clang-tools  10.0.0git
URI.cpp
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1 //===---- URI.h - File URIs with schemes -------------------------*- 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 #include "URI.h"
10 #include "llvm/ADT/StringExtras.h"
11 #include "llvm/ADT/Twine.h"
12 #include "llvm/Support/Error.h"
13 #include "llvm/Support/Format.h"
14 #include "llvm/Support/FormatVariadic.h"
15 #include "llvm/Support/Path.h"
16 #include <algorithm>
17 
18 LLVM_INSTANTIATE_REGISTRY(clang::clangd::URISchemeRegistry)
19 
20 namespace clang {
21 namespace clangd {
22 namespace {
23 
24 inline llvm::Error make_string_error(const llvm::Twine &Message) {
25  return llvm::make_error<llvm::StringError>(Message,
26  llvm::inconvertibleErrorCode());
27 }
28 
29 /// This manages file paths in the file system. All paths in the scheme
30 /// are absolute (with leading '/').
31 /// Note that this scheme is hardcoded into the library and not registered in
32 /// registry.
33 class FileSystemScheme : public URIScheme {
34 public:
35  llvm::Expected<std::string>
36  getAbsolutePath(llvm::StringRef /*Authority*/, llvm::StringRef Body,
37  llvm::StringRef /*HintPath*/) const override {
38  if (!Body.startswith("/"))
39  return make_string_error("File scheme: expect body to be an absolute "
40  "path starting with '/': " +
41  Body);
42  // For Windows paths e.g. /X:
43  if (Body.size() > 2 && Body[0] == '/' && Body[2] == ':')
44  Body.consume_front("/");
45  llvm::SmallVector<char, 16> Path(Body.begin(), Body.end());
46  llvm::sys::path::native(Path);
47  return std::string(Path.begin(), Path.end());
48  }
49 
50  llvm::Expected<URI>
51  uriFromAbsolutePath(llvm::StringRef AbsolutePath) const override {
52  std::string Body;
53  // For Windows paths e.g. X:
54  if (AbsolutePath.size() > 1 && AbsolutePath[1] == ':')
55  Body = "/";
56  Body += llvm::sys::path::convert_to_slash(AbsolutePath);
57  return URI("file", /*Authority=*/"", Body);
58  }
59 };
60 
61 llvm::Expected<std::unique_ptr<URIScheme>>
62 findSchemeByName(llvm::StringRef Scheme) {
63  if (Scheme == "file")
64  return std::make_unique<FileSystemScheme>();
65 
66  for (auto I = URISchemeRegistry::begin(), E = URISchemeRegistry::end();
67  I != E; ++I) {
68  if (I->getName() != Scheme)
69  continue;
70  return I->instantiate();
71  }
72  return make_string_error("Can't find scheme: " + Scheme);
73 }
74 
75 bool shouldEscape(unsigned char C) {
76  // Unreserved characters.
77  if ((C >= 'a' && C <= 'z') || (C >= 'A' && C <= 'Z') ||
78  (C >= '0' && C <= '9'))
79  return false;
80  switch (C) {
81  case '-':
82  case '_':
83  case '.':
84  case '~':
85  case '/': // '/' is only reserved when parsing.
86  // ':' is only reserved for relative URI paths, which clangd doesn't produce.
87  case ':':
88  return false;
89  }
90  return true;
91 }
92 
93 /// Encodes a string according to percent-encoding.
94 /// - Unreserved characters are not escaped.
95 /// - Reserved characters always escaped with exceptions like '/'.
96 /// - All other characters are escaped.
97 void percentEncode(llvm::StringRef Content, std::string &Out) {
98  std::string Result;
99  for (unsigned char C : Content)
100  if (shouldEscape(C))
101  {
102  Out.push_back('%');
103  Out.push_back(llvm::hexdigit(C / 16));
104  Out.push_back(llvm::hexdigit(C % 16));
105  } else
106  { Out.push_back(C); }
107 }
108 
109 /// Decodes a string according to percent-encoding.
