Breakpad Linux dumper: Add file comments as required by the style guide.

This also includes some comments I promised Cary Coutant I'd write
about the appropriateness of processing attributes in EndAttributes
calls.

The Google C++ Style Guide requires each file to have an author notice
and a comment explaining the file's general purpose. For the record, I
don't think putting an author notice on the files is a good idea; it's
odd to have the original author retain prominence even if the file has
been heavily edited by others; the version control system answers this
question more accurately. This is only for Style Guide compliance. The
Apache group decided to discourage author annotations, partially for
these reasons:

http://mail-archives.apache.org/mod_mbox/jakarta-jmeter-dev/200402.mbox/%3C4039F65E.7020406@atg.com%3E

a=jimblandy, r=nealsid


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@518 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/dwarf/dwarf2diehandler.cc

@@ -26,7 +26,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Implementation of dwarf2reader::DieDispatcher class.
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dwarf2diehandler.cc: Implement the dwarf2reader::DieDispatcher class.
+// See dwarf2diehandler.h for details.
 
 #include <cassert>
 

src/common/dwarf/dwarf2diehandler.h

@@ -28,6 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // dwarf2reader::CompilationUnit is a simple and direct parser for
 // DWARF data, but its handler interface is not convenient to use.  In
 // particular:
@@ -56,7 +58,7 @@
 //   type DIEs don't.  It would be nice to be able to have separate
 //   handler classes for separate kinds of DIEs, each with the members
 //   appropriate to its role, instead of having one handler class that
-//   needs to hold data for all every DIE type.
+//   needs to hold data for every DIE type.
 //
 // - There should be a separate instance of the appropriate handler
 //   class for each DIE, instead of a single object with tables
@@ -184,6 +186,12 @@ class DIEHandler {
   // same restrictions as the corresponding member functions of
   // dwarf2reader::Dwarf2Handler.
   //
+  // Since DWARF does not specify in what order attributes must
+  // appear, avoid making decisions in these functions that would be
+  // affected by the presence of other attributes. The EndAttributes
+  // function is a more appropriate place for such work, as all the
+  // DIE's attributes have been seen at that point.
+  //
   // The default definitions ignore the values they are passed.
   virtual void ProcessAttributeUnsigned(enum DwarfAttribute attr,
                                         enum DwarfForm form,
@@ -208,6 +216,11 @@ class DIEHandler {
   // child.  If that returns a handler object, we use that to visit
   // the child; otherwise, we skip the child.
   //
+  // This is a good place to make decisions that depend on more than
+  // one attribute. DWARF does not specify in what order attributes
+  // must appear, so only when the EndAttributes function is called
+  // does the handler have a complete picture of the DIE's attributes.
+  //
   // The default definition elects to ignore the DIE's children.
   // You'll need to override this if you override FindChildHandler,
   // but at least the default behavior isn't to pass the children to

src/common/dwarf/dwarf2diehandler_unittest.cc

@@ -28,6 +28,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dwarf2diehander_unittest.cc: Unit tests for google_breakpad::DIEDispatcher.
+
 #include "breakpad_googletest_includes.h"
 
 #include "common/dwarf/dwarf2diehandler.h"

src/common/dwarf/dwarf2reader.cc

@@ -26,6 +26,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Implementation of dwarf2reader::LineInfo and dwarf2reader::CompilationUnit.
+// See dwarf2reader.h for details.
+
 #include <cassert>
 #include <cstdio>
 #include <cstring>

src/common/linux/dump_stabs.cc

@@ -27,6 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // dump_stabs.cc --- implement the DumpStabsHandler class.
 
 #include <cstdarg>

src/common/linux/dump_stabs.h

@@ -29,7 +29,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// dump_stabs.h: A StabsHandler that populates a Module.
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dump_stabs.h: Define the DumpStabsHandler class, which receives
+// STABS debugging information from a parser and adds it to a Breakpad
+// symbol file.
 
 #ifndef COMMON_LINUX_DUMP_STABS_H__
 #define COMMON_LINUX_DUMP_STABS_H__

src/common/linux/dump_stabs_unittest.cc

@@ -27,6 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // dump_stabs_unittest.cc: Unit tests for DumpStabsHandler.
 
 #include <vector>

src/common/linux/dump_symbols.cc

@@ -27,6 +27,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Restructured in 2009 by: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dump_symbols.cc: implement google_breakpad::WriteSymbolFile:
+// Find all the debugging info in a file and dump it as a Breakpad symbol file.
+
 #include <elf.h>
 #include <fcntl.h>
 #include <link.h>

src/common/linux/dump_symbols.h

@@ -26,9 +26,9 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-//
-// dump_symbols.cc: Implements a linux stab debugging format dumper.
-//
+
+// dump_symbols.h: Read debugging information from an ELF file, and write
+// it out as a Breakpad symbol file.
 
