clang-tools 10.0.0

FSProvider.cpp
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1 //===--- FSProvider.cpp - VFS provider for ClangdServer -------------------===//
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 #include "FSProvider.h"
10 #include "llvm/ADT/STLExtras.h"
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/Support/Path.h"
14 #include "llvm/Support/VirtualFileSystem.h"
15 #include <memory>
16
17 namespace clang {
18 namespace clangd {
19
20 namespace {
21 /// Always opens files in the underlying filesystem as "volatile", meaning they
22 /// won't be memory-mapped. Memory-mapping isn't desirable for clangd:
23 /// - edits to the underlying files change contents MemoryBuffers owned by
24 // SourceManager, breaking its invariants and leading to crashes
25 /// - it locks files on windows, preventing edits
26 class VolatileFileSystem : public llvm::vfs::ProxyFileSystem {
27 public:
28 explicit VolatileFileSystem(llvm::IntrusiveRefCntPtr<FileSystem> FS)
29 : ProxyFileSystem(std::move(FS)) {}
30
31 llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
32 openFileForRead(const llvm::Twine &InPath) override {
33 llvm::SmallString<128> Path;
34 InPath.toVector(Path);
35
36 auto File = getUnderlyingFS().openFileForRead(Path);
37 if (!File)
38 return File;
39 // Try to guess preamble files, they can be memory-mapped even on Windows as
40 // clangd has exclusive access to those and nothing else should touch them.
41 llvm::StringRef FileName = llvm::sys::path::filename(Path);
42 if (FileName.startswith("preamble-") && FileName.endswith(".pch"))
43 return File;
44 return std::unique_ptr<VolatileFile>(new VolatileFile(std::move(*File)));
45 }
46
47 private:
48 class VolatileFile : public llvm::vfs::File {
49 public:
50 VolatileFile(std::unique_ptr<llvm::vfs::File> Wrapped)
51 : Wrapped(std::move(Wrapped)) {
52 assert(this->Wrapped);
53 }
54
55 virtual llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
56 getBuffer(const llvm::Twine &Name, int64_t FileSize,
57 bool RequiresNullTerminator, bool /*IsVolatile*/) override {
58 return Wrapped->getBuffer(Name, FileSize, RequiresNullTerminator,
59 /*IsVolatile=*/true);
60 }
61
62 llvm::ErrorOr<llvm::vfs::Status> status() override {
63 return Wrapped->status();
64 }
65 llvm::ErrorOr<std::string> getName() override { return Wrapped->getName(); }
66 std::error_code close() override { return Wrapped->close(); }
67
68 private:
69 std::unique_ptr<File> Wrapped;
70 };
71 };
72 } // namespace
73
74 llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>
75 clang::clangd::RealFileSystemProvider::getFileSystem() const {
76 // Avoid using memory-mapped files.
77 // FIXME: Try to use a similar approach in Sema instead of relying on
78 // propagation of the 'isVolatile' flag through all layers.
79 return new VolatileFileSystem(
80 llvm::vfs::createPhysicalFileSystem().release());
81 }
82 } // namespace clangd
83 } // namespace clang
FS
MockFSProvider FS
Definition: HeadersTests.cpp:119
clang::clangd::Path
std::string Path
A typedef to represent a file path.
Definition: Path.h:20
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
FileName
PathRef FileName
Definition: CodeComplete.cpp:1018
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
FSProvider.h
clang::clangd::RealFileSystemProvider::getFileSystem
llvm::IntrusiveRefCntPtr< llvm::vfs::FileSystem > getFileSystem() const override
Called by ClangdServer to obtain a vfs::FileSystem to be used for parsing.
Definition: FSProvider.cpp:75
clang::clangd::CompletionItemKind::File