1 //===- JSONCompilationDatabase.cpp ----------------------------------------===//
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 contains the implementation of the JSONCompilationDatabase.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/Tooling/JSONCompilationDatabase.h"
14 #include "clang/Basic/LLVM.h"
15 #include "clang/Tooling/CompilationDatabase.h"
16 #include "clang/Tooling/CompilationDatabasePluginRegistry.h"
17 #include "clang/Tooling/Tooling.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/Support/Allocator.h"
24 #include "llvm/Support/Casting.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/ErrorOr.h"
27 #include "llvm/Support/Host.h"
28 #include "llvm/Support/MemoryBuffer.h"
29 #include "llvm/Support/Path.h"
30 #include "llvm/Support/StringSaver.h"
31 #include "llvm/Support/VirtualFileSystem.h"
32 #include "llvm/Support/YAMLParser.h"
33 #include "llvm/Support/raw_ostream.h"
34 #include <cassert>
35 #include <memory>
36 #include <optional>
37 #include <string>
38 #include <system_error>
39 #include <tuple>
40 #include <utility>
41 #include <vector>
42 
43 using namespace clang;
44 using namespace tooling;
45 
46 namespace {
47 
48 /// A parser for escaped strings of command line arguments.
49 ///
50 /// Assumes \-escaping for quoted arguments (see the documentation of
51 /// unescapeCommandLine(...)).
52 class CommandLineArgumentParser {
53  public:
54   CommandLineArgumentParser(StringRef CommandLine)
55       : Input(CommandLine), Position(Input.begin()-1) {}
56 
57   std::vector<std::string> parse() {
58     bool HasMoreInput = true;
59     while (HasMoreInput && nextNonWhitespace()) {
60       std::string Argument;
61       HasMoreInput = parseStringInto(Argument);
62       CommandLine.push_back(Argument);
63     }
64     return CommandLine;
65   }
66 
67  private:
68   // All private methods return true if there is more input available.
69 
70   bool parseStringInto(std::string &String) {
71     do {
72       if (*Position == '"') {
73         if (!parseDoubleQuotedStringInto(String)) return false;
74       } else if (*Position == '\'') {
75         if (!parseSingleQuotedStringInto(String)) return false;
76       } else {
77         if (!parseFreeStringInto(String)) return false;
78       }
79     } while (*Position != ' ');
80     return true;
81   }
82 
83   bool parseDoubleQuotedStringInto(std::string &String) {
84     if (!next()) return false;
85     while (*Position != '"') {
86       if (!skipEscapeCharacter()) return false;
87       String.push_back(*Position);
88       if (!next()) return false;
89     }
90     return next();
91   }
92 
93   bool parseSingleQuotedStringInto(std::string &String) {
94     if (!next()) return false;
95     while (*Position != '\'') {
96       String.push_back(*Position);
97       if (!next()) return false;
98     }
99     return next();
100   }
101 
102   bool parseFreeStringInto(std::string &String) {
103     do {
104       if (!skipEscapeCharacter()) return false;
105       String.push_back(*Position);
106       if (!next()) return false;
107     } while (*Position != ' ' && *Position != '"' && *Position != '\'');
108     return true;
109   }
110 
111   bool skipEscapeCharacter() {
112     if (*Position == '\\') {
113       return next();
114     }
115     return true;
116   }
117 
118   bool nextNonWhitespace() {
119     do {
120       if (!next()) return false;
121     } while (*Position == ' ');
122     return true;
123   }
124 
125   bool next() {
126     ++Position;
127     return Position != Input.end();
128   }
129 
130   const StringRef Input;
131   StringRef::iterator Position;
132   std::vector<std::string> CommandLine;
133 };
134 
135 std::vector<std::string> unescapeCommandLine(JSONCommandLineSyntax Syntax,
136                                              StringRef EscapedCommandLine) {
137   if (Syntax == JSONCommandLineSyntax::AutoDetect) {
138 #ifdef _WIN32
139     // Assume Windows command line parsing on Win32
140     Syntax = JSONCommandLineSyntax::Windows;
141 #else
142     Syntax = JSONCommandLineSyntax::Gnu;
143 #endif
144   }
145 
146   if (Syntax == JSONCommandLineSyntax::Windows) {
147     llvm::BumpPtrAllocator Alloc;
148     llvm::StringSaver Saver(Alloc);
149     llvm::SmallVector<const char *, 64> T;
150     llvm::cl::TokenizeWindowsCommandLine(EscapedCommandLine, Saver, T);
151     std::vector<std::string> Result(T.begin(), T.end());
152     return Result;
153   }
154   assert(Syntax == JSONCommandLineSyntax::Gnu);
155   CommandLineArgumentParser parser(EscapedCommandLine);
156   return parser.parse();
157 }
158 
159 // This plugin locates a nearby compile_command.json file, and also infers
160 // compile commands for files not present in the database.