110 std::string percentDecode(llvm::StringRef Content) {
111  std::string Result;
112  for (auto I = Content.begin(), E = Content.end(); I != E; ++I) {
113  if (*I != '%') {
114  Result += *I;
115  continue;
116  }
117  if (*I == '%' && I + 2 < Content.end() && llvm::isHexDigit(*(I + 1)) &&
118  llvm::isHexDigit(*(I + 2))) {
119  Result.push_back(llvm::hexFromNibbles(*(I + 1), *(I + 2)));
120  I += 2;
121  } else
122  Result.push_back(*I);
123  }
124  return Result;
125 }
126 
127 bool isValidScheme(llvm::StringRef Scheme) {
128  if (Scheme.empty())
129  return false;
130  if (!llvm::isAlpha(Scheme[0]))
131  return false;
132  return std::all_of(Scheme.begin() + 1, Scheme.end(), [](char C) {
133  return llvm::isAlnum(C) || C == '+' || C == '.' || C == '-';
134  });
135 }
136 
137 } // namespace
138 
139 URI::URI(llvm::StringRef Scheme, llvm::StringRef Authority,
140  llvm::StringRef Body)
141  : Scheme(Scheme), Authority(Authority), Body(Body) {
142  assert(!Scheme.empty());
143  assert((Authority.empty() || Body.startswith("/")) &&
144  "URI body must start with '/' when authority is present.");
145 }
146 
147 std::string URI::toString() const {
148  std::string Result;
149  percentEncode(Scheme, Result);
150  Result.push_back(':');
151  if (Authority.empty() && Body.empty())
152  return Result;
153  // If authority if empty, we only print body if it starts with "/"; otherwise,
154  // the URI is invalid.
155  if (!Authority.empty() || llvm::StringRef(Body).startswith("/"))
156  {
157  Result.append("//");
158  percentEncode(Authority, Result);
159  }
160  percentEncode(Body, Result);
161  return Result;
162 }
163 
164 llvm::Expected<URI> URI::parse(llvm::StringRef OrigUri) {
165  URI U;
166  llvm::StringRef Uri = OrigUri;
167 
168  auto Pos = Uri.find(':');
169  if (Pos == llvm::StringRef::npos)
170  return make_string_error("Scheme must be provided in URI: " + OrigUri);
171  auto SchemeStr = Uri.substr(0, Pos);
172  U.Scheme = percentDecode(SchemeStr);
173  if (!isValidScheme(U.Scheme))
174  return make_string_error(llvm::formatv("Invalid scheme: {0} (decoded: {1})",
175  SchemeStr, U.Scheme));
176  Uri = Uri.substr(Pos + 1);
177  if (Uri.consume_front("//")) {
178  Pos = Uri.find('/');
179  U.Authority = percentDecode(Uri.substr(0, Pos));
180  Uri = Uri.substr(Pos);
181  }
182  U.Body = percentDecode(Uri);
183  return U;
184 }
185 
186 llvm::Expected<std::string> URI::resolve(llvm::StringRef FileURI,
187  llvm::StringRef HintPath) {
188  auto Uri = URI::parse(FileURI);
189  if (!Uri)
190  return Uri.takeError();
191  auto Path = URI::resolve(*Uri, HintPath);
192  if (!Path)
193  return Path.takeError();
194  return *Path;
195 }
196 
197 llvm::Expected<URI> URI::create(llvm::StringRef AbsolutePath,
198  llvm::StringRef Scheme) {
199  if (!llvm::sys::path::is_absolute(AbsolutePath))
200  return make_string_error("Not a valid absolute path: " + AbsolutePath);
201  auto S = findSchemeByName(Scheme);
202  if (!S)
203  return S.takeError();
204  return S->get()->uriFromAbsolutePath(AbsolutePath);
205 }
206 
207 URI URI::create(llvm::StringRef AbsolutePath) {
208  if (!llvm::sys::path::is_absolute(AbsolutePath))
209  llvm_unreachable(
210  ("Not a valid absolute path: " + AbsolutePath).str().c_str());
211  for (auto &Entry : URISchemeRegistry::entries()) {
212  auto URI = Entry.instantiate()->uriFromAbsolutePath(AbsolutePath);
213  // For some paths, conversion to different URI schemes is impossible. These
214  // should be just skipped.
