//===- BinaryStreamReader.h - Reads objects from a binary stream *- 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 LLVM_SUPPORT_BINARYSTREAMREADER_H
#define LLVM_SUPPORT_BINARYSTREAMREADER_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/BinaryStreamArray.h"
#include "llvm/Support/BinaryStreamRef.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include <type_traits>
namespace llvm {
/// Provides read only access to a subclass of `BinaryStream`. Provides
/// bounds checking and helpers for writing certain common data types such as
/// null-terminated strings, integers in various flavors of endianness, etc.
/// Can be subclassed to provide reading of custom datatypes, although no
/// are overridable.
class BinaryStreamReader {
public:
BinaryStreamReader() = default;
explicit BinaryStreamReader(BinaryStreamRef Ref);
explicit BinaryStreamReader(BinaryStream &Stream);
explicit BinaryStreamReader(ArrayRef<uint8_t> Data,
llvm::support::endianness Endian);
explicit BinaryStreamReader(StringRef Data, llvm::support::endianness Endian);
BinaryStreamReader(const BinaryStreamReader &Other) = default;
BinaryStreamReader &operator=(const BinaryStreamReader &Other) = default;
virtual ~BinaryStreamReader() = default;
/// Read as much as possible from the underlying string at the current offset
/// without invoking a copy, and set \p Buffer to the resulting data slice.
/// Updates the stream's offset to point after the newly read data.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer);
/// Read \p Size bytes from the underlying stream at the current offset and
/// and set \p Buffer to the resulting data slice. Whether a copy occurs
/// depends on the implementation of the underlying stream. Updates the
/// stream's offset to point after the newly read data.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size);
/// Read an integer of the specified endianness into \p Dest and update the
/// stream's offset. The data is always copied from the stream's underlying
/// buffer into \p Dest. Updates the stream's offset to point after the newly
/// read data.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
template <typename T> Error readInteger(T &Dest) {
static_assert(std::is_integral_v<T>,
"Cannot call readInteger with non-integral value!");
ArrayRef<uint8_t> Bytes;
if (auto EC = readBytes(Bytes, sizeof(T)))
return EC;
Dest = llvm::support::endian::read<T, llvm::support::unaligned>(
Bytes.data(), Stream.getEndian());
return Error::success();
}
/// Similar to readInteger.
template <typename T> Error readEnum(T &Dest) {
static_assert(std::is_enum<T>::value,
"Cannot call readEnum with non-enum value!");
std::underlying_type_t<T> N;
if (auto EC = readInteger(N))
return EC;
Dest = static_cast<T>(N);
return Error::success();
}
/// Read an unsigned LEB128 encoded value.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readULEB128(uint64_t &Dest);
/// Read a signed LEB128 encoded value.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readSLEB128(int64_t &Dest);
/// Read a null terminated string from \p Dest. Whether a copy occurs depends
/// on the implementation of the underlying stream. Updates the stream's
/// offset to point after the newly read data.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readCString(StringRef &Dest);
/// Similar to readCString, however read a null-terminated UTF16 string
/// instead.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readWideString(ArrayRef<UTF16> &Dest);
/// Read a \p Length byte string into \p Dest. Whether a copy occurs depends
/// on the implementation of the underlying stream. Updates the stream's
/// offset to point after the newly read data.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readFixedString(StringRef &Dest, uint32_t Length);
/// Read the entire remainder of the underlying stream into \p Ref. This is
/// equivalent to calling getUnderlyingStream().slice(Offset). Updates the
/// stream's offset to point to the end of the stream. Never causes a copy.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readStreamRef(BinaryStreamRef &Ref);
/// Read \p Length bytes from the underlying stream into \p Ref. This is
/// equivalent to calling getUnderlyingStream().slice(Offset, Length).
/// Updates the stream's offset to point after the newly read object. Never
/// causes a copy.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readStreamRef(BinaryStreamRef &Ref, uint32_t Length);
/// Read \p Length bytes from the underlying stream into \p Ref. This is
/// equivalent to calling getUnderlyingStream().slice(Offset, Length).
