Class ClassfileReader
java.lang.Object
nonapi.io.github.classgraph.fileslice.reader.ClassfileReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,RandomAccessReader
,SequentialReader
public class ClassfileReader
extends Object
implements RandomAccessReader, SequentialReader, 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
FieldsModifier and TypeFieldDescriptionprivate byte[]
Buffer.private int
The number of bytes used in arr.private static final int
Read this many bytes each time there is a buffer underrun.private int
The length of the classfile if known (because it is not deflated), or -1 if unknown (because it is deflated).private int
The current read index within the slice.private InputStream
If slice is deflated, a wrapper forinvalid reference
InflateInputStream
private static final int
Initial buffer size.private RandomAccessReader
If slice is not deflated, aRandomAccessReader
for either theArraySlice
orFileSlice
concrete subclass.private Resource
The underlying resource to close whenclose()
is called. -
Constructor Summary
ConstructorsConstructorDescriptionClassfileReader
(InputStream inputStream, Resource resourceToClose) Constructor for reader of moduleInputStream
(which is not deflated).ClassfileReader
(Slice slice, Resource resourceToClose) Constructor. -
Method Summary
Modifier and TypeMethodDescriptionbyte[]
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, ByteBuffer dstBuf, int dstBufStart, int numBytes) Read bytes into aByteBuffer
.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
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).readString
(int numBytes) Reads the "modified UTF8" format defined in the Java classfile spec.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 ";".readString
(long offset, int numBytes) Reads the "modified UTF8" format defined in the Java classfile spec.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
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
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
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.
-
Field Details
-
resourceToClose
The underlying resource to close whenclose()
is called. -
inflaterInputStream
If slice is deflated, a wrapper forinvalid reference
InflateInputStream
-
randomAccessReader
If slice is not deflated, aRandomAccessReader
for either theArraySlice
orFileSlice
concrete subclass. -
arr
private byte[] arrBuffer. -
arrUsed
private int arrUsedThe number of bytes used in arr. -
currIdx
private int currIdxThe current read index within the slice. -
classfileLengthHint
private int classfileLengthHintThe 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_SIZEInitial buffer size. For most classfiles, only the first 16-64kb needs to be read (we don't read the bytecodes).- See Also:
-
BUF_CHUNK_SIZE
private static final int BUF_CHUNK_SIZERead 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:
-
-
Constructor Details
-
ClassfileReader
Constructor.- Parameters:
slice
- theSlice
to read.resourceToClose
- the resource to close whenclose()
is called, or null.- Throws:
IOException
- If an inflater cannot be opened on theSlice
.
-
ClassfileReader
Constructor for reader of moduleInputStream
(which is not deflated).- Parameters:
inputStream
- theInputStream
to read from.resourceToClose
- the underlying resource to close whenclose()
is called, or null.- Throws:
IOException
- If an inflater cannot be opened on theSlice
.
-
-
Method Details
-
currPos
public int currPos()Curr pos.- Returns:
- the current read position.
-
buf
public byte[] buf()Buf.- Returns:
- the buffer.
-
readTo
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 forarrUsed
(i.e. the number of bytes that must be filled in the array)- Throws:
IOException
- Signals that an I/O exception has occurred.
-
bufferTo
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:
IOException
- on EOF or if the bytes could not be read.
-
read
Description copied from interface:RandomAccessReader
Read bytes into a byte array.- Specified by:
read
in interfaceRandomAccessReader
- 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:
IOException
- If there was an exception while reading.
-
read
public int read(long srcOffset, ByteBuffer dstBuf, int dstBufStart, int numBytes) throws IOException Description copied from interface:RandomAccessReader
Read bytes into aByteBuffer
.- Specified by:
read
in interfaceRandomAccessReader
- Parameters:
srcOffset
- The offset to start reading from.dstBuf
- TheByteBuffer
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:
IOException
- If there was an exception while reading.
