DataExtractor.h

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//===-- DataExtractor.h -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLDB_UTILITY_DATAEXTRACTOR_H
#define LLDB_UTILITY_DATAEXTRACTOR_H
 
#include "lldb/Utility/DataBuffer.h"
#include "lldb/Utility/Endian.h"
#include "lldb/lldb-defines.h"
#include "lldb/lldb-enumerations.h"
#include "lldb/lldb-forward.h"
#include "lldb/lldb-types.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/SwapByteOrder.h"
 
#include <cassert>
#include <cstdint>
#include <cstring>
#include <optional>
 
namespace lldb_private {
class Log;
class Stream;
}
namespace llvm {
template <typename T> class SmallVectorImpl;
}
 
 
namespace lldb_private {
 
/// \class DataExtractor DataExtractor.h "lldb/Core/DataExtractor.h" An data
/// extractor class.
///
/// DataExtractor is a class that can extract data (swapping if needed) from a
/// data buffer. The data buffer can be caller owned, or can be shared data
/// that can be shared between multiple DataExtractor instances. Multiple
/// DataExtractor objects can share the same data, yet extract values in
/// different address sizes and byte order modes. Each object can have a
/// unique position in the shared data and extract data from different
/// offsets.
///
/// \see DataBuffer
class DataExtractor {
public:
  /// \typedef DataExtractor::Type
  /// Type enumerations used in the dump routines.
  enum Type {
    TypeUInt8,   ///< Format output as unsigned 8 bit integers
    TypeChar,    ///< Format output as characters
    TypeUInt16,  ///< Format output as unsigned 16 bit integers
    TypeUInt32,  ///< Format output as unsigned 32 bit integers
    TypeUInt64,  ///< Format output as unsigned 64 bit integers
    TypePointer, ///< Format output as pointers
    TypeULEB128, ///< Format output as ULEB128 numbers
    TypeSLEB128  ///< Format output as SLEB128 numbers
  };
 
  /// Default constructor.
  ///
  /// Initialize all members to a default empty state.
  DataExtractor();
 
  /// Construct with a buffer that is owned by the caller.
  ///
  /// This constructor allows us to use data that is owned by the caller. The
  /// data must stay around as long as this object is valid.
  ///
  /// \param[in] data
  ///     A pointer to caller owned data.
  ///
  /// \param[in] data_length
  ///     The length in bytes of \a data.
  ///
  /// \param[in] byte_order
  ///     A byte order of the data that we are extracting from.
  ///
  /// \param[in] addr_size
  ///     A new address byte size value.
  DataExtractor(const void *data, lldb::offset_t data_length,
                lldb::ByteOrder byte_order, uint32_t addr_size);
 
  /// Construct with shared data.
  ///
  /// Copies the data shared pointer which adds a reference to the data
  /// contained in \a data_sp. The shared data reference is reference counted to
  /// ensure the data lives as long as anyone still has a valid shared pointer
  /// to the data in \a data_sp.
  ///
  /// \param[in] data_sp
  ///     A shared pointer to data.
  ///
  /// \param[in] byte_order
  ///     A byte order of the data that we are extracting from.
  ///
  /// \param[in] addr_size
  ///     A new address byte size value.
  DataExtractor(const lldb::DataBufferSP &data_sp, lldb::ByteOrder byte_order,
                uint32_t addr_size);
 
  /// Construct with shared data, but byte-order & addr-size are unspecified.
  ///
  /// Copies the data shared pointer which adds a reference to the data
  /// contained in \a data_sp. The shared data reference is reference counted to
  /// ensure the data lives as long as anyone still has a valid shared pointer
  /// to the data in \a data_sp.
  ///
  /// \param[in] data_sp
  ///     A shared pointer to data.
  explicit DataExtractor(const lldb::DataBufferSP &data_sp);
 
  /// Construct with a subset of \a data.
  ///
  /// Initialize this object with a subset of the data bytes in \a data. If \a
  /// data contains shared data, then a reference to the shared data will be
  /// added to ensure the shared data stays around as long as any objects have
  /// references to the shared data. The byte order value and the address size
  /// settings are copied from \a data. If \a offset is not a valid offset in
  /// \a data, then no reference to the shared data will be added. If there
  /// are not \a length bytes available in \a data starting at \a offset, the
  /// length will be truncated to contain as many bytes as possible.
  ///
  /// \param[in] data
  ///     Another DataExtractor object that contains data.
  ///
  /// \param[in] offset
  ///     The offset into \a data at which the subset starts.
  ///
  /// \param[in] length
  ///     The length in bytes of the subset of data.
  DataExtractor(const DataExtractor &data, lldb::offset_t offset,
                lldb::offset_t length);
 
