[PATCH] mknod: be more vocal about danger of running tests as root

[Eric Blake]

* m4/mknod.m4 (gl_FUNC_MKNOD): Make it harder to run configure as
root, since that is just asking for problems.
Based on a report by Bruno Haible.

Signed-off-by: Eric Blake <address@hidden>
---

What do you think of this?

 ChangeLog   |    7 +++++++
 m4/mknod.m4 |   11 ++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7158e92..f6c1b1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-07-30  Eric Blake  <address@hidden>
+
+       mknod: be more vocal about danger of running tests as root
+       * m4/mknod.m4 (gl_FUNC_MKNOD): Make it harder to run configure as
+       root, since that is just asking for problems.
+       Based on a report by Bruno Haible.
+
 2010-02-17  Eric Blake  <address@hidden>

        manywarnings: add more warnings
diff --git a/m4/mknod.m4 b/m4/mknod.m4
index 4d9214d..c13644b 100644
--- a/m4/mknod.m4
+++ b/m4/mknod.m4
@@ -1,4 +1,4 @@
-# serial 1
+# serial 2
 # See if we need to provide mknod replacement.

 dnl Copyright (C) 2009, 2010 Free Software Foundation, Inc.
@@ -27,9 +27,14 @@ AC_DEFUN([gl_FUNC_MKNOD],
              #include <unistd.h>
 ]], [[/* Indeterminate for super-user, assume no.  Why are you running
          configure as root, anyway?  */
-      if (!geteuid ()) return 1;
+      if (!geteuid ()) return 99;
       if (mknod ("conftest.fifo", S_IFIFO | 0600, 0)) return 2;]])],
-         [gl_cv_func_mknod_works=yes], [gl_cv_func_mknod_works=no],
+         [gl_cv_func_mknod_works=yes],
+         [if test $? == 99 && test x"$FORCE_UNSAFE_CONFIGURE" = x; then
+            AC_MSG_FAILURE([you should not run configure as root ]dnl
+[(set FORCE_UNSAFE_CONFIGURE=1 in environment to bypass this check)])
+          fi
+          gl_cv_func_mknod_works=no],
          [gl_cv_func_mknod_works="guessing no"])
        rm -f conftest.fifo])
     if test "$gl_cv_func_mknod_works" != yes; then
-- 
1.7.2