Package nonapi.io.github.classgraph.fileslice.reader

Class ClassfileReader

java.lang.Object

nonapi.io.github.classgraph.fileslice.reader.ClassfileReader

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, RandomAccessReader, SequentialReader

public class ClassfileReader
extends java.lang.Object
implements RandomAccessReader, SequentialReader, java.io.Closeable

A Slice reader that works as either a RandomAccessReader or a SequentialReader. The file is buffered up to the point it has been read so far. Reads in big endian order, as required by the classfile format.

Field Summary

Fields

Modifier and Type	Field	Description
private byte[]	arr	Buffer.
private int	arrUsed	The number of bytes used in arr.
private static int	BUF_CHUNK_SIZE	Read this many bytes each time there is a buffer underrun.
private int	classfileLengthHint	The length of the classfile if known (because it is not deflated), or -1 if unknown (because it is deflated).
private int	currIdx	The current read index within the slice.
private java.io.InputStream	inflaterInputStream	If slice is deflated, a wrapper for InflateInputStream.
private static int	INITIAL_BUF_SIZE	Initial buffer size.
private RandomAccessReader	randomAccessReader	If slice is not deflated, a RandomAccessReader for either the ArraySlice or FileSlice concrete subclass.
private Resource	resourceToClose	The underlying resource to close when close() is called.

Constructor Summary

Constructors

Constructor	Description
ClassfileReader(java.io.InputStream inputStream, Resource resourceToClose)	Constructor for reader of module InputStream (which is not deflated).
ClassfileReader(Slice slice, Resource resourceToClose)	Constructor.

Method Summary

Modifier and Type	Method	Description
byte[]	buf()	Buf.
void	bufferTo(int numBytes)	Ensure that the given number of bytes have been read into the buffer from the beginning of the slice.
void	close()
int	currPos()	Curr pos.
int	read(long srcOffset, byte[] dstArr, int dstArrStart, int numBytes)	Read bytes into a byte array.
int	read(long srcOffset, java.nio.ByteBuffer dstBuf, int dstBufStart, int numBytes)	Read bytes into a ByteBuffer.
byte	readByte()	Read a byte at the current cursor position.
byte	readByte(long offset)	Read a byte at a specific offset (without changing the current cursor offset).
int	readInt()	Read a int at the current cursor position.
int	readInt(long offset)	Read a int at a specific offset (without changing the current cursor offset).
long	readLong()	Read a long at the current cursor position.
long	readLong(long offset)	Read a long at a specific offset (without changing the current cursor offset).
short	readShort()	Read a short at the current cursor position.
short	readShort(long offset)	Read a short at a specific offset (without changing the current cursor offset).
java.lang.String	readString(int numBytes)	Reads the "modified UTF8" format defined in the Java classfile spec.
java.lang.String	readString(int numBytes, boolean replaceSlashWithDot, boolean stripLSemicolon)	Reads the "modified UTF8" format defined in the Java classfile spec, optionally replacing '/' with '.', and optionally removing the prefix "L" and the suffix ";".
java.lang.String	readString(long offset, int numBytes)	Reads the "modified UTF8" format defined in the Java classfile spec.
java.lang.String	readString(long offset, int numBytes, boolean replaceSlashWithDot, boolean stripLSemicolon)	Reads the "modified UTF8" format defined in the Java classfile spec, optionally replacing '/' with '.', and optionally removing the prefix "L" and the suffix ";".
private void	readTo(int targetArrUsed)	Called when there is a buffer underrun to ensure there are sufficient bytes available in the array to read the given number of bytes at the given start index.
int	readUnsignedByte()	Read an unsigned byte at the current cursor position.
int	readUnsignedByte(long offset)	Read an unsigned byte at a specific offset (without changing the current cursor offset).
long	readUnsignedInt()	Read a unsigned int at the current cursor position.
long	readUnsignedInt(long offset)	Read a unsigned int at a specific offset (without changing the current cursor offset).
int	readUnsignedShort()	Read a unsigned short at the current cursor position.
int	readUnsignedShort(long offset)	Read a unsigned short at a specific offset (without changing the current cursor offset).
void	skip(int bytesToSkip)	Skip the given number of bytes.

Methods inherited from class java.lang.Object

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

Field Detail

resourceToClose

private Resource resourceToClose

The underlying resource to close when close() is called.

inflaterInputStream

private java.io.InputStream inflaterInputStream

If slice is deflated, a wrapper for InflateInputStream.

randomAccessReader

private RandomAccessReader randomAccessReader

If slice is not deflated, a RandomAccessReader for either the ArraySlice or FileSlice concrete subclass.

arr

private byte[] arr

Buffer.

arrUsed

private int arrUsed

The number of bytes used in arr.

currIdx

private int currIdx

The current read index within the slice.

classfileLengthHint

private int classfileLengthHint

The length of the classfile if known (because it is not deflated), or -1 if unknown (because it is deflated).