161 class JSONCompilationDatabasePlugin : public CompilationDatabasePlugin {
162   std::unique_ptr<CompilationDatabase>
163   loadFromDirectory(StringRef Directory, std::string &ErrorMessage) override {
164     SmallString<1024> JSONDatabasePath(Directory);
165     llvm::sys::path::append(JSONDatabasePath, "compile_commands.json");
166     auto Base = JSONCompilationDatabase::loadFromFile(
167         JSONDatabasePath, ErrorMessage, JSONCommandLineSyntax::AutoDetect);
168     return Base ? inferTargetAndDriverMode(
169                       inferMissingCompileCommands(expandResponseFiles(
170                           std::move(Base), llvm::vfs::getRealFileSystem())))
171                 : nullptr;
172   }
173 };
174 
175 } // namespace
176 
177 // Register the JSONCompilationDatabasePlugin with the
178 // CompilationDatabasePluginRegistry using this statically initialized variable.
179 static CompilationDatabasePluginRegistry::Add<JSONCompilationDatabasePlugin>
180 X("json-compilation-database", "Reads JSON formatted compilation databases");
181 
182 namespace clang {
183 namespace tooling {
184 
185 // This anchor is used to force the linker to link in the generated object file
186 // and thus register the JSONCompilationDatabasePlugin.
187 volatile int JSONAnchorSource = 0;
188 
189 } // namespace tooling
190 } // namespace clang
191 
192 std::unique_ptr<JSONCompilationDatabase>
193 JSONCompilationDatabase::loadFromFile(StringRef FilePath,
194                                       std::string &ErrorMessage,
195                                       JSONCommandLineSyntax Syntax) {
196   // Don't mmap: if we're a long-lived process, the build system may overwrite.
197   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> DatabaseBuffer =
198       llvm::MemoryBuffer::getFile(FilePath, /*IsText=*/false,
199                                   /*RequiresNullTerminator=*/true,
200                                   /*IsVolatile=*/true);
201   if (std::error_code Result = DatabaseBuffer.getError()) {
202     ErrorMessage = "Error while opening JSON database: " + Result.message();
203     return nullptr;
204   }
205   std::unique_ptr<JSONCompilationDatabase> Database(
206       new JSONCompilationDatabase(std::move(*DatabaseBuffer), Syntax));
207   if (!Database->parse(ErrorMessage))
208     return nullptr;
209   return Database;
210 }
211 
212 std::unique_ptr<JSONCompilationDatabase>
213 JSONCompilationDatabase::loadFromBuffer(StringRef DatabaseString,
214                                         std::string &ErrorMessage,
215                                         JSONCommandLineSyntax Syntax) {
216   std::unique_ptr<llvm::MemoryBuffer> DatabaseBuffer(
217       llvm::MemoryBuffer::getMemBufferCopy(DatabaseString));
218   std::unique_ptr<JSONCompilationDatabase> Database(
219       new JSONCompilationDatabase(std::move(DatabaseBuffer), Syntax));
220   if (!Database->parse(ErrorMessage))
221     return nullptr;
222   return Database;
223 }
224 
225 std::vector<CompileCommand>
226 JSONCompilationDatabase::getCompileCommands(StringRef FilePath) const {
227   SmallString<128> NativeFilePath;
228   llvm::sys::path::native(FilePath, NativeFilePath);
229 
230   std::string Error;
231   llvm::raw_string_ostream ES(Error);
232   StringRef Match = MatchTrie.findEquivalent(NativeFilePath, ES);
233   if (Match.empty())
234     return {};
235   const auto CommandsRefI = IndexByFile.find(Match);
236   if (CommandsRefI == IndexByFile.end())
237     return {};
238   std::vector<CompileCommand> Commands;
239   getCommands(CommandsRefI->getValue(), Commands);
240   return Commands;
241 }
242 
243 std::vector<std::string>
244 JSONCompilationDatabase::getAllFiles() const {
245   std::vector<std::string> Result;
246   for (const auto &CommandRef : IndexByFile)
247     Result.push_back(CommandRef.first().str());
248   return Result;
249 }
250 
251 std::vector<CompileCommand>
252 JSONCompilationDatabase::getAllCompileCommands() const {
253   std::vector<CompileCommand> Commands;
254   getCommands(AllCommands, Commands);
255   return Commands;
256 }
257 
258 static llvm::StringRef stripExecutableExtension(llvm::StringRef Name) {
259   Name.consume_back(".exe");
260   return Name;
261 }
262 
263 // There are compiler-wrappers (ccache, distcc, gomacc) that take the "real"
264 // compiler as an argument, e.g. distcc gcc -O3 foo.c.