  /// Copy constructor.
  ///
  /// The copy constructor is explicit as otherwise it is easy to make
  /// unintended modification of a local copy instead of a caller's instance.
  /// Also a needless copy of the \a m_data_sp shared pointer is/ expensive.
  explicit DataExtractor(const DataExtractor &rhs);
 
  /// Assignment operator.
  ///
  /// Copies all data, byte order and address size settings from \a rhs into
  /// this object. If \a rhs contains shared data, a reference to that shared
  /// data will be added.
  ///
  /// \param[in] rhs
  ///     Another DataExtractor object to copy.
  ///
  /// \return
  ///     A const reference to this object.
  const DataExtractor &operator=(const DataExtractor &rhs);
 
  /// Move constructor and move assignment operators to complete the rule of 5.
  ///
  /// They would get deleted as we already defined those of rule of 3.
  DataExtractor(DataExtractor &&rhs) = default;
  DataExtractor &operator=(DataExtractor &&rhs) = default;
 
  /// Destructor
  ///
  /// If this object contains a valid shared data reference, the reference
  /// count on the data will be decremented, and if zero, the data will be
  /// freed.
  virtual ~DataExtractor();
 
  /// Clears the object state.
  ///
  /// Clears the object contents back to a default invalid state, and release
  /// any references to shared data that this object may contain.
  void Clear();
 
  /// Return a shared pointer to a copy of this object.
  /// May be overridden by a subclass, so the object is copied correctly.
  virtual lldb::DataExtractorSP Clone() const {
    return std::make_shared<DataExtractor>(*this);
  }
 
  /// Dumps the binary data as \a type objects to stream \a s (or to Log() if
  /// \a s is nullptr) starting \a offset bytes into the data and stopping
  /// after dumping \a length bytes. The offset into the data is displayed at
  /// the beginning of each line and can be offset by base address \a
  /// base_addr. \a num_per_line objects will be displayed on each line.
  ///
  /// \param[in] log
  ///     The log to dump the output to.
  ///
  /// \param[in] offset
  ///     The offset into the data at which to start dumping.
  ///
  /// \param[in] length
  ///     The number of bytes to dump.
  ///
  /// \param[in] base_addr
  ///     The base address that gets added to the offset displayed on
  ///     each line.
  ///
  /// \param[in] num_per_line
  ///     The number of \a type objects to display on each line.
  ///
  /// \param[in] type
  ///     The type of objects to use when dumping data from this
  ///     object. See DataExtractor::Type.
  ///
  /// \return
  ///     The offset at which dumping ended.
  lldb::offset_t PutToLog(Log *log, lldb::offset_t offset,
                          lldb::offset_t length, uint64_t base_addr,
                          uint32_t num_per_line, Type type) const;
 
  /// Extract an arbitrary number of bytes in the specified byte order.
  ///
  /// Attemps to extract \a length bytes starting at \a offset bytes into this
  /// data in the requested byte order (\a dst_byte_order) and place the
  /// results in \a dst. \a dst must be at least \a length bytes long.
  ///
  /// \param[in] offset
  ///     The offset in bytes into the contained data at which to
  ///     start extracting.
  ///
  /// \param[in] length
  ///     The number of bytes to extract.
  ///
  /// \param[in] dst_byte_order
  ///     A byte order of the data that we want when the value in
  ///     copied to \a dst.
  ///
  /// \param[out] dst
  ///     The buffer that will receive the extracted value if there
  ///     are enough bytes available in the current data.
  ///
  /// \return
  ///     The number of bytes that were extracted which will be \a
  ///     length when the value is successfully extracted, or zero
  ///     if there aren't enough bytes at the specified offset.
  size_t ExtractBytes(lldb::offset_t offset, lldb::offset_t length,
                      lldb::ByteOrder dst_byte_order, void *dst) const;
 