INITIAL_BUF_SIZE

private static final int INITIAL_BUF_SIZE

Initial buffer size. For most classfiles, only the first 16-64kb needs to be read (we don't read the bytecodes).

See Also:

Constant Field Values

BUF_CHUNK_SIZE

private static final int BUF_CHUNK_SIZE

Read this many bytes each time there is a buffer underrun. This is smaller than 8k by 8 bytes to prevent the doubling of the array size when the last chunk doesn't quite fit within the 16kb of INITIAL_BUF_SIZE, since the number of bytes that can be requested is up to 8 (for longs). Otherwise we could request to read to (8kb * 2 + 8), which would double the size of the buffer to 32kb, but if we only need to read between 8kb and 16kb, then we unnecessarily copied the buffer content one extra time.

See Also:

Constant Field Values

Constructor Detail

ClassfileReader

public ClassfileReader(Slice slice,
                       Resource resourceToClose)
                throws java.io.IOException

Constructor.

Parameters:

slice - the Slice to read.

resourceToClose - the resource to close when close() is called, or null.

Throws:

java.io.IOException - If an inflater cannot be opened on the Slice.

ClassfileReader

public ClassfileReader(java.io.InputStream inputStream,
                       Resource resourceToClose)
                throws java.io.IOException

Constructor for reader of module InputStream (which is not deflated).

Parameters:

inputStream - the InputStream to read from.

resourceToClose - the underlying resource to close when close() is called, or null.

Throws:

java.io.IOException - If an inflater cannot be opened on the Slice.

Method Detail

currPos

public int currPos()

Curr pos.

Returns:

the current read position.

buf

public byte[] buf()

Buf.

Returns:

the buffer.

readTo

private void readTo(int targetArrUsed)
             throws java.io.IOException

Called when there is a buffer underrun to ensure there are sufficient bytes available in the array to read the given number of bytes at the given start index.

Parameters:

targetArrUsed - the target value for arrUsed (i.e. the number of bytes that must be filled in the array)

Throws:

java.io.IOException - Signals that an I/O exception has occurred.

bufferTo

public void bufferTo(int numBytes)
              throws java.io.IOException

Ensure that the given number of bytes have been read into the buffer from the beginning of the slice.

Parameters:

numBytes - the number of bytes to ensure have been buffered

Throws:

java.io.IOException - on EOF or if the bytes could not be read.

read

public int read(long srcOffset,
                byte[] dstArr,
                int dstArrStart,
                int numBytes)
         throws java.io.IOException

Description copied from interface: RandomAccessReader

Read bytes into a byte array.

Specified by:

read in interface RandomAccessReader

Parameters:

srcOffset - The offset to start reading from.

dstArr - The byte array to write into.

dstArrStart - The offset within the destination array to start writing at.

numBytes - The number of bytes to read.

Returns:

The number of bytes actually read, or -1 if no more bytes could be read.

Throws:

java.io.IOException - If there was an exception while reading.

read

public int read(long srcOffset,
                java.nio.ByteBuffer dstBuf,
                int dstBufStart,
                int numBytes)
         throws java.io.IOException

Description copied from interface: RandomAccessReader

Read bytes into a ByteBuffer.

Specified by:

read in interface RandomAccessReader

Parameters:

srcOffset - The offset to start reading from.

dstBuf - The ByteBuffer to write into.

dstBufStart - The offset within the destination buffer to start writing at.

numBytes - The number of bytes to read.

Returns:

The number of bytes actually read, or -1 if no more bytes could be read.

Throws:

java.io.IOException - If there was an exception while reading.

readByte

public byte readByte(long offset)
              throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a byte at a specific offset (without changing the current cursor offset).

Specified by:

readByte in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The byte at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedByte

public int readUnsignedByte(long offset)
                     throws java.io.IOException

Description copied from interface: RandomAccessReader

Read an unsigned byte at a specific offset (without changing the current cursor offset).

Specified by:

readUnsignedByte in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The unsigned byte at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readShort

public short readShort(long offset)
                throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a short at a specific offset (without changing the current cursor offset).

Specified by:

readShort in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The short at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedShort

public int readUnsignedShort(long offset)
                      throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a unsigned short at a specific offset (without changing the current cursor offset).

Specified by:

readUnsignedShort in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The unsigned short at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readInt

public int readInt(long offset)
            throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a int at a specific offset (without changing the current cursor offset).

Specified by:

readInt in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The int at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedInt

public long readUnsignedInt(long offset)
                     throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a unsigned int at a specific offset (without changing the current cursor offset).

Specified by:

readUnsignedInt in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The int at the offset, as a long.

