llvm/lib/ObjCopy/COFF/COFFReader.cpp

   1 //===- COFFReader.cpp -----------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "COFFReader.h"
  10 #include "COFFObject.h"
  11 #include "llvm/ADT/ArrayRef.h"
  12 #include "llvm/ADT/StringRef.h"
  13 #include "llvm/BinaryFormat/COFF.h"
  14 #include "llvm/Object/COFF.h"
  15 #include "llvm/Support/ErrorHandling.h"
  16 #include <cstddef>
  17 #include <cstdint>
  18
  19 namespace llvm {
  20 namespace objcopy {
  21 namespace coff {
  22
  23 using namespace object;
  24 using namespace COFF;
  25
  26 Error COFFReader::readExecutableHeaders(Object &Obj) const {
  27   const dos_header *DH = COFFObj.getDOSHeader();
  28   Obj.Is64 = COFFObj.is64();
  29   if (!DH)
  30     return Error::success();
  31
  32   Obj.IsPE = true;
  33   Obj.DosHeader = *DH;
  34   if (DH->AddressOfNewExeHeader > sizeof(*DH))
  35     Obj.DosStub = ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(&DH[1]),
  36                                     DH->AddressOfNewExeHeader - sizeof(*DH));
  37
  38   if (COFFObj.is64()) {
  39     Obj.PeHeader = *COFFObj.getPE32PlusHeader();
  40   } else {
  41     const pe32_header *PE32 = COFFObj.getPE32Header();
  42     copyPeHeader(Obj.PeHeader, *PE32);
  43     // The pe32plus_header (stored in Object) lacks the BaseOfData field.
  44     Obj.BaseOfData = PE32->BaseOfData;
  45   }
  46
  47   for (size_t I = 0; I < Obj.PeHeader.NumberOfRvaAndSize; I++) {
  48     const data_directory *Dir = COFFObj.getDataDirectory(I);
  49     if (!Dir)
  50       return errorCodeToError(object_error::parse_failed);
  51     Obj.DataDirectories.emplace_back(*Dir);
  52   }
  53   return Error::success();
  54 }
  55
  56 Error COFFReader::readSections(Object &Obj) const {
  57   std::vector<Section> Sections;
  58   // Section indexing starts from 1.
  59   for (size_t I = 1, E = COFFObj.getNumberOfSections(); I <= E; I++) {
  60     Expected<const coff_section *> SecOrErr = COFFObj.getSection(I);
  61     if (!SecOrErr)
  62       return SecOrErr.takeError();
  63     const coff_section *Sec = *SecOrErr;
  64     Sections.push_back(Section());
  65     Section &S = Sections.back();
  66     S.Header = *Sec;
  67     S.Header.Characteristics &= ~COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
  68     ArrayRef<uint8_t> Contents;
  69     if (Error E = COFFObj.getSectionContents(Sec, Contents))
  70       return E;
  71     S.setContentsRef(Contents);
  72     ArrayRef<coff_relocation> Relocs = COFFObj.getRelocations(Sec);
  73     for (const coff_relocation &R : Relocs)
  74       S.Relocs.push_back(R);
  75     if (Expected<StringRef> NameOrErr = COFFObj.getSectionName(Sec))
  76       S.Name = *NameOrErr;
  77     else
  78       return NameOrErr.takeError();
  79   }
  80   Obj.addSections(Sections);
  81   return Error::success();
  82 }
  83
  84 Error COFFReader::readSymbols(Object &Obj, bool IsBigObj) const {
  85   std::vector<Symbol> Symbols;
  86   Symbols.reserve(COFFObj.getNumberOfSymbols());
  87   ArrayRef<Section> Sections = Obj.getSections();
  88   for (uint32_t I = 0, E = COFFObj.getNumberOfSymbols(); I < E;) {
  89     Expected<COFFSymbolRef> SymOrErr = COFFObj.getSymbol(I);
  90     if (!SymOrErr)
  91       return SymOrErr.takeError();
  92     COFFSymbolRef SymRef = *SymOrErr;
  93
  94     Symbols.push_back(Symbol());
  95     Symbol &Sym = Symbols.back();
  96     // Copy symbols from the original form into an intermediate coff_symbol32.
  97     if (IsBigObj)
  98       copySymbol(Sym.Sym,
  99                  *reinterpret_cast<const coff_symbol32 *>(SymRef.getRawPtr()));
 100     else
 101       copySymbol(Sym.Sym,
 102                  *reinterpret_cast<const coff_symbol16 *>(SymRef.getRawPtr()));
 103     auto NameOrErr = COFFObj.getSymbolName(SymRef);
 104     if (!NameOrErr)
 105       return NameOrErr.takeError();
 106     Sym.Name = *NameOrErr;
 107
 108     ArrayRef<uint8_t> AuxData = COFFObj.getSymbolAuxData(SymRef);
 109     size_t SymSize = IsBigObj ? sizeof(coff_symbol32) : sizeof(coff_symbol16);
 110     assert(AuxData.size() == SymSize * SymRef.getNumberOfAuxSymbols());
 111     // The auxillary symbols are structs of sizeof(coff_symbol16) each.
 112     // In the big object format (where symbols are coff_symbol32), each
 113     // auxillary symbol is padded with 2 bytes at the end. Copy each
 114     // auxillary symbol to the Sym.AuxData vector. For file symbols,
 115     // the whole range of aux symbols are interpreted as one null padded
 116     // string instead.
