[llvm] r364000 - [llvm-objcopy][MachO] Rebuild the symbol/string table in the writer
Seiya Nuta via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 20 17:21:50 PDT 2019
Author: seiya
Date: Thu Jun 20 17:21:50 2019
New Revision: 364000
URL: http://llvm.org/viewvc/llvm-project?rev=364000&view=rev
Log:
[llvm-objcopy][MachO] Rebuild the symbol/string table in the writer
Summary: Build the string table using StringTableBuilder, reassign symbol indices, and update symbol indices in relocations to allow adding/modifying/removing symbols from the object.
Reviewers: alexshap, rupprecht, jhenderson
Reviewed By: alexshap
Subscribers: mgorny, jakehehrlich, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63309
Added:
llvm/trunk/tools/llvm-objcopy/MachO/Object.cpp
Modified:
llvm/trunk/tools/llvm-objcopy/CMakeLists.txt
llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.cpp
llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.h
llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.cpp
llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.h
llvm/trunk/tools/llvm-objcopy/MachO/Object.h
Modified: llvm/trunk/tools/llvm-objcopy/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/CMakeLists.txt?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/CMakeLists.txt (original)
+++ llvm/trunk/tools/llvm-objcopy/CMakeLists.txt Thu Jun 20 17:21:50 2019
@@ -26,6 +26,7 @@ add_llvm_tool(llvm-objcopy
MachO/MachOObjcopy.cpp
MachO/MachOReader.cpp
MachO/MachOWriter.cpp
+ MachO/Object.cpp
DEPENDS
ObjcopyOptsTableGen
StripOptsTableGen
Modified: llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.cpp?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.cpp Thu Jun 20 17:21:50 2019
@@ -97,8 +97,16 @@ extractSections(const object::MachOObjec
S.Relocations.reserve(S.NReloc);
for (auto RI = MachOObj.section_rel_begin(SecRef->getRawDataRefImpl()),
RE = MachOObj.section_rel_end(SecRef->getRawDataRefImpl());
- RI != RE; ++RI)
- S.Relocations.push_back(MachOObj.getRelocation(RI->getRawDataRefImpl()));
+ RI != RE; ++RI) {
+ RelocationInfo R;
+ R.Symbol = nullptr; // We'll fill this field later.
+ R.Info = MachOObj.getRelocation(RI->getRawDataRefImpl());
+ R.Scattered =
+ reinterpret_cast<MachO::scattered_relocation_info *>(&R.Info)
+ ->r_scattered;
+ S.Relocations.push_back(R);
+ }
+
assert(S.NReloc == S.Relocations.size() &&
"Incorrect number of relocations");
}
@@ -157,35 +165,43 @@ void MachOReader::readLoadCommands(Objec
}
}
-template <typename nlist_t> NListEntry constructNameList(const nlist_t &nlist) {
- NListEntry NL;
- NL.n_strx = nlist.n_strx;
- NL.n_type = nlist.n_type;
- NL.n_sect = nlist.n_sect;
- NL.n_desc = nlist.n_desc;
- NL.n_value = nlist.n_value;
- return NL;
+template <typename nlist_t>
+SymbolEntry constructSymbolEntry(StringRef StrTable, const nlist_t &nlist) {
+ assert(nlist.n_strx < StrTable.size() &&
+ "n_strx exceeds the size of the string table");
+ SymbolEntry SE;
+ SE.Name = StringRef(StrTable.data() + nlist.n_strx).str();
+ SE.n_type = nlist.n_type;
+ SE.n_sect = nlist.n_sect;
+ SE.n_desc = nlist.n_desc;
+ SE.n_value = nlist.n_value;
+ return SE;
}
void MachOReader::readSymbolTable(Object &O) const {
+ StringRef StrTable = MachOObj.getStringTableData();
for (auto Symbol : MachOObj.symbols()) {
- NListEntry NLE =
- MachOObj.is64Bit()
- ? constructNameList<MachO::nlist_64>(
- MachOObj.getSymbol64TableEntry(Symbol.getRawDataRefImpl()))
- : constructNameList<MachO::nlist>(
- MachOObj.getSymbolTableEntry(Symbol.getRawDataRefImpl()));
