1 //===- llvm-objcopy.cpp ---------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm-objcopy.h"
12 #include "llvm/ADT/STLExtras.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/ADT/Twine.h"
15 #include "llvm/BinaryFormat/ELF.h"
16 #include "llvm/Object/Binary.h"
17 #include "llvm/Object/ELFObjectFile.h"
18 #include "llvm/Object/ELFTypes.h"
19 #include "llvm/Object/Error.h"
20 #include "llvm/Support/Casting.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/Compiler.h"
23 #include "llvm/Support/Error.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/ErrorOr.h"
26 #include "llvm/Support/FileOutputBuffer.h"
27 #include "llvm/Support/ManagedStatic.h"
28 #include "llvm/Support/PrettyStackTrace.h"
29 #include "llvm/Support/Signals.h"
30 #include "llvm/Support/raw_ostream.h"
38 #include <system_error>
42 using namespace object;
45 // The name this program was invoked as.
46 static StringRef ToolName;
50 LLVM_ATTRIBUTE_NORETURN void error(Twine Message) {
51 errs() << ToolName << ": " << Message << ".\n";
56 LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, std::error_code EC) {
58 errs() << ToolName << ": '" << File << "': " << EC.message() << ".\n";
62 LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, Error E) {
65 raw_string_ostream OS(Buf);
66 logAllUnhandledErrors(std::move(E), OS, "");
68 errs() << ToolName << ": '" << File << "': " << Buf;
72 } // end namespace llvm
74 static cl::opt<std::string> InputFilename(cl::Positional, cl::desc("<input>"));
75 static cl::opt<std::string> OutputFilename(cl::Positional, cl::desc("<output>"),
77 static cl::opt<std::string>
78 OutputFormat("O", cl::desc("Set output format to one of the following:"
80 static cl::list<std::string> ToRemove("remove-section",
81 cl::desc("Remove <section>"),
82 cl::value_desc("section"));
83 static cl::alias ToRemoveA("R", cl::desc("Alias for remove-section"),
84 cl::aliasopt(ToRemove));
85 static cl::opt<bool> StripAll(
88 "Removes non-allocated sections other than .gnu.warning* sections"));
90 StripAllGNU("strip-all-gnu",
91 cl::desc("Removes symbol, relocation, and debug information"));
92 static cl::list<std::string> Keep("keep", cl::desc("Keep <section>"),
93 cl::value_desc("section"));
94 static cl::list<std::string> OnlyKeep("only-keep",
95 cl::desc("Remove all but <section>"),
96 cl::value_desc("section"));
97 static cl::alias OnlyKeepA("j", cl::desc("Alias for only-keep"),
98 cl::aliasopt(OnlyKeep));
99 static cl::opt<bool> StripDebug("strip-debug",
100 cl::desc("Removes all debug information"));
101 static cl::opt<bool> StripSections("strip-sections",
102 cl::desc("Remove all section headers"));
104 StripNonAlloc("strip-non-alloc",
105 cl::desc("Remove all non-allocated sections"));
107 StripDWO("strip-dwo", cl::desc("Remove all DWARF .dwo sections from file"));
108 static cl::opt<bool> ExtractDWO(
110 cl::desc("Remove all sections that are not DWARF .dwo sections from file"));
111 static cl::opt<std::string>
112 SplitDWO("split-dwo",
113 cl::desc("Equivalent to extract-dwo on the input file to "
114 "<dwo-file>, then strip-dwo on the input file"),
115 cl::value_desc("dwo-file"));
117 using SectionPred = std::function<bool(const SectionBase &Sec)>;
119 bool IsDWOSection(const SectionBase &Sec) { return Sec.Name.endswith(".dwo"); }
121 template <class ELFT>
122 bool OnlyKeepDWOPred(const Object<ELFT> &Obj, const SectionBase &Sec) {
123 // We can't remove the section header string table.
124 if (&Sec == Obj.getSectionHeaderStrTab())
126 // Short of keeping the string table we want to keep everything that is a DWO
127 // section and remove everything else.
128 return !IsDWOSection(Sec);
131 template <class ELFT>
132 void WriteObjectFile(const Object<ELFT> &Obj, StringRef File) {
133 std::unique_ptr<FileOutputBuffer> Buffer;
134 Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
135 FileOutputBuffer::create(File, Obj.totalSize(),
136 FileOutputBuffer::F_executable);
137 handleAllErrors(BufferOrErr.takeError(), [](const ErrorInfoBase &) {
138 error("failed to open " + OutputFilename);
140 Buffer = std::move(*BufferOrErr);
143 if (auto E = Buffer->commit())
144 reportError(File, errorToErrorCode(std::move(E)));
147 template <class ELFT>
148 void SplitDWOToFile(const ELFObjectFile<ELFT> &ObjFile, StringRef File) {
149 // Construct a second output file for the DWO sections.