  /// Extract an address from \a *offset_ptr.
  ///
  /// Extract a single address from the data and update the offset pointed to
  /// by \a offset_ptr. The size of the extracted address comes from the \a
  /// m_addr_size member variable and should be set correctly prior to
  /// extracting any address values.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted address value.
  uint64_t GetAddress(lldb::offset_t *offset_ptr) const;
 
  uint64_t GetAddress_unchecked(lldb::offset_t *offset_ptr) const;
 
  /// Get the current address size.
  ///
  /// Return the size in bytes of any address values this object will extract.
  ///
  /// \return
  ///     The size in bytes of address values that will be extracted.
  uint32_t GetAddressByteSize() const { return m_addr_size; }
 
  /// Get the number of bytes contained in this object.
  ///
  /// \return
  ///     The total number of bytes of data this object refers to.
  virtual uint64_t GetByteSize() const { return m_end - m_start; }
 
  /// Extract a C string from \a *offset_ptr.
  ///
  /// Returns a pointer to a C String from the data at the offset pointed to
  /// by \a offset_ptr. A variable length null-terminated C string will be
  /// extracted and the \a offset_ptr will be updated with the offset of the
  /// byte that follows the null terminator.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     A pointer to the C string value in the data. If the offset
  ///     pointed to by \a offset_ptr is out of bounds, or if the
  ///     offset plus the length of the C string is out of bounds,
  ///     nullptr will be returned.
  const char *GetCStr(lldb::offset_t *offset_ptr) const;
 
  /// Extract a C string from \a *offset_ptr with field size \a len.
  ///
  /// Returns a pointer to a C String from the data at the offset pointed to
  /// by \a offset_ptr, with a field length of \a len.
  /// A null-terminated C string will be extracted and the \a offset_ptr
  /// will be updated with the offset of the byte that follows the fixed
  /// length field.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     A pointer to the C string value in the data. If the offset
  ///     pointed to by \a offset_ptr is out of bounds, or if the
  ///     offset plus the length of the field is out of bounds, or if
  ///     the field does not contain a null terminator, nullptr will be
  ///     returned.
  const char *GetCStr(lldb::offset_t *offset_ptr, lldb::offset_t len) const;
 
  /// Extract \a length bytes from \a *offset_ptr.
  ///
  /// Returns a pointer to a bytes in this object's data at the offset pointed
  /// to by \a offset_ptr. If \a length is zero or too large, then the offset
  /// pointed to by \a offset_ptr will not be updated and nullptr will be
  /// returned.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] length
  ///     The optional length of a string to extract. If the value is
  ///     zero, a null-terminated C string will be extracted.
  ///
  /// \return
  ///     A pointer to the bytes in this object's data if the offset
  ///     and length are valid, or nullptr otherwise.
  virtual const void *GetData(lldb::offset_t *offset_ptr,
                              lldb::offset_t length) const {
    const uint8_t *ptr = PeekData(*offset_ptr, length);
    if (ptr)
      *offset_ptr += length;
    return ptr;
  }
 
  /// Copy \a length bytes from \a *offset, without swapping bytes.
  ///
  /// \param[in] offset
  ///     The offset into this data from which to start copying
  ///
  /// \param[in] length
  ///     The length of the data to copy from this object
  ///
  /// \param[out] dst
  ///     The buffer to place the output data.
  ///
  /// \return
  ///     Returns the number of bytes that were copied, or zero if
  ///     anything goes wrong.
  lldb::offset_t CopyData(lldb::offset_t offset, lldb::offset_t length,
                          void *dst) const;
 
  /// Copy \a dst_len bytes from \a *offset_ptr and ensure the copied data is
  /// treated as a value that can be swapped to match the specified byte
  /// order.
  ///
  /// For values that are larger than the supported integer sizes, this
  /// function can be used to extract data in a specified byte order. It can
  /// also be used to copy a smaller integer value from to a larger value. The
  /// extra bytes left over will be padded correctly according to the byte
  /// order of this object and the \a dst_byte_order. This can be very handy
  /// when say copying a partial data value into a register.
  ///
  /// \param[in] src_offset
  ///     The offset into this data from which to start copying an endian
  ///     entity
  ///
  /// \param[in] src_len
  ///     The length of the endian data to copy from this object into the \a
  ///     dst object
  ///
  /// \param[out] dst
  ///     The buffer where to place the endian data. The data might need to be
  ///     byte swapped (and appropriately padded with zeroes if \a src_len !=
  ///     \a dst_len) if \a dst_byte_order does not match the byte order in
  ///     this object.
  ///
  /// \param[in] dst_len
  ///     The length number of bytes that the endian value will occupy is \a
  ///     dst.
  ///
  /// \param[in] dst_byte_order
  ///     The byte order that the endian value should be in the \a dst buffer.
  ///
  /// \return
  ///     Returns the number of bytes that were copied, or zero if anything
  ///     goes wrong.
  lldb::offset_t CopyByteOrderedData(lldb::offset_t src_offset,
                                     lldb::offset_t src_len, void *dst,
                                     lldb::offset_t dst_len,
                                     lldb::ByteOrder dst_byte_order) const;
 