215  if (!URI) {
216  // Ignore the error.
217  llvm::consumeError(URI.takeError());
218  continue;
219  }
220  return std::move(*URI);
221  }
222  // Fallback to file: scheme which should work for any paths.
223  return URI::createFile(AbsolutePath);
224 }
225 
226 URI URI::createFile(llvm::StringRef AbsolutePath) {
227  auto U = FileSystemScheme().uriFromAbsolutePath(AbsolutePath);
228  if (!U)
229  llvm_unreachable(llvm::toString(U.takeError()).c_str());
230  return std::move(*U);
231 }
232 
233 llvm::Expected<std::string> URI::resolve(const URI &Uri,
234  llvm::StringRef HintPath) {
235  auto S = findSchemeByName(Uri.Scheme);
236  if (!S)
237  return S.takeError();
238  return S->get()->getAbsolutePath(Uri.Authority, Uri.Body, HintPath);
239 }
240 
241 llvm::Expected<std::string> URI::resolvePath(llvm::StringRef AbsPath,
242  llvm::StringRef HintPath) {
243  if (!llvm::sys::path::is_absolute(AbsPath))
244  llvm_unreachable(("Not a valid absolute path: " + AbsPath).str().c_str());
245  for (auto &Entry : URISchemeRegistry::entries()) {
246  auto S = Entry.instantiate();
247  auto U = S->uriFromAbsolutePath(AbsPath);
248  // For some paths, conversion to different URI schemes is impossible. These
249  // should be just skipped.
250  if (!U) {
251  // Ignore the error.
252  llvm::consumeError(U.takeError());
253  continue;
254  }
255  return S->getAbsolutePath(U->Authority, U->Body, HintPath);
256  }
257  // Fallback to file: scheme which doesn't do any canonicalization.
258  return AbsPath;
259 }
260 
261 llvm::Expected<std::string> URI::includeSpelling(const URI &Uri) {
262  auto S = findSchemeByName(Uri.Scheme);
263  if (!S)
264  return S.takeError();
265  return S->get()->getIncludeSpelling(Uri);
266 }
267 
268 } // namespace clangd
269 } // namespace clang
constexpr llvm::StringLiteral Message
static llvm::StringRef toString(SpecialMemberFunctionsCheck::SpecialMemberFunctionKind K)
static URI createFile(llvm::StringRef AbsolutePath)
This creates a file:// URI for AbsolutePath. The path must be absolute.
Definition: URI.cpp:226
llvm::Registry< URIScheme > URISchemeRegistry
By default, a "file" scheme is supported where URI paths are always absolute in the file system...
Definition: URI.h:131
static llvm::Expected< std::string > resolvePath(llvm::StringRef AbsPath, llvm::StringRef HintPath="")
Resolves AbsPath into a canonical path of its URI, by converting AbsPath to URI and resolving the URI...
Definition: URI.cpp:241
std::string Path
A typedef to represent a file path.
Definition: Path.h:20
Position Pos
Definition: SourceCode.cpp:772
static llvm::Expected< URI > create(llvm::StringRef AbsolutePath, llvm::StringRef Scheme)
Creates a URI for a file in the given scheme.
Definition: URI.cpp:197
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
A URI describes the location of a source file.
Definition: URI.h:28
const Expr * E
static llvm::Expected< std::string > resolve(const URI &U, llvm::StringRef HintPath="")
Resolves the absolute path of U.
Definition: URI.cpp:233
static llvm::Expected< std::string > includeSpelling(const URI &U)
Gets the preferred spelling of this file for #include, if there is one, e.g.
Definition: URI.cpp:261
static llvm::Expected< URI > parse(llvm::StringRef Uri)
Parse a URI string "<scheme>:[//<authority>/]<path>".
Definition: URI.cpp:164
std::string toString() const
Returns a string URI with all components percent-encoded.
Definition: URI.cpp:147