- O.SymTable.NameList.push_back(NLE);
+ SymbolEntry SE =
+ (MachOObj.is64Bit()
+ ? constructSymbolEntry(
+ StrTable,
+ MachOObj.getSymbol64TableEntry(Symbol.getRawDataRefImpl()))
+ : constructSymbolEntry(
+ StrTable,
+ MachOObj.getSymbolTableEntry(Symbol.getRawDataRefImpl())));
+
+ O.SymTable.Symbols.push_back(llvm::make_unique<SymbolEntry>(SE));
}
}
-void MachOReader::readStringTable(Object &O) const {
- StringRef Data = MachOObj.getStringTableData();
- SmallVector<StringRef, 10> Strs;
- Data.split(Strs, '\0');
- O.StrTable.Strings.reserve(Strs.size());
- for (auto S : Strs)
- O.StrTable.Strings.push_back(S.str());
+void MachOReader::setSymbolInRelocationInfo(Object &O) const {
+ for (auto &LC : O.LoadCommands)
+ for (auto &Sec : LC.Sections)
+ for (auto &Reloc : Sec.Relocations)
+ if (!Reloc.Scattered) {
+ auto *Info = reinterpret_cast<MachO::relocation_info *>(&Reloc.Info);
+ Reloc.Symbol = O.SymTable.getSymbolByIndex(Info->r_symbolnum);
+ }
}
void MachOReader::readRebaseInfo(Object &O) const {
@@ -213,7 +229,7 @@ std::unique_ptr<Object> MachOReader::cre
readHeader(*Obj);
readLoadCommands(*Obj);
readSymbolTable(*Obj);
- readStringTable(*Obj);
+ setSymbolInRelocationInfo(*Obj);
readRebaseInfo(*Obj);
readBindInfo(*Obj);
readWeakBindInfo(*Obj);
Modified: llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.h?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.h (original)
+++ llvm/trunk/tools/llvm-objcopy/MachO/MachOReader.h Thu Jun 20 17:21:50 2019
@@ -30,7 +30,7 @@ class MachOReader : public Reader {
void readHeader(Object &O) const;
void readLoadCommands(Object &O) const;
void readSymbolTable(Object &O) const;
- void readStringTable(Object &O) const;
+ void setSymbolInRelocationInfo(Object &O) const;
void readRebaseInfo(Object &O) const;
void readBindInfo(Object &O) const;
void readWeakBindInfo(Object &O) const;
Modified: llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.cpp?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.cpp Thu Jun 20 17:21:50 2019
@@ -26,18 +26,10 @@ size_t MachOWriter::headerSize() const {
size_t MachOWriter::loadCommandsSize() const { return O.Header.SizeOfCmds; }
size_t MachOWriter::symTableSize() const {
- return O.SymTable.NameList.size() *
+ return O.SymTable.Symbols.size() *
(Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist));
}
-size_t MachOWriter::strTableSize() const {
- size_t S = 0;
- for (const auto &Str : O.StrTable.Strings)
- S += Str.size();
- S += (O.StrTable.Strings.empty() ? 0 : O.StrTable.Strings.size() - 1);
- return S;
-}
-
size_t MachOWriter::totalSize() const {
// Going from tail to head and looking for an appropriate "anchor" to
// calculate the total size assuming that all the offsets are either valid
@@ -49,12 +41,12 @@ size_t MachOWriter::totalSize() const {
O.LoadCommands[*O.SymTabCommandIndex]
.MachOLoadCommand.symtab_command_data;
if (SymTabCommand.symoff) {
- assert((SymTabCommand.nsyms == O.SymTable.NameList.size()) &&
+ assert((SymTabCommand.nsyms == O.SymTable.Symbols.size()) &&
"Incorrect number of symbols");
Ends.push_back(SymTabCommand.symoff + symTableSize());
}
if (SymTabCommand.stroff) {
- assert((SymTabCommand.strsize == strTableSize()) &&
+ assert((SymTabCommand.strsize == StrTableBuilder.getSize()) &&
"Incorrect string table size");
Ends.push_back(SymTabCommand.stroff + SymTabCommand.strsize);
}
@@ -128,6 +120,14 @@ void MachOWriter::writeHeader() {
memcpy(B.getBufferStart(), &Header, HeaderSize);
}
+void MachOWriter::updateSymbolIndexes() {