265 // These end up in compile_commands.json when people set CC="distcc gcc".
266 // Clang's driver doesn't understand this, so we need to unwrap.
267 static bool unwrapCommand(std::vector<std::string> &Args) {
268   if (Args.size() < 2)
269     return false;
270   StringRef Wrapper =
271       stripExecutableExtension(llvm::sys::path::filename(Args.front()));
272   if (Wrapper == "distcc" || Wrapper == "gomacc" || Wrapper == "ccache" ||
273       Wrapper == "sccache") {
274     // Most of these wrappers support being invoked 3 ways:
275     // `distcc g++ file.c` This is the mode we're trying to match.
276     //                     We need to drop `distcc`.
277     // `distcc file.c`     This acts like compiler is cc or similar.
278     //                     Clang's driver can handle this, no change needed.
279     // `g++ file.c`        g++ is a symlink to distcc.
280     //                     We don't even notice this case, and all is well.
281     //
282     // We need to distinguish between the first and second case.
283     // The wrappers themselves don't take flags, so Args[1] is a compiler flag,
284     // an input file, or a compiler. Inputs have extensions, compilers don't.
285     bool HasCompiler =
286         (Args[1][0] != '-') &&
287         !llvm::sys::path::has_extension(stripExecutableExtension(Args[1]));
288     if (HasCompiler) {
289       Args.erase(Args.begin());
290       return true;
291     }
292     // If !HasCompiler, wrappers act like GCC. Fine: so do we.
293   }
294   return false;
295 }
296 
297 static std::vector<std::string>
298 nodeToCommandLine(JSONCommandLineSyntax Syntax,
299                   const std::vector<llvm::yaml::ScalarNode *> &Nodes) {
300   SmallString<1024> Storage;
301   std::vector<std::string> Arguments;
302   if (Nodes.size() == 1)
303     Arguments = unescapeCommandLine(Syntax, Nodes[0]->getValue(Storage));
304   else
305     for (const auto *Node : Nodes)
306       Arguments.push_back(std::string(Node->getValue(Storage)));
307   // There may be multiple wrappers: using distcc and ccache together is common.
