[llvm-objcopy][MachO] Handle relocation entries where r_extern is zero
Fix handling of relocations with r_extern == 0.
If r_extern == 0 then r_symbolnum is an index of a section rather than a symbol index.
Patch by Seiya Nuta and Alexander Shaposhnikov.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D78946
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
index b4662ec..b12e39c 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
@@ -103,6 +103,7 @@
R.Symbol = nullptr; // We'll fill this field later.
R.Info = MachOObj.getRelocation(RI->getRawDataRefImpl());
R.Scattered = MachOObj.isRelocationScattered(R.Info);
+ R.Extern = !R.Scattered && MachOObj.getPlainRelocationExternal(R.Info);
S.Relocations.push_back(R);
}
@@ -203,12 +204,27 @@
}
void MachOReader::setSymbolInRelocationInfo(Object &O) const {
+ std::vector<const Section *> Sections;
+ for (auto &LC : O.LoadCommands)
+ for (std::unique_ptr<Section> &Sec : LC.Sections)
+ Sections.push_back(Sec.get());
+
for (LoadCommand &LC : O.LoadCommands)
for (std::unique_ptr<Section> &Sec : LC.Sections)
for (auto &Reloc : Sec->Relocations)
- if (!Reloc.Scattered)
- Reloc.Symbol = O.SymTable.getSymbolByIndex(
- Reloc.getPlainRelocationSymbolNum(MachOObj.isLittleEndian()));
+ if (!Reloc.Scattered) {
+ const uint32_t SymbolNum =
+ Reloc.getPlainRelocationSymbolNum(MachOObj.isLittleEndian());
+ if (Reloc.Extern) {
+ Reloc.Symbol = O.SymTable.getSymbolByIndex(SymbolNum);
+ } else {
+ // FIXME: Refactor error handling in MachOReader and report an error
+ // if we encounter an invalid relocation.
+ assert(SymbolNum >= 1 && SymbolNum <= Sections.size() &&
+ "Invalid section index.");
+ Reloc.Section = Sections[SymbolNum - 1];
+ }
+ }
}
void MachOReader::readRebaseInfo(Object &O) const {
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
index db31ef5..4a8d1ae 100644
--- a/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
@@ -239,11 +239,13 @@
memcpy(B.getBufferStart() + Sec->Offset, Sec->Content.data(),
Sec->Content.size());
for (size_t Index = 0; Index < Sec->Relocations.size(); ++Index) {
- auto RelocInfo = Sec->Relocations[Index];
- if (!RelocInfo.Scattered)
- RelocInfo.setPlainRelocationSymbolNum(RelocInfo.Symbol->Index,
- IsLittleEndian);
-
+ RelocationInfo RelocInfo = Sec->Relocations[Index];
+ if (!RelocInfo.Scattered) {
+ const uint32_t SymbolNum = RelocInfo.Extern
+ ? (*RelocInfo.Symbol)->Index
+ : (*RelocInfo.Section)->Index;
+ RelocInfo.setPlainRelocationSymbolNum(SymbolNum, IsLittleEndian);
+ }
if (IsLittleEndian != sys::IsLittleEndianHost)
MachO::swapStruct(
reinterpret_cast<MachO::any_relocation_info &>(RelocInfo.Info));
diff --git a/llvm/tools/llvm-objcopy/MachO/Object.cpp b/llvm/tools/llvm-objcopy/MachO/Object.cpp
index 89fe994..0f28cb0 100644
--- a/llvm/tools/llvm-objcopy/MachO/Object.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/Object.cpp
@@ -60,13 +60,13 @@
for (const LoadCommand &LC : LoadCommands)
for (const std::unique_ptr<Section> &Sec : LC.Sections)
for (const RelocationInfo &R : Sec->Relocations)
- if (R.Symbol && DeadSymbols.count(R.Symbol))
+ if (R.Symbol && *R.Symbol && DeadSymbols.count(*R.Symbol))
return createStringError(std::errc::invalid_argument,
"symbol '%s' defined in section with index "
"'%u' cannot be removed because it is "
"referenced by a relocation in section '%s'",
- R.Symbol->Name.c_str(),
- *(R.Symbol->section()),
+ (*R.Symbol)->Name.c_str(),
+ *((*R.Symbol)->section()),
Sec->CanonicalName.c_str());
SymTable.removeSymbols(IsDead);
for (std::unique_ptr<SymbolEntry> &S : SymTable.Symbols)
diff --git a/llvm/tools/llvm-objcopy/MachO/Object.h b/llvm/tools/llvm-objcopy/MachO/Object.h
index dc828e6..703c31f 100644
--- a/llvm/tools/llvm-objcopy/MachO/Object.h
+++ b/llvm/tools/llvm-objcopy/MachO/Object.h
@@ -162,9 +162,14 @@
};
struct RelocationInfo {
- const SymbolEntry *Symbol;
+ // The referenced symbol entry. Set if !Scattered && Extern.
+ Optional<const SymbolEntry *> Symbol;
+ // The referenced section. Set if !Scattered && !Extern.
+ Optional<const Section *> Section;
// True if Info is a scattered_relocation_info.
bool Scattered;
+ // True if the r_symbolnum points to a section number (i.e. r_extern=0).
+ bool Extern;
MachO::any_relocation_info Info;
unsigned getPlainRelocationSymbolNum(bool IsLittleEndian) {