  /// Get the data end pointer.
  ///
  /// \return
  ///     Returns a pointer to the next byte contained in this
  ///     object's data, or nullptr of there is no data in this object.
  const uint8_t *GetDataEnd() const { return m_end; }
 
  /// Get the shared data offset.
  ///
  /// Get the offset of the first byte of data in the shared data (if any).
  ///
  /// \return
  ///     If this object contains shared data, this function returns
  ///     the offset in bytes into that shared data, zero otherwise.
  size_t GetSharedDataOffset() const;
 
  /// Get the data start pointer.
  ///
  /// \return
  ///     Returns a pointer to the first byte contained in this
  ///     object's data, or nullptr of there is no data in this object.
  const uint8_t *GetDataStart() const { return m_start; }
 
  /// Extract a float from \a *offset_ptr.
  ///
  /// Extract a single float value.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The floating value that was extracted, or zero on failure.
  float GetFloat(lldb::offset_t *offset_ptr) const;
 
  double GetDouble(lldb::offset_t *offset_ptr) const;
 
  long double GetLongDouble(lldb::offset_t *offset_ptr) const;
 
  /// Extract an integer of size \a byte_size from \a *offset_ptr.
  ///
  /// Extract a single integer value and update the offset pointed to by \a
  /// offset_ptr. The size of the extracted integer is specified by the \a
  /// byte_size argument. \a byte_size must have a value >= 1 and <= 4 since
  /// the return value is only 32 bits wide.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] byte_size
  ///     The size in byte of the integer to extract.
  ///
  /// \return
  ///     The integer value that was extracted, or zero on failure.
  uint32_t GetMaxU32(lldb::offset_t *offset_ptr, size_t byte_size) const;
 
  /// Extract an unsigned integer of size \a byte_size from \a *offset_ptr.
  ///
  /// Extract a single unsigned integer value and update the offset pointed to
  /// by \a offset_ptr. The size of the extracted integer is specified by the
  /// \a byte_size argument. \a byte_size must have a value greater than or
  /// equal to one and less than or equal to eight since the return value is
  /// 64 bits wide.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] byte_size
  ///     The size in byte of the integer to extract.
  ///
  /// \return
  ///     The unsigned integer value that was extracted, or zero on
  ///     failure.
  uint64_t GetMaxU64(lldb::offset_t *offset_ptr, size_t byte_size) const;
 
  uint64_t GetMaxU64_unchecked(lldb::offset_t *offset_ptr,
                               size_t byte_size) const;
 
  /// Extract an signed integer of size \a byte_size from \a *offset_ptr.
  ///
  /// Extract a single signed integer value (sign extending if required) and
  /// update the offset pointed to by \a offset_ptr. The size of the extracted
  /// integer is specified by the \a byte_size argument. \a byte_size must
  /// have a value greater than or equal to one and less than or equal to
  /// eight since the return value is 64 bits wide.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] byte_size
  ///     The size in byte of the integer to extract.
  ///
  /// \return
  ///     The sign extended signed integer value that was extracted,
  ///     or zero on failure.
  int64_t GetMaxS64(lldb::offset_t *offset_ptr, size_t byte_size) const;
 
