1 //===- DriverUtils.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 utility functions for the driver. Because there
10 // are so many small functions, we created this separate file to make
11 // Driver.cpp less cluttered.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "Config.h"
16 #include "Driver.h"
17 #include "lld/Common/CommonLinkerContext.h"
18 #include "lld/Common/Reproduce.h"
19 #include "llvm/ADT/Optional.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/Option/Option.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/FileSystem.h"
24 #include "llvm/Support/Host.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/TimeProfiler.h"
27 
28 using namespace llvm;
29 using namespace llvm::sys;
30 using namespace llvm::opt;
31 using namespace lld;
32 using namespace lld::elf;
33 
34 // Create OptTable
35 
36 // Create prefix string literals used in Options.td
37 #define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
38 #include "Options.inc"
39 #undef PREFIX
40 
41 // Create table mapping all options defined in Options.td
42 static const opt::OptTable::Info optInfo[] = {
43 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
44   {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
45    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
46 #include "Options.inc"
47 #undef OPTION
48 };
49 
50 ELFOptTable::ELFOptTable() : OptTable(optInfo) {}
51 
52 // Set color diagnostics according to --color-diagnostics={auto,always,never}
53 // or --no-color-diagnostics flags.
54 static void handleColorDiagnostics(opt::InputArgList &args) {
55   auto *arg = args.getLastArg(OPT_color_diagnostics);
56   if (!arg)
57     return;
58   StringRef s = arg->getValue();
59   if (s == "always")
60     lld::errs().enable_colors(true);
61   else if (s == "never")
62     lld::errs().enable_colors(false);
63   else if (s != "auto")
64     error("unknown option: --color-diagnostics=" + s);
65 }
66 
67 static cl::TokenizerCallback getQuotingStyle(opt::InputArgList &args) {
68   if (auto *arg = args.getLastArg(OPT_rsp_quoting)) {
69     StringRef s = arg->getValue();
70     if (s != "windows" && s != "posix")
71       error("invalid response file quoting: " + s);
72     if (s == "windows")
73       return cl::TokenizeWindowsCommandLine;
74     return cl::TokenizeGNUCommandLine;
75   }
76   if (Triple(sys::getProcessTriple()).isOSWindows())
77     return cl::TokenizeWindowsCommandLine;
78   return cl::TokenizeGNUCommandLine;
79 }
80 
81 // Gold LTO plugin takes a `--plugin-opt foo=bar` option as an alias for
82 // `--plugin-opt=foo=bar`. We want to handle `--plugin-opt=foo=` as an
83 // option name and `bar` as a value. Unfortunately, OptParser cannot
84 // handle an option with a space in it.
85 //
86 // In this function, we concatenate command line arguments so that
87 // `--plugin-opt <foo>` is converted to `--plugin-opt=<foo>`. This is a
88 // bit hacky, but looks like it is still better than handling --plugin-opt
89 // options by hand.
90 static void concatLTOPluginOptions(SmallVectorImpl<const char *> &args) {
91   SmallVector<const char *, 256> v;
92   for (size_t i = 0, e = args.size(); i != e; ++i) {
93     StringRef s = args[i];
94     if ((s == "-plugin-opt" || s == "--plugin-opt") && i + 1 != e) {
95       v.push_back(saver().save(s + "=" + args[i + 1]).data());
96       ++i;
97     } else {
98       v.push_back(args[i]);
99     }
100   }
101   args = std::move(v);
102 }
103 
104 // Parses a given list of options.
105 opt::InputArgList ELFOptTable::parse(ArrayRef<const char *> argv) {
106   // Make InputArgList from string vectors.
107   unsigned missingIndex;
108   unsigned missingCount;
109   SmallVector<const char *, 256> vec(argv.data(), argv.data() + argv.size());
110 
111   // We need to get the quoting style for response files before parsing all
112   // options so we parse here before and ignore all the options but
113   // --rsp-quoting.
114   opt::InputArgList args = this->ParseArgs(vec, missingIndex, missingCount);
115 
116   // Expand response files (arguments in the form of @<filename>)
117   // and then parse the argument again.