Throws:

java.io.IOException - If there was an exception while reading.

readLong

public long readLong(long offset)
              throws java.io.IOException

Description copied from interface: RandomAccessReader

Read a long at a specific offset (without changing the current cursor offset).

Specified by:

readLong in interface RandomAccessReader

Parameters:

offset - The buffer offset to read from.

Returns:

The long at the offset.

Throws:

java.io.IOException - If there was an exception while reading.

readByte

public byte readByte()
              throws java.io.IOException

Description copied from interface: SequentialReader

Read a byte at the current cursor position.

Specified by:

readByte in interface SequentialReader

Returns:

The byte at the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedByte

public int readUnsignedByte()
                     throws java.io.IOException

Description copied from interface: SequentialReader

Read an unsigned byte at the current cursor position.

Specified by:

readUnsignedByte in interface SequentialReader

Returns:

The unsigned byte at the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

readShort

public short readShort()
                throws java.io.IOException

Description copied from interface: SequentialReader

Read a short at the current cursor position.

Specified by:

readShort in interface SequentialReader

Returns:

The short at the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedShort

public int readUnsignedShort()
                      throws java.io.IOException

Description copied from interface: SequentialReader

Read a unsigned short at the current cursor position.

Specified by:

readUnsignedShort in interface SequentialReader

Returns:

The unsigned shortat the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

readInt

public int readInt()
            throws java.io.IOException

Description copied from interface: SequentialReader

Read a int at the current cursor position.

Specified by:

readInt in interface SequentialReader

Returns:

The int at the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

readUnsignedInt

public long readUnsignedInt()
                     throws java.io.IOException

Description copied from interface: SequentialReader

Read a unsigned int at the current cursor position.

Specified by:

readUnsignedInt in interface SequentialReader

Returns:

The int at the current cursor position, as a long.

Throws:

java.io.IOException - If there was an exception while reading.

readLong

public long readLong()
              throws java.io.IOException

Description copied from interface: SequentialReader

Read a long at the current cursor position.

Specified by:

readLong in interface SequentialReader

Returns:

The long at the current cursor position.

Throws:

java.io.IOException - If there was an exception while reading.

skip

public void skip(int bytesToSkip)
          throws java.io.IOException

Description copied from interface: SequentialReader

Skip the given number of bytes.

Specified by:

skip in interface SequentialReader

Parameters:

bytesToSkip - The number of bytes to skip.

Throws:

java.io.IOException - If there was an exception while reading.

readString

public java.lang.String readString(long offset,
                                   int numBytes,
                                   boolean replaceSlashWithDot,
                                   boolean stripLSemicolon)
                            throws java.io.IOException

Description copied from interface: RandomAccessReader

Reads the "modified UTF8" format defined in the Java classfile spec, optionally replacing '/' with '.', and optionally removing the prefix "L" and the suffix ";".

Specified by:

readString in interface RandomAccessReader

Parameters:

offset - The start offset of the string.

numBytes - The number of bytes of the UTF8 encoding of the string.

replaceSlashWithDot - If true, replace '/' with '.'.

stripLSemicolon - If true, string final ';' character.

Returns:

The string.

Throws:

java.io.IOException - If an I/O exception occurs.

readString

public java.lang.String readString(int numBytes,
                                   boolean replaceSlashWithDot,
                                   boolean stripLSemicolon)
                            throws java.io.IOException

Description copied from interface: SequentialReader

Reads the "modified UTF8" format defined in the Java classfile spec, optionally replacing '/' with '.', and optionally removing the prefix "L" and the suffix ";".

Specified by:

readString in interface SequentialReader

Parameters:

numBytes - The number of bytes of the UTF8 encoding of the string.

replaceSlashWithDot - If true, replace '/' with '.'.

stripLSemicolon - If true, string final ';' character.

Returns:

The string.

Throws:

java.io.IOException - If an I/O exception occurs.

readString

public java.lang.String readString(long offset,
                                   int numBytes)
                            throws java.io.IOException

Description copied from interface: RandomAccessReader

Reads the "modified UTF8" format defined in the Java classfile spec.

Specified by:

readString in interface RandomAccessReader

Parameters:

offset - The start offset of the string.

numBytes - The number of bytes of the UTF8 encoding of the string.

Returns:

The string.

Throws:

java.io.IOException - If an I/O exception occurs.

readString

public java.lang.String readString(int numBytes)
                            throws java.io.IOException

Description copied from interface: SequentialReader

Reads the "modified UTF8" format defined in the Java classfile spec.

Specified by:

readString in interface SequentialReader

Parameters:

numBytes - The number of bytes of the UTF8 encoding of the string.

Returns:

The string.

Throws:

java.io.IOException - If an I/O exception occurs.

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable