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 ctx.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/Triple.h"
20 #include "llvm/Option/Option.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/FileSystem.h"
23 #include "llvm/Support/Host.h"
24 #include "llvm/Support/Path.h"
25 #include "llvm/Support/TimeProfiler.h"
26 #include <optional>
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)                                                    \
38   static constexpr StringLiteral NAME##_init[] = VALUE;                        \
39   static constexpr ArrayRef<StringLiteral> NAME(NAME##_init,                   \
40                                                 std::size(NAME##_init) - 1);
41 #include "Options.inc"
42 #undef PREFIX
43 
44 // Create table mapping all options defined in Options.td
45 static constexpr opt::OptTable::Info optInfo[] = {
46 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
47   {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
48    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
49 #include "Options.inc"
50 #undef OPTION
51 };
52 
53 ELFOptTable::ELFOptTable() : GenericOptTable(optInfo) {}
54 
55 // Set color diagnostics according to --color-diagnostics={auto,always,never}
56 // or --no-color-diagnostics flags.
57 static void handleColorDiagnostics(opt::InputArgList &args) {
58   auto *arg = args.getLastArg(OPT_color_diagnostics);
59   if (!arg)
60     return;
61   StringRef s = arg->getValue();
62   if (s == "always")
63     lld::errs().enable_colors(true);
64   else if (s == "never")
65     lld::errs().enable_colors(false);
66   else if (s != "auto")
67     error("unknown option: --color-diagnostics=" + s);
68 }
69 
70 static cl::TokenizerCallback getQuotingStyle(opt::InputArgList &args) {
71   if (auto *arg = args.getLastArg(OPT_rsp_quoting)) {
72     StringRef s = arg->getValue();
73     if (s != "windows" && s != "posix")
74       error("invalid response file quoting: " + s);
75     if (s == "windows")
76       return cl::TokenizeWindowsCommandLine;
77     return cl::TokenizeGNUCommandLine;
78   }
79   if (Triple(sys::getProcessTriple()).isOSWindows())
80     return cl::TokenizeWindowsCommandLine;
81   return cl::TokenizeGNUCommandLine;
82 }
83 
84 // Gold LTO plugin takes a `--plugin-opt foo=bar` option as an alias for
85 // `--plugin-opt=foo=bar`. We want to handle `--plugin-opt=foo=` as an
86 // option name and `bar` as a value. Unfortunately, OptParser cannot
87 // handle an option with a space in it.
88 //
89 // In this function, we concatenate command line arguments so that
90 // `--plugin-opt <foo>` is converted to `--plugin-opt=<foo>`. This is a
91 // bit hacky, but looks like it is still better than handling --plugin-opt
92 // options by hand.
93 static void concatLTOPluginOptions(SmallVectorImpl<const char *> &args) {
94   SmallVector<const char *, 256> v;
95   for (size_t i = 0, e = args.size(); i != e; ++i) {
96     StringRef s = args[i];
97     if ((s == "-plugin-opt" || s == "--plugin-opt") && i + 1 != e) {
98       v.push_back(saver().save(s + "=" + args[i + 1]).data());
99       ++i;
100     } else {
101       v.push_back(args[i]);
102     }
103   }
104   args = std::move(v);
105 }
106 
107 // Parses a given list of options.
108 opt::InputArgList ELFOptTable::parse(ArrayRef<const char *> argv) {
109   // Make InputArgList from string vectors.
110   unsigned missingIndex;
111   unsigned missingCount;
112   SmallVector<const char *, 256> vec(argv.data(), argv.data() + argv.size());
113 
114   // We need to get the quoting style for response files before parsing all
115   // options so we parse here before and ignore all the options but
116   // --rsp-quoting.
117   opt::InputArgList args = this->ParseArgs(vec, missingIndex, missingCount);
118 
119   // Expand response files (arguments in the form of @<filename>)
120   // and then parse the argument again.
121   cl::ExpandResponseFiles(saver(), getQuotingStyle(args), vec);
122   concatLTOPluginOptions(vec);
123   args = this->ParseArgs(vec, missingIndex, missingCount);
124 
125   handleColorDiagnostics(args);
126   if (missingCount)
127     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
128 
129   for (opt::Arg *arg : args.filtered(OPT_UNKNOWN)) {
130     std::string nearest;
131     if (findNearest(arg->getAsString(args), nearest) > 1)
132       error("unknown argument '" + arg->getAsString(args) + "'");
133     else
134       error("unknown argument '" + arg->getAsString(args) +
135             "', did you mean '" + nearest + "'");
136   }
137   return args;
138 }
139 
140 void elf::printHelp() {
141   ELFOptTable().printHelp(
142       lld::outs(), (config->progName + " [options] file...").str().c_str(),
143       "lld", false /*ShowHidden*/, true /*ShowAllAliases*/);
144   lld::outs() << "\n";
145 
146   // Scripts generated by Libtool versions up to 2021-10 expect /: supported
147   // targets:.* elf/ in a message for the --help option. If it doesn't match,
148   // the scripts assume that the linker doesn't support very basic features
149   // such as shared libraries. Therefore, we need to print out at least "elf".
