a new java implementation of base64 for android-common (b7cc1ec7) · Commits · e / os / android_frameworks_native-old

common/java/com/android/common/Base64.java

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		/*
		* Copyright (C) 2010 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.common;

		/**
		* Utilities for encoding and decoding the Base64 encoding. See RFCs
		* 2045 and 3548.
		*/
		public class Base64 {
		/**
		* Encoder flag bit to indicate you want the padding '='
		* characters at the end (if any) to be omitted.
		*/
		public static final int NO_PADDING = 1;

		/**
		* Encoder flag bit to indicate you want all line terminators to
		* be omitted (ie, the output will be on one long line).
		*/
		public static final int NO_WRAP = 2;

		/**
		* Encoder flag bit to indicate you want lines to be ended with
		* CRLF instead of just LF.
		*/
		public static final int CRLF = 4;

		/**
		* Encoder/decoder flag bit to indicate using the "web safe"
		* variant of Base64 (see RFC 3548 section 4) where '-' and '_'
		* are used in place of '+' and '/'.
		*/
		public static final int WEB_SAFE = 8;

		/**
		* Lookup table for turning bytes into their position in the
		* Base64 alphabet.
		*/
		private static final int DECODE[] = {
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
		52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
		-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
		15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
		-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
		41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		};

		/**
		* Decode lookup table for the "web safe" variant (RFC 3548
		* sec. 4) where - and _ replace + and /.
		*/
		private static final int DECODE_WEBSAFE[] = {
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
		52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
		-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
		15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,
		-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
		41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		};

		/** Non-data values in the DECODE arrays. */
		private static final int SKIP = -1;
		private static final int EQUALS = -2;

		/**
		* Decode the Base64-encoded data in input and return the data in
		* a new byte array.
		*
		* The padding '=' characters at the end are considered optional, but
		* if any are present, there must be the correct number of them.
		*
		* @param input the input String to decode, which is converted to
		* bytes using the default charset
		* @param flags controls certain features of the decoded output.
		* Passing 0 to decode standard Base64.
		*
		* @throws IllegalArgumentException if the input contains
		* incorrect padding
		*/
		public static byte[] decode(String str, int flags) {
		return decode(str.getBytes(), flags);
		}

		/**
		* Decode the Base64-encoded data in input and return the data in
		* a new byte array.
		*
		* The padding '=' characters at the end are considered optional, but
		* if any are present, there must be the correct number of them.
		*
		* @param input the input array to decode
		* @param flags controls certain features of the decoded output.
		* Passing 0 to decode standard Base64.
		*
		* @throws IllegalArgumentException if the input contains
		* incorrect padding
		*/
		public static byte[] decode(byte[] input, int flags) {
		return decode(input, 0, input.length, flags);
		}

		/**
		* Decode the Base64-encoded data in input and return the data in
		* a new byte array.
		*
		* The padding '=' characters at the end are considered optional, but
		* if any are present, there must be the correct number of them.
		*
		* @param input the data to decode
		* @param offset the position within the input array at which to start
		* @param len the number of bytes of input to decode
		* @param flags controls certain features of the decoded output.
		* Passing 0 to decode standard Base64.
		*
		* @throws IllegalArgumentException if the input contains
		* incorrect padding
		*/
		public static byte[] decode(byte[] input, int offset, int len, int flags) {
		int p = offset;
		// Allocate space for the most data the input could represent.
		// (It could contain less if it contains whitespace, etc.)
		byte[] output = new byte[len*3/4];
		len += offset;
		int op = 0;

		final int[] decode = ((flags & WEB_SAFE) == 0) ?
		DECODE : DECODE_WEBSAFE;

		int state = 0;
		int value = 0;

		while (p < len) {

		// Try the fast path: we're starting a new tuple and the
		// next four bytes of the input stream are all data
		// bytes. This corresponds to going through states
		// 0-1-2-3-0. We expect to use this method for most of
		// the data.
		//
		// If any of the next four bytes of input are non-data
		// (whitespace, etc.), value will end up negative. (All
		// the non-data values in decode are small negative
		// numbers, so shifting any of them up and or'ing them
		// together will result in a value with its top bit set.)
		//
		// You can remove this whole block and the output should
		// be the same, just slower.
		if (state == 0 && p+4 <= len &&
		(value = ((decode[input[p] & 0xff] << 18) \|
		(decode[input[p+1] & 0xff] << 12) \|
		(decode[input[p+2] & 0xff] << 6) \|
		(decode[input[p+3] & 0xff]))) >= 0) {
		output[op+2] = (byte) value;
		output[op+1] = (byte) (value >> 8);
		output[op] = (byte) (value >> 16);
		op += 3;
		p += 4;
		continue;
		}

