LLVM 17.0.0git
BinaryStream.h
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1//===- BinaryStream.h - Base interface for a stream of data -----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_SUPPORT_BINARYSTREAM_H
10#define LLVM_SUPPORT_BINARYSTREAM_H
11
12#include "llvm/ADT/ArrayRef.h"
15#include "llvm/Support/Endian.h"
16#include "llvm/Support/Error.h"
17#include <cstdint>
18
19namespace llvm {
20
23 BSF_Write = 1, // Stream supports writing.
24 BSF_Append = 2, // Writing can occur at offset == length.
25 LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ BSF_Append)
26};
27
28/// An interface for accessing data in a stream-like format, but which
29/// discourages copying. Instead of specifying a buffer in which to copy
30/// data on a read, the API returns an ArrayRef to data owned by the stream's
31/// implementation. Since implementations may not necessarily store data in a
32/// single contiguous buffer (or even in memory at all), in such cases a it may
33/// be necessary for an implementation to cache such a buffer so that it can
34/// return it.
36public:
37 virtual ~BinaryStream() = default;
38
40
41 /// Given an offset into the stream and a number of bytes, attempt to
42 /// read the bytes and set the output ArrayRef to point to data owned by the
43 /// stream.
45 ArrayRef<uint8_t> &Buffer) = 0;
46
47 /// Given an offset into the stream, read as much as possible without
48 /// copying any data.
50 ArrayRef<uint8_t> &Buffer) = 0;
51
52 /// Return the number of bytes of data in this stream.
53 virtual uint64_t getLength() = 0;
54
55 /// Return the properties of this stream.
56 virtual BinaryStreamFlags getFlags() const { return BSF_None; }
57
58protected:
60 if (Offset > getLength())
61 return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
62 if (getLength() < DataSize + Offset)
63 return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
64 return Error::success();
65 }
66};
67
68/// A BinaryStream which can be read from as well as written to. Note
69/// that writing to a BinaryStream always necessitates copying from the input
70/// buffer to the stream's backing store. Streams are assumed to be buffered
71/// so that to be portable it is necessary to call commit() on the stream when
72/// all data has been written.
74public:
75 ~WritableBinaryStream() override = default;
76
77 /// Attempt to write the given bytes into the stream at the desired
78 /// offset. This will always necessitate a copy. Cannot shrink or grow the
79 /// stream, only writes into existing allocated space.
81
82 /// For buffered streams, commits changes to the backing store.
83 virtual Error commit() = 0;
84
85 /// Return the properties of this stream.
86 BinaryStreamFlags getFlags() const override { return BSF_Write; }
87
88protected:
90 if (!(getFlags() & BSF_Append))
91 return checkOffsetForRead(Offset, DataSize);
92
93 if (Offset > getLength())
94 return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
95 return Error::success();
96 }
97};
98
99} // end namespace llvm
100
101#endif // LLVM_SUPPORT_BINARYSTREAM_H
uint64_t Size
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
An interface for accessing data in a stream-like format, but which discourages copying.
Definition: BinaryStream.h:35
virtual uint64_t getLength()=0
Return the number of bytes of data in this stream.
virtual ~BinaryStream()=default
virtual Error readBytes(uint64_t Offset, uint64_t Size, ArrayRef< uint8_t > &Buffer)=0
Given an offset into the stream and a number of bytes, attempt to read the bytes and set the output A...
virtual llvm::support::endianness getEndian() const =0
virtual Error readLongestContiguousChunk(uint64_t Offset, ArrayRef< uint8_t > &Buffer)=0
Given an offset into the stream, read as much as possible without copying any data.
virtual BinaryStreamFlags getFlags() const
Return the properties of this stream.
Definition: BinaryStream.h:56
Error checkOffsetForRead(uint64_t Offset, uint64_t DataSize)
Definition: BinaryStream.h:59
Lightweight error class with error context and mandatory checking.
Definition: Error.h:156
static ErrorSuccess success()
Create a success value.
Definition: Error.h:330
A BinaryStream which can be read from as well as written to.
Definition: BinaryStream.h:73
Error checkOffsetForWrite(uint64_t Offset, uint64_t DataSize)
Definition: BinaryStream.h:89
~WritableBinaryStream() override=default
virtual Error writeBytes(uint64_t Offset, ArrayRef< uint8_t > Data)=0
Attempt to write the given bytes into the stream at the desired offset.
BinaryStreamFlags getFlags() const override
Return the properties of this stream.
Definition: BinaryStream.h:86
virtual Error commit()=0
For buffered streams, commits changes to the backing store.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Offset
Definition: DWP.cpp:406
BinaryStreamFlags
Definition: BinaryStream.h:21
@ BSF_None
Definition: BinaryStream.h:22
@ BSF_Append
Definition: BinaryStream.h:24
@ BSF_Write
Definition: BinaryStream.h:23