150 ELFObject<ELFT> DWOFile(ObjFile);
152 DWOFile.removeSections([&](const SectionBase &Sec) {
153 return OnlyKeepDWOPred<ELFT>(DWOFile, Sec);
156 WriteObjectFile(DWOFile, File);
159 // This function handles the high level operations of GNU objcopy including
160 // handling command line options. It's important to outline certain properties
161 // we expect to hold of the command line operations. Any operation that "keeps"
162 // should keep regardless of a remove. Additionally any removal should respect
163 // any previous removals. Lastly whether or not something is removed shouldn't
164 // depend a) on the order the options occur in or b) on some opaque priority
165 // system. The only priority is that keeps/copies overrule removes.
166 template <class ELFT> void CopyBinary(const ELFObjectFile<ELFT> &ObjFile) {
167 std::unique_ptr<Object<ELFT>> Obj;
169 if (!OutputFormat.empty() && OutputFormat != "binary")
170 error("invalid output format '" + OutputFormat + "'");
171 if (!OutputFormat.empty() && OutputFormat == "binary")
172 Obj = llvm::make_unique<BinaryObject<ELFT>>(ObjFile);
174 Obj = llvm::make_unique<ELFObject<ELFT>>(ObjFile);
176 if (!SplitDWO.empty())
177 SplitDWOToFile<ELFT>(ObjFile, SplitDWO.getValue());
179 SectionPred RemovePred = [](const SectionBase &) { return false; };
183 if (!ToRemove.empty()) {
184 RemovePred = [&](const SectionBase &Sec) {
185 return std::find(std::begin(ToRemove), std::end(ToRemove), Sec.Name) !=
190 if (StripDWO || !SplitDWO.empty())
191 RemovePred = [RemovePred](const SectionBase &Sec) {
192 return IsDWOSection(Sec) || RemovePred(Sec);
196 RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
197 return OnlyKeepDWOPred(*Obj, Sec) || RemovePred(Sec);
201 RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
204 if ((Sec.Flags & SHF_ALLOC) != 0)
206 if (&Sec == Obj->getSectionHeaderStrTab())
215 return Sec.Name.startswith(".debug");
219 RemovePred = [RemovePred](const SectionBase &Sec) {
220 return RemovePred(Sec) || (Sec.Flags & SHF_ALLOC) == 0;
222 Obj->WriteSectionHeaders = false;
226 RemovePred = [RemovePred](const SectionBase &Sec) {
227 return RemovePred(Sec) || Sec.Name.startswith(".debug");
232 RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
235 if (&Sec == Obj->getSectionHeaderStrTab())
237 return (Sec.Flags & SHF_ALLOC) == 0;
241 RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
244 if (&Sec == Obj->getSectionHeaderStrTab())
246 if (Sec.Name.startswith(".gnu.warning"))
248 return (Sec.Flags & SHF_ALLOC) == 0;
253 if (!OnlyKeep.empty()) {
254 RemovePred = [RemovePred, &Obj](const SectionBase &Sec) {
255 // Explicitly keep these sections regardless of previous removes.
256 if (std::find(std::begin(OnlyKeep), std::end(OnlyKeep), Sec.Name) !=
260 // Allow all implicit removes.
261 if (RemovePred(Sec)) {
265 // Keep special sections.
266 if (Obj->getSectionHeaderStrTab() == &Sec) {
269 if (Obj->getSymTab() == &Sec || Obj->getSymTab()->getStrTab() == &Sec) {
272 // Remove everything else.
278 RemovePred = [RemovePred](const SectionBase &Sec) {
279 // Explicitly keep these sections regardless of previous removes.
280 if (std::find(std::begin(Keep), std::end(Keep), Sec.Name) !=
283 // Otherwise defer to RemovePred.
284 return RemovePred(Sec);
288 Obj->removeSections(RemovePred);
290 WriteObjectFile(*Obj, OutputFilename.getValue());
293 int main(int argc, char **argv) {
294 // Print a stack trace if we signal out.
295 sys::PrintStackTraceOnErrorSignal(argv[0]);
296 PrettyStackTraceProgram X(argc, argv);
297 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
298 cl::ParseCommandLineOptions(argc, argv, "llvm objcopy utility\n");
300 if (InputFilename.empty()) {
301 cl::PrintHelpMessage();
304 Expected<OwningBinary<Binary>> BinaryOrErr = createBinary(InputFilename);
306 reportError(InputFilename, BinaryOrErr.takeError());
307 Binary &Binary = *BinaryOrErr.get().getBinary();
308 if (auto *o = dyn_cast<ELFObjectFile<ELF64LE>>(&Binary)) {
312 if (auto *o = dyn_cast<ELFObjectFile<ELF32LE>>(&Binary)) {
316 if (auto *o = dyn_cast<ELFObjectFile<ELF64BE>>(&Binary)) {
320 if (auto *o = dyn_cast<ELFObjectFile<ELF32BE>>(&Binary)) {
324 reportError(InputFilename, object_error::invalid_file_type);