		// The fast path isn't available -- either we've read a
		// partial tuple, or the next four input bytes aren't all
		// data, or whatever. Fall back to the slower state
		// machine implementation.
		//
		// States 0-3 are reading through the next input tuple.
		// State 4 is having read one '=' and expecting exactly
		// one more.
		// State 5 is expecting no more data or padding characters
		// in the input.

		int d = decode[input[p++] & 0xff];

		switch (state) {
		case 0:
		if (d >= 0) {
		value = d;
		++state;
		} else if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;

		case 1:
		if (d >= 0) {
		value = (value << 6) \| d;
		++state;
		} else if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;

		case 2:
		if (d >= 0) {
		value = (value << 6) \| d;
		++state;
		} else if (d == EQUALS) {
		// Emit the last (partial) output tuple;
		// expect exactly one more padding character.
		output[op++] = (byte) (value >> 4);
		state = 4;
		} else if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;

		case 3:
		if (d >= 0) {
		// Emit the output triple and return to state 0.
		value = (value << 6) \| d;
		output[op+2] = (byte) value;
		output[op+1] = (byte) (value >> 8);
		output[op] = (byte) (value >> 16);
		op += 3;
		state = 0;
		} else if (d == EQUALS) {
		// Emit the last (partial) output tuple;
		// expect no further data or padding characters.
		output[op+1] = (byte) (value >> 2);
		output[op] = (byte) (value >> 10);
		op += 2;
		state = 5;
		} else if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;

		case 4:
		if (d == EQUALS) {
		++state;
		} else if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;

		case 5:
		if (d != SKIP) {
		throw new IllegalArgumentException("bad base-64");
		}
		break;
		}
		}

		// Done reading input. Now figure out where we are left in
		// the state machine and finish up.

		switch (state) {
		case 0:
		// Output length is a multiple of three. Fine.
		break;
		case 1:
		// Read one extra input byte, which isn't enough to
		// make another output byte. Illegal.
		throw new IllegalArgumentException("bad base-64");
		case 2:
		// Read two extra input bytes, enough to emit 1 more
		// output byte. Fine.
		output[op++] = (byte) (value >> 4);
		break;
		case 3:
		// Read three extra input bytes, enough to emit 2 more
		// output bytes. Fine.
		output[op+1] = (byte) (value >> 2);
		output[op] = (byte) (value >> 10);
		op += 2;
		break;
		case 4:
		// Read one padding '=' when we expected 2. Illegal.
		throw new IllegalArgumentException("bad base-64");
		case 5:
		// Read all the padding '='s we expected and no more.
		// Fine.
		break;
		}

		// Maybe we got lucky and allocated exactly enough output space.
		if (op == output.length) {
		return output;
		}

		// Need to shorten the array, so allocate a new one of the
		// right size and copy.
		byte[] temp = new byte[op];
		System.arraycopy(output, 0, temp, 0, op);
		return temp;
		}

		/**
		* Emit a new line every this many output tuples. Corresponds to
		* a 76-character line length (the maximum allowable according to
		* RFC 2045).
		*/
		private static final int LINE_GROUPS = 19;

		/**
		* Lookup table for turning Base64 alphabet positions (6 bits)
		* into output bytes.
		*/
		private static final byte ENCODE[] = {
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
		'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
		'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
		'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
		'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
		'w', 'x', 'y', 'z', '0', '1', '2', '3',
		'4', '5', '6', '7', '8', '9', '+', '/',
		};

		/**
		* Lookup table for turning Base64 alphabet positions (6 bits)
		* into output bytes.
		*/
		private static final byte ENCODE_WEBSAFE[] = {
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
		'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
		'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
		'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
		'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
		'w', 'x', 'y', 'z', '0', '1', '2', '3',
		'4', '5', '6', '7', '8', '9', '-', '_',
		};

