1 //===- DriverUtils.cpp ----------------------------------------------------===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains utility functions for the driver. Because there
11 // are so many small functions, we created this separate file to make
12 // Driver.cpp less cluttered.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "Driver.h"
17 #include "lld/Common/ErrorHandler.h"
18 #include "lld/Common/Memory.h"
19 #include "lld/Common/Reproduce.h"
20 #include "lld/Common/Version.h"
21 #include "llvm/ADT/Optional.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/Triple.h"
24 #include "llvm/Option/Option.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/FileSystem.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/Process.h"
29 
30 using namespace llvm;
31 using namespace llvm::sys;
32 using namespace llvm::opt;
33 
34 using namespace lld;
35 using namespace lld::elf;
36 
37 // Create OptTable
38 
39 // Create prefix string literals used in Options.td
40 #define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
41 #include "Options.inc"
42 #undef PREFIX
43 
44 // Create table mapping all options defined in Options.td
45 static const 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() : OptTable(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, OPT_color_diagnostics_eq,
59                               OPT_no_color_diagnostics);
60   if (!Arg)
61     return;
62   else if (Arg->getOption().getID() == OPT_color_diagnostics)
63     errorHandler().ColorDiagnostics = true;
64   else if (Arg->getOption().getID() == OPT_no_color_diagnostics)
65     errorHandler().ColorDiagnostics = false;
66   else {
67     StringRef S = Arg->getValue();
68     if (S == "always")
69       errorHandler().ColorDiagnostics = true;
70     else if (S == "never")
71       errorHandler().ColorDiagnostics = false;
72     else if (S != "auto")
73       error("unknown option: -color-diagnostics=" + S);
74   }
75 }
76 
77 static cl::TokenizerCallback getQuotingStyle(opt::InputArgList &Args) {
78   if (auto *Arg = Args.getLastArg(OPT_rsp_quoting)) {
79     StringRef S = Arg->getValue();
80     if (S != "windows" && S != "posix")
81       error("invalid response file quoting: " + S);
82     if (S == "windows")
83       return cl::TokenizeWindowsCommandLine;
84     return cl::TokenizeGNUCommandLine;
85   }
86   if (Triple(sys::getProcessTriple()).getOS() == Triple::Win32)
87     return cl::TokenizeWindowsCommandLine;
88   return cl::TokenizeGNUCommandLine;
89 }
90 
91 // Parses a given list of options.
92 opt::InputArgList ELFOptTable::parse(ArrayRef<const char *> Argv) {
93   // Make InputArgList from string vectors.
94   unsigned MissingIndex;
95   unsigned MissingCount;
96   SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());
97 
98   // We need to get the quoting style for response files before parsing all
99   // options so we parse here before and ignore all the options but
100   // --rsp-quoting.
101   opt::InputArgList Args = this->ParseArgs(Vec, MissingIndex, MissingCount);
102 
103   // Expand response files (arguments in the form of @<filename>)
104   // and then parse the argument again.
105   cl::ExpandResponseFiles(Saver, getQuotingStyle(Args), Vec);
106   Args = this->ParseArgs(Vec, MissingIndex, MissingCount);
107 
108   handleColorDiagnostics(Args);
109   if (MissingCount)
110     error(Twine(Args.getArgString(MissingIndex)) + ": missing argument");
111 
112   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
113     error("unknown argument: " + Arg->getSpelling());
114   return Args;
115 }
116 
117 void elf::printHelp() {
118   ELFOptTable().PrintHelp(outs(), Config->ProgName.data(), "lld",
119                           false /*ShowHidden*/, true /*ShowAllAliases*/);
120   outs() << "\n";
121 
122   // Scripts generated by Libtool versions up to at least 2.4.6 (the most
123   // recent version as of March 2017) expect /: supported targets:.* elf/
124   // in a message for the -help option. If it doesn't match, the scripts
125   // assume that the linker doesn't support very basic features such as
126   // shared libraries. Therefore, we need to print out at least "elf".
127   outs() << Config->ProgName << ": supported targets: elf\n";
128 }
129 
130 // Reconstructs command line arguments so that so that you can re-run
131 // the same command with the same inputs. This is for --reproduce.
132 std::string elf::createResponseFile(const opt::InputArgList &Args) {
133   SmallString<0> Data;
134   raw_svector_ostream OS(Data);
135   OS << "--chroot .\n";
136 
137   // Copy the command line to the output while rewriting paths.
138   for (auto *Arg : Args) {
139     switch (Arg->getOption().getUnaliasedOption().getID()) {
140     case OPT_reproduce:
141       break;
142     case OPT_INPUT:
143       OS << quote(rewritePath(Arg->getValue())) << "\n";
144       break;
145     case OPT_o:
146       // If -o path contains directories, "lld @response.txt" will likely
147       // fail because the archive we are creating doesn't contain empty
148       // directories for the output path (-o doesn't create directories).
149       // Strip directories to prevent the issue.
150       OS << "-o " << quote(sys::path::filename(Arg->getValue())) << "\n";
151       break;
152     case OPT_dynamic_list:
153     case OPT_library_path:
154     case OPT_rpath:
155     case OPT_script:
156     case OPT_symbol_ordering_file:
157     case OPT_sysroot:
158     case OPT_version_script:
159       OS << Arg->getSpelling() << " " << quote(rewritePath(Arg->getValue()))
160          << "\n";
161       break;
162     default:
163       OS << toString(*Arg) << "\n";
164     }
165   }
166   return Data.str();
167 }
168 
169 // Find a file by concatenating given paths. If a resulting path
170 // starts with "=", the character is replaced with a --sysroot value.
171 static Optional<std::string> findFile(StringRef Path1, const Twine &Path2) {
172   SmallString<128> S;
173   if (Path1.startswith("="))
174     path::append(S, Config->Sysroot, Path1.substr(1), Path2);
175   else
176     path::append(S, Path1, Path2);
177 
178   if (fs::exists(S))
179     return S.str().str();
180   return None;
181 }
182 
183 Optional<std::string> elf::findFromSearchPaths(StringRef Path) {
184   for (StringRef Dir : Config->SearchPaths)
185     if (Optional<std::string> S = findFile(Dir, Path))
186       return S;
187   return None;
188 }
189 
190 // This is for -lfoo. We'll look for libfoo.so or libfoo.a from
191 // search paths.
192 Optional<std::string> elf::searchLibrary(StringRef Name) {
193   if (Name.startswith(":"))
194     return findFromSearchPaths(Name.substr(1));
195 
196   for (StringRef Dir : Config->SearchPaths) {
197     if (!Config->Static)
198       if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".so"))
199         return S;
200     if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".a"))
201       return S;
202   }
203   return None;
204 }
205 
206 // If a linker script doesn't exist in the current directory, we also look for
207 // the script in the '-L' search paths. This matches the behaviour of both '-T'
208 // and linker script INPUT() directives in ld.bfd.
209 Optional<std::string> elf::searchLinkerScript(StringRef Name) {
210   if (fs::exists(Name))
211     return Name.str();
212   return findFromSearchPaths(Name);
213 }
214