1 files changed, 225 insertions, 0 deletions
diff --git a/llvm/tools/llvm-objcopy/COFF/Reader.cpp b/llvm/tools/llvm-objcopy/COFF/Reader.cpp
new file mode 100644
index 000000000000..2fcec0057c03
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/COFF/Reader.cpp
@@ -0,0 +1,225 @@
+//===- Reader.cpp ---------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Reader.h"
+#include "Object.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/COFF.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cstddef>
+#include <cstdint>
+
+namespace llvm {
+namespace objcopy {
+namespace coff {
+
+using namespace object;
+using namespace COFF;
+
+Error COFFReader::readExecutableHeaders(Object &Obj) const {
+  const dos_header *DH = COFFObj.getDOSHeader();
+  Obj.Is64 = COFFObj.is64();
+  if (!DH)
+    return Error::success();
+
+  Obj.IsPE = true;
+  Obj.DosHeader = *DH;
+  if (DH->AddressOfNewExeHeader > sizeof(*DH))
+    Obj.DosStub = ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(&DH[1]),
+                                    DH->AddressOfNewExeHeader - sizeof(*DH));
+
+  if (COFFObj.is64()) {
+    Obj.PeHeader = *COFFObj.getPE32PlusHeader();
+  } else {
+    const pe32_header *PE32 = COFFObj.getPE32Header();
+    copyPeHeader(Obj.PeHeader, *PE32);
+    // The pe32plus_header (stored in Object) lacks the BaseOfData field.
+    Obj.BaseOfData = PE32->BaseOfData;
+  }
+
+  for (size_t I = 0; I < Obj.PeHeader.NumberOfRvaAndSize; I++) {
+    const data_directory *Dir;
+    if (auto EC = COFFObj.getDataDirectory(I, Dir))
+      return errorCodeToError(EC);
+    Obj.DataDirectories.emplace_back(*Dir);
+  }
+  return Error::success();
+}
+
+Error COFFReader::readSections(Object &Obj) const {
+  std::vector<Section> Sections;
+  // Section indexing starts from 1.
+  for (size_t I = 1, E = COFFObj.getNumberOfSections(); I <= E; I++) {
+    const coff_section *Sec;
+    if (auto EC = COFFObj.getSection(I, Sec))
+      return errorCodeToError(EC);
+    Sections.push_back(Section());
+    Section &S = Sections.back();
+    S.Header = *Sec;
+    ArrayRef<uint8_t> Contents;
+    if (Error E = COFFObj.getSectionContents(Sec, Contents))
+      return E;
+    S.setContentsRef(Contents);
+    ArrayRef<coff_relocation> Relocs = COFFObj.getRelocations(Sec);
+    for (const coff_relocation &R : Relocs)
+      S.Relocs.push_back(R);
+    if (Expected<StringRef> NameOrErr = COFFObj.getSectionName(Sec))
+      S.Name = *NameOrErr;
+    else
+      return NameOrErr.takeError();
+    if (Sec->hasExtendedRelocations())
+      return createStringError(object_error::parse_failed,
+                               "extended relocations not supported yet");
+  }
+  Obj.addSections(Sections);
+  return Error::success();
+}
+
+Error COFFReader::readSymbols(Object &Obj, bool IsBigObj) const {
+  std::vector<Symbol> Symbols;
+  Symbols.reserve(COFFObj.getRawNumberOfSymbols());
+  ArrayRef<Section> Sections = Obj.getSections();
+  for (uint32_t I = 0, E = COFFObj.getRawNumberOfSymbols(); I < E;) {
+    Expected<COFFSymbolRef> SymOrErr = COFFObj.getSymbol(I);
+    if (!SymOrErr)
+      return SymOrErr.takeError();
+    COFFSymbolRef SymRef = *SymOrErr;
+
+    Symbols.push_back(Symbol());
+    Symbol &Sym = Symbols.back();
+    // Copy symbols from the original form into an intermediate coff_symbol32.
+    if (IsBigObj)
+      copySymbol(Sym.Sym,
+                 *reinterpret_cast<const coff_symbol32 *>(SymRef.getRawPtr()));
+    else
+      copySymbol(Sym.Sym,
+                 *reinterpret_cast<const coff_symbol16 *>(SymRef.getRawPtr()));
+    if (auto EC = COFFObj.getSymbolName(SymRef, Sym.Name))
+      return errorCodeToError(EC);
+
+    ArrayRef<uint8_t> AuxData = COFFObj.getSymbolAuxData(SymRef);
+    size_t SymSize = IsBigObj ? sizeof(coff_symbol32) : sizeof(coff_symbol16);
+    assert(AuxData.size() == SymSize * SymRef.getNumberOfAuxSymbols());
+    // The auxillary symbols are structs of sizeof(coff_symbol16) each.
+    // In the big object format (where symbols are coff_symbol32), each
+    // auxillary symbol is padded with 2 bytes at the end. Copy each
+    // auxillary symbol to the Sym.AuxData vector. For file symbols,
+    // the whole range of aux symbols are interpreted as one null padded
+    // string instead.