/// Updates the stream's offset to point after the newly read object. Never
/// causes a copy.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
Error readSubstream(BinarySubstreamRef &Ref, uint32_t Length);
/// Get a pointer to an object of type T from the underlying stream, as if by
/// memcpy, and store the result into \p Dest. It is up to the caller to
/// ensure that objects of type T can be safely treated in this manner.
/// Updates the stream's offset to point after the newly read object. Whether
/// a copy occurs depends upon the implementation of the underlying
/// stream.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
template <typename T> Error readObject(const T *&Dest) {
ArrayRef<uint8_t> Buffer;
if (auto EC = readBytes(Buffer, sizeof(T)))
return EC;
Dest = reinterpret_cast<const T *>(Buffer.data());
return Error::success();
}
/// Get a reference to a \p NumElements element array of objects of type T
/// from the underlying stream as if by memcpy, and store the resulting array
/// slice into \p array. It is up to the caller to ensure that objects of
/// type T can be safely treated in this manner. Updates the stream's offset
/// to point after the newly read object. Whether a copy occurs depends upon
/// the implementation of the underlying stream.
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
template <typename T>
Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
ArrayRef<uint8_t> Bytes;
if (NumElements == 0) {
Array = ArrayRef<T>();
return Error::success();
}
if (NumElements > UINT32_MAX / sizeof(T))
return make_error<BinaryStreamError>(
stream_error_code::invalid_array_size);
if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
return EC;
assert(isAddrAligned(Align::Of<T>(), Bytes.data()) &&
"Reading at invalid alignment!");
Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
return Error::success();
}
/// Read a VarStreamArray of size \p Size bytes and store the result into
/// \p Array. Updates the stream's offset to point after the newly read
/// array. Never causes a copy (although iterating the elements of the
/// VarStreamArray may, depending upon the implementation of the underlying
/// stream).
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
template <typename T, typename U>
Error readArray(VarStreamArray<T, U> &Array, uint32_t Size,
uint32_t Skew = 0) {
BinaryStreamRef S;
if (auto EC = readStreamRef(S, Size))
return EC;
Array.setUnderlyingStream(S, Skew);
return Error::success();
}
/// Read a FixedStreamArray of \p NumItems elements and store the result into
/// \p Array. Updates the stream's offset to point after the newly read
/// array. Never causes a copy (although iterating the elements of the
/// FixedStreamArray may, depending upon the implementation of the underlying
/// stream).
///
/// \returns a success error code if the data was successfully read, otherwise
/// returns an appropriate error code.
template <typename T>
Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) {
if (NumItems == 0) {
Array = FixedStreamArray<T>();
return Error::success();
}
if (NumItems > UINT32_MAX / sizeof(T))
return make_error<BinaryStreamError>(
stream_error_code::invalid_array_size);
BinaryStreamRef View;
if (auto EC = readStreamRef(View, NumItems * sizeof(T)))
return EC;
Array = FixedStreamArray<T>(View);
return Error::success();
}
bool empty() const { return bytesRemaining() == 0; }
void setOffset(uint64_t Off) { Offset = Off; }
uint64_t getOffset() const { return Offset; }
uint64_t getLength() const { return Stream.getLength(); }
uint64_t bytesRemaining() const { return getLength() - getOffset(); }
/// Advance the stream's offset by \p Amount bytes.
///
/// \returns a success error code if at least \p Amount bytes remain in the
/// stream, otherwise returns an appropriate error code.
Error skip(uint64_t Amount);
/// Examine the next byte of the underlying stream without advancing the
/// stream's offset. If the stream is empty the behavior is undefined.
///
/// \returns the next byte in the stream.
uint8_t peek() const;
Error padToAlignment(uint32_t Align);
std::pair<BinaryStreamReader, BinaryStreamReader>
split(uint64_t Offset) const;
private:
BinaryStreamRef Stream;
uint64_t Offset = 0;
};
} // namespace llvm
#endif // LLVM_SUPPORT_BINARYSTREAMREADER_H