  /// Extract an unsigned integer of size \a byte_size from \a *offset_ptr,
  /// then extract the bitfield from this value if \a bitfield_bit_size is
  /// non-zero.
  ///
  /// Extract a single unsigned integer value and update the offset pointed to
  /// by \a offset_ptr. The size of the extracted integer is specified by the
  /// \a byte_size argument. \a byte_size must have a value greater than or
  /// equal to one and less than or equal to 8 since the return value is 64
  /// bits wide.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] size
  ///     The size in byte of the integer to extract.
  ///
  /// \param[in] bitfield_bit_size
  ///     The size in bits of the bitfield value to extract, or zero
  ///     to just extract the entire integer value.
  ///
  /// \param[in] bitfield_bit_offset
  ///     The bit offset of the bitfield value in the extracted
  ///     integer.  For little-endian data, this is the offset of
  ///     the LSB of the bitfield from the LSB of the integer.
  ///     For big-endian data, this is the offset of the MSB of the
  ///     bitfield from the MSB of the integer.
  ///
  /// \return
  ///     The unsigned bitfield integer value that was extracted, or
  ///     zero on failure.
  uint64_t GetMaxU64Bitfield(lldb::offset_t *offset_ptr, size_t size,
                             uint32_t bitfield_bit_size,
                             uint32_t bitfield_bit_offset) const;
 
  /// Extract an signed integer of size \a size from \a *offset_ptr, then
  /// extract and sign-extend the bitfield from this value if \a
  /// bitfield_bit_size is non-zero.
  ///
  /// Extract a single signed integer value (sign-extending if required) and
  /// update the offset pointed to by \a offset_ptr. The size of the extracted
  /// integer is specified by the \a size argument. \a size must
  /// have a value greater than or equal to one and less than or equal to
  /// eight since the return value is 64 bits wide.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[in] size
  ///     The size in bytes of the integer to extract.
  ///
  /// \param[in] bitfield_bit_size
  ///     The size in bits of the bitfield value to extract, or zero
  ///     to just extract the entire integer value.
  ///
  /// \param[in] bitfield_bit_offset
  ///     The bit offset of the bitfield value in the extracted
  ///     integer.  For little-endian data, this is the offset of
  ///     the LSB of the bitfield from the LSB of the integer.
  ///     For big-endian data, this is the offset of the MSB of the
  ///     bitfield from the MSB of the integer.
  ///
  /// \return
  ///     The signed bitfield integer value that was extracted, or
  ///     zero on failure.
  int64_t GetMaxS64Bitfield(lldb::offset_t *offset_ptr, size_t size,
                            uint32_t bitfield_bit_size,
                            uint32_t bitfield_bit_offset) const;
 
  /// Get the current byte order value.
  ///
  /// \return
  ///     The current byte order value from this object's internal
  ///     state.
  lldb::ByteOrder GetByteOrder() const { return m_byte_order; }
 
  /// Extract a uint8_t value from \a *offset_ptr.
  ///
  /// Extract a single uint8_t from the binary data at the offset pointed to
  /// by \a offset_ptr, and advance the offset on success.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted uint8_t value.
  uint8_t GetU8(lldb::offset_t *offset_ptr) const;
 
  virtual uint8_t GetU8_unchecked(lldb::offset_t *offset_ptr) const {
    uint8_t val = m_start[*offset_ptr];
    *offset_ptr += 1;
    return val;
  }
 
  virtual uint16_t GetU16_unchecked(lldb::offset_t *offset_ptr) const;
 
  virtual uint32_t GetU32_unchecked(lldb::offset_t *offset_ptr) const;
 
  virtual uint64_t GetU64_unchecked(lldb::offset_t *offset_ptr) const;
  /// Extract \a count uint8_t values from \a *offset_ptr.
  ///
  /// Extract \a count uint8_t values from the binary data at the offset
  /// pointed to by \a offset_ptr, and advance the offset on success. The
  /// extracted values are copied into \a dst.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[out] dst
  ///     A buffer to copy \a count uint8_t values into. \a dst must
  ///     be large enough to hold all requested data.
  ///
  /// \param[in] count
  ///     The number of uint8_t values to extract.
  ///
  /// \return
  ///     \a dst if all values were properly extracted and copied,
  ///     nullptr otherwise.
  void *GetU8(lldb::offset_t *offset_ptr, void *dst, uint32_t count) const;
 
  /// Extract a uint16_t value from \a *offset_ptr.
  ///
  /// Extract a single uint16_t from the binary data at the offset pointed to
  /// by \a offset_ptr, and update the offset on success.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted uint16_t value.
  uint16_t GetU16(lldb::offset_t *offset_ptr) const;
 
