From 778c379f889c1ba23684594e7a0386930f85c1f0 Mon Sep 17 00:00:00 2001
From: Oleg Krasilnikov <oleg.krasilnikov@intel.com>
Date: Thu, 31 Aug 2006 10:25:42 +0000
Subject: [PATCH] From: Davasam, Sunil K Sent: Monday, August 28, 2006 9:57 PM
 To: Treggiari, Leo; Sennikovsky, Mikhail Cc: Monteleone, Robert; Davasam,
 Sunil K Subject: Issue with CDT dwarf reader..
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Hi,

            I found an issue with CDT dwarf reader. The method ‘read_unsigned_leb128()’ contains a bug. Due to this bug, if the control reaches to this method, it goes in infinite loop and Eclipse hangs.  This bug is exposed during the Intel Compiler integration testing into Eclipse/CDT. If the user tries to expand the debug binary (built by Intel Compiler) in ‘C/C++ Projects view’, Eclipse hangs. Even though I found this problem during the Intel Compiler integration testing, I think that the problem will appear when ever the control reaches this method.



According to DWARF standard, algorithm to decode an unsigned LEB128 number:

result = 0;

shift = 0;

size = number of bits in signed integer;

while(true)

{

byte = next byte in input;

result |= (low order 7 bits of byte << shift);

shift += 7;

/* sign bit of byte is second high order bit (0x40) */

if (high order bit of byte == 0)

break;

}



if ((shift <size) && (sign bit of byte is set))

/* sign extend */

result |= - (1 << shift);



--



            But in the implementation, it is reading the same bits again and again.  Here I attached a patch that fixes the problem. Please check in the patch to CDT. I hope you have permission to check in to cdt core package.



The method is defined in the following location.



Method:    read_unsigned_leb128

Line     :    213

File     :     utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java

Package:  org.eclipse.cdt.core



Thanks & Regards,

Sunil
---
 .../utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java
index 8db60e4c0c7..0afca3dbba1 100644
--- a/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java
+++ b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/utils/debug/dwarf/DwarfReader.java
@@ -218,7 +218,7 @@ public class DwarfReader extends Dwarf implements ISymbolReader {
 
 		m_leb128Size = 0;
 		while (true) {
-			b = (short) data[offset];
+			b = (short) data[offset++];
 			if (b == -1)
 				break; //throw new IOException("no more data");
 			m_leb128Size++;