118   cl::ExpandResponseFiles(saver(), getQuotingStyle(args), vec);
119   concatLTOPluginOptions(vec);
120   args = this->ParseArgs(vec, missingIndex, missingCount);
121 
122   handleColorDiagnostics(args);
123   if (missingCount)
124     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
125 
126   for (opt::Arg *arg : args.filtered(OPT_UNKNOWN)) {
127     std::string nearest;
128     if (findNearest(arg->getAsString(args), nearest) > 1)
129       error("unknown argument '" + arg->getAsString(args) + "'");
130     else
131       error("unknown argument '" + arg->getAsString(args) +
132             "', did you mean '" + nearest + "'");
133   }
134   return args;
135 }
136 
137 void elf::printHelp() {
138   ELFOptTable().printHelp(
139       lld::outs(), (config->progName + " [options] file...").str().c_str(),
140       "lld", false /*ShowHidden*/, true /*ShowAllAliases*/);
141   lld::outs() << "\n";
142 
143   // Scripts generated by Libtool versions up to 2021-10 expect /: supported
144   // targets:.* elf/ in a message for the --help option. If it doesn't match,
145   // the scripts assume that the linker doesn't support very basic features
146   // such as shared libraries. Therefore, we need to print out at least "elf".
147   lld::outs() << config->progName << ": supported targets: elf\n";
148 }
149 
150 static std::string rewritePath(StringRef s) {
151   if (fs::exists(s))
152     return relativeToRoot(s);
153   return std::string(s);
154 }
155 
156 // Reconstructs command line arguments so that so that you can re-run
157 // the same command with the same inputs. This is for --reproduce.
158 std::string elf::createResponseFile(const opt::InputArgList &args) {
159   SmallString<0> data;
160   raw_svector_ostream os(data);
161   os << "--chroot .\n";
162 
163   // Copy the command line to the output while rewriting paths.
164   for (auto *arg : args) {
165     switch (arg->getOption().getID()) {
166     case OPT_reproduce:
167       break;
168     case OPT_INPUT:
169       os << quote(rewritePath(arg->getValue())) << "\n";
170       break;
171     case OPT_o:
172       // If -o path contains directories, "lld @response.txt" will likely
173       // fail because the archive we are creating doesn't contain empty
174       // directories for the output path (-o doesn't create directories).
175       // Strip directories to prevent the issue.
176       os << "-o " << quote(path::filename(arg->getValue())) << "\n";
177       break;
178     case OPT_lto_sample_profile:
179       os << arg->getSpelling() << quote(rewritePath(arg->getValue())) << "\n";
180       break;
181     case OPT_call_graph_ordering_file:
182     case OPT_dynamic_list:
183     case OPT_export_dynamic_symbol_list:
184     case OPT_just_symbols:
185     case OPT_library_path:
186     case OPT_retain_symbols_file:
187     case OPT_rpath:
188     case OPT_script:
189     case OPT_symbol_ordering_file:
190     case OPT_sysroot:
191     case OPT_version_script:
192       os << arg->getSpelling() << " " << quote(rewritePath(arg->getValue()))
193          << "\n";
194       break;
195     default:
196       os << toString(*arg) << "\n";
197     }
198   }
199   return std::string(data.str());
200 }
201 
202 // Find a file by concatenating given paths. If a resulting path
203 // starts with "=", the character is replaced with a --sysroot value.
204 static Optional<std::string> findFile(StringRef path1, const Twine &path2) {
205   SmallString<128> s;
206   if (path1.startswith("="))
207     path::append(s, config->sysroot, path1.substr(1), path2);
208   else
209     path::append(s, path1, path2);
210 
211   if (fs::exists(s))
212     return std::string(s);
213   return None;
214 }
215 
216 Optional<std::string> elf::findFromSearchPaths(StringRef path) {
217   for (StringRef dir : config->searchPaths)
218     if (Optional<std::string> s = findFile(dir, path))
219       return s;
220   return None;
221 }
222 
223 // This is for -l<basename>. We'll look for lib<basename>.so or lib<basename>.a from
224 // search paths.
225 Optional<std::string> elf::searchLibraryBaseName(StringRef name) {
226   for (StringRef dir : config->searchPaths) {
227     if (!config->isStatic)
228       if (Optional<std::string> s = findFile(dir, "lib" + name + ".so"))
229         return s;
230     if (Optional<std::string> s = findFile(dir, "lib" + name + ".a"))
231       return s;
232   }
233   return None;
234 }
235 
236 // This is for -l<namespec>.
237 Optional<std::string> elf::searchLibrary(StringRef name) {
238   llvm::TimeTraceScope timeScope("Locate library", name);
239   if (name.startswith(":"))
240     return findFromSearchPaths(name.substr(1));
241   return searchLibraryBaseName(name);
242 }
243 
244 // If a linker/version script doesn't exist in the current directory, we also
245 // look for the script in the '-L' search paths. This matches the behaviour of
246 // '-T', --version-script=, and linker script INPUT() command in ld.bfd.
247 Optional<std::string> elf::searchScript(StringRef name) {
248   if (fs::exists(name))
249     return name.str();
250   return findFromSearchPaths(name);
251 }
252