  /// Extract \a count uint16_t values from \a *offset_ptr.
  ///
  /// Extract \a count uint16_t values from the binary data at the offset
  /// pointed to by \a offset_ptr, and advance the offset on success. The
  /// extracted values are copied into \a dst.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[out] dst
  ///     A buffer to copy \a count uint16_t values into. \a dst must
  ///     be large enough to hold all requested data.
  ///
  /// \param[in] count
  ///     The number of uint16_t values to extract.
  ///
  /// \return
  ///     \a dst if all values were properly extracted and copied,
  ///     nullptr otherwise.
  void *GetU16(lldb::offset_t *offset_ptr, void *dst, uint32_t count) const;
 
  /// Extract a uint32_t value from \a *offset_ptr.
  ///
  /// Extract a single uint32_t from the binary data at the offset pointed to
  /// by \a offset_ptr, and update the offset on success.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted uint32_t value.
  uint32_t GetU32(lldb::offset_t *offset_ptr) const;
 
  /// Extract \a count uint32_t values from \a *offset_ptr.
  ///
  /// Extract \a count uint32_t values from the binary data at the offset
  /// pointed to by \a offset_ptr, and advance the offset on success. The
  /// extracted values are copied into \a dst.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[out] dst
  ///     A buffer to copy \a count uint32_t values into. \a dst must
  ///     be large enough to hold all requested data.
  ///
  /// \param[in] count
  ///     The number of uint32_t values to extract.
  ///
  /// \return
  ///     \a dst if all values were properly extracted and copied,
  ///     nullptr otherwise.
  void *GetU32(lldb::offset_t *offset_ptr, void *dst, uint32_t count) const;
 
  /// Extract a uint64_t value from \a *offset_ptr.
  ///
  /// Extract a single uint64_t from the binary data at the offset pointed to
  /// by \a offset_ptr, and update the offset on success.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted uint64_t value.
  uint64_t GetU64(lldb::offset_t *offset_ptr) const;
 
  /// Extract \a count uint64_t values from \a *offset_ptr.
  ///
  /// Extract \a count uint64_t values from the binary data at the offset
  /// pointed to by \a offset_ptr, and advance the offset on success. The
  /// extracted values are copied into \a dst.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \param[out] dst
  ///     A buffer to copy \a count uint64_t values into. \a dst must
  ///     be large enough to hold all requested data.
  ///
  /// \param[in] count
  ///     The number of uint64_t values to extract.
  ///
  /// \return
  ///     \a dst if all values were properly extracted and copied,
  ///     nullptr otherwise.
  void *GetU64(lldb::offset_t *offset_ptr, void *dst, uint32_t count) const;
 
  /// Extract a signed LEB128 value from \a *offset_ptr.
  ///
  /// Extracts an signed LEB128 number from this object's data starting at the
  /// offset pointed to by \a offset_ptr. The offset pointed to by \a
  /// offset_ptr will be updated with the offset of the byte following the
  /// last extracted byte.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted signed integer value.
  int64_t GetSLEB128(lldb::offset_t *offset_ptr) const;
 
  /// Extract a unsigned LEB128 value from \a *offset_ptr.
  ///
  /// Extracts an unsigned LEB128 number from this object's data starting at
  /// the offset pointed to by \a offset_ptr. The offset pointed to by \a
  /// offset_ptr will be updated with the offset of the byte following the
  /// last extracted byte.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The extracted unsigned integer value.
  uint64_t GetULEB128(lldb::offset_t *offset_ptr) const;
 
  /// Return a new DataExtractor which represents a subset of an existing
  /// data extractor's bytes, copying all other fields from the existing
  /// data extractor.
  ///
  /// \param[in] offset
  ///     The starting byte offset into the shared data buffer.
  /// \param[in] length
  ///     The length of bytes that the new extractor can operate on.
  ///
  /// \return
  ///     A shared pointer to a new DataExtractor.
  virtual lldb::DataExtractorSP GetSubsetExtractorSP(lldb::offset_t offset,
                                                     lldb::offset_t length);
 
  /// Return a new DataExtractor which represents a subset of an existing
  /// data extractor's bytes, copying all other fields from the existing
  /// data extractor.  The length will be the largest contiguous region that
  /// can be provided starting at \a offset; it is safe to read any bytes
  /// within the returned subset Extractor.
  ///
  /// \param[in] offset
  ///     The starting byte offset into the shared data buffer.
  ///
  /// \return
  ///     A shared pointer to a new DataExtractor.
  virtual lldb::DataExtractorSP GetSubsetExtractorSP(lldb::offset_t offset);
 
