Adding jtar

[gigi.git] / lib / jtar / org / kamranzafar / jtar / Octal.java

diff --git a/lib/jtar/org/kamranzafar/jtar/Octal.java b/lib/jtar/org/kamranzafar/jtar/Octal.java
new file mode 100644 (file)
index 0000000..7a40ea1
--- /dev/null
+++ b/lib/jtar/org/kamranzafar/jtar/Octal.java
@@ -0,0 +1,141 @@
+/**
+ * Copyright 2012 Kamran Zafar 
+ * 
+ * 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.kamranzafar.jtar;
+
+/**
+ * @author Kamran Zafar
+ * 
+ */
+public class Octal {
+
+    /**
+     * Parse an octal string from a header buffer. This is used for the file
+     * permission mode value.
+     * 
+     * @param header
+     *            The header buffer from which to parse.
+     * @param offset
+     *            The offset into the buffer from which to parse.
+     * @param length
+     *            The number of header bytes to parse.
+     * 
+     * @return The long value of the octal string.
+     */
+    public static long parseOctal(byte[] header, int offset, int length) {
+        long result = 0;
+        boolean stillPadding = true;
+
+        int end = offset + length;
+        for (int i = offset; i < end; ++i) {
+            if (header[i] == 0)
+                break;
+
+            if (header[i] == (byte) ' ' || header[i] == '0') {
+                if (stillPadding)
+                    continue;
+
+                if (header[i] == (byte) ' ')
+                    break;
+            }
+
+            stillPadding = false;
+
+            result = ( result << 3 ) + ( header[i] - '0' );
+        }
+
+        return result;
+    }
+
+    /**
+     * Parse an octal integer from a header buffer.
+     * 
+     * @param value
+     * @param buf
+     *            The header buffer from which to parse.
+     * @param offset
+     *            The offset into the buffer from which to parse.
+     * @param length
+     *            The number of header bytes to parse.
+     * 
+     * @return The integer value of the octal bytes.
+     */
+    public static int getOctalBytes(long value, byte[] buf, int offset, int length) {
+        int idx = length - 1;
+
+        buf[offset + idx] = 0;
+        --idx;
+        buf[offset + idx] = (byte) ' ';
+        --idx;
+
+        if (value == 0) {
+            buf[offset + idx] = (byte) '0';
+            --idx;
+        } else {
+            for (long val = value; idx >= 0 && val > 0; --idx) {
+                buf[offset + idx] = (byte) ( (byte) '0' + (byte) ( val & 7 ) );
+                val = val >> 3;
+            }
+        }
+
+        for (; idx >= 0; --idx) {
+            buf[offset + idx] = (byte) ' ';
+        }
+
+        return offset + length;
+    }
+
+    /**
+     * Parse the checksum octal integer from a header buffer.
+     * 
+     * @param value
+     * @param buf
+     *            The header buffer from which to parse.
+     * @param offset
+     *            The offset into the buffer from which to parse.
+     * @param length
+     *            The number of header bytes to parse.
+     * @return The integer value of the entry's checksum.
+     */
+    public static int getCheckSumOctalBytes(long value, byte[] buf, int offset, int length) {
+        getOctalBytes( value, buf, offset, length );
+        buf[offset + length - 1] = (byte) ' ';
+        buf[offset + length - 2] = 0;
+        return offset + length;
+    }
+
+    /**
+     * Parse an octal long integer from a header buffer.
+     * 
+     * @param value
+     * @param buf
+     *            The header buffer from which to parse.
+     * @param offset
+     *            The offset into the buffer from which to parse.
+     * @param length
+     *            The number of header bytes to parse.
+     * 
+     * @return The long value of the octal bytes.
+     */
+    public static int getLongOctalBytes(long value, byte[] buf, int offset, int length) {
+        byte[] temp = new byte[length + 1];
+        getOctalBytes( value, temp, 0, length + 1 );
+        System.arraycopy( temp, 0, buf, offset, length );
+        return offset + length;
+    }
+
+}