Merge pull request #208694 from ncfavier/resolvconf-nixos-enter

nixos/modules/system/etc/setup-etc.pl

···
     my $tmp = "$target.tmp";
     unlink $tmp;
     symlink $source, $tmp or return 0;
-    rename $tmp, $target or return 0;
-    return 1;
+    if (rename $tmp, $target) {
+        return 1;
+    } else {
+        unlink $tmp;
+        return 0;
+    }
 }
 
 
···
 
 sub link {
     my $fn = substr $File::Find::name, length($etc) + 1 or next;
+
+    # nixos-enter sets up /etc/resolv.conf as a bind mount, so skip it.
+    if ($fn eq "resolv.conf" and $ENV{'IN_NIXOS_ENTER'}) {
+        return;
+    }
+
     my $target = "/etc/$fn";
     File::Path::make_path(dirname $target);
     $created{$fn} = 1;
···
     if (-e "$_.mode") {
         my $mode = read_file("$_.mode"); chomp $mode;
         if ($mode eq "direct-symlink") {
-            atomicSymlink readlink("$static/$fn"), $target or warn;
+            atomicSymlink readlink("$static/$fn"), $target or warn "could not create symlink $target";
         } else {
             my $uid = read_file("$_.uid"); chomp $uid;
             my $gid = read_file("$_.gid"); chomp $gid;
···
             $gid = getgrnam $gid unless $gid =~ /^\+/;
             chown int($uid), int($gid), "$target.tmp" or warn;
             chmod oct($mode), "$target.tmp" or warn;
-            rename "$target.tmp", $target or warn;
+            unless (rename "$target.tmp", $target) {
+                warn "could not create target $target";
+                unlink "$target.tmp";
+            }
         }
         push @copied, $fn;
         print CLEAN "$fn\n";
     } elsif (-l "$_") {
-        atomicSymlink "$static/$fn", $target or warn;
+        atomicSymlink "$static/$fn", $target or warn "could not create symlink $target";
     }
 }