+ uint32_t Index = 0;
+ for (auto &Symbol : O.SymTable.Symbols) {
+ Symbol->Index = Index;
+ Index++;
+ }
+}
+
void MachOWriter::writeLoadCommands() {
uint8_t *Begin = B.getBufferStart() + headerSize();
for (const auto &LC : O.LoadCommands) {
@@ -220,24 +220,32 @@ void MachOWriter::writeSections() {
memcpy(B.getBufferStart() + Sec.Offset, Sec.Content.data(),
Sec.Content.size());
for (size_t Index = 0; Index < Sec.Relocations.size(); ++Index) {
- MachO::any_relocation_info R = Sec.Relocations[Index];
+ auto RelocInfo = Sec.Relocations[Index];
+ if (!RelocInfo.Scattered) {
+ auto *Info =
+ reinterpret_cast<MachO::relocation_info *>(&RelocInfo.Info);
+ Info->r_symbolnum = RelocInfo.Symbol->Index;
+ }
+
if (IsLittleEndian != sys::IsLittleEndianHost)
- MachO::swapStruct(R);
+ MachO::swapStruct(
+ reinterpret_cast<MachO::any_relocation_info &>(RelocInfo.Info));
memcpy(B.getBufferStart() + Sec.RelOff +
Index * sizeof(MachO::any_relocation_info),
- &R, sizeof(R));
+ &RelocInfo.Info, sizeof(RelocInfo.Info));
}
}
}
template <typename NListType>
-void writeNListEntry(const NListEntry &NLE, bool IsLittleEndian, char *&Out) {
+void writeNListEntry(const SymbolEntry &SE, bool IsLittleEndian, char *&Out,
+ uint32_t Nstrx) {
NListType ListEntry;
- ListEntry.n_strx = NLE.n_strx;
- ListEntry.n_type = NLE.n_type;
- ListEntry.n_sect = NLE.n_sect;
- ListEntry.n_desc = NLE.n_desc;
- ListEntry.n_value = NLE.n_value;
+ ListEntry.n_strx = Nstrx;
+ ListEntry.n_type = SE.n_type;
+ ListEntry.n_sect = SE.n_sect;
+ ListEntry.n_desc = SE.n_desc;
+ ListEntry.n_value = SE.n_value;
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(ListEntry);
@@ -251,15 +259,9 @@ void MachOWriter::writeSymbolTable() {
const MachO::symtab_command &SymTabCommand =
O.LoadCommands[*O.SymTabCommandIndex]
.MachOLoadCommand.symtab_command_data;
- assert((SymTabCommand.nsyms == O.SymTable.NameList.size()) &&
- "Incorrect number of symbols");
- char *Out = (char *)B.getBufferStart() + SymTabCommand.symoff;
- for (auto NLE : O.SymTable.NameList) {
- if (Is64Bit)
- writeNListEntry<MachO::nlist_64>(NLE, IsLittleEndian, Out);
- else
- writeNListEntry<MachO::nlist>(NLE, IsLittleEndian, Out);
- }
+
+ uint8_t *StrTable = (uint8_t *)B.getBufferStart() + SymTabCommand.stroff;
+ StrTableBuilder.write(StrTable);
}
void MachOWriter::writeStringTable() {
@@ -268,17 +270,17 @@ void MachOWriter::writeStringTable() {
const MachO::symtab_command &SymTabCommand =
O.LoadCommands[*O.SymTabCommandIndex]
.MachOLoadCommand.symtab_command_data;
- char *Out = (char *)B.getBufferStart() + SymTabCommand.stroff;
- assert((SymTabCommand.strsize == strTableSize()) &&
- "Incorrect string table size");
- for (size_t Index = 0; Index < O.StrTable.Strings.size(); ++Index) {
- memcpy(Out, O.StrTable.Strings[Index].data(),
- O.StrTable.Strings[Index].size());
- Out += O.StrTable.Strings[Index].size();
- if (Index + 1 != O.StrTable.Strings.size()) {
- memcpy(Out, "\0", 1);
- Out += 1;
- }
+
+ char *SymTable = (char *)B.getBufferStart() + SymTabCommand.symoff;
+ for (auto Iter = O.SymTable.Symbols.begin(), End = O.SymTable.Symbols.end();
+ Iter != End; Iter++) {
+ SymbolEntry *Sym = Iter->get();
+ auto Nstrx = StrTableBuilder.getOffset(Sym->Name);
+
+ if (Is64Bit)
+ writeNListEntry<MachO::nlist_64>(*Sym, IsLittleEndian, SymTable, Nstrx);
+ else
+ writeNListEntry<MachO::nlist>(*Sym, IsLittleEndian, SymTable, Nstrx);
}
}
@@ -420,10 +422,10 @@ void MachOWriter::updateSizeOfCmds() {
// are already sorted by the those types.
