gold patch committed: Don't crash on empty warning section

[Ian Lance Taylor <ian at airs dot com>]

I committed this patch to gold to avoid crashing on an empty warning
section.  In that case we take the name of the section to be the
warning to give.

Ian


2009-06-23  Ian Lance Taylor  <iant@google.com>

	PR 10147
	* object.cc (Object::section_contents): Don't try to get a view if
	the section has length zero.
	(Object::handle_gnu_warning_section): If the section is empty, use
	the name of the section as the warning.


Index: object.cc
===================================================================
RCS file: /cvs/src/src/gold/object.cc,v
retrieving revision 1.94
diff -u -r1.94 object.cc
--- object.cc	22 Jun 2009 06:51:53 -0000	1.94
+++ object.cc	23 Jun 2009 07:17:31 -0000
@@ -170,6 +170,11 @@
 {
   Location loc(this->do_section_contents(shndx));
   *plen = convert_to_section_size_type(loc.data_size);
+  if (*plen == 0)
+    {
+      static const unsigned char empty[1] = { '\0' };
+      return empty;
+    }
   return this->get_view(loc.file_offset, *plen, true, cache);
 }
 
@@ -226,6 +231,12 @@
       section_size_type len;
       const unsigned char* contents = this->section_contents(shndx, &len,
 							     false);
+      if (len == 0)
+	{
+	  const char* warning = name + warn_prefix_len;
+	  contents = reinterpret_cast<const unsigned char*>(warning);
+	  len = strlen(warning);
+	}
       std::string warning(reinterpret_cast<const char*>(contents), len);
       symtab->add_warning(name + warn_prefix_len, this, warning);
       return true;