com.helger.commons.base64.Base64InputStream Maven / Gradle / Ivy
Show all versions of ph-commons Show documentation
/*
* Copyright (C) 2014-2022 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* 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.helger.commons.base64;
import java.io.IOException;
import java.io.InputStream;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.NotThreadSafe;
import com.helger.commons.io.stream.WrappedInputStream;
/**
* A {@link Base64InputStream} will read data from another
* InputStream, given in the constructor, and encode/decode to/from
* Base64 notation on the fly.
*
* @see Base64
* @since 1.3
*/
@NotThreadSafe
public class Base64InputStream extends WrappedInputStream
{
// Encoding or decoding
private final boolean m_bEncode;
// Current position in the buffer
private int m_nPosition;
// Small buffer holding converted data
private final byte [] m_aBuffer;
// Length of buffer (3 or 4)
private final int m_nBufferLength;
// Number of meaningful bytes in the buffer
private int m_nNumSigBytes;
private int m_nLineLength;
// Break lines at less than 80 characters
private final boolean m_bBreakLines;
// Record options used to create the stream.
private final int m_nOptions;
// Local copies to avoid extra method calls
private final byte [] m_aDecodabet;
/**
* Constructs a {@link Base64InputStream} in DECODE mode.
*
* @param pin
* the InputStream from which to read data.
* @since 1.3
*/
public Base64InputStream (@Nonnull final InputStream pin)
{
this (pin, Base64.DECODE);
}
/**
* Constructs a {@link Base64InputStream} in either ENCODE or DECODE mode.
*
* Valid options:
*
*
* ENCODE or DECODE: Encode or Decode as data is read.
* DO_BREAK_LINES: break lines at 76 characters
* (only meaningful when encoding)
*
*
* Example: new Base64.InputStream( in, Base64.DECODE )
*
* @param aIS
* the InputStream from which to read data.
* @param nOptions
* Specified options
* @see Base64#ENCODE
* @see Base64#DECODE
* @see Base64#DO_BREAK_LINES
* @since 2.0
*/
public Base64InputStream (@Nonnull final InputStream aIS, final int nOptions)
{
super (aIS);
m_nOptions = nOptions;
m_bBreakLines = (nOptions & Base64.DO_BREAK_LINES) > 0;
m_bEncode = (nOptions & Base64.ENCODE) > 0;
m_nBufferLength = m_bEncode ? 4 : 3;
m_aBuffer = new byte [m_nBufferLength];
m_nPosition = -1;
m_nLineLength = 0;
m_aDecodabet = Base64._getDecodabet (nOptions);
}
/**
* Reads enough of the input stream to convert to/from Base64 and returns the
* next byte.
*
* @return next byte
* @since 1.3
*/
@Override
public int read () throws IOException
{
// Do we need to get data?
if (m_nPosition < 0)
{
if (m_bEncode)
{
final byte [] b3 = new byte [3];
int numBinaryBytes = 0;
for (int i = 0; i < 3; i++)
{
final int b = in.read ();
// If end of stream, b is -1.
if (b < 0)
break;
b3[i] = (byte) b;
numBinaryBytes++;
}
if (numBinaryBytes > 0)
{
Base64._encode3to4 (b3, 0, numBinaryBytes, m_aBuffer, 0, m_nOptions);
m_nPosition = 0;
m_nNumSigBytes = 4;
}
else
{
return -1; // Must be end of stream
}
}
else
{
// Else decoding
final byte [] b4 = new byte [4];
int i;
for (i = 0; i < 4; i++)
{
// Read four "meaningful" bytes:
int b;
do
{
b = in.read ();
} while (b >= 0 && m_aDecodabet[b & 0x7f] <= Base64.WHITE_SPACE_ENC);
if (b < 0)
{
// Reads a -1 if end of stream
break;
}
b4[i] = (byte) b;
}
if (i == 4)
{
m_nNumSigBytes = Base64._decode4to3 (b4, 0, m_aBuffer, 0, m_nOptions);
m_nPosition = 0;
}
else
if (i == 0)
{
return -1;
}
else
{
// Must have broken out from above.
throw new IOException ("Improperly padded Base64 input.");
}
}
}
// Got data?
if (m_nPosition >= 0)
{
if ( /* !encode && */m_nPosition >= m_nNumSigBytes)
{
return -1;
}
if (m_bEncode && m_bBreakLines && m_nLineLength >= Base64.MAX_LINE_LENGTH)
{
m_nLineLength = 0;
return '\n';
}
{
m_nLineLength++;
// This isn't important when decoding
// but throwing an extra "if" seems
// just as wasteful.
final int b = m_aBuffer[m_nPosition++];
if (m_nPosition >= m_nBufferLength)
m_nPosition = -1;
// This is how you "cast" a byte that's
// intended to be unsigned.
return b & 0xFF;
}
}
// Else error
throw new IOException ("Error in Base64 code reading stream.");
}
/**
* Calls {@link #read()} repeatedly until the end of stream is reached or
* len bytes are read. Returns number of bytes read into array or -1
* if end of stream is encountered.
*
* @param aDest
* array to hold values
* @param nOfs
* offset for array
* @param nLen
* max number of bytes to read into array
* @return bytes read into array or -1 if end of stream is encountered.
* @since 1.3
*/
@Override
public int read (@Nonnull final byte [] aDest, @Nonnegative final int nOfs, @Nonnegative final int nLen) throws IOException
{
int nIndex = 0;
for (; nIndex < nLen; nIndex++)
{
final int nByte = read ();
if (nByte >= 0)
aDest[nOfs + nIndex] = (byte) nByte;
else
{
// EOF
if (nIndex == 0)
{
// First byte is not Base64 - nothing read
return -1;
}
// Out of 'for' loop
break;
}
}
return nIndex;
}
}