 #ifndef COMMON_LINUX_DUMP_SYMBOLS_H__
 #define COMMON_LINUX_DUMP_SYMBOLS_H__

src/common/linux/dwarf_cu_to_module.cc

@@ -27,6 +27,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// Implement the DwarfCUToModule class; see dwarf_cu_to_module.h.
+
 #include <algorithm>
 #include <cassert>
 
@@ -168,6 +172,10 @@ class DwarfCUToModule::GenericDIEHandler: public dwarf2reader::DIEHandler {
   // DIE is a declaration DIE, to be cited by other DIEs'
   // DW_AT_specification attributes, record its enclosing name and
   // unqualified name in the specification table.
+  //
+  // Use this from EndAttributes member functions, not ProcessAttribute*
+  // functions; only the former can be sure that all the DIE's attributes
+  // have been seen.
   string ComputeQualifiedName();
 
   CUContext *cu_context_;
@@ -204,6 +212,11 @@ void DwarfCUToModule::GenericDIEHandler::ProcessAttributeReference(
     uint64 data) {
   switch (attr) {
     case dwarf2reader::DW_AT_specification: {
+      // Find the Specification to which this attribute refers, and
+      // set specification_ appropriately. We could do more processing
+      // here, but it's better to leave the real work to our
+      // EndAttribute member function, at which point we know we have
+      // seen all the DIE's attributes.
       FileContext *file_context = cu_context_->file_context;
       SpecificationByOffset *specifications
           = &file_context->file_private->specifications;

src/common/linux/dwarf_cu_to_module.h

@@ -29,6 +29,13 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// Add DWARF debugging information to a Breakpad symbol file. This
+// file defines the DwarfCUToModule class, which accepts parsed DWARF
+// data and populates a google_breakpad::Module with the results; the
+// Module can then write its contents as a Breakpad symbol file.
+
 #ifndef COMMON_LINUX_DWARF_CU_TO_MODULE_H__
 #define COMMON_LINUX_DWARF_CU_TO_MODULE_H__
 

src/common/linux/dwarf_cu_to_module_unittest.cc

@@ -27,6 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // dwarf_cu_to_module.cc: Unit tests for google_breakpad::DwarfCUToModule.
 
 #include <vector>

src/common/linux/dwarf_line_to_module.cc

@@ -27,6 +27,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// dwarf_line_to_module.cc: Implementation of DwarfLineToModule class.
+// See dwarf_line_to_module.h for details. 
+
 #include "common/linux/dwarf_line_to_module.h"
 
 // Trying to support Windows paths in a reasonable way adds a lot of

src/common/linux/dwarf_line_to_module.h

@@ -29,6 +29,12 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// The DwarfLineToModule class accepts line number information from a
+// DWARF parser and adds it to a google_breakpad::Module. The Module
+// can write that data out as a Breakpad symbol file.
+
 #ifndef COMMON_LINUX_DWARF_LINE_TO_MODULE_H
 #define COMMON_LINUX_DWARF_LINE_TO_MODULE_H
 

src/common/linux/dwarf_line_to_module_unittest.cc

@@ -27,6 +27,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // dwarf_line_to_module.cc: Unit tests for google_breakpad::DwarfLineToModule.
 
 #include "breakpad_googletest_includes.h"

src/common/linux/language.cc

@@ -27,6 +27,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// language.cc: Subclasses and singletons for google_breakpad::Language.
+// See language.h for details.
+
 #include "common/linux/language.h"
 
 namespace google_breakpad {

src/common/linux/language.h

@@ -29,8 +29,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// language.h: defines google_breakpad::Language, providing
-// language-specific operations for use by the dumper.
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// language.h: Define google_breakpad::Language. Instances of
+// subclasses of this class provide language-appropriate operations
+// for the Breakpad symbol dumper.
 
 #ifndef COMMON_LINUX_LANGUAGE_H__
 #define COMMON_LINUX_LANGUAGE_H__

src/common/linux/module.cc

@@ -27,6 +27,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// module.cc: Implement google_breakpad::Module.  See module.h.
+
 #include <cerrno>
 #include <cstring>
 

src/common/linux/module.h

@@ -29,7 +29,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// module.h: defines google_breakpad::Module, for writing breakpad symbol files
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// module.h: Define google_breakpad::Module. A Module holds debugging
+// information, and can write that information out as a Breakpad
+// symbol file.
 
 #ifndef COMMON_LINUX_MODULE_H__
 #define COMMON_LINUX_MODULE_H__

src/common/linux/module_unittest.cc

@@ -27,7 +27,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// module_unittest.cc: Unit tests for google_breakpad::Module
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// module_unittest.cc: Unit tests for google_breakpad::Module.
 
 #include <cerrno>
 #include <cstdio>

src/common/linux/stabs_reader.cc

@@ -26,7 +26,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
 // This file implements the google_breakpad::StabsReader class.
+// See stabs_reader.h.
 
 #include <a.out.h>
 #include <stab.h>

src/common/linux/stabs_reader.h

@@ -28,15 +28,20 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// This file contains definitions related to the STABS reader and
-// its handler interfaces.
-// A description of the STABS debugging format can be found at
-// http://sourceware.org/gdb/current/onlinedocs/stabs_toc.html
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// stabs_reader.h: Define StabsReader, a parser for STABS debugging
+// information. A description of the STABS debugging format can be
+// found at:
+//
+//    http://sourceware.org/gdb/current/onlinedocs/stabs_toc.html
+//
 // The comments here assume you understand the format.
 //
-// This reader assumes that the system's <a.out.h> and <stab.h>
+// This parser assumes that the system's <a.out.h> and <stab.h>
 // headers accurately describe the layout of the STABS data; this code
-// is not cross-platform safe.
+// will not parse STABS data for a system with a different address
+// size or endianness.
 
 #ifndef COMMON_LINUX_STABS_READER_H__
 #define COMMON_LINUX_STABS_READER_H__

src/common/linux/stabs_reader_unittest.cc

@@ -27,7 +27,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// stabs_reader_unittest.cc: Unit tests for StabsReader.
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// stabs_reader_unittest.cc: Unit tests for google_breakpad::StabsReader.
 
 #include <a.out.h>
 #include <cassert>