  /// Return a new DataExtractor which represents a subset of an existing
  /// data extractor's bytes, copying all other fields from the existing
  /// data extractor.  The length will be the largest contiguous region that
  /// can be provided starting the beginning of this extractor; it is safe
  /// to read any bytes within the returned subset Extractor.
  ///
  /// \return
  ///     A shared pointer to a new DataExtractor.
  virtual lldb::DataExtractorSP GetContiguousDataExtractorSP() {
    return GetSubsetExtractorSP(0);
  }
 
  lldb::DataBufferSP GetSharedDataBuffer() const { return m_data_sp; }
 
  bool HasData() { return m_start && m_end && m_end - m_start > 0; }
 
  /// Peek at a null-terminated C string at \a offset.
  ///
  /// The terminator must lie within the bounds of this object's data, so the
  /// returned string never extends past the end of the data. Its data() is a
  /// valid C string pointer, and its size() is the length the caller would
  /// otherwise have to compute with strlen.
  ///
  /// \param[in] offset
  ///     An offset into the data.
  ///
  /// \return
  ///     The string at \a offset, or std::nullopt if \a offset is not a valid
  ///     offset or the string is not terminated within the data. An empty
  ///     string and a missing one are distinct.
  std::optional<llvm::StringRef> PeekCStr(lldb::offset_t offset) const;
 
  /// Peek at a bytes at \a offset.
  ///
  /// Returns a pointer to \a length bytes at \a offset as long as there are
  /// \a length bytes available starting at \a offset.
  ///
  /// \return
  ///     A non-nullptr data pointer if \a offset is a valid offset and
  ///     there are \a length bytes available at that offset, nullptr
  ///     otherwise.
  virtual const uint8_t *PeekData(lldb::offset_t offset,
                                  lldb::offset_t length) const {
    if (ValidOffsetForDataOfSize(offset, length))
      return m_start + offset;
    return nullptr;
  }
 
  /// Set the address byte size.
  ///
  /// Set the size in bytes that will be used when extracting any address and
  /// pointer values from data contained in this object.
  ///
  /// \param[in] addr_size
  ///     The size in bytes to use when extracting addresses.
  void SetAddressByteSize(uint32_t addr_size) {
    assert(addr_size == 2 || addr_size == 4 || addr_size == 8);
    m_addr_size = addr_size;
  }
 
  /// Set data with a buffer that is caller owned.
  ///
  /// Use data that is owned by the caller when extracting values. The data
  /// must stay around as long as this object, or any object that copies a
  /// subset of this object's data, is valid. If \a bytes is nullptr, or \a
  /// length is zero, this object will contain no data.
  ///
  /// \param[in] bytes
  ///     A pointer to caller owned data.
  ///
  /// \param[in] length
  ///     The length in bytes of \a bytes.
  ///
  /// \param[in] byte_order
  ///     A byte order of the data that we are extracting from.
  ///
  /// \return
  ///     The number of bytes that this object now contains.
  virtual lldb::offset_t SetData(const void *bytes, lldb::offset_t length,
                                 lldb::ByteOrder byte_order);
 
  /// Adopt a subset of \a data.
  ///
  /// Set this object's data to be a subset of the data bytes in \a data. If
  /// \a data contains shared data, then a reference to the shared data will
  /// be added to ensure the shared data stays around as long as any objects
  /// have references to the shared data. The byte order and the address size
  /// settings are copied from \a data. If \a offset is not a valid offset in
  /// \a data, then no reference to the shared data will be added. If there
  /// are not \a length bytes available in \a data starting at \a offset, the
  /// length will be truncated to contains as many bytes as possible.
  ///
  /// \param[in] data
  ///     Another DataExtractor object that contains data.
  ///
  /// \param[in] offset
  ///     The offset into \a data at which the subset starts.
  ///
  /// \param[in] length
  ///     The length in bytes of the subset of \a data.
  ///
  /// \return
  ///     The number of bytes that this object now contains.
  virtual lldb::offset_t SetData(const DataExtractor &data,
                                 lldb::offset_t offset, lldb::offset_t length);
 
