real.write(data, len);
}
+/* Provide checksumming of a data stream. */
+ChecksumOutputStream::ChecksumOutputStream(OutputStream &o)
+ : real(o)
+{
+}
+
+void ChecksumOutputStream::write_internal(const void *data, size_t len)
+{
+ real.write(data, len);
+ csum.process(data, len);
+}
+
+const uint8_t *ChecksumOutputStream::finish_and_checksum()
+{
+ return csum.checksum();
+}
+
/* Utility functions, for encoding data types to strings. */
string encode_u16(uint16_t val)
{
return s.contents();
}
-SegmentWriter::SegmentWriter(OutputStream &output, struct uuid u)
- : out(output),
+SegmentWriter::SegmentWriter(OutputStream *output, struct uuid u)
+ : raw_out(output),
id(u),
object_stream(NULL)
{
+ /* All output data will be checksummed except the very last few bytes,
+ * which are the checksum itself. */
+ out = new ChecksumOutputStream(*raw_out);
+
/* Write out the segment header first. */
static const char signature[] = "LBSSEG0\n";
- out.write(signature, strlen(signature));
- out.write(id.bytes, sizeof(struct uuid));
+ out->write(signature, strlen(signature));
+ out->write(id.bytes, sizeof(struct uuid));
}
SegmentWriter::~SegmentWriter()
// Write out the object table which gives the sizes and locations of all
// objects, and then add the trailing signature, which indicates the end of
// the segment and gives the offset of the object table.
- int64_t index_offset = out.get_pos();
+ int64_t index_offset = out->get_pos();
for (object_table::const_iterator i = objects.begin();
i != objects.end(); ++i) {
- out.write_s64(i->first);
- out.write_s64(i->second);
+ out->write_s64(i->first);
+ out->write_s64(i->second);
}
static const char signature2[] = "LBSEND";
- out.write(signature2, strlen(signature2));
- out.write_s64(index_offset);
- out.write_u32(objects.size());
+ out->write(signature2, strlen(signature2));
+ out->write_s64(index_offset);
+ out->write_u32(objects.size());
+
+ /* Finally, append a checksum to the end of the file, so that its integrity
+ * (against accidental, not malicious, corruption) can be verified. */
+ const uint8_t *csum = out->finish_and_checksum();
+ raw_out->write(csum, out->checksum_size());
+
+ /* The SegmentWriter takes ownership of the OutputStream it is writing to,
+ * and destroys it automatically when done with the segment. */
+ delete out;
+ delete raw_out;
}
OutputStream *SegmentWriter::new_object()
if (object_stream)
finish_object();
- object_start_offset = out.get_pos();
- object_stream = new WrapperOutputStream(out);
+ object_start_offset = out->get_pos();
+ object_stream = new WrapperOutputStream(*out);
return object_stream;
}
return string(buf);
}
+
+SegmentStore::SegmentStore(const string &path)
+ : directory(path)
+{
+}
+
+SegmentWriter *SegmentStore::new_segment()
+{
+ struct uuid id = SegmentWriter::generate_uuid();
+ string filename = directory + "/" + SegmentWriter::format_uuid(id);
+
+ FILE *f = fopen(filename.c_str(), "wb");
+ if (f == NULL)
+ throw IOException("Unable to open new segment");
+
+ return new SegmentWriter(new FileOutputStream(f), id);
+}