-
readByte
Description copied from interface:RandomAccessReader
Read a byte at a specific offset (without changing the current cursor offset).- Specified by:
readByte
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The byte at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedByte
Description copied from interface:RandomAccessReader
Read an unsigned byte at a specific offset (without changing the current cursor offset).- Specified by:
readUnsignedByte
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The unsigned byte at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readShort
Description copied from interface:RandomAccessReader
Read a short at a specific offset (without changing the current cursor offset).- Specified by:
readShort
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The short at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedShort
Description copied from interface:RandomAccessReader
Read a unsigned short at a specific offset (without changing the current cursor offset).- Specified by:
readUnsignedShort
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The unsigned short at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readInt
Description copied from interface:RandomAccessReader
Read a int at a specific offset (without changing the current cursor offset).- Specified by:
readInt
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The int at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedInt
Description copied from interface:RandomAccessReader
Read a unsigned int at a specific offset (without changing the current cursor offset).- Specified by:
readUnsignedInt
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The int at the offset, as a long.
- Throws:
IOException
- If there was an exception while reading.
-
readLong
Description copied from interface:RandomAccessReader
Read a long at a specific offset (without changing the current cursor offset).- Specified by:
readLong
in interfaceRandomAccessReader
- Parameters:
offset
- The buffer offset to read from.- Returns:
- The long at the offset.
- Throws:
IOException
- If there was an exception while reading.
-
readByte
Description copied from interface:SequentialReader
Read a byte at the current cursor position.- Specified by:
readByte
in interfaceSequentialReader
- Returns:
- The byte at the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedByte
Description copied from interface:SequentialReader
Read an unsigned byte at the current cursor position.- Specified by:
readUnsignedByte
in interfaceSequentialReader
- Returns:
- The unsigned byte at the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
readShort
Description copied from interface:SequentialReader
Read a short at the current cursor position.- Specified by:
readShort
in interfaceSequentialReader
- Returns:
- The short at the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedShort
Description copied from interface:SequentialReader
Read a unsigned short at the current cursor position.- Specified by:
readUnsignedShort
in interfaceSequentialReader
- Returns:
- The unsigned shortat the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
readInt
Description copied from interface:SequentialReader
Read a int at the current cursor position.- Specified by:
readInt
in interfaceSequentialReader
- Returns:
- The int at the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
readUnsignedInt
Description copied from interface:SequentialReader
Read a unsigned int at the current cursor position.- Specified by:
readUnsignedInt
in interfaceSequentialReader
- Returns:
- The int at the current cursor position, as a long.
- Throws:
IOException
- If there was an exception while reading.
-
readLong
Description copied from interface:SequentialReader
Read a long at the current cursor position.- Specified by:
readLong
in interfaceSequentialReader
- Returns:
- The long at the current cursor position.
- Throws:
IOException
- If there was an exception while reading.
-
skip
Description copied from interface:SequentialReader
Skip the given number of bytes.- Specified by:
skip
in interfaceSequentialReader
- Parameters:
bytesToSkip
- The number of bytes to skip.- Throws:
IOException
- If there was an exception while reading.
-
readString
public String readString(long offset, int numBytes, boolean replaceSlashWithDot, boolean stripLSemicolon) throws 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 interfaceRandomAccessReader
- 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:
IOException
- If an I/O exception occurs.
-
readString
public String readString(int numBytes, boolean replaceSlashWithDot, boolean stripLSemicolon) throws 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 interfaceSequentialReader
- 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:
IOException
- If an I/O exception occurs.
-
readString
Description copied from interface:RandomAccessReader
Reads the "modified UTF8" format defined in the Java classfile spec.- Specified by:
readString
in interfaceRandomAccessReader
- Parameters:
offset
- The start offset of the string.numBytes
- The number of bytes of the UTF8 encoding of the string.- Returns:
- The string.
- Throws:
IOException
- If an I/O exception occurs.
-
readString
Description copied from interface:SequentialReader
Reads the "modified UTF8" format defined in the Java classfile spec.- Specified by:
readString
in interfaceSequentialReader
- Parameters:
numBytes
- The number of bytes of the UTF8 encoding of the string.- Returns:
- The string.
- Throws:
IOException
- If an I/O exception occurs.
-
close
public void close()- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
-