From d676ad1050c0f570d6a2d1f983c1223611d45570 Mon Sep 17 00:00:00 2001
From: tenderlove <tenderlove@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 26 Apr 2018 22:49:00 +0000
Subject: Fix use of `rb_profile_frames` start parameter

rb_profile_frames was always behaving as if the value given for the
start parameter was 0.

The reason for this was that it would check if (start > 0) { then
continue without updating the control frame pointer or anything other
than decrementing start.

[ruby-core:86147] [Bug #14607]

Co-authored-by: Dylan Thacker-Smith <Dylan.Smith@shopify.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63265 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 vm_backtrace.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

(limited to 'vm_backtrace.c')

diff --git a/vm_backtrace.c b/vm_backtrace.c
index 59340292cf..3a13088855 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -1276,7 +1276,7 @@ rb_profile_frames(int start, int limit, VALUE *buff, int *lines)
     const rb_control_frame_t *cfp = ec->cfp, *end_cfp = RUBY_VM_END_CONTROL_FRAME(ec);
     const rb_callable_method_entry_t *cme;
 
-    for (i=0; i<limit && cfp != end_cfp;) {
+    for (i=0; i<limit && cfp != end_cfp; cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp)) {
 	if (cfp->iseq && cfp->pc) {
 	    if (start > 0) {
 		start--;
@@ -1296,7 +1296,6 @@ rb_profile_frames(int start, int limit, VALUE *buff, int *lines)
 
 	    i++;
 	}
-	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
     }
 
     return i;
-- 
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