Merge pull request #10 from embulk/revive-embulk-guess-bzip2-src

Revive src of embulk-guess-bzip2

embulk-guess-bzip2/src/main/java/org/embulk/guess/bzip2/Bzip2GuessPlugin.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2021 The Embulk project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.embulk.guess.bzip2;
+
+import org.embulk.config.ConfigDiff;
+import org.embulk.config.ConfigSource;
+import org.embulk.spi.Buffer;
+import org.embulk.spi.GuessPlugin;
+import org.embulk.util.config.ConfigMapperFactory;
+
+public class Bzip2GuessPlugin implements GuessPlugin {
+    @Override
+    public ConfigDiff guess(final ConfigSource config, final Buffer sample) {
+        final byte[] header = new byte[10];
+        sample.getBytes(0, header, 0, 10);
+
+        final ConfigDiff configDiff = CONFIG_MAPPER_FACTORY.newConfigDiff();
+
+        // magic: BZ
+        // version: 'h' = bzip2
+        // blocksize: 1 .. 9
+        // block magic: 0x314159265359 (6 bytes)
+        if (header[0] == (byte) 'B'
+                && header[1] == (byte) 'Z'
+                && header[2] == (byte) 'h'
+                && (byte) '1' <= header[3] && header[3] <= (byte) '9'
+                && header[4] == (byte) 0x31
+                && header[5] == (byte) 0x41
+                && header[6] == (byte) 0x59
+                && header[7] == (byte) 0x26
+                && header[8] == (byte) 0x53
+                && header[9] == (byte) 0x59) {
+            final ConfigDiff typeBzip2 = CONFIG_MAPPER_FACTORY.newConfigDiff();
+            typeBzip2.set("type", "bzip2");
+            final ConfigDiff[] decoders = new ConfigDiff[1];
+            decoders[0] = typeBzip2;
+            configDiff.set("decoders", decoders);
+        }
+
+        return configDiff;
+    }
+
+    private static final ConfigMapperFactory CONFIG_MAPPER_FACTORY = ConfigMapperFactory.builder().addDefaultModules().build();
+}