syscallcompat: MknodatUser: work around changed syscall.Setgroups semantics

Since go1.16beta1 (commit d1b1145cace8b968307f9311ff611e4bb810710c ,
https://go-review.googlesource.com/c/go/+/210639 )
syscall.{Setgroups,Setregid,Setreuid} affects all threads, which
is exactly what we not want.

We now use unix.{Setgroups,Setregid,Setreuid} instead.

Workarounds https://github.com/golang/go/issues/1435 .

1 files changed, 8 insertions, 1 deletions

diff --git a/test.bash b/test.bash
index ce2d392..266a875 100755
--- a/test.bash
+++ b/test.bash
@@ -80,7 +80,14 @@ else
 fi
 
 if grep -R "panic(" ./*.go internal ; then
-	echo "Please use log.Panic instead of naked panic!"
+	echo "$MYNAME: Please use log.Panic instead of naked panic!"
+	exit 1
+fi
+
+# All functions from the commit msg in https://go-review.googlesource.com/c/go/+/210639
+if grep -R -E 'syscall.(Setegid|Seteuid|Setgroups|Setgid|Setregid|Setreuid|Setresgid|Setresuid|Setuid)\(' \
+	./*.go internal ; then
+	echo "$MYNAME: You probably want to use unix.Setgroups and friends. See the comments in OpenatUser() for why."
 	exit 1
 fi