From f6ce26fb027d2bad5a07076f04f1b2e9cc924dec Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmolenda@apple.com>
Date: Wed, 10 Apr 2013 05:58:57 +0000
Subject: [PATCH] When ObjectFileMachO::ParseSections() notices that it has a
 truncated file, zero out the SectionList so we don't try to do anything with
 this file.  Currently we end up crashing later in the debug session when we
 read past the end of the file -- this at least gets us closer with something
 like ProcessMachCore printing "error: core file has no sections".
 <rdar://problem/13468295>

llvm-svn: 179152
---
 lldb/include/lldb/Core/Section.h              |  6 +++++
 .../ObjectFile/Mach-O/ObjectFileMachO.cpp     | 26 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/lldb/include/lldb/Core/Section.h b/lldb/include/lldb/Core/Section.h
index 153a2e51a3ac..cc03aac2b107 100644
--- a/lldb/include/lldb/Core/Section.h
+++ b/lldb/include/lldb/Core/Section.h
@@ -88,6 +88,12 @@ public:
     void
     Finalize ();
 
+    void
+    Clear ()
+    {
+        m_sections.clear();
+    }
+
 protected:
     collection  m_sections;
 };
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 36bd9292ba94..b3a81a195e92 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -15,6 +15,7 @@
 #include "lldb/lldb-private-log.h"
 #include "lldb/Core/ArchSpec.h"
 #include "lldb/Core/DataBuffer.h"
+#include "lldb/Core/Debugger.h"
 #include "lldb/Core/FileSpecList.h"
 #include "lldb/Core/Log.h"
 #include "lldb/Core/Module.h"
@@ -836,6 +837,31 @@ ObjectFileMachO::ParseSections ()
                 load_cmd.vmsize = m_data.GetAddress(&offset);
                 load_cmd.fileoff = m_data.GetAddress(&offset);
                 load_cmd.filesize = m_data.GetAddress(&offset);
+                if (m_length != 0 && load_cmd.filesize != 0)
+                {
+                    if (load_cmd.fileoff + load_cmd.filesize > m_length)
+                    {
+                        // We have a load command that says it extends past the end of hte file.  This is likely
+                        // a corrupt file.  We don't have any way to return an error condition here (this method
+                        // was likely invokved from something like ObjectFile::GetSectionList()) -- all we can do
+                        // is null out the SectionList vector and if a process has been set up, dump a message
+                        // to stdout.  The most common case here is core file debugging with a truncated file - and
+                        // in that case we don't have a Process yet so nothing will be printed.  Not really ideal;
+                        // the ObjectFile needs some way of reporting an error message for methods like GetSectionList
+                        // which fail.
+                        ProcessSP process_sp (m_process_wp.lock());
+                        if (process_sp)
+                        {
+                            Stream *s = &process_sp->GetTarget().GetDebugger().GetOutputStream();
+                            if (s)
+                            {
+                                s->Printf ("Corrupt/invalid Mach-O object file -- a load command extends past the end of the file.\n");
+                            }
+                        }
+                        m_sections_ap->Clear();
+                        return 0;
+                    }
+                }
                 if (m_data.GetU32(&offset, &load_cmd.maxprot, 4))
                 {