Recommit "[llvm-objcopy][MachO] Support load commands used in executables/shared libraries"
Summary:
This patch implements copying some load commands that appear in executables/shared libraries such as the indirect symbol table.
I don't add tests intentionally because this patch is incomplete: we need a layout algorithm for executables/shared libraries. I'll submit it as a separate patch with tests.
Reviewers: alexshap, rupprecht, jhenderson, compnerd
Reviewed By: alexshap
Subscribers: abrachet, mgorny, mgrang, MaskRay, mtrent, jakehehrlich, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63395
llvm-svn: 369298
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
index 74200c5..0d3d235 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "MachOWriter.h"
+#include "MachOLayoutBuilder.h"
#include "Object.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/BinaryFormat/MachO.h"
@@ -40,16 +41,10 @@
const MachO::symtab_command &SymTabCommand =
O.LoadCommands[*O.SymTabCommandIndex]
.MachOLoadCommand.symtab_command_data;
- if (SymTabCommand.symoff) {
- assert((SymTabCommand.nsyms == O.SymTable.Symbols.size()) &&
- "Incorrect number of symbols");
+ if (SymTabCommand.symoff)
Ends.push_back(SymTabCommand.symoff + symTableSize());
- }
- if (SymTabCommand.stroff) {
- assert((SymTabCommand.strsize == StrTableBuilder.getSize()) &&
- "Incorrect string table size");
+ if (SymTabCommand.stroff)
Ends.push_back(SymTabCommand.stroff + SymTabCommand.strsize);
- }
}
if (O.DyLdInfoCommandIndex) {
const MachO::dyld_info_command &DyLdInfoCommand =
@@ -84,6 +79,36 @@
}
}
+ if (O.DySymTabCommandIndex) {
+ const MachO::dysymtab_command &DySymTabCommand =
+ O.LoadCommands[*O.DySymTabCommandIndex]
+ .MachOLoadCommand.dysymtab_command_data;
+
+ if (DySymTabCommand.indirectsymoff)
+ Ends.push_back(DySymTabCommand.indirectsymoff +
+ sizeof(uint32_t) * O.IndirectSymTable.Symbols.size());
+ }
+
+ if (O.DataInCodeCommandIndex) {
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.DataInCodeCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+
+ if (LinkEditDataCommand.dataoff)
+ Ends.push_back(LinkEditDataCommand.dataoff +
+ LinkEditDataCommand.datasize);
+ }
+
+ if (O.FunctionStartsCommandIndex) {
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.FunctionStartsCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+
+ if (LinkEditDataCommand.dataoff)
+ Ends.push_back(LinkEditDataCommand.dataoff +
+ LinkEditDataCommand.datasize);
+ }
+
// Otherwise, use the last section / reloction.
for (const auto &LC : O.LoadCommands)
for (const auto &S : LC.Sections) {
@@ -120,14 +145,6 @@
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) {
@@ -261,7 +278,7 @@
.MachOLoadCommand.symtab_command_data;
uint8_t *StrTable = (uint8_t *)B.getBufferStart() + SymTabCommand.stroff;
- StrTableBuilder.write(StrTable);
+ LayoutBuilder.getStringTableBuilder().write(StrTable);
}
void MachOWriter::writeStringTable() {
@@ -275,7 +292,7 @@
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);
+ uint32_t Nstrx = LayoutBuilder.getStringTableBuilder().getOffset(Sym->Name);
if (Is64Bit)
writeNListEntry<MachO::nlist_64>(*Sym, IsLittleEndian, SymTable, Nstrx);
@@ -344,6 +361,45 @@
memcpy(Out, O.Exports.Trie.data(), O.Exports.Trie.size());
}
+void MachOWriter::writeIndirectSymbolTable() {
+ if (!O.DySymTabCommandIndex)
+ return;
+
+ const MachO::dysymtab_command &DySymTabCommand =
+ O.LoadCommands[*O.DySymTabCommandIndex]
+ .MachOLoadCommand.dysymtab_command_data;
+
+ char *Out = (char *)B.getBufferStart() + DySymTabCommand.indirectsymoff;
+ assert((DySymTabCommand.nindirectsyms == O.IndirectSymTable.Symbols.size()) &&
+ "Incorrect indirect symbol table size");
+ memcpy(Out, O.IndirectSymTable.Symbols.data(),
+ sizeof(uint32_t) * O.IndirectSymTable.Symbols.size());
+}
+
+void MachOWriter::writeDataInCodeData() {
+ if (!O.DataInCodeCommandIndex)
+ return;
