1 files changed, 179 insertions, 0 deletions
diff --git a/src/main/java/com/android/apkzlib/zip/GPFlags.java b/src/main/java/com/android/apkzlib/zip/GPFlags.java
new file mode 100644
index 0000000..40965e8
--- /dev/null
+++ b/src/main/java/com/android/apkzlib/zip/GPFlags.java
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2015 The Android Open Source 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 com.android.apkzlib.zip;
+
+import com.android.annotations.NonNull;
+
+import java.io.IOException;
+
+/**
+ * General purpose bit flags. Contains the encoding of the zip's general purpose bits.
+ *
+ * <p>We don't really care about the method bit(s). These are bits 1 and 2. Here are the values:
+ * <ul>
+ *  <li>0 (00): Normal (-en) compression option was used.
+ *  <li>1 (01): Maximum (-exx/-ex) compression option was used.
+ *  <li>2 (10): Fast (-ef) compression option was used.
+ *  <li>3 (11): Super Fast (-es) compression option was used.
+ * </ul>
+ */
+class GPFlags {
+
+    /**
+     * Is the entry encrypted?
+     */
+    private static final int BIT_ENCRYPTION = 1;
+
+    /**
+     * Has CRC computation been deferred and, therefore, does a data description block exist?
+     */
+    private static final int BIT_DEFERRED_CRC = (1 << 3);
+
+    /**
+     * Is enhanced deflating used?
+     */
+    private static final int BIT_ENHANCED_DEFLATING = (1 << 4);
+
+    /**
+     * Does the entry contain patched data?
+     */
+    private static final int BIT_PATCHED_DATA = (1 << 5);
+
+    /**
+     * Is strong encryption used?
+     */
+    private static final int BIT_STRONG_ENCRYPTION = (1 << 6) | (1 << 13);
+
+    /**
+     * If this bit is set the filename and comment fields for this file must be encoded using UTF-8.
+     */
+    private static final int BIT_EFS  = (1 << 11);
+
+    /**
+     * Unused bits.
+     */
+    private static final int BIT_UNUSED = (1 << 7) | (1 << 8) | (1 << 9) | (1 << 10)
+            | (1 << 14) | (1 << 15);
+    /**
+     * Bit flag value.
+     */
+    private final long mValue;
+
+    /**
+     * Has the CRC computation beeen deferred?
+     */
+    private boolean mDeferredCrc;
+
+    /**
+     * Is the file name encoded in UTF-8?
+     */
+    private boolean mUtf8FileName;
+
+    /**
+     * Creates a new flags object.
+     *
+     * @param value the value of the bit mask
+     */
+    private GPFlags(long value) {
+        mValue = value;
+
+        mDeferredCrc = ((value & BIT_DEFERRED_CRC) != 0);
+        mUtf8FileName = ((value & BIT_EFS) != 0);
+    }
+
+    /**
+     * Obtains the flags value.
+     *
+     * @return the value of the bit mask
+     */
+    public long getValue() {
+        return mValue;
+    }
+
+    /**
+     * Is the CRC computation deferred?
+     *
+     * @return is the CRC computation deferred?
+     */
+    public boolean isDeferredCrc() {
+        return mDeferredCrc;
+    }
+
+    /**
+     * Is the file name encoded in UTF-8?
+     *
+     * @return is the file name encoded in UTF-8?
+     */
+    public boolean isUtf8FileName() {
+        return mUtf8FileName;
+    }
+
+    /**
+     * Creates a new bit mask.
+     *
+     * @param utf8Encoding should UTF-8 encoding be used?
+     * @return the new bit mask
+     */
+    @NonNull
+    static GPFlags make(boolean utf8Encoding) {
+        long flags = 0;
+
+        if (utf8Encoding) {
+            flags |= BIT_EFS;
+        }
+
+        return new GPFlags(flags);
+    }
+
+    /**
+     * Creates the flag information from a byte. This method will also validate that only
+     * supported options are defined in the flag.
+     *
+     * @param bits the bit mask
+     * @return the created flag information
+     * @throws IOException unsupported options are used in the bit mask
+     */
+    @NonNull
+    static GPFlags from(long bits) throws IOException {
+        if ((bits & BIT_ENCRYPTION) != 0) {
+            throw new IOException("Zip files with encrypted of entries not supported.");
+        }
+
+        if ((bits & BIT_ENHANCED_DEFLATING) != 0) {
+            throw new IOException("Enhanced deflating not supported.");
+        }
+
+        if ((bits & BIT_PATCHED_DATA) != 0) {
+            throw new IOException("Compressed patched data not supported.");
+        }
+
+        if ((bits & BIT_STRONG_ENCRYPTION) != 0) {
+            throw new IOException("Strong encryption not supported.");
+        }
+
+        if ((bits & BIT_UNUSED) != 0) {
+            throw new IOException("Unused bits set in directory entry. Weird. I don't know what's "
+                    + "going on.");
+        }
+
+        if ((bits & 0xffffffff00000000L) != 0) {
+            throw new IOException("Unsupported bits after 32.");
+        }
+
+        return new GPFlags(bits);
+    }
+}