com.pi4j.io.file

Class LinuxFile

java.lang.Object

java.io.RandomAccessFile

com.pi4j.io.file.LinuxFile

All Implemented Interfaces:

Closeable, DataInput, DataOutput, AutoCloseable

public class LinuxFile
extends RandomAccessFile

Extends RandomAccessFile to provide access to Linux ioctl.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LinuxFile.LinuxFileException
static class	LinuxFile.MMAPFlags
static class	LinuxFile.MMAPProt
static class	LinuxFile.ScratchBufferOverrun

Field Summary

Fields

Modifier and Type	Field and Description
static int	localBufferSize
static ThreadLocal<ByteBuffer>	localDataBuffer
static ThreadLocal<IntBuffer>	localOffsetsBuffer
static int	wordSize

Constructor Summary

Constructors

Constructor and Description
LinuxFile(String name, String mode)

Method Summary

Modifier and Type	Method and Description
protected static int	directIOCTL(int fd, long command, int value)
protected static int	directIOCTLStructure(int fd, long command, ByteBuffer data, int dataOffset, IntBuffer offsetMap, int offsetMapOffset, int offsetCapacity)
static int	errno()
protected void	finalize()
void	ioctl(long command, ByteBuffer data, IntBuffer offsets) Runs an ioctl on a file descriptor.
void	ioctl(long command, int value) Runs an ioctl value command on a file descriptor.
protected static long	mmap(int fd, int length, int prot, int flags, int offset)
ByteBuffer	mmap(int length, LinuxFile.MMAPProt prot, LinuxFile.MMAPFlags flags, int offset) Direct memory mapping from a file descriptor.
static void	munmap(ByteBuffer mappedBuffer)
protected static int	munmapDirect(long address, long capacity)
static String	strerror(int code)

Methods inherited from class java.io.RandomAccessFile

close, getChannel, getFD, getFilePointer, length, read, read, read, readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF, seek, setLength, skipBytes, write, write, write, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeDouble, writeFloat, writeInt, writeLong, writeShort, writeUTF

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

wordSize

public static final int wordSize

localBufferSize

public static final int localBufferSize

See Also:

Constant Field Values

localDataBuffer

public static final ThreadLocal<ByteBuffer> localDataBuffer

localOffsetsBuffer

public static final ThreadLocal<IntBuffer> localOffsetsBuffer

Constructor Detail

LinuxFile

public LinuxFile(String name,
                 String mode)
          throws FileNotFoundException

Throws:

FileNotFoundException

Method Detail

ioctl

public void ioctl(long command,
                  int value)
           throws IOException

Runs an ioctl value command on a file descriptor.

Parameters:

command - ioctl command

value - int ioctl value

Throws:

IOException

ioctl

public void ioctl(long command,
                  ByteBuffer data,
                  IntBuffer offsets)
           throws IOException

Runs an ioctl on a file descriptor. Uses special offset buffer to produce real C-like structures with pointers. Advanced use only! Must be able to produce byte-perfect data structures just as gcc would on this system, including struct padding and pointer size. The data ByteBuffer uses the current position to determine the head point of data passed to the ioctl. This is useful for appending entry-point data structures at the end of the buffer, while referring to other structures/data that come before them in the buffer. When assembling the structured data, use wordSize to determine the size in bytes needed for a pointer. Also be sure to consider GCC padding and structure alignment. GCC will try a field to its word size (32b ints align at 4-byte, etc), and will align the structure size with the native word size (4-byte for 32b, 8-byte for 64b). Provided IntBuffer offsets must use native byte order (endianness).

 
    <NEED BETTER EXAMPLE HERE>
 
 

DANGER: check your buffer length! The possible length varies depending on the ioctl call. Overruns are very possible. ioctl tries to determine EFAULTs, but sometimes you might trample JVM data if you are not careful.

Parameters:

command - ioctl command

data - values in bytes for all structures, with 4 or 8 byte size holes for pointers

offsets - byte offsets of pointer at given index

Throws:

IOException

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

mmap

public ByteBuffer mmap(int length,
                       LinuxFile.MMAPProt prot,
                       LinuxFile.MMAPFlags flags,
                       int offset)
                throws IOException

Direct memory mapping from a file descriptor. This is normally possible through the local FileChannel, but NIO will try to truncate files if they don't report a correct size. This will avoid that.

Parameters:

length - length of desired mapping

prot - protocol used for mapping

flags - flags for mapping

offset - offset in file for mapping

Returns:

direct mapped ByteBuffer

Throws:

IOException

munmap

public static void munmap(ByteBuffer mappedBuffer)
                   throws IOException

Throws:

IOException

errno

public static int errno()

strerror

public static String strerror(int code)

directIOCTL

protected static int directIOCTL(int fd,
                                 long command,
                                 int value)

mmap

protected static long mmap(int fd,
                           int length,
                           int prot,
                           int flags,
                           int offset)

munmapDirect

protected static int munmapDirect(long address,
                                  long capacity)

directIOCTLStructure

protected static int directIOCTLStructure(int fd,
                                          long command,
                                          ByteBuffer data,
                                          int dataOffset,
                                          IntBuffer offsetMap,
                                          int offsetMapOffset,
                                          int offsetCapacity)