Package ghidra.program.model.mem
Interface MemBuffer
- All Known Subinterfaces:
CodeUnit
,Data
,Instruction
,MemBufferMixin
,MutableMemBuffer
- All Known Implementing Classes:
AbstractBytesPcodeExecutorStatePiece.StateMemBuffer
,ByteMemBufferImpl
,DataStub
,DumbMemBufferImpl
,EmulateMemoryStateBuffer
,InstructionDB
,InstructionStub
,MemoryBufferImpl
,PseudoData
,PseudoInstruction
,WrappedMemBuffer
public interface MemBuffer
MemBuffer provides an array like interface into memory at a
specific address. Bytes can be retrieved by using a positive
offset from the current position. Depending on the implementation,
the offset may be restricted to a specific positive range. If the
implementation does have a restriction, then a MemoryAccessException
will be thrown, except for the
getBytes(byte[], int)
method which will return 0.
The purpose of this class is to
allow an efficient implementation that buffers memory accesses and
does not have to keep translating addresses. This was designed to
be passed to a language parser. One advantage of MemBuffer over a
byte array is that if necessary the actual Memory and Address can
be retrieved in case all of the necessary bytes are not local.
This interface does not provide methods to reposition the memory
buffer. This is so that it is clear that methods accepting this
base class are not to mess which the base Address for this object.
Memory-backed access is an optional implementation dependent
capability. In addition, the use of the relative offset is
implementation dependent, but in general those implementations
which are backed by memory may choose to wrap the offset
when computing the corresponding memory address. The treatment
of the offset argument should be consistent across the various
methods for a given implementation.- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionGet the Address which corresponds to the offset 0.getBigInteger
(int offset, int size, boolean signed) returns the value at the given offset, taking into account the endianness.byte
getByte
(int offset) Get one byte from memory at the current position plus offset.int
getBytes
(byte[] b, int offset) Readsb.length
bytes from this memory buffer starting at the address of this memory buffer plus the given memoryBufferOffset from that position.default InputStream
Returns a stream that supplies the bytes of this buffer, starting at offset 0.default InputStream
getInputStream
(int initialPosition, int length) Returns a stream that supplies the bytes of this buffer, starting at the specified offset.int
getInt
(int offset) returns the int at the given offset, taking into account the endianness.long
getLong
(int offset) returns the long at the given offset, taking into account the endianness.Get the Memory object actually used by the MemBuffer.short
getShort
(int offset) returns the short at the given offset, taking into account the endianness.default int
getUnsignedByte
(int offset) Get one unsigned byte from memory at the current position plus offset.default long
getUnsignedInt
(int offset) Returns the unsigned int at the given offset, taking into account the endianness.default int
getUnsignedShort
(int offset) Returns the unsigned short at the given offset, taking into account the endian-ness.default int
getVarLengthInt
(int offset, int len) Returns the signed value of the integer (of the specified length) at the specified offset.default long
getVarLengthUnsignedInt
(int offset, int len) Returns the unsigned value of the integer (of the specified length) at the specified offset.boolean
Returns true if the underlying bytes are in big-endian order, false if they are little endian.default boolean
Returns true if this buffer's starting address has valid data.
-
Method Details
-
isInitializedMemory
default boolean isInitializedMemory()Returns true if this buffer's starting address has valid data.- Returns:
- boolean true if first byte of memory buffer can be read
-
getByte
Get one byte from memory at the current position plus offset.- Parameters:
offset
- the displacement from the current position.- Returns:
- the data at offset from the current position.
- Throws:
MemoryAccessException
- if memory cannot be read at the specified offset
-
getUnsignedByte
Get one unsigned byte from memory at the current position plus offset.- Parameters:
offset
- the displacement from the current position.- Returns:
- the byte data at offset from the current position, as a
int
value. - Throws:
MemoryAccessException
- if memory cannot be read at the specified offset
-
getBytes
int getBytes(byte[] b, int offset) Readsb.length
bytes from this memory buffer starting at the address of this memory buffer plus the given memoryBufferOffset from that position. The actual number of bytes may be fewer if bytes can't be read.- Parameters:
b
- the buffer into which bytes will be placedoffset
- the offset in this memory buffer from which to start reading bytes.- Returns:
- the number of bytes read which may be fewer than b.length if available bytes are exhausted or no bytes are available at the specified offset.
-
getAddress
Address getAddress()Get the Address which corresponds to the offset 0.- Returns:
- the current address of offset 0.
-
getMemory
Memory getMemory()Get the Memory object actually used by the MemBuffer.- Returns:
- the Memory used by this MemBuffer or null if not available.
-
isBigEndian
boolean isBigEndian()Returns true if the underlying bytes are in big-endian order, false if they are little endian.- Returns:
- true if the underlying bytes are in big-endian order, false if they are little endian.
-
getShort
returns the short at the given offset, taking into account the endianness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)- Returns:
- the short at the given offset, taking into account the endianness.
- Throws:
MemoryAccessException
- if a 2-byte short value cannot be read at the specified offset
-
getUnsignedShort
Returns the unsigned short at the given offset, taking into account the endian-ness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)- Returns:
- the unsigned short at the given offset, as a
int
, taking into account the endianness. - Throws:
MemoryAccessException
- if a 2-byte short value cannot be read at the specified offset
-
getInt
returns the int at the given offset, taking into account the endianness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)- Returns:
- the int at the given offset, taking into account the endianness.
- Throws:
MemoryAccessException
- if a 4-byte integer value cannot be read at the specified offset
-
getUnsignedInt
Returns the unsigned int at the given offset, taking into account the endianness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)- Returns:
- the unsigned int at the given offset, as a
long
, taking into account the endianness. - Throws:
MemoryAccessException
- if a 4-byte integer value cannot be read at the specified offset
-
getLong
returns the long at the given offset, taking into account the endianness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)- Returns:
- the long at the given offset, taking into account the endianness.
- Throws:
MemoryAccessException
- if a 8-byte long value cannot be read at the specified offset
-
getBigInteger
returns the value at the given offset, taking into account the endianness.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)size
- the number of bytes to include in the valuesigned
- true if value should be treated as a signed twos-compliment value.- Returns:
- the value at the given offset, taking into account the endianness.
- Throws:
MemoryAccessException
- if the request size value cannot be read at the specified offset
-
getVarLengthInt
Returns the signed value of the integer (of the specified length) at the specified offset.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)len
- the number of bytes that the integer occupies (ie. 2 bytes == short int, 4 bytes == 32bit int, etc), valid lens are 1, 2 and 4.- Returns:
- int integer value
- Throws:
MemoryAccessException
-
getVarLengthUnsignedInt
Returns the unsigned value of the integer (of the specified length) at the specified offset.- Parameters:
offset
- the offset from the membuffers origin (the address that it is set at)len
- the number of bytes that the integer occupies (ie. 2 bytes == short int, 4 bytes == 32bit int, etc), valid lens are 1, 2 and 4.- Returns:
- long integer value
- Throws:
MemoryAccessException
-
getInputStream
Returns a stream that supplies the bytes of this buffer, starting at offset 0.Note: the default implementation will produce invalid results if the underlying MemBuffer instance is is mutated to point to different memory.
- Returns:
- an InputStream that returns the bytes of this mem buffer
-
getInputStream
Returns a stream that supplies the bytes of this buffer, starting at the specified offset.Note: the default implementation will produce invalid results if the underlying MemBuffer instance is is mutated to point to different memory.
- Parameters:
initialPosition
- location in membuffer where the stream should startlength
- number of bytes to limit the stream to- Returns:
- an InputSTream that returns the bytes of this mem buffer
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