make dbcheck support new doclen format

write a simple test for the change in dbcheck

xapian-core/backends/brass/brass_dbcheck.cc

@@ -215,15 +215,100 @@ check_brass_table(const char * tablename, string filename,
 		}
 		lastdid += did;
 		bool bad = false;
+
+
+		bool is_in_block = false;
+		unsigned len_info = 0;
+		unsigned bytes_info = 0;
+
 		while (true) {
-		    Xapian::termcount doclen;
-		    if (!unpack_uint(&pos, end, &doclen)) {
-			if (out)
-			    *out << "Failed to unpack doclen" << endl;
-			++errors;
-			bad = true;
-			break;
-		    }
+
+			Xapian::termcount doclen = 0;
+			if ( is_in_block && len_info )
+			{
+				did++;
+				len_info--;
+				if ( len_info == 0 )
+				{
+					is_in_block = false;
+				}
+				if( !unpack_uint_in_bytes( &pos, bytes_info, &doclen ) )
+				{
+					if (out)
+						*out << "Failed to unpack doclen" << endl;
+					++errors;
+					bad = true;
+					break;
+				}
+			}
+			else
+			{
+				Xapian::docid incre_did = 0;
+				if( !unpack_uint( &pos, end, &incre_did ) )
+				{
+					if (out)
+						*out << "Failed to unpack docid increase" << endl;
+					++errors;
+					bad = true;
+					break;
+				}
+				if ( incre_did != (Xapian::docid)-1 )
+				{
+					is_in_block = false;
+					did += incre_did;
+					if( !unpack_uint_in_bytes( &pos, bytes_info, &doclen ) )
+					{
+						if (out)
+							*out << "Failed to unpack doclen" << endl;
+						++errors;
+						bad = true;
+						break;
+					}
+				}
+				else
+				{
+					is_in_block = true;
+					if( !unpack_uint( &pos, end, &incre_did ) )
+					{
+						if (out)
+							*out << "Failed to unpack docid increase" << endl;
+						++errors;
+						bad = true;
+						break;
+					}
+					if( !unpack_uint_in_bytes( &pos, 2, &len_info ) )
+					{
+						if (out)
+							*out << "Failed to unpack length info of fixed width doclen chunk" << endl;
+						++errors;
+						bad = true;
+						break;
+					}
+					if( !unpack_uint_in_bytes( &pos, 1, &bytes_info ) )
+					{
+						if (out)
+							*out << "Failed to unpack bytes info of fixed width doclen chunk" << endl;
+						++errors;
+						bad = true;
+						break;
+					}
+					did += incre_did;
+					if( !unpack_uint_in_bytes( &pos, bytes_info, &doclen ) )
+					{
+						if (out)
+							*out << "Failed to unpack doclen" << endl;
+						++errors;
+						bad = true;
+						break;
+					}
+					len_info--;
+					if ( len_info == 0 )
+					{
+						is_in_block = false;
+					}
+				}
+
+			}
 
 		    if (did > db_last_docid) {
 			if (out)
@@ -252,16 +337,6 @@ check_brass_table(const char * tablename, string filename,
 
 		    if (pos == end) break;
 
-		    Xapian::docid inc;
-		    if (!unpack_uint(&pos, end, &inc)) {
-			if (out)
-			    *out << "Failed to unpack docid increase" << endl;
-			++errors;
-			bad = true;
-			break;
-		    }
-		    ++inc;
-		    did += inc;
 		    if (did > lastdid) {
 			if (out)
 			    *out << "docid " << did << " > last docid "

xapian-core/tests/api_wrdb.cc

@@ -1880,6 +1880,33 @@ DEFINE_TESTCASE(cursordelbug1, brass || chert) {
     return Xapian::Database::check(db_path) == 0;
 }
 
+/*A test for brass_dbcheck.cc modified for fixed width brass doclen chunk.
+ *It just use the database for cursordelbug1*/
+DEFINE_TESTCASE(fixedwidthdoclenchunk, brass )
+{
+	static const int terms[] = { 219, 221, 222, 223, 224, 225, 226 };
+	static const int copies[] = { 74, 116, 199, 21, 45, 155, 189 };
+
+	Xapian::WritableDatabase db;
+	db = get_named_writable_database("cursordelbug1", string());
+
+	for (size_t i = 0; i < sizeof(terms) / sizeof(terms[0]); ++i) {
+		Xapian::Document doc;
+		doc.add_term("XC" + str(terms[i]));
+		doc.add_term("XTabc");
+		doc.add_term("XAdef");
+		doc.add_term("XRghi");
+		doc.add_term("XYabc");
+		size_t c = copies[i];
+		while (c--) db.add_document(doc);
+	}
+
+	db.commit();
+
+	const string & db_path = get_named_writable_database_path("cursordelbug1");
+	return Xapian::Database::check(db_path) == 0;
+}
+
 /** Helper function for modifyvalues1.
  *
  * Check that the values stored in the database match */