From: Brandon Black <blblack@gmail.com>
Date: Thu, 28 Jun 2007 15:58:32 +0000 (-0500)
Subject: Re: valgrind findings
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=fdef73f9d3c637571d3ab9a9d73990f87b1ad2d9;p=p5sagit%2Fp5-mst-13.2.git

Re: valgrind findings
From: "Brandon Black" <blblack@gmail.com>
Message-ID: <84621a60706281358o3b379b20k2c1e53566587d79b@mail.gmail.com>

p4raw-id: //depot/perl@31501
---

diff --git a/mro.c b/mro.c
index 01461b1..7074e7a 100644
--- a/mro.c
+++ b/mro.c
@@ -87,6 +87,7 @@ AV*
 Perl_mro_get_linear_isa_dfs(pTHX_ HV *stash, I32 level)
 {
     AV* retval;
+    AV* tmp_retval; /* mortal to avoid leaks */
     GV** gvp;
     GV* gv;
     AV* av;
@@ -113,8 +114,8 @@ Perl_mro_get_linear_isa_dfs(pTHX_ HV *stash, I32 level)
 
     /* not in cache, make a new one */
 
-    retval = newAV();
-    av_push(retval, newSVpv(stashname, 0)); /* add ourselves at the top */
+    tmp_retval = (AV*)sv_2mortal((SV*)newAV());
+    av_push(tmp_retval, newSVpv(stashname, 0)); /* add ourselves at the top */
 
     /* fetch our @ISA */
     gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
@@ -146,7 +147,9 @@ Perl_mro_get_linear_isa_dfs(pTHX_ HV *stash, I32 level)
             }
             else {
                 /* otherwise, recurse into ourselves for the MRO
-                   of this @ISA member, and append their MRO to ours */
+                   of this @ISA member, and append their MRO to ours.
+                   The recursive call could throw an exception, which
+                   has memory management implications here (tmp_retval) */
 		const AV *const subrv
 		    = mro_get_linear_isa_dfs(basestash, level + 1);
 
@@ -157,12 +160,16 @@ Perl_mro_get_linear_isa_dfs(pTHX_ HV *stash, I32 level)
 		SV *const subsv = *subrv_p++;
 		if(!hv_exists_ent(stored, subsv, 0)) {
 		    hv_store_ent(stored, subsv, &PL_sv_undef, 0);
-		    av_push(retval, newSVsv(subsv));
+		    av_push(tmp_retval, newSVsv(subsv));
 		}
             }
         }
     }
 
+    /* make the real retval out of tmp_retval, now that we're
+       past the exception dangers */
+    retval = av_make(AvFILLp(tmp_retval)+1, AvARRAY(tmp_retval));
+
     /* we don't want anyone modifying the cache entry but us,
        and we do so by replacing it completely */
     SvREADONLY_on(retval);