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.DataInCodeCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+ char *Out = (char *)B.getBufferStart() + LinkEditDataCommand.dataoff;
+ assert((LinkEditDataCommand.datasize == O.DataInCode.Data.size()) &&
+ "Incorrect data in code data size");
+ memcpy(Out, O.DataInCode.Data.data(), O.DataInCode.Data.size());
+}
+
+void MachOWriter::writeFunctionStartsData() {
+ if (!O.FunctionStartsCommandIndex)
+ return;
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.FunctionStartsCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+ char *Out = (char *)B.getBufferStart() + LinkEditDataCommand.dataoff;
+ assert((LinkEditDataCommand.datasize == O.FunctionStarts.Data.size()) &&
+ "Incorrect function starts data size");
+ memcpy(Out, O.FunctionStarts.Data.data(), O.FunctionStarts.Data.size());
+}
+
void MachOWriter::writeTail() {
typedef void (MachOWriter::*WriteHandlerType)(void);
typedef std::pair<uint64_t, WriteHandlerType> WriteOperation;
@@ -379,6 +435,36 @@
{DyLdInfoCommand.export_off, &MachOWriter::writeExportInfo});
}
+ if (O.DySymTabCommandIndex) {
+ const MachO::dysymtab_command &DySymTabCommand =
+ O.LoadCommands[*O.DySymTabCommandIndex]
+ .MachOLoadCommand.dysymtab_command_data;
+
+ if (DySymTabCommand.indirectsymoff)
+ Queue.emplace_back(DySymTabCommand.indirectsymoff,
+ &MachOWriter::writeIndirectSymbolTable);
+ }
+
+ if (O.DataInCodeCommandIndex) {
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.DataInCodeCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+
+ if (LinkEditDataCommand.dataoff)
+ Queue.emplace_back(LinkEditDataCommand.dataoff,
+ &MachOWriter::writeDataInCodeData);
+ }
+
+ if (O.FunctionStartsCommandIndex) {
+ const MachO::linkedit_data_command &LinkEditDataCommand =
+ O.LoadCommands[*O.FunctionStartsCommandIndex]
+ .MachOLoadCommand.linkedit_data_command_data;
+
+ if (LinkEditDataCommand.dataoff)
+ Queue.emplace_back(LinkEditDataCommand.dataoff,
+ &MachOWriter::writeFunctionStartsData);
+ }
+
llvm::sort(Queue, [](const WriteOperation &LHS, const WriteOperation &RHS) {
return LHS.first < RHS.first;
});
@@ -387,198 +473,13 @@
(this->*WriteOp.second)();
}
-void MachOWriter::updateSizeOfCmds() {
- auto Size = 0;
- for (const auto &LC : O.LoadCommands) {
- auto &MLC = LC.MachOLoadCommand;
- auto cmd = MLC.load_command_data.cmd;
-
- switch (cmd) {
- case MachO::LC_SEGMENT:
- Size += sizeof(MachO::segment_command) +
- sizeof(MachO::section) * LC.Sections.size();
- continue;
- case MachO::LC_SEGMENT_64:
- Size += sizeof(MachO::segment_command_64) +
- sizeof(MachO::section_64) * LC.Sections.size();
- continue;
- }
-
- switch (cmd) {
-#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
- case MachO::LCName: \
- Size += sizeof(MachO::LCStruct); \
- break;
-#include "llvm/BinaryFormat/MachO.def"
-#undef HANDLE_LOAD_COMMAND
- }
- }
-
- O.Header.SizeOfCmds = Size;
-}
-
-// Updates the index and the number of local/external/undefined symbols. Here we
-// assume that MLC is a LC_DYSYMTAB and the nlist entries in the symbol table
-// are already sorted by the those types.
-void MachOWriter::updateDySymTab(MachO::macho_load_command &MLC) {
- uint32_t NumLocalSymbols = 0;
- 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))
- break;
-
- NumLocalSymbols++;
- }
-
- uint32_t NumExtDefSymbols = 0;
- for (; Iter != End; Iter++) {
- if (((*Iter)->n_type & MachO::N_TYPE) == MachO::N_UNDF)
- break;
-
- NumExtDefSymbols++;
- }
-
- MLC.dysymtab_command_data.ilocalsym = 0;
- MLC.dysymtab_command_data.nlocalsym = NumLocalSymbols;
- MLC.dysymtab_command_data.iextdefsym = NumLocalSymbols;
- MLC.dysymtab_command_data.nextdefsym = NumExtDefSymbols;
- MLC.dysymtab_command_data.iundefsym = NumLocalSymbols + NumExtDefSymbols;
- MLC.dysymtab_command_data.nundefsym =
- O.SymTable.Symbols.size() - (NumLocalSymbols + NumExtDefSymbols);
-}
-
-// Recomputes and updates offset and size fields in load commands and sections
-// since they could be modified.