		/**
		* Base64-encode the given data and return a newly allocated
		* String with the result.
		*
		* @param input the data to encode
		* @param flags controls certain features of the encoded output.
		* Passing 0 results in output that adheres to RFC
		* 2045.
		*/
		public static String encodeString(byte[] input, int flags) {
		return new String(encode(input, flags));
		}

		/**
		* Base64-encode the given data and return a newly allocated
		* String with the result.
		*
		* @param input the data to encode
		* @param offset the position within the input array at which to
		* start
		* @param len the number of bytes of input to encode
		* @param flags controls certain features of the encoded output.
		* Passing 0 results in output that adheres to RFC
		* 2045.
		*/
		public static String encodeString(byte[] input, int offset, int len, int flags) {
		return new String(encode(input, offset, len, flags));
		}

		/**
		* Base64-encode the given data and return a newly allocated
		* byte[] with the result.
		*
		* @param input the data to encode
		* @param flags controls certain features of the encoded output.
		* Passing 0 results in output that adheres to RFC
		* 2045.
		*/
		public static byte[] encode(byte[] input, int flags) {
		return encode(input, 0, input.length, flags);
		}

		/**
		* Base64-encode the given data and return a newly allocated
		* byte[] with the result.
		*
		* @param input the data to encode
		* @param offset the position within the input array at which to
		* start
		* @param len the number of bytes of input to encode
		* @param flags controls certain features of the encoded output.
		* Passing 0 results in output that adheres to RFC
		* 2045.
		*/
		public static byte[] encode(byte[] input, int offset, int len, int flags) {
		final boolean do_padding = (flags & NO_PADDING) == 0;
		final boolean do_newline = (flags & NO_WRAP) == 0;
		final boolean do_cr = (flags & CRLF) != 0;

		final byte[] encode = ((flags & WEB_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;

		// Compute the exact length of the array we will produce.
		int output_len = len / 3 * 4;

		// Account for the tail of the data and the padding bytes, if any.
		if (do_padding) {
		if (len % 3 > 0) {
		output_len += 4;
		}
		} else {
		switch (len % 3) {
		case 0: break;
		case 1: output_len += 2; break;
		case 2: output_len += 3; break;
		}
		}

		// Account for the newlines, if any.
		if (do_newline && len > 0) {
		output_len += (((len-1) / (3 * LINE_GROUPS)) + 1) * (do_cr ? 2 : 1);
		}

		int op = 0;
		byte[] output = new byte[output_len];

		// The main loop, turning 3 input bytes into 4 output bytes on
		// each iteration.
		int count = do_newline ? LINE_GROUPS : -1;
		int p = offset;
		len += offset;
		while (p+3 <= len) {
		int v = ((input[p++] & 0xff) << 16) \|
		((input[p++] & 0xff) << 8) \|
		(input[p++] & 0xff);
		output[op++] = encode[(v >> 18) & 0x3f];
		output[op++] = encode[(v >> 12) & 0x3f];
		output[op++] = encode[(v >> 6) & 0x3f];
		output[op++] = encode[v & 0x3f];
		if (--count == 0) {
		if (do_cr) output[op++] = '\r';
		output[op++] = '\n';
		count = LINE_GROUPS;
		}
		}

		// Finish up the tail of the input.
		if (p == len-1) {
		int v = (input[p] & 0xff) << 4;
		output[op++] = encode[(v >> 6) & 0x3f];
		output[op++] = encode[v & 0x3f];
		if (do_padding) {
		output[op++] = '=';
		output[op++] = '=';
		}
		if (do_newline) {
		if (do_cr) output[op++] = '\r';
		output[op++] = '\n';
		}
		} else if (p == len-2) {
		int v = ((input[p] & 0xff) << 10) \| ((input[p+1] & 0xff) << 2);
		output[op++] = encode[(v >> 12) & 0x3f];
		output[op++] = encode[(v >> 6) & 0x3f];
		output[op++] = encode[v & 0x3f];
		if (do_padding) {
		output[op++] = '=';
		}
		if (do_newline) {
		if (do_cr) output[op++] = '\r';
		output[op++] = '\n';
		}
		} else if (do_newline && op > 0 && count != LINE_GROUPS) {
		if (do_cr) output[op++] = '\r';
		output[op++] = '\n';
		}

		assert op == output.length;
		return output;
		}
		}

common/tests/src/com/android/common/Base64Test.java

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