thin-provisioning-tools/caching/xml_format.cc

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2013-09-11 16:10:46 +05:30
#include "caching/xml_format.h"
#include <boost/lexical_cast.hpp>
#include <expat.h>
using namespace boost;
using namespace caching;
using namespace persistent_data;
using namespace std;
//----------------------------------------------------------------
namespace {
// base64 encoding?
string encode(string const &data) {
return data;
}
string decode(string const &data) {
return data;
}
//--------------------------------
// Emitter
//--------------------------------
class xml_emitter : public emitter {
public:
xml_emitter(ostream &out)
: out_(out),
indent_(0) {
}
void begin_superblock(std::string const &uuid,
block_address block_size,
block_address nr_cache_blocks,
std::string const &policy) {
indent();
out_ << "<superblock uuid=\"" << uuid << "\""
<< " block_size=\"" << block_size << "\""
<< " nr_cache_blocks=\"" << nr_cache_blocks << "\""
<< " policy=\"" << policy << "\">" << endl;
inc();
}
virtual void end_superblock() {
dec();
indent();
out_ << "</superblock>" << endl;
}
virtual void begin_mappings() {
indent();
out_ << "<mappings>" << endl;
inc();
}
virtual void end_mappings() {
dec();
indent();
out_ << "</mappings>" << endl;
}
virtual void mapping(block_address cblock,
block_address oblock,
bool dirty) {
indent();
out_ << "<mapping"
<< " cache_block=\"" << cblock << "\""
<< " origin_block=\"" << oblock << "\""
<< " dirty=\"" << as_truth(dirty) << "\""
<< "/>" << endl;
}
virtual void begin_hints() {
indent();
out_ << "<hints>" << endl;
inc();
}
virtual void end_hints() {
dec();
indent();
out_ << "</hints>" << endl;
}
virtual void hint(block_address cblock,
std::string const &data) {
out_ << "<hint"
<< " cache_block=\"" << cblock << "\""
<< " data=\"" << encode(data) << "\""
<< ">" << endl;
}
private:
string as_truth(bool v) const {
return v ? "true" : "false";
}
// FIXME: factor out a common class with the thin_provisioning emitter
void indent() {
for (unsigned i = 0; i < indent_ * 2; i++)
out_ << ' ';
}
void inc() {
indent_++;
}
void dec() {
indent_--;
}
ostream &out_;
unsigned indent_;
};
//--------------------------------
// Parser
//--------------------------------
// FIXME: factor out common code with thinp one
typedef std::map<string, string> attributes;
void build_attributes(attributes &a, char const **attr) {
while (*attr) {
char const *key = *attr;
attr++;
if (!*attr) {
ostringstream out;
out << "No value given for xml attribute: " << key;
throw runtime_error(out.str());
}
char const *value = *attr;
a.insert(make_pair(string(key), string(value)));
attr++;
}
}
template <typename T>
T get_attr(attributes const &attr, string const &key) {
attributes::const_iterator it = attr.find(key);
if (it == attr.end()) {
ostringstream out;
out << "could not find attribute: " << key;
throw runtime_error(out.str());
}
return boost::lexical_cast<T>(it->second);
}
template <typename T>
boost::optional<T> get_opt_attr(attributes const &attr, string const &key) {
typedef boost::optional<T> rtype;
attributes::const_iterator it = attr.find(key);
if (it == attr.end())
return rtype();
return rtype(boost::lexical_cast<T>(it->second));
}
void parse_superblock(emitter *e, attributes const &attr) {
e->begin_superblock(get_attr<string>(attr, "uuid"),
get_attr<uint64_t>(attr, "block_size"),
get_attr<uint64_t>(attr, "nr_cache_blocks"),
get_attr<string>(attr, "policy"));
}
bool to_bool(string const &str) {
if (str == "true")
return true;
else if (str == "false")
return false;
throw runtime_error("bad boolean value");
}
void parse_mapping(emitter *e, attributes const &attr) {
e->mapping(get_attr<uint64_t>(attr, "cache_block"),
get_attr<uint64_t>(attr, "origin_block"),
to_bool(get_attr<string>(attr, "dirty")));
}
void parse_hint(emitter *e, attributes const &attr) {
e->hint(get_attr<uint64_t>(attr, "cache_block"),
decode(get_attr<string>(attr, "data")));
}
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"))
parse_superblock(e, a);
else if (!strcmp(el, "mappings"))
e->begin_mappings();
else if (!strcmp(el, "mapping"))
parse_mapping(e, a);
else if (!strcmp(el, "hints"))
e->begin_hints();
else if (!strcmp(el, "hint"))
parse_hint(e, a);
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, "mappings"))
e->end_mappings();
else if (!strcmp(el, "mapping"))
// do nothing
;
else if (!strcmp(el, "hints"))
e->end_hints();
else if (!strcmp(el, "hint"))
// do nothing
;
else
throw runtime_error("unknown tag close");
}
}
//----------------------------------------------------------------
caching::emitter::ptr
caching::create_xml_emitter(ostream &out)
{
return emitter::ptr(new xml_emitter(out));
}
void
caching::parse_xml(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());
}
}
}
//----------------------------------------------------------------