-Error MachOWriter::layout() {
- auto SizeOfCmds = loadCommandsSize();
- auto Offset = headerSize() + SizeOfCmds;
- O.Header.NCmds = O.LoadCommands.size();
- O.Header.SizeOfCmds = SizeOfCmds;
-
- // Lay out sections.
- for (auto &LC : O.LoadCommands) {
- uint64_t FileOff = Offset;
- uint64_t VMSize = 0;
- uint64_t FileOffsetInSegment = 0;
- for (auto &Sec : LC.Sections) {
- if (!Sec.isVirtualSection()) {
- auto FilePaddingSize =
- OffsetToAlignment(FileOffsetInSegment, 1ull << Sec.Align);
- Sec.Offset = Offset + FileOffsetInSegment + FilePaddingSize;
- Sec.Size = Sec.Content.size();
- FileOffsetInSegment += FilePaddingSize + Sec.Size;
- }
-
- VMSize = std::max(VMSize, Sec.Addr + Sec.Size);
- }
-
- // TODO: Handle the __PAGEZERO segment.
- auto &MLC = LC.MachOLoadCommand;
- switch (MLC.load_command_data.cmd) {
- case MachO::LC_SEGMENT:
- MLC.segment_command_data.cmdsize =
- sizeof(MachO::segment_command) +
- sizeof(MachO::section) * LC.Sections.size();
- MLC.segment_command_data.nsects = LC.Sections.size();
- MLC.segment_command_data.fileoff = FileOff;
- MLC.segment_command_data.vmsize = VMSize;
- MLC.segment_command_data.filesize = FileOffsetInSegment;
- break;
- case MachO::LC_SEGMENT_64:
- MLC.segment_command_64_data.cmdsize =
- sizeof(MachO::segment_command_64) +
- sizeof(MachO::section_64) * LC.Sections.size();
- MLC.segment_command_64_data.nsects = LC.Sections.size();
- MLC.segment_command_64_data.fileoff = FileOff;
- MLC.segment_command_64_data.vmsize = VMSize;
- MLC.segment_command_64_data.filesize = FileOffsetInSegment;
- break;
- }
-
- Offset += FileOffsetInSegment;
- }
-
- // Lay out relocations.
- for (auto &LC : O.LoadCommands)
- for (auto &Sec : LC.Sections) {
- Sec.RelOff = Sec.Relocations.empty() ? 0 : Offset;
- Sec.NReloc = Sec.Relocations.size();
- Offset += sizeof(MachO::any_relocation_info) * Sec.NReloc;
- }
-
- // Lay out tail stuff.
- auto NListSize = Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
- for (auto &LC : O.LoadCommands) {
- auto &MLC = LC.MachOLoadCommand;
- 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;
- Offset += NListSize * MLC.symtab_command_data.nsyms;
- MLC.symtab_command_data.stroff = Offset;
- Offset += MLC.symtab_command_data.strsize;
- break;
- case MachO::LC_DYSYMTAB: {
- if (MLC.dysymtab_command_data.ntoc != 0 ||
- MLC.dysymtab_command_data.nmodtab != 0 ||
- MLC.dysymtab_command_data.nextrefsyms != 0 ||
- MLC.dysymtab_command_data.nlocrel != 0 ||
- MLC.dysymtab_command_data.nextrel != 0)
- return createStringError(llvm::errc::not_supported,
- "shared library is not yet supported");
-
- if (MLC.dysymtab_command_data.nindirectsyms != 0)
- return createStringError(llvm::errc::not_supported,
- "indirect symbol table is not yet supported");
-
- updateDySymTab(MLC);
- break;
- }
- case MachO::LC_SEGMENT:
- case MachO::LC_SEGMENT_64:
- case MachO::LC_VERSION_MIN_MACOSX:
- case MachO::LC_BUILD_VERSION:
- case MachO::LC_ID_DYLIB:
- case MachO::LC_LOAD_DYLIB:
- case MachO::LC_UUID:
- case MachO::LC_SOURCE_VERSION:
- // Nothing to update.
- break;
- default:
- // Abort if it's unsupported in order to prevent corrupting the object.
- return createStringError(llvm::errc::not_supported,
- "unsupported load command (cmd=0x%x)", cmd);
- }
- }
-
- 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;
-
- return Error::success();
-}
+Error MachOWriter::finalize() { return LayoutBuilder.layout(); }
Error MachOWriter::write() {
if (Error E = B.allocate(totalSize()))
return E;
memset(B.getBufferStart(), 0, totalSize());
writeHeader();
- updateSymbolIndexes();
writeLoadCommands();
writeSections();
writeTail();