/*
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Git Development Community nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.spearce.jgit.util;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/** Conversion utilities for network byte order handling. */
public final class NB {
/**
* Read an entire local file into memory as a byte array.
*
* @param path
* location of the file to read.
* @return complete contents of the requested local file.
* @throws FileNotFoundException
* the file does not exist.
* @throws IOException
* the file exists, but its contents cannot be read.
*/
public static final byte[] readFully(final File path)
throws FileNotFoundException, IOException {
return readFully(path, Integer.MAX_VALUE);
}
/**
* Read an entire local file into memory as a byte array.
*
* @param path
* location of the file to read.
* @param max
* maximum number of bytes to read, if the file is larger than
* this limit an IOException is thrown.
* @return complete contents of the requested local file.
* @throws FileNotFoundException
* the file does not exist.
* @throws IOException
* the file exists, but its contents cannot be read.
*/
public static final byte[] readFully(final File path, final int max)
throws FileNotFoundException, IOException {
final FileInputStream in = new FileInputStream(path);
try {
final long sz = in.getChannel().size();
if (sz > max)
throw new IOException("File is too large: " + path);
final byte[] buf = new byte[(int) sz];
readFully(in, buf, 0, buf.length);
return buf;
} finally {
try {
in.close();
} catch (IOException ignored) {
// ignore any close errors, this was a read only stream
}
}
}
/**
* Read the entire byte array into memory, or throw an exception.
*
* @param fd
* input stream to read the data from.
* @param dst
* buffer that must be fully populated, [off, off+len).
* @param off
* position within the buffer to start writing to.
* @param len
* number of bytes that must be read.
* @throws EOFException
* the stream ended before dst was fully populated.
* @throws IOException
* there was an error reading from the stream.
*/
public static void readFully(final InputStream fd, final byte[] dst,
int off, int len) throws IOException {
while (len > 0) {
final int r = fd.read(dst, off, len);
if (r <= 0)
throw new EOFException("Short read of block.");
off += r;
len -= r;
}
}
/**
* Read the entire byte array into memory, or throw an exception.
*
* @param fd
* file to read the data from.
* @param pos
* position to read from the file at.
* @param dst
* buffer that must be fully populated, [off, off+len).
* @param off
* position within the buffer to start writing to.
* @param len
* number of bytes that must be read.
* @throws EOFException
* the stream ended before dst was fully populated.
* @throws IOException
* there was an error reading from the stream.
*/
public static void readFully(final FileChannel fd, long pos,
final byte[] dst, int off, int len) throws IOException {
while (len > 0) {
final int r = fd.read(ByteBuffer.wrap(dst, off, len), pos);
if (r <= 0)
throw new EOFException("Short read of block.");
pos += r;
off += r;
len -= r;
}
}
/**
* Skip an entire region of an input stream.
* <p>
* The input stream's position is moved forward by the number of requested
* bytes, discarding them from the input. This method does not return until
* the exact number of bytes requested has been skipped.
*
* @param fd
* the stream to skip bytes from.
* @param toSkip
* total number of bytes to be discarded. Must be >= 0.
* @throws EOFException
* the stream ended before the requested number of bytes were
* skipped.
* @throws IOException
* there was an error reading from the stream.
*/
public static void skipFully(final InputStream fd, long toSkip)
throws IOException {
while (toSkip > 0) {
final long r = fd.skip(toSkip);
if (r <= 0)
throw new EOFException("Short skip of block");
toSkip -= r;
}
}
/**
* Compare a 32 bit unsigned integer stored in a 32 bit signed integer.
* <p>
* This function performs an unsigned compare operation, even though Java
* does not natively support unsigned integer values. Negative numbers are
* treated as larger than positive ones.
*
* @param a
* the first value to compare.
* @param b
* the second value to compare.
* @return < 0 if a < b; 0 if a == b; > 0 if a > b.
*/
public static int compareUInt32(final int a, final int b) {
final int cmp = (a >>> 1) - (b >>> 1);
if (cmp != 0)
return cmp;
return (a & 1) - (b & 1);
}
/**
* Convert sequence of 2 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 2 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next byte after it (for a total of 2 bytes)
* will be read.
* @return unsigned integer value that matches the 16 bits read.
*/
public static int decodeUInt16(final byte[] intbuf, final int offset) {
int r = (intbuf[offset] & 0xff) << 8;
return r | (intbuf[offset + 1] & 0xff);
}
/**
* Convert sequence of 4 bytes (network byte order) into signed value.
*
* @param intbuf
* buffer to acquire the 4 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 3 bytes after it (for a total of 4
* bytes) will be read.
* @return signed integer value that matches the 32 bits read.
*/
public static int decodeInt32(final byte[] intbuf, final int offset) {
int r = intbuf[offset] << 8;
r |= intbuf[offset + 1] & 0xff;
r <<= 8;
r |= intbuf[offset + 2] & 0xff;
return (r << 8) | (intbuf[offset + 3] & 0xff);
}
/**
* Convert sequence of 4 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 4 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 3 bytes after it (for a total of 4
* bytes) will be read.
* @return unsigned integer value that matches the 32 bits read.
*/
public static long decodeUInt32(final byte[] intbuf, final int offset) {
int low = (intbuf[offset + 1] & 0xff) << 8;
low |= (intbuf[offset + 2] & 0xff);
low <<= 8;
low |= (intbuf[offset + 3] & 0xff);
return ((long) (intbuf[offset] & 0xff)) << 24 | low;
}
/**
* Convert sequence of 8 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 8 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 7 bytes after it (for a total of 8
* bytes) will be read.
* @return unsigned integer value that matches the 64 bits read.
*/
public static long decodeUInt64(final byte[] intbuf, final int offset) {
return (decodeUInt32(intbuf, offset) << 32)
| decodeUInt32(intbuf, offset + 4);
}
/**
* Write a 16 bit integer as a sequence of 2 bytes (network byte order).
*
* @param intbuf
* buffer to write the 2 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next byte after it (for a total of 2 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt16(final byte[] intbuf, final int offset, int v) {
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
/**
* Write a 32 bit integer as a sequence of 4 bytes (network byte order).
*
* @param intbuf
* buffer to write the 4 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next 3 bytes after it (for a total of 4 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt32(final byte[] intbuf, final int offset, int v) {
intbuf[offset + 3] = (byte) v;
v >>>= 8;
intbuf[offset + 2] = (byte) v;
v >>>= 8;
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
/**
* Write a 64 bit integer as a sequence of 8 bytes (network byte order).
*
* @param intbuf
* buffer to write the 48bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next 7 bytes after it (for a total of 8 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt64(final byte[] intbuf, final int offset, long v) {
intbuf[offset + 7] = (byte) v;
v >>>= 8;
intbuf[offset + 6] = (byte) v;
v >>>= 8;
intbuf[offset + 5] = (byte) v;
v >>>= 8;
intbuf[offset + 4] = (byte) v;
v >>>= 8;
intbuf[offset + 3] = (byte) v;
v >>>= 8;
intbuf[offset + 2] = (byte) v;
v >>>= 8;
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
private NB() {
// Don't create instances of a static only utility.
}
}