 117     if (SymRef.isFileRecord())
 118       Sym.AuxFile = StringRef(reinterpret_cast<const char *>(AuxData.data()),
 119                               AuxData.size())
 120                         .rtrim('\0');
 121     else
 122       for (size_t I = 0; I < SymRef.getNumberOfAuxSymbols(); I++)
 123         Sym.AuxData.push_back(AuxData.slice(I * SymSize, sizeof(AuxSymbol)));
 124
 125     // Find the unique id of the section
 126     if (SymRef.getSectionNumber() <=
 127         0) // Special symbol (undefined/absolute/debug)
 128       Sym.TargetSectionId = SymRef.getSectionNumber();
 129     else if (static_cast<uint32_t>(SymRef.getSectionNumber() - 1) <
 130              Sections.size())
 131       Sym.TargetSectionId = Sections[SymRef.getSectionNumber() - 1].UniqueId;
 132     else
 133       return createStringError(object_error::parse_failed,
 134                                "section number out of range");
 135     // For section definitions, check if it is comdat associative, and if
 136     // it is, find the target section unique id.
 137     const coff_aux_section_definition *SD = SymRef.getSectionDefinition();
 138     const coff_aux_weak_external *WE = SymRef.getWeakExternal();
 139     if (SD && SD->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
 140       int32_t Index = SD->getNumber(IsBigObj);
 141       if (Index <= 0 || static_cast<uint32_t>(Index - 1) >= Sections.size())
 142         return createStringError(object_error::parse_failed,
 143                                  "unexpected associative section index");
 144       Sym.AssociativeComdatTargetSectionId = Sections[Index - 1].UniqueId;
 145     } else if (WE) {
 146       // This is a raw symbol index for now, but store it in the Symbol
 147       // until we've added them to the Object, which assigns the final
 148       // unique ids.
 149       Sym.WeakTargetSymbolId = WE->TagIndex;
 150     }
 151     I += 1 + SymRef.getNumberOfAuxSymbols();
 152   }
 153   Obj.addSymbols(Symbols);
 154   return Error::success();
 155 }
 156
 157 Error COFFReader::setSymbolTargets(Object &Obj) const {
 158   std::vector<const Symbol *> RawSymbolTable;
 159   for (const Symbol &Sym : Obj.getSymbols()) {
 160     RawSymbolTable.push_back(&Sym);
 161     for (size_t I = 0; I < Sym.Sym.NumberOfAuxSymbols; I++)
 162       RawSymbolTable.push_back(nullptr);
 163   }
 164   for (Symbol &Sym : Obj.getMutableSymbols()) {
 165     // Convert WeakTargetSymbolId from the original raw symbol index to
 166     // a proper unique id.
 167     if (Sym.WeakTargetSymbolId) {
 168       if (*Sym.WeakTargetSymbolId >= RawSymbolTable.size())
 169         return createStringError(object_error::parse_failed,
 170                                  "weak external reference out of range");
 171       const Symbol *Target = RawSymbolTable[*Sym.WeakTargetSymbolId];
 172       if (Target == nullptr)
 173         return createStringError(object_error::parse_failed,
 174                                  "invalid SymbolTableIndex");
 175       Sym.WeakTargetSymbolId = Target->UniqueId;
 176     }
 177   }
 178   for (Section &Sec : Obj.getMutableSections()) {
 179     for (Relocation &R : Sec.Relocs) {
 180       if (R.Reloc.SymbolTableIndex >= RawSymbolTable.size())
 181         return createStringError(object_error::parse_failed,
 182                                  "SymbolTableIndex out of range");
 183       const Symbol *Sym = RawSymbolTable[R.Reloc.SymbolTableIndex];
 184       if (Sym == nullptr)
 185         return createStringError(object_error::parse_failed,
 186                                  "invalid SymbolTableIndex");
 187       R.Target = Sym->UniqueId;
 188       R.TargetName = Sym->Name;
 189     }
 190   }
 191   return Error::success();
 192 }
 193
 194 Expected<std::unique_ptr<Object>> COFFReader::create() const {
 195   auto Obj = std::make_unique<Object>();
 196
 197   bool IsBigObj = false;
 198   if (const coff_file_header *CFH = COFFObj.getCOFFHeader()) {
 199     Obj->CoffFileHeader = *CFH;
 200   } else {
 201     const coff_bigobj_file_header *CBFH = COFFObj.getCOFFBigObjHeader();
 202     if (!CBFH)
 203       return createStringError(object_error::parse_failed,
 204                                "no COFF file header returned");
 205     // Only copying the few fields from the bigobj header that we need
 206     // and won't recreate in the end.
 207     Obj->CoffFileHeader.Machine = CBFH->Machine;
 208     Obj->CoffFileHeader.TimeDateStamp = CBFH->TimeDateStamp;
 209     IsBigObj = true;
 210   }
 211
 212   if (Error E = readExecutableHeaders(*Obj))
 213     return std::move(E);
 214   if (Error E = readSections(*Obj))
 215     return std::move(E);
 216   if (Error E = readSymbols(*Obj, IsBigObj))
 217     return std::move(E);
 218   if (Error E = setSymbolTargets(*Obj))
 219     return std::move(E);
 220
 221   return std::move(Obj);
 222 }
 223
 224 } // end namespace coff
 225 } // end namespace objcopy
 226 } // end namespace llvm