getgroups: work around FreeBSD bug

[gnulib.git] / m4 / getgroups.m4

diff --git a/m4/getgroups.m4 b/m4/getgroups.m4
index 4d96712..0f8e89e 100644 (file)
--- a/m4/getgroups.m4
+++ b/m4/getgroups.m4
@@ -1,4 +1,4 @@
-# serial 14
+# serial 15
 
 dnl From Jim Meyering.
 dnl A wrapper around AC_FUNC_GETGROUPS.
@@ -21,6 +21,23 @@ AC_DEFUN([gl_FUNC_GETGROUPS],
   then
     AC_LIBOBJ([getgroups])
     REPLACE_GETGROUPS=1
+    AC_DEFINE([GETGROUPS_ZERO_BUG], [1], [Define this to 1 if
+      getgroups(0,NULL) does not return the number of groups.])
+  else
+    dnl Detect FreeBSD bug; POSIX requires getgroups(-1,ptr) to fail.
+    AC_CACHE_CHECK([whether getgroups handles negative values],
+      [gl_cv_func_getgroups_works],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
+        [[int size = getgroups (0, 0);
+          gid_t *list = malloc (size * sizeof *list);
+          return getgroups (-1, list) != -1;]])],
+        [gl_cv_func_getgroups_works=yes],
+        [gl_cv_func_getgroups_works=no],
+        [gl_cv_func_getgroups_works="guessing no"])])
+    if test "$gl_cv_func_getgroups_works" != yes; then
+      AC_LIBOBJ([getgroups])
+      REPLACE_GETGROUPS=1
+    fi
   fi
   test -n "$GETGROUPS_LIB" && LIBS="$GETGROUPS_LIB $LIBS"
 ])