From: Nicholas Clark <nick@ccl4.org>
Date: Mon, 27 Feb 2006 14:19:32 +0000 (+0000)
Subject: There is now the potential for an upgrade from something without an
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=f9ba3d20d5b73b0f2fcbb19d0c0c0ff2222c412a;p=p5sagit%2Fp5-mst-13.2.git

There is now the potential for an upgrade from something without an
offset (PVNV or PVMG) to something with one (PVCV, PVFM). Deal with
this correctly.

p4raw-id: //depot/perl@27340
---

diff --git a/sv.c b/sv.c
index 5fc24dc..b4bc5a7 100644
--- a/sv.c
+++ b/sv.c
@@ -1351,9 +1351,21 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 new_type)
 	SvANY(sv) = new_body;
 
 	if (old_type_details->copy) {
-	    Copy((char *)old_body + old_type_details->offset,
-		 (char *)new_body + old_type_details->offset,
-		 old_type_details->copy, char);
+	    /* There is now the potential for an upgrade from something without
+	       an offset (PVNV or PVMG) to something with one (PVCV, PVFM)  */
+	    int offset = old_type_details->offset;
+	    int length = old_type_details->copy;
+
+	    if (new_type_details->offset > old_type_details->offset) {
+		int difference
+		    = new_type_details->offset - old_type_details->offset;
+		offset += difference;
+		length -= difference;
+	    }
+	    assert (length >= 0);
+		
+	    Copy((char *)old_body + offset, (char *)new_body + offset, length,
+		 char);
 	}
 
 #ifndef NV_ZERO_IS_ALLBITS_ZERO