void MachOWriter::updateDySymTab(MachO::macho_load_command &MLC) {
uint32_t NumLocalSymbols = 0;
- auto Iter = O.SymTable.NameList.begin();
- auto End = O.SymTable.NameList.end();
+ auto Iter = O.SymTable.Symbols.begin();
+ auto End = O.SymTable.Symbols.end();
for (; Iter != End; Iter++) {
- if (Iter->n_type & (MachO::N_EXT | MachO::N_PEXT))
+ if ((*Iter)->n_type & (MachO::N_EXT | MachO::N_PEXT))
break;
NumLocalSymbols++;
@@ -431,7 +433,7 @@ void MachOWriter::updateDySymTab(MachO::
uint32_t NumExtDefSymbols = 0;
for (; Iter != End; Iter++) {
- if ((Iter->n_type & MachO::N_TYPE) == MachO::N_UNDF)
+ if (((*Iter)->n_type & MachO::N_TYPE) == MachO::N_UNDF)
break;
NumExtDefSymbols++;
@@ -443,7 +445,7 @@ void MachOWriter::updateDySymTab(MachO::
MLC.dysymtab_command_data.nextdefsym = NumExtDefSymbols;
MLC.dysymtab_command_data.iundefsym = NumLocalSymbols + NumExtDefSymbols;
MLC.dysymtab_command_data.nundefsym =
- O.SymTable.NameList.size() - (NumLocalSymbols + NumExtDefSymbols);
+ O.SymTable.Symbols.size() - (NumLocalSymbols + NumExtDefSymbols);
}
// Recomputes and updates offset and size fields in load commands and sections
@@ -512,8 +514,9 @@ Error MachOWriter::layout() {
auto cmd = MLC.load_command_data.cmd;
switch (cmd) {
case MachO::LC_SYMTAB:
+ MLC.symtab_command_data.nsyms = O.SymTable.Symbols.size();
+ MLC.symtab_command_data.strsize = StrTableBuilder.getSize();
MLC.symtab_command_data.symoff = Offset;
- MLC.symtab_command_data.nsyms = O.SymTable.NameList.size();
Offset += NListSize * MLC.symtab_command_data.nsyms;
MLC.symtab_command_data.stroff = Offset;
Offset += MLC.symtab_command_data.strsize;
@@ -554,8 +557,15 @@ Error MachOWriter::layout() {
return Error::success();
}
+void MachOWriter::constructStringTable() {
+ for (std::unique_ptr<SymbolEntry> &Sym : O.SymTable.Symbols)
+ StrTableBuilder.add(Sym->Name);
+ StrTableBuilder.finalize();
+}
+
Error MachOWriter::finalize() {
updateSizeOfCmds();
+ constructStringTable();
if (auto E = layout())
return E;
@@ -568,6 +578,7 @@ Error MachOWriter::write() {
return E;
memset(B.getBufferStart(), 0, totalSize());
writeHeader();
+ updateSymbolIndexes();
writeLoadCommands();
writeSections();
writeTail();
Modified: llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.h?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.h (original)
+++ llvm/trunk/tools/llvm-objcopy/MachO/MachOWriter.h Thu Jun 20 17:21:50 2019
@@ -23,6 +23,7 @@ class MachOWriter {
bool Is64Bit;
bool IsLittleEndian;
Buffer &B;
+ StringTableBuilder StrTableBuilder{StringTableBuilder::MachO};
size_t headerSize() const;
size_t loadCommandsSize() const;
@@ -31,6 +32,8 @@ class MachOWriter {
void updateDySymTab(MachO::macho_load_command &MLC);
void updateSizeOfCmds();
+ void updateSymbolIndexes();
+ void constructStringTable();
Error layout();
void writeHeader();