  /// Adopt a subset of shared data in \a data_sp.
  ///
  /// Copies the data shared pointer which adds a reference to the contained
  /// in \a data_sp. The shared data reference is reference counted to ensure
  /// the data lives as long as anyone still has a valid shared pointer to the
  /// data in \a data_sp. The byte order and address byte size settings remain
  /// the same. If \a offset is not a valid offset in \a data_sp, then no
  /// reference to the shared data will be added. If there are not \a length
  /// bytes available in \a data starting at \a offset, the length will be
  /// truncated to contains as many bytes as possible.
  ///
  /// \param[in] data_sp
  ///     A shared pointer to data.
  ///
  /// \param[in] offset
  ///     The offset into \a data_sp at which the subset starts.
  ///
  /// \param[in] length
  ///     The length in bytes of the subset of \a data_sp.
  ///
  /// \return
  ///     The number of bytes that this object now contains.
  virtual lldb::offset_t SetData(const lldb::DataBufferSP &data_sp,
                                 lldb::offset_t offset = 0,
                                 lldb::offset_t length = LLDB_INVALID_OFFSET);
 
  /// Set the byte_order value.
  ///
  /// Sets the byte order of the data to extract. Extracted values will be
  /// swapped if necessary when decoding.
  ///
  /// \param[in] byte_order
  ///     The byte order value to use when extracting data.
  void SetByteOrder(lldb::ByteOrder byte_order) { m_byte_order = byte_order; }
 
  /// Skip an LEB128 number at \a *offset_ptr.
  ///
  /// Skips a LEB128 number (signed or unsigned) from this object's data
  /// starting at the offset pointed to by \a offset_ptr. The offset pointed
  /// to by \a offset_ptr will be updated with the offset of the byte
  /// following the last extracted byte.
  ///
  /// \param[in,out] offset_ptr
  ///     A pointer to an offset within the data that will be advanced
  ///     by the appropriate number of bytes if the value is extracted
  ///     correctly. If the offset is out of bounds or there are not
  ///     enough bytes to extract this value, the offset will be left
  ///     unmodified.
  ///
  /// \return
  ///     The number of bytes consumed during the extraction.
  uint32_t Skip_LEB128(lldb::offset_t *offset_ptr) const;
 
  /// Test the validity of \a offset.
  ///
  /// \return
  ///     true if \a offset is a valid offset into the data in this object,
  ///     false otherwise.
  bool ValidOffset(lldb::offset_t offset) const {
    return offset < GetByteSize();
  }
 
  /// Test the availability of \a length bytes of data from \a offset.
  ///
  /// \return
  ///     true if \a offset is a valid offset and there are \a
  ///     length bytes available at that offset, false otherwise.
  bool ValidOffsetForDataOfSize(lldb::offset_t offset,
                                lldb::offset_t length) const {
    return length <= BytesLeft(offset);
  }
 
  size_t Copy(DataExtractor &dest_data) const;
 
  bool Append(DataExtractor &rhs);
 
  bool Append(void *bytes, lldb::offset_t length);
 
  virtual lldb::offset_t BytesLeft(lldb::offset_t offset) const {
    const lldb::offset_t size = GetByteSize();
    if (size > offset)
      return size - offset;
    return 0;
  }
 
  void Checksum(llvm::SmallVectorImpl<uint8_t> &dest, uint64_t max_data = 0);
 
  virtual llvm::ArrayRef<uint8_t> GetData() const {
    return {GetDataStart(), size_t(GetByteSize())};
  }
 
  llvm::DataExtractor GetAsLLVM() const {
    return {GetData(), GetByteOrder() == lldb::eByteOrderLittle};
  }
 
protected:
  template <typename T> T Get(lldb::offset_t *offset_ptr, T fail_value) const {
    constexpr size_t src_size = sizeof(T);
    T val = fail_value;
 
    const void *src = GetData(offset_ptr, src_size);
    if (!src)
      return val;
 
    memcpy(&val, src, src_size);
    if (m_byte_order != endian::InlHostByteOrder())
      llvm::sys::swapByteOrder(val);
 
    return val;
  }
 
  // Member variables
  const uint8_t *m_start = nullptr; ///< A pointer to the first byte of data.
  const uint8_t *m_end =
      nullptr; ///< A pointer to the byte that is past the end of the data.
  lldb::ByteOrder
      m_byte_order;     ///< The byte order of the data we are extracting from.
  uint32_t m_addr_size; ///< The address size to use when extracting addresses.
  /// The shared pointer to data that can be shared among multiple instances
  lldb::DataBufferSP m_data_sp;
};
 
} // namespace lldb_private
 
#endif // LLDB_UTILITY_DATAEXTRACTOR_H