[era] parser for the XML format

Makefile.in

@@ -411,7 +411,7 @@ ERA_DUMP_OBJECTS=$(subst .cc,.o,$(ERA_DUMP_SOURCE))
 
 era_dump: $(ERA_DUMP_OBJECTS)  era/era_dump.o
 	@echo "    [LD]  $@"
-	$(V) $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $+ $(LIBS)
+	$(V) $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $+ $(LIBS) $(LIBEXPAT)
 
 ERA_INVALIDATE_SOURCE=\
 	block-cache/block_cache.cc \
@@ -445,7 +445,7 @@ ERA_INVALIDATE_OBJECTS=$(subst .cc,.o,$(ERA_INVALIDATE_SOURCE))
 
 era_invalidate: $(ERA_INVALIDATE_OBJECTS)  era/era_invalidate.o
 	@echo "    [LD]  $@"
-	$(V) $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $+ $(LIBS)
+	$(V) $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $+ $(LIBS) $(LIBEXPAT)
 
 #----------------------------------------------------------------
 

era/xml_format.cc

@@ -1,11 +1,15 @@
 #include "era/xml_format.h"
 
 #include "base/indented_stream.h"
+#include "base/xml_utils.h"
+
+#include <expat.h>
 
 using namespace boost;
 using namespace era;
 using namespace persistent_data;
 using namespace std;
+using namespace xml_utils;
 
 //----------------------------------------------------------------
 
@@ -75,6 +79,56 @@ namespace {
 	private:
 		indented_stream out_;
 	};
+
+	//--------------------------------
+	// Parser
+	//--------------------------------
+	void start_tag(void *data, char const *el, char const **attr) {
+		emitter *e = static_cast<emitter *>(data);
+		attributes a;
+
+		build_attributes(a, attr);
+
+		if (!strcmp(el, "superblock"))
+			e->begin_superblock(get_attr<string>(a, "uuid"),
+					    get_attr<uint32_t>(a, "block_size"),
+					    get_attr<pd::block_address>(a, "nr_blocks"),
+					    get_attr<uint32_t>(a, "current_era"));
+
+		else if (!strcmp(el, "writeset"))
+			e->begin_writeset(get_attr<uint32_t>(a, "era"),
+					  get_attr<uint32_t>(a, "nr_bits"));
+
+		else if (!strcmp(el, "bit"))
+			e->writeset_bit(get_attr<uint32_t>(a, "bit"),
+					get_attr<bool>(a, "value"));
+
+		else if (!strcmp(el, "era_array"))
+			e->begin_era_array();
+
+		else if (!strcmp(el, "era"))
+			e->era(get_attr<pd::block_address>(a, "block"),
+			       get_attr<uint32_t>(a, "era"));
+
+		else
+			throw runtime_error("unknown tag type");
+	}
+
+	void end_tag(void *data, const char *el) {
+		emitter *e = static_cast<emitter *>(data);
+
+		if (!strcmp(el, "superblock"))
+			e->end_superblock();
+
+		else if (!strcmp(el, "writeset"))
+			e->end_writeset();
+
+		else if (!strcmp(el, "era_array"))
+			e->end_era_array();
+
+		else
+			throw runtime_error("unknown tag type");
+	}
 }
 
 //----------------------------------------------------------------
@@ -85,4 +139,32 @@ era::create_xml_emitter(std::ostream &out)
 	return emitter::ptr(new xml_emitter(out));
 }
 
+void
+era::parse_xml(std::istream &in, emitter::ptr e)
+{
+	XML_Parser parser = XML_ParserCreate(NULL);
+	if (!parser)
+		throw runtime_error("couldn't create xml parser");
+
+	XML_SetUserData(parser, e.get());
+	XML_SetElementHandler(parser, start_tag, end_tag);
+
+	while (!in.eof()) {
+		char buffer[4096];
+		in.read(buffer, sizeof(buffer));
+		size_t len = in.gcount();
+		int done = in.eof();
+
+		if (!XML_Parse(parser, buffer, len, done)) {
+			ostringstream out;
+			out << "Parse error at line "
+			    << XML_GetCurrentLineNumber(parser)
+			    << ":\n"
+			    << XML_ErrorString(XML_GetErrorCode(parser))
+			    << endl;
+			throw runtime_error(out.str());
+		}
+	}
+}
+
 //----------------------------------------------------------------