Added: llvm/trunk/tools/llvm-objcopy/MachO/Object.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/Object.cpp?rev=364000&view=auto
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/Object.cpp (added)
+++ llvm/trunk/tools/llvm-objcopy/MachO/Object.cpp Thu Jun 20 17:21:50 2019
@@ -0,0 +1,15 @@
+#include "Object.h"
+#include "../llvm-objcopy.h"
+
+namespace llvm {
+namespace objcopy {
+namespace macho {
+
+const SymbolEntry *SymbolTable::getSymbolByIndex(uint32_t Index) const {
+ assert(Index < Symbols.size() && "invalid symbol index");
+ return Symbols[Index].get();
+}
+
+} // end namespace macho
+} // end namespace objcopy
+} // end namespace llvm
Modified: llvm/trunk/tools/llvm-objcopy/MachO/Object.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/MachO/Object.h?rev=364000&r1=363999&r2=364000&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/MachO/Object.h (original)
+++ llvm/trunk/tools/llvm-objcopy/MachO/Object.h Thu Jun 20 17:21:50 2019
@@ -12,6 +12,7 @@
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/MachO.h"
+#include "llvm/MC/StringTableBuilder.h"
#include "llvm/ObjectYAML/DWARFYAML.h"
#include "llvm/Support/YAMLTraits.h"
#include <cstdint>
@@ -33,6 +34,7 @@ struct MachHeader {
uint32_t Reserved = 0;
};
+struct RelocationInfo;
struct Section {
std::string Sectname;
std::string Segname;
@@ -48,7 +50,7 @@ struct Section {
uint32_t Reserved3;
StringRef Content;
- std::vector<MachO::any_relocation_info> Relocations;
+ std::vector<RelocationInfo> Relocations;
MachO::SectionType getType() const {
return static_cast<MachO::SectionType>(Flags & MachO::SECTION_TYPE);
@@ -79,8 +81,11 @@ struct LoadCommand {
std::vector<Section> Sections;
};
-struct NListEntry {
- uint32_t n_strx;
+// A symbol information. Fields which starts with "n_" are same as them in the
+// nlist.
+struct SymbolEntry {
+ std::string Name;
+ uint32_t Index;
uint8_t n_type;
uint8_t n_sect;
uint16_t n_desc;
@@ -90,7 +95,9 @@ struct NListEntry {
/// The location of the symbol table inside the binary is described by LC_SYMTAB
/// load command.
struct SymbolTable {
- std::vector<NListEntry> NameList;
+ std::vector<std::unique_ptr<SymbolEntry>> Symbols;
+
+ const SymbolEntry *getSymbolByIndex(uint32_t Index) const;
};
/// The location of the string table inside the binary is described by LC_SYMTAB
@@ -99,6 +106,13 @@ struct StringTable {
std::vector<std::string> Strings;
};
+struct RelocationInfo {
+ const SymbolEntry *Symbol;
+ // True if Info is a scattered_relocation_info.
+ bool Scattered;
+ MachO::any_relocation_info Info;
+};
+
/// The location of the rebase info inside the binary is described by
/// LC_DYLD_INFO load command. Dyld rebases an image whenever dyld loads it at
/// an address different from its preferred address. The rebase information is
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