1 //===-- MsgPackDocument.cpp - MsgPack Document --------------------------*-===//
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 /// This file implements a class that exposes a simple in-memory representation
10 /// of a document of MsgPack objects, that can be read from MsgPack, written to
11 /// MsgPack, and inspected and modified in memory. This is intended to be a
12 /// lighter-weight (in terms of memory allocations) replacement for
13 /// MsgPackTypes.
14 ///
15 //===----------------------------------------------------------------------===//
16 
17 #include "llvm/BinaryFormat/MsgPackDocument.h"
18 #include "llvm/BinaryFormat/MsgPackWriter.h"
19 
20 using namespace llvm;
21 using namespace msgpack;
22 
23 // Convert this DocNode into an empty array.
24 void DocNode::convertToArray() { *this = getDocument()->getArrayNode(); }
25 
26 // Convert this DocNode into an empty map.
27 void DocNode::convertToMap() { *this = getDocument()->getMapNode(); }
28 
29 /// Find the key in the MapDocNode.
30 DocNode::MapTy::iterator MapDocNode::find(StringRef S) {
31   return find(getDocument()->getNode(S));
32 }
33 
34 /// Member access for MapDocNode. The string data must remain valid for the
35 /// lifetime of the Document.
36 DocNode &MapDocNode::operator[](StringRef S) {
37   return (*this)[getDocument()->getNode(S)];
38 }
39 
40 /// Member access for MapDocNode.
41 DocNode &MapDocNode::operator[](DocNode Key) {
42   assert(!Key.isEmpty());
43   DocNode &N = (*Map)[Key];
44   if (N.isEmpty()) {
45     // Ensure a new element has its KindAndDoc initialized.
46     N = getDocument()->getEmptyNode();
47   }
48   return N;
49 }
50 
51 /// Member access for MapDocNode for integer key.
52 DocNode &MapDocNode::operator[](int Key) {
53   return (*this)[getDocument()->getNode(Key)];
54 }
55 DocNode &MapDocNode::operator[](unsigned Key) {
56   return (*this)[getDocument()->getNode(Key)];
57 }
58 DocNode &MapDocNode::operator[](int64_t Key) {
59   return (*this)[getDocument()->getNode(Key)];
60 }
61 DocNode &MapDocNode::operator[](uint64_t Key) {
62   return (*this)[getDocument()->getNode(Key)];
63 }
64 
65 /// Array element access. This extends the array if necessary.
66 DocNode &ArrayDocNode::operator[](size_t Index) {
67   if (size() <= Index) {
68     // Ensure new elements have their KindAndDoc initialized.
69     Array->resize(Index + 1, getDocument()->getEmptyNode());
70   }
71   return (*Array)[Index];
72 }
73 
74 // Convenience assignment operators. This only works if the destination
75 // DocNode has an associated Document, i.e. it was not constructed using the
76 // default constructor. The string one does not copy, so the string must
77 // remain valid for the lifetime of the Document. Use fromString to avoid
78 // that restriction.
79 DocNode &DocNode::operator=(StringRef Val) {
80   *this = getDocument()->getNode(Val);
81   return *this;
82 }
83 DocNode &DocNode::operator=(bool Val) {
84   *this = getDocument()->getNode(Val);
85   return *this;
86 }
87 DocNode &DocNode::operator=(int Val) {
88   *this = getDocument()->getNode(Val);
89   return *this;
90 }
91 DocNode &DocNode::operator=(unsigned Val) {
92   *this = getDocument()->getNode(Val);
93   return *this;
94 }
95 DocNode &DocNode::operator=(int64_t Val) {
96   *this = getDocument()->getNode(Val);
97   return *this;
98 }
99 DocNode &DocNode::operator=(uint64_t Val) {
100   *this = getDocument()->getNode(Val);
101   return *this;
102 }
103 
104 // A level in the document reading stack.
105 struct StackLevel {
106   StackLevel(DocNode Node, size_t StartIndex, size_t Length,
107              DocNode *MapEntry = nullptr)
108       : Node(Node), Index(StartIndex), End(StartIndex + Length),
109         MapEntry(MapEntry) {}
110   DocNode Node;
111   size_t Index;
112   size_t End;
113   // Points to map entry when we have just processed a map key.
114   DocNode *MapEntry;
115   DocNode MapKey;
116 };
117 
118 // Read a document from a binary msgpack blob, merging into anything already in
119 // the Document.
120 // The blob data must remain valid for the lifetime of this Document (because a
121 // string object in the document contains a StringRef into the original blob).
122 // If Multi, then this sets root to an array and adds top-level objects to it.
123 // If !Multi, then it only reads a single top-level object, even if there are
124 // more, and sets root to that.
125 // Returns false if failed due to illegal format or merge error.
126 
127 bool Document::readFromBlob(
128     StringRef Blob, bool Multi,
129     function_ref<int(DocNode *DestNode, DocNode SrcNode, DocNode MapKey)>
130         Merger) {
131   msgpack::Reader MPReader(Blob);
132   SmallVector<StackLevel, 4> Stack;
133   if (Multi) {
134     // Create the array for multiple top-level objects.
135     Root = getArrayNode();
136     Stack.push_back(StackLevel(Root, 0, (size_t)-1));
137   }
138   do {
139     // On to next element (or key if doing a map key next).
140     // Read the value.
141     Object Obj;
142     if (!MPReader.read(Obj)) {
143       if (Multi && Stack.size() == 1) {
144         // OK to finish here as we've just done a top-level element with Multi
145         break;
146       }
147       return false; // Finished too early
148     }
149     // Convert it into a DocNode.