150   lld::outs() << config->progName << ": supported targets: elf\n";
151 }
152 
153 static std::string rewritePath(StringRef s) {
154   if (fs::exists(s))
155     return relativeToRoot(s);
156   return std::string(s);
157 }
158 
159 // Reconstructs command line arguments so that so that you can re-run
160 // the same command with the same inputs. This is for --reproduce.
161 std::string elf::createResponseFile(const opt::InputArgList &args) {
162   SmallString<0> data;
163   raw_svector_ostream os(data);
164   os << "--chroot .\n";
165 
166   // Copy the command line to the output while rewriting paths.
167   for (auto *arg : args) {
168     switch (arg->getOption().getID()) {
169     case OPT_reproduce:
170       break;
171     case OPT_INPUT:
172       os << quote(rewritePath(arg->getValue())) << "\n";
173       break;
174     case OPT_o:
175     case OPT_Map:
176     case OPT_print_archive_stats:
177     case OPT_why_extract:
178       // If an output path contains directories, "lld @response.txt" will
179       // likely fail because the archive we are creating doesn't contain empty
180       // directories for the output path (-o doesn't create directories).
181       // Strip directories to prevent the issue.
182       os << arg->getSpelling();
183       if (arg->getOption().getRenderStyle() == opt::Option::RenderSeparateStyle)
184         os << ' ';
185       os << quote(path::filename(arg->getValue())) << '\n';
186       break;
187     case OPT_lto_sample_profile:
188       os << arg->getSpelling() << quote(rewritePath(arg->getValue())) << "\n";
189       break;
190     case OPT_call_graph_ordering_file:
191     case OPT_dynamic_list:
192     case OPT_export_dynamic_symbol_list:
193     case OPT_just_symbols:
194     case OPT_library_path:
195     case OPT_retain_symbols_file:
196     case OPT_rpath:
197     case OPT_script:
198     case OPT_symbol_ordering_file:
199     case OPT_sysroot:
200     case OPT_version_script:
201       os << arg->getSpelling() << " " << quote(rewritePath(arg->getValue()))
202          << "\n";
203       break;
204     default:
205       os << toString(*arg) << "\n";
206     }
207   }
208   return std::string(data.str());
209 }
210 
211 // Find a file by concatenating given paths. If a resulting path
212 // starts with "=", the character is replaced with a --sysroot value.
213 static std::optional<std::string> findFile(StringRef path1,
214                                            const Twine &path2) {
215   SmallString<128> s;
216   if (path1.startswith("="))
217     path::append(s, config->sysroot, path1.substr(1), path2);
218   else
219     path::append(s, path1, path2);
220 
221   if (fs::exists(s))
222     return std::string(s);
223   return std::nullopt;
224 }
225 
226 std::optional<std::string> elf::findFromSearchPaths(StringRef path) {
227   for (StringRef dir : config->searchPaths)
228     if (std::optional<std::string> s = findFile(dir, path))
229       return s;
230   return std::nullopt;
231 }
232 
233 // This is for -l<basename>. We'll look for lib<basename>.so or lib<basename>.a from
234 // search paths.
235 std::optional<std::string> elf::searchLibraryBaseName(StringRef name) {
236   for (StringRef dir : config->searchPaths) {
237     if (!config->isStatic)
238       if (std::optional<std::string> s = findFile(dir, "lib" + name + ".so"))
239         return s;
240     if (std::optional<std::string> s = findFile(dir, "lib" + name + ".a"))
241       return s;
242   }
243   return std::nullopt;
244 }
245 
246 // This is for -l<namespec>.
247 std::optional<std::string> elf::searchLibrary(StringRef name) {
248   llvm::TimeTraceScope timeScope("Locate library", name);
249   if (name.startswith(":"))
250     return findFromSearchPaths(name.substr(1));
251   return searchLibraryBaseName(name);
252 }
253 
254 // If a linker/version script doesn't exist in the current directory, we also
255 // look for the script in the '-L' search paths. This matches the behaviour of
256 // '-T', --version-script=, and linker script INPUT() command in ld.bfd.
257 std::optional<std::string> elf::searchScript(StringRef name) {
258   if (fs::exists(name))
259     return name.str();
260   return findFromSearchPaths(name);
261 }
262