Google Breakpad Issue 417: Handle DWARF that omits function names.

This patch makes sure dump_syms behaves properly when presented with
malformed DWARF data that provides no name for a function. We print a
warning message to stderr, and subsitute "<name omitted>" for the empty
string, so that the "FUNC" record written to the symbol file for the
function is still well-formed. (We may have line number data covering the
function, so it would be a shame to omit the function altogether.)

Unit tests included.
a=jimblandy, r=ted.mielczarek


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@779 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/dwarf_cu_to_module.cc

@@ -428,7 +428,14 @@ void DwarfCUToModule::FuncHandler::Finish() {
     // Create a Module::Function based on the data we've gathered, and
     // add it to the functions_ list.
     Module::Function *func = new Module::Function;
-    func->name = name_;
+    // Malformed DWARF may omit the name, but all Module::Functions must
+    // have names.
+    if (!name_.empty()) {
+      func->name = name_;
+    } else {
+      cu_context_->reporter->UnnamedFunction(offset_);
+      func->name = "<name omitted>";
+    }
     func->address = low_pc_;
     func->size = high_pc_ - low_pc_;
     func->parameter_size = 0;
@@ -543,6 +550,12 @@ void DwarfCUToModule::WarningReporter::UncoveredLine(const Module::Line &line) {
           line.file->name.c_str(), line.number, line.address);
 }
 
+void DwarfCUToModule::WarningReporter::UnnamedFunction(uint64 offset) {
+  CUHeading();
+  fprintf(stderr, "%s: warning: function at offset 0x%" PRIx64 " has no name\n",
+          filename_.c_str(), offset);
+}
+
 DwarfCUToModule::DwarfCUToModule(FileContext *file_context,
                                  LineToModuleFunctor *line_reader,
                                  WarningReporter *reporter)