/*
* gets an (uncompressed) stream representing the chunk data returns null if
* the chunk is not found or an error occurs
*/
public synchronized DataInputStream getChunkDataInputStream(int x, int z) {
if (outOfBounds(x, z)) {
debugln("READ", x, z, "out of bounds");
return null;
}
try {
int offset = getOffset(x, z);
if (offset == 0) {
// debugln("READ", x, z, "miss");
return null;
}
int sectorNumber = offset >> 8;
int numSectors = offset & 0xFF;
if (sectorNumber + numSectors > sectorFree.size()) {
debugln("READ", x, z, "invalid sector");
return null;
}
file.seek(sectorNumber * SECTOR_BYTES);
int length = file.readInt();
if (length > SECTOR_BYTES * numSectors) {
debugln("READ", x, z, "invalid length: " + length + " > 4096 * " + numSectors);
return null;
}
byte version = file.readByte();
if (version == VERSION_GZIP) {
byte[] data = new byte[length - 1];
file.read(data);
DataInputStream ret =
new DataInputStream(
new BufferedInputStream(new GZIPInputStream(new ByteArrayInputStream(data))));
// debug("READ", x, z, " = found");
return ret;
} else if (version == VERSION_DEFLATE) {
byte[] data = new byte[length - 1];
file.read(data);
DataInputStream ret =
new DataInputStream(
new BufferedInputStream(new InflaterInputStream(new ByteArrayInputStream(data))));
// debug("READ", x, z, " = found");
return ret;
}
debugln("READ", x, z, "unknown version " + version);
return null;
} catch (IOException e) {
debugln("READ", x, z, "exception");
return null;
}
}
/**
* Read block from file.
*
* @param file - File to read.
* @param off - Marker position in file to start read from if {@code -1} read last blockSz bytes.
* @param blockSz - Maximum number of chars to read.
* @param lastModified - File last modification time.
* @return Read file block.
* @throws IOException In case of error.
*/
public static VisorFileBlock readBlock(File file, long off, int blockSz, long lastModified)
throws IOException {
RandomAccessFile raf = null;
try {
long fSz = file.length();
long fLastModified = file.lastModified();
long pos = off >= 0 ? off : Math.max(fSz - blockSz, 0);
// Try read more that file length.
if (fLastModified == lastModified && fSz != 0 && pos >= fSz)
throw new IOException(
"Trying to read file block with wrong offset: " + pos + " while file size: " + fSz);
if (fSz == 0)
return new VisorFileBlock(file.getPath(), pos, fLastModified, 0, false, EMPTY_FILE_BUF);
else {
int toRead = Math.min(blockSz, (int) (fSz - pos));
byte[] buf = new byte[toRead];
raf = new RandomAccessFile(file, "r");
raf.seek(pos);
int cntRead = raf.read(buf, 0, toRead);
if (cntRead != toRead)
throw new IOException(
"Count of requested and actually read bytes does not match [cntRead="
+ cntRead
+ ", toRead="
+ toRead
+ ']');
boolean zipped = buf.length > 512;
return new VisorFileBlock(
file.getPath(), pos, fSz, fLastModified, zipped, zipped ? zipBytes(buf) : buf);
}
} finally {
U.close(raf, null);
}
}
