configure: check for Linux specific unshare() with CLONE_FS

Note we still need some kind of runtime detection as
it can fail in some constraint container setups, which
reject the whole unshare() syscall instead of just the
once used for container features.

In case unshare(CLONE_FS) works, we can have a per thread
current working directory and use [f]chdir() safely in
worker threads.

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Ralph Boehme <slow@samba.org>

diff --git a/source3/wscript b/source3/wscript
index aed784ef0179ad40946d36947e8a9415a1b5554a..a14d76d7469ec2fc1a0032c8df26d920828a00f7 100644 (file)
--- a/source3/wscript
+++ b/source3/wscript
@@ -1505,6 +1505,11 @@ main() {
                 legacy_quota_libs = ''
     conf.env['legacy_quota_libs'] = legacy_quota_libs
 
+    conf.CHECK_CODE('(void)unshare(CLONE_FS);',
+                    headers='sched.h',
+                    define='HAVE_UNSHARE_CLONE_FS',
+                    msg='for Linux unshare(CLONE_FS)')
+
     #
     # cluster support (CTDB)
     #