150     DocNode Node;
151     switch (Obj.Kind) {
152     case Type::Nil:
153       Node = getNode();
154       break;
155     case Type::Int:
156       Node = getNode(Obj.Int);
157       break;
158     case Type::UInt:
159       Node = getNode(Obj.UInt);
160       break;
161     case Type::Boolean:
162       Node = getNode(Obj.Bool);
163       break;
164     case Type::Float:
165       Node = getNode(Obj.Float);
166       break;
167     case Type::String:
168       Node = getNode(Obj.Raw);
169       break;
170     case Type::Map:
171       Node = getMapNode();
172       break;
173     case Type::Array:
174       Node = getArrayNode();
175       break;
176     default:
177       return false; // Raw and Extension not supported
178     }
179 
180     // Store it.
181     DocNode *DestNode = nullptr;
182     if (Stack.empty())
183       DestNode = &Root;
184     else if (Stack.back().Node.getKind() == Type::Array) {
185       // Reading an array entry.
186       auto &Array = Stack.back().Node.getArray();
187       DestNode = &Array[Stack.back().Index++];
188     } else {
189       auto &Map = Stack.back().Node.getMap();
190       if (!Stack.back().MapEntry) {
191         // Reading a map key.
192         Stack.back().MapKey = Node;
193         Stack.back().MapEntry = &Map[Node];
194         continue;
195       }
196       // Reading the value for the map key read in the last iteration.
197       DestNode = Stack.back().MapEntry;
198       Stack.back().MapEntry = nullptr;
199       ++Stack.back().Index;
200     }
201     int MergeResult = 0;
202     if (!DestNode->isEmpty()) {
203       // In a merge, there is already a value at this position. Call the
204       // callback to attempt to resolve the conflict. The resolution must result
205       // in an array or map if Node is an array or map respectively.
206       DocNode MapKey = !Stack.empty() && !Stack.back().MapKey.isEmpty()
207                            ? Stack.back().MapKey
208                            : getNode();
209       MergeResult = Merger(DestNode, Node, MapKey);
210       if (MergeResult < 0)
211         return false; // Merge conflict resolution failed
212       assert(!((Node.isMap() && !DestNode->isMap()) ||
213                (Node.isArray() && !DestNode->isArray())));
214     } else
215       *DestNode = Node;
216 
217     // See if we're starting a new array or map.
218     switch (DestNode->getKind()) {
219     case msgpack::Type::Array:
220     case msgpack::Type::Map:
221       Stack.push_back(StackLevel(*DestNode, MergeResult, Obj.Length, nullptr));
222       break;
223     default:
224       break;
225     }
226 
227     // Pop finished stack levels.
228     while (!Stack.empty()) {
229       if (Stack.back().MapEntry)
230         break;
231       if (Stack.back().Index != Stack.back().End)
232         break;
233       Stack.pop_back();
234     }
235   } while (!Stack.empty());
236   return true;
237 }
238 
239 struct WriterStackLevel {
240   DocNode Node;
241   DocNode::MapTy::iterator MapIt;
242   DocNode::ArrayTy::iterator ArrayIt;
243   bool OnKey;
244 };
245 
246 /// Write a MsgPack document to a binary MsgPack blob.
247 void Document::writeToBlob(std::string &Blob) {
248   Blob.clear();
249   raw_string_ostream OS(Blob);
250   msgpack::Writer MPWriter(OS);
251   SmallVector<WriterStackLevel, 4> Stack;
252   DocNode Node = getRoot();
253   for (;;) {
254     switch (Node.getKind()) {
255     case Type::Array:
256       MPWriter.writeArraySize(Node.getArray().size());
257       Stack.push_back(
258           {Node, DocNode::MapTy::iterator(), Node.getArray().begin(), false});
259       break;
260     case Type::Map:
261       MPWriter.writeMapSize(Node.getMap().size());
262       Stack.push_back(
263           {Node, Node.getMap().begin(), DocNode::ArrayTy::iterator(), true});
264       break;
265     case Type::Nil:
266       MPWriter.writeNil();
267       break;
268     case Type::Boolean:
269       MPWriter.write(Node.getBool());
270       break;
271     case Type::Int:
272       MPWriter.write(Node.getInt());
273       break;
274     case Type::UInt:
275       MPWriter.write(Node.getUInt());
276       break;
277     case Type::String:
278       MPWriter.write(Node.getString());
279       break;
280     case Type::Empty:
281       llvm_unreachable("unhandled empty msgpack node");
282     default:
283       llvm_unreachable("unhandled msgpack object kind");
284     }
285     // Pop finished stack levels.
286     while (!Stack.empty()) {
287       if (Stack.back().Node.getKind() == Type::Map) {
288         if (Stack.back().MapIt != Stack.back().Node.getMap().end())
289           break;
290       } else {
291         if (Stack.back().ArrayIt != Stack.back().Node.getArray().end())
292           break;
293       }
294       Stack.pop_back();
295     }
296     if (Stack.empty())
297       break;
298     // Get the next value.
299     if (Stack.back().Node.getKind() == Type::Map) {
300       if (Stack.back().OnKey) {
301         // Do the key of a key,value pair in a map.
302         Node = Stack.back().MapIt->first;
303         Stack.back().OnKey = false;
304       } else {
305         Node = Stack.back().MapIt->second;
306         ++Stack.back().MapIt;
307         Stack.back().OnKey = true;
308       }
309     } else {
310       Node = *Stack.back().ArrayIt;
311       ++Stack.back().ArrayIt;
312     }
313   }
314 }
315