From: Frazer Clement
Date: August 27 2008 3:19pm
Subject: bzr commit into mysql-5.1 tree (frazer:2667) Bug#39037
List-Archive: http://lists.mysql.com/commits/52742
X-Bug: 39037
Message-Id: <200808271519.m7RFJK6b015804@forth.ndb.mysql.com>
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#At file:///home/frazer/bzr/mysql-5.1-telco-6.2-bugs/

------------------------------------------------------------
revno: 2667
revision-id: frazer@stripped
parent: frazer@stripped
committer: Frazer Clement <frazer@stripped>
branch nick: mysql-5.1-telco-6.2-bugs
timestamp: Wed 2008-08-27 16:19:05 +0100
message:
  Bug#39037 Segment linking bug
  
  Modify import() to ensure nextSegment ptr set when importing
  
  Add assert-only linked segment integrity check
modified:
  storage/ndb/src/kernel/vm/LongSignal.hpp sp1f-longsignal.hpp-20040414082422-zttdipy55hdqoxdh4ubjdgn4lydokjyq
  storage/ndb/src/kernel/vm/TransporterCallback.cpp sp1f-transportercallback.-20040414082423-orvgt4lovbdsqu5gjdkhc6oefovmavrk
per-file comments:
  storage/ndb/src/kernel/vm/LongSignal.hpp
    Add new linked-segment integrity check function
  storage/ndb/src/kernel/vm/TransporterCallback.cpp
    Fix import().
    Add integrity check method

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=== modified file 'storage/ndb/src/kernel/vm/LongSignal.hpp'
--- a/storage/ndb/src/kernel/vm/LongSignal.hpp	2006-12-23 19:20:40 +0000
+++ b/storage/ndb/src/kernel/vm/LongSignal.hpp	2008-08-27 15:19:05 +0000
@@ -61,6 +61,9 @@
 void getSections(Uint32 secCount, SegmentedSectionPtr ptr[3]);
 void releaseSections(Uint32 secCount, SegmentedSectionPtr ptr[3]);
 
+/* Internal verification */
+bool verifySection(Uint32 firstIVal, 
+                   SectionSegmentPool& thePool= g_sectionSegmentPool);
 
 #include "DataBuffer.hpp"
 

=== modified file 'storage/ndb/src/kernel/vm/TransporterCallback.cpp'
--- a/storage/ndb/src/kernel/vm/TransporterCallback.cpp	2006-12-23 19:20:40 +0000
+++ b/storage/ndb/src/kernel/vm/TransporterCallback.cpp	2008-08-27 15:19:05 +0000
@@ -60,13 +60,72 @@
   return connectionError[i].text;
 }
 
+
+/**
+ * verifySection
+ * Assertion method to check that a segmented section is constructed 
+ * 'properly' where 'properly' is loosly defined. 
+ */
+bool
+verifySection(Uint32 firstIVal, SectionSegmentPool& thePool)
+{
+  if (firstIVal == RNIL)
+    return true;
+
+  /* Get first section ptr (With assertions in getPtr) */
+  SectionSegment* first= thePool.getPtr(firstIVal);
+
+  assert(first != NULL);
+  Uint32 totalSize= first->m_sz;
+  Uint32 lastSegIVal= first->m_lastSegment;
+
+  /* Hmm, need to be careful of length == 0 
+   * Nature abhors a segmented section with length 0
+   */
+  //assert(totalSize != 0);
+  assert(lastSegIVal != RNIL); /* Should never be == RNIL */
+  /* We ignore m_ownerRef */
+
+  if (totalSize <= SectionSegment::DataLength)
+  {
+    /* 1 segment */
+    assert(first->m_lastSegment == firstIVal);
+    // m_nextSegment not always set to RNIL on last segment
+    //assert(first->m_nextSegment == RNIL);
+  }
+  else
+  {
+    /* > 1 segment */
+    assert(first->m_nextSegment != RNIL);
+    assert(first->m_lastSegment != firstIVal);
+    Uint32 currIVal= firstIVal;
+    SectionSegment* curr= first;
+
+    /* Traverse segments to where we think the end should be */
+    while (totalSize > SectionSegment::DataLength)
+    {
+      currIVal= curr->m_nextSegment;
+      curr= thePool.getPtr(currIVal);
+      totalSize-= SectionSegment::DataLength;
+      /* Ignore m_ownerRef, m_sz, m_lastSegment of intermediate
+       * Segments
+       */
+    }
+    
+    /* Once we are here, we are on the last Segment of this Section
+     * Check that last segment is as stated in the first segment
+     */
+    assert(currIVal == lastSegIVal);
+    // m_nextSegment not always set properly on last segment
+    //assert(curr->m_nextSegment == RNIL);
+    /* Ignore m_ownerRef, m_sz, m_lastSegment of last segment */
+  }
+
+  return true;
+}
+
 bool
 import(Ptr<SectionSegment> & first, const Uint32 * src, Uint32 len){
-  /**
-   * Dummy data used when setting prev.m_nextSegment for first segment of a
-   *   section
-   */
-  Uint32 dummyPrev[4]; 
 
   first.p = 0;
   if(g_sectionSegmentPool.seize(first)){
@@ -78,16 +137,15 @@
   first.p->m_sz = len;
   first.p->m_ownerRef = 0;
   
-  Ptr<SectionSegment> prevPtr = { (SectionSegment *)&dummyPrev[0], 0 };
   Ptr<SectionSegment> currPtr = first;
   
   while(len > SectionSegment::DataLength){
-    prevPtr.p->m_nextSegment = currPtr.i;
     memcpy(&currPtr.p->theData[0], src, 4 * SectionSegment::DataLength);
     src += SectionSegment::DataLength;
     len -= SectionSegment::DataLength;
-    prevPtr = currPtr;
+    Ptr<SectionSegment> prevPtr = currPtr;
     if(g_sectionSegmentPool.seize(currPtr)){
+      prevPtr.p->m_nextSegment = currPtr.i;
       ;
     } else {
       first.p->m_lastSegment = prevPtr.i;
@@ -98,6 +156,8 @@
   first.p->m_lastSegment = currPtr.i;
   currPtr.p->m_nextSegment = RNIL;
   memcpy(&currPtr.p->theData[0], src, 4 * len);
+
+  assert(verifySection(first.i));
   return true;
 }
 
@@ -117,6 +177,8 @@
   headPtr.p->m_sz += tailPtr.p->m_sz;
   
   oldTailPtr.p->m_nextSegment = tailPtr.i;
+
+  assert(verifySection(head));
 }
 
 void 
@@ -125,6 +187,8 @@
 
   Uint32 len = _ptr.sz;
   SectionSegment * ptrP = _ptr.p;
+
+  assert(verifySection(_ptr.i, thePool));
   
   while(len > 60){
     memcpy(insertPtr, &ptrP->theData[0], 4 * 60);
@@ -180,6 +244,7 @@
 
 void
 release(SegmentedSectionPtr & ptr){
+  assert(verifySection(ptr.i));
   g_sectionSegmentPool.releaseList(relSz(ptr.sz),
 				   ptr.i, 
 				   ptr.p->m_lastSegment);


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