1//===- StreamableMemoryObject.cpp - Streamable data interface -------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Support/StreamableMemoryObject.h"
11#include "llvm/Support/Compiler.h"
12#include <cassert>
13#include <cstddef>
14#include <cstring>
15
16
17using namespace llvm;
18
19namespace {
20
21class RawMemoryObject : public StreamableMemoryObject {
22public:
23  RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
24    FirstChar(Start), LastChar(End) {
25    assert(LastChar >= FirstChar && "Invalid start/end range");
26  }
27
28  uint64_t getBase() const override { return 0; }
29  uint64_t getExtent() const override {
30    return LastChar - FirstChar;
31  }
32  int readByte(uint64_t address, uint8_t* ptr) const override;
33  int readBytes(uint64_t address, uint64_t size,
34                uint8_t *buf) const override;
35  const uint8_t *getPointer(uint64_t address, uint64_t size) const override;
36  bool isValidAddress(uint64_t address) const override {
37    return validAddress(address);
38  }
39  bool isObjectEnd(uint64_t address) const override {
40    return objectEnd(address);
41  }
42
43private:
44  const uint8_t* const FirstChar;
45  const uint8_t* const LastChar;
46
47  // These are implemented as inline functions here to avoid multiple virtual
48  // calls per public function
49  bool validAddress(uint64_t address) const {
50    return static_cast<std::ptrdiff_t>(address) < LastChar - FirstChar;
51  }
52  bool objectEnd(uint64_t address) const {
53    return static_cast<std::ptrdiff_t>(address) == LastChar - FirstChar;
54  }
55
56  RawMemoryObject(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
57  void operator=(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
58};
59
60int RawMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
61  if (!validAddress(address)) return -1;
62  *ptr = *((uint8_t *)(uintptr_t)(address + FirstChar));
63  return 0;
64}
65
66int RawMemoryObject::readBytes(uint64_t address,
67                               uint64_t size,
68                               uint8_t *buf) const {
69  if (!validAddress(address) || !validAddress(address + size - 1)) return -1;
70  memcpy(buf, (uint8_t *)(uintptr_t)(address + FirstChar), size);
71  return size;
72}
73
74const uint8_t *RawMemoryObject::getPointer(uint64_t address,
75                                           uint64_t size) const {
76  return FirstChar + address;
77}
78} // anonymous namespace
79
80namespace llvm {
81// If the bitcode has a header, then its size is known, and we don't have to
82// block until we actually want to read it.
83bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
84  if (ObjectSize && address < ObjectSize) return true;
85    return fetchToPos(address);
86}
87
88bool StreamingMemoryObject::isObjectEnd(uint64_t address) const {
89  if (ObjectSize) return address == ObjectSize;
90  fetchToPos(address);
91  return address == ObjectSize && address != 0;
92}
93
94uint64_t StreamingMemoryObject::getExtent() const {
95  if (ObjectSize) return ObjectSize;
96  size_t pos = BytesRead + kChunkSize;
97  // keep fetching until we run out of bytes
98  while (fetchToPos(pos)) pos += kChunkSize;
99  return ObjectSize;
100}
101
102int StreamingMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
103  if (!fetchToPos(address)) return -1;
104  *ptr = Bytes[address + BytesSkipped];
105  return 0;
106}
107
108int StreamingMemoryObject::readBytes(uint64_t address,
109                                     uint64_t size,
110                                     uint8_t *buf) const {
111  if (!fetchToPos(address + size - 1)) return -1;
112  memcpy(buf, &Bytes[address + BytesSkipped], size);
113  return 0;
114}
115
116bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
117  if (BytesRead < s) return true;
118  BytesSkipped = s;
119  BytesRead -= s;
120  return false;
121}
122
123void StreamingMemoryObject::setKnownObjectSize(size_t size) {
124  ObjectSize = size;
125  Bytes.reserve(size);
126}
127
128StreamableMemoryObject *getNonStreamedMemoryObject(
129    const unsigned char *Start, const unsigned char *End) {
130  return new RawMemoryObject(Start, End);
131}
132
133StreamableMemoryObject::~StreamableMemoryObject() { }
134
135StreamingMemoryObject::StreamingMemoryObject(DataStreamer *streamer) :
136  Bytes(kChunkSize), Streamer(streamer), BytesRead(0), BytesSkipped(0),
137  ObjectSize(0), EOFReached(false) {
138  BytesRead = streamer->GetBytes(&Bytes[0], kChunkSize);
139}
140}
141