Fix the syswrite downgrade bug of

[perl #23428] Somethings rotten in unicode semantics

p4raw-id: //depot/perl@20804

1 files changed, 6 insertions, 3 deletions

diff --git a/pp_sys.c b/pp_sys.c
index d8dc103b20..f35bc8a6ac 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -1807,9 +1807,12 @@ PP(pp_send)
 	buffer = SvPVutf8(bufsv, blen);
     }
     else {
-	if (DO_UTF8(bufsv))
-	    sv_utf8_downgrade(bufsv, FALSE);
-	buffer = SvPV(bufsv, blen);
+	 if (DO_UTF8(bufsv)) {
+	      /* Not modifying source SV, so making a temporary copy. */
+	      bufsv = sv_2mortal(newSVsv(bufsv));
+	      sv_utf8_downgrade(bufsv, FALSE);
+	 }
+	 buffer = SvPV(bufsv, blen);
     }
 
     if (PL_op->op_type == OP_SYSWRITE) {