308   while (unwrapCommand(Arguments))
309     ;
310   return Arguments;
311 }
312 
313 void JSONCompilationDatabase::getCommands(
314     ArrayRef<CompileCommandRef> CommandsRef,
315     std::vector<CompileCommand> &Commands) const {
316   for (const auto &CommandRef : CommandsRef) {
317     SmallString<8> DirectoryStorage;
318     SmallString<32> FilenameStorage;
319     SmallString<32> OutputStorage;
320     auto Output = std::get<3>(CommandRef);
321     Commands.emplace_back(
322         std::get<0>(CommandRef)->getValue(DirectoryStorage),
323         std::get<1>(CommandRef)->getValue(FilenameStorage),
324         nodeToCommandLine(Syntax, std::get<2>(CommandRef)),
325         Output ? Output->getValue(OutputStorage) : "");
326   }
327 }
328 
329 bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
330   llvm::yaml::document_iterator I = YAMLStream.begin();
331   if (I == YAMLStream.end()) {
332     ErrorMessage = "Error while parsing YAML.";
333     return false;
334   }
335   llvm::yaml::Node *Root = I->getRoot();
336   if (!Root) {
337     ErrorMessage = "Error while parsing YAML.";
338     return false;
339   }
340   auto *Array = dyn_cast<llvm::yaml::SequenceNode>(Root);
341   if (!Array) {
342     ErrorMessage = "Expected array.";
343     return false;
344   }
345   for (auto &NextObject : *Array) {
346     auto *Object = dyn_cast<llvm::yaml::MappingNode>(&NextObject);
347     if (!Object) {
348       ErrorMessage = "Expected object.";
349       return false;
350     }
351     llvm::yaml::ScalarNode *Directory = nullptr;
352     std::optional<std::vector<llvm::yaml::ScalarNode *>> Command;
353     llvm::yaml::ScalarNode *File = nullptr;
354     llvm::yaml::ScalarNode *Output = nullptr;
355     for (auto& NextKeyValue : *Object) {
356       auto *KeyString = dyn_cast<llvm::yaml::ScalarNode>(NextKeyValue.getKey());
357       if (!KeyString) {
358         ErrorMessage = "Expected strings as key.";
359         return false;
360       }
361       SmallString<10> KeyStorage;
362       StringRef KeyValue = KeyString->getValue(KeyStorage);
363       llvm::yaml::Node *Value = NextKeyValue.getValue();
364       if (!Value) {
365         ErrorMessage = "Expected value.";
366         return false;
367       }
368       auto *ValueString = dyn_cast<llvm::yaml::ScalarNode>(Value);
369       auto *SequenceString = dyn_cast<llvm::yaml::SequenceNode>(Value);
370       if (KeyValue == "arguments") {
371         if (!SequenceString) {
372           ErrorMessage = "Expected sequence as value.";
373           return false;
374         }
375         Command = std::vector<llvm::yaml::ScalarNode *>();
376         for (auto &Argument : *SequenceString) {
377           auto *Scalar = dyn_cast<llvm::yaml::ScalarNode>(&Argument);
378           if (!Scalar) {
379             ErrorMessage = "Only strings are allowed in 'arguments'.";
380             return false;
381           }
382           Command->push_back(Scalar);
383         }
384       } else {
385         if (!ValueString) {
386           ErrorMessage = "Expected string as value.";
387           return false;
388         }
389         if (KeyValue == "directory") {
390           Directory = ValueString;
391         } else if (KeyValue == "command") {
392           if (!Command)
393             Command = std::vector<llvm::yaml::ScalarNode *>(1, ValueString);
394         } else if (KeyValue == "file") {
395           File = ValueString;
396         } else if (KeyValue == "output") {
397           Output = ValueString;
398         } else {
399           ErrorMessage =
400               ("Unknown key: \"" + KeyString->getRawValue() + "\"").str();
401           return false;
402         }
403       }
404     }
405     if (!File) {
406       ErrorMessage = "Missing key: \"file\".";
407       return false;
408     }
409     if (!Command) {
410       ErrorMessage = "Missing key: \"command\" or \"arguments\".";
411       return false;
412     }
413     if (!Directory) {
414       ErrorMessage = "Missing key: \"directory\".";
415       return false;
416     }
417     SmallString<8> FileStorage;
418     StringRef FileName = File->getValue(FileStorage);
419     SmallString<128> NativeFilePath;
420     if (llvm::sys::path::is_relative(FileName)) {
421       SmallString<8> DirectoryStorage;
422       SmallString<128> AbsolutePath(Directory->getValue(DirectoryStorage));
423       llvm::sys::path::append(AbsolutePath, FileName);
424       llvm::sys::path::native(AbsolutePath, NativeFilePath);
425     } else {
426       llvm::sys::path::native(FileName, NativeFilePath);
427     }
428     llvm::sys::path::remove_dots(NativeFilePath, /*remove_dot_dot=*/true);
429     auto Cmd = CompileCommandRef(Directory, File, *Command, Output);
430     IndexByFile[NativeFilePath].push_back(Cmd);
431     AllCommands.push_back(Cmd);
432     MatchTrie.insert(NativeFilePath);
433   }
434   return true;
435 }
436