+    if (SymRef.isFileRecord())
+      Sym.AuxFile = StringRef(reinterpret_cast<const char *>(AuxData.data()),
+                              AuxData.size())
+                        .rtrim('\0');
+    else
+      for (size_t I = 0; I < SymRef.getNumberOfAuxSymbols(); I++)
+        Sym.AuxData.push_back(AuxData.slice(I * SymSize, sizeof(AuxSymbol)));
+
+    // Find the unique id of the section
+    if (SymRef.getSectionNumber() <=
+        0) // Special symbol (undefined/absolute/debug)
+      Sym.TargetSectionId = SymRef.getSectionNumber();
+    else if (static_cast<uint32_t>(SymRef.getSectionNumber() - 1) <
+             Sections.size())
+      Sym.TargetSectionId = Sections[SymRef.getSectionNumber() - 1].UniqueId;
+    else
+      return createStringError(object_error::parse_failed,
+                               "section number out of range");
+    // For section definitions, check if it is comdat associative, and if
+    // it is, find the target section unique id.
+    const coff_aux_section_definition *SD = SymRef.getSectionDefinition();
+    const coff_aux_weak_external *WE = SymRef.getWeakExternal();
+    if (SD && SD->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
+      int32_t Index = SD->getNumber(IsBigObj);
+      if (Index <= 0 || static_cast<uint32_t>(Index - 1) >= Sections.size())
+        return createStringError(object_error::parse_failed,
+                                 "unexpected associative section index");
+      Sym.AssociativeComdatTargetSectionId = Sections[Index - 1].UniqueId;
+    } else if (WE) {
+      // This is a raw symbol index for now, but store it in the Symbol
+      // until we've added them to the Object, which assigns the final
+      // unique ids.
+      Sym.WeakTargetSymbolId = WE->TagIndex;
+    }
+    I += 1 + SymRef.getNumberOfAuxSymbols();
+  }
+  Obj.addSymbols(Symbols);
+  return Error::success();
+}
+
+Error COFFReader::setSymbolTargets(Object &Obj) const {
+  std::vector<const Symbol *> RawSymbolTable;
+  for (const Symbol &Sym : Obj.getSymbols()) {
+    RawSymbolTable.push_back(&Sym);
+    for (size_t I = 0; I < Sym.Sym.NumberOfAuxSymbols; I++)
+      RawSymbolTable.push_back(nullptr);
+  }
+  for (Symbol &Sym : Obj.getMutableSymbols()) {
+    // Convert WeakTargetSymbolId from the original raw symbol index to
+    // a proper unique id.
+    if (Sym.WeakTargetSymbolId) {
+      if (*Sym.WeakTargetSymbolId >= RawSymbolTable.size())
+        return createStringError(object_error::parse_failed,
+                                 "weak external reference out of range");
+      const Symbol *Target = RawSymbolTable[*Sym.WeakTargetSymbolId];
+      if (Target == nullptr)
+        return createStringError(object_error::parse_failed,
+                                 "invalid SymbolTableIndex");
+      Sym.WeakTargetSymbolId = Target->UniqueId;
+    }
+  }
+  for (Section &Sec : Obj.getMutableSections()) {
+    for (Relocation &R : Sec.Relocs) {
+      if (R.Reloc.SymbolTableIndex >= RawSymbolTable.size())
+        return createStringError(object_error::parse_failed,
+                                 "SymbolTableIndex out of range");
+      const Symbol *Sym = RawSymbolTable[R.Reloc.SymbolTableIndex];
+      if (Sym == nullptr)
+        return createStringError(object_error::parse_failed,
+                                 "invalid SymbolTableIndex");
+      R.Target = Sym->UniqueId;
+      R.TargetName = Sym->Name;
+    }
+  }
+  return Error::success();
+}
+
+Expected<std::unique_ptr<Object>> COFFReader::create() const {
+  auto Obj = std::make_unique<Object>();
+
+  bool IsBigObj = false;
+  if (const coff_file_header *CFH = COFFObj.getCOFFHeader()) {
+    Obj->CoffFileHeader = *CFH;
+  } else {
+    const coff_bigobj_file_header *CBFH = COFFObj.getCOFFBigObjHeader();
+    if (!CBFH)
+      return createStringError(object_error::parse_failed,
+                               "no COFF file header returned");
+    // Only copying the few fields from the bigobj header that we need
+    // and won't recreate in the end.
+    Obj->CoffFileHeader.Machine = CBFH->Machine;
+    Obj->CoffFileHeader.TimeDateStamp = CBFH->TimeDateStamp;
+    IsBigObj = true;
+  }
+
+  if (Error E = readExecutableHeaders(*Obj))
+    return std::move(E);
+  if (Error E = readSections(*Obj))
+    return std::move(E);
+  if (Error E = readSymbols(*Obj, IsBigObj))
+    return std::move(E);
+  if (Error E = setSymbolTargets(*Obj))
+    return std::move(E);
+
+  return std::move(Obj);
+}
+
+} // end namespace coff
+} // end namespace objcopy
+} // end namespace llvm