, ac_cv_func_setpgrp_void, AC_TRY_RUN([
 #include <unistd.h>
 /* If setpgrp() takes no arguments, this may fail to compile, but
-if it compiles the call should succeed.  */
+if it compiles the call should succeed.  Note that the assignments
+to ac_cv_func_setpgrp_void are the other way round from what you
+would expect. */
 int main(void) {
 	return setpgrp(1,1) != -1;
 }