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      1 //===- MachOUniversal.cpp - Mach-O universal binary -------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines the MachOUniversalBinary class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/Object/MachOUniversal.h"
     15 #include "llvm/Object/Archive.h"
     16 #include "llvm/Object/MachO.h"
     17 #include "llvm/Object/ObjectFile.h"
     18 #include "llvm/Support/Casting.h"
     19 #include "llvm/Support/Host.h"
     20 #include "llvm/Support/MemoryBuffer.h"
     21 
     22 using namespace llvm;
     23 using namespace object;
     24 
     25 template<typename T>
     26 static void SwapStruct(T &Value);
     27 
     28 template<>
     29 void SwapStruct(MachO::fat_header &H) {
     30   sys::swapByteOrder(H.magic);
     31   sys::swapByteOrder(H.nfat_arch);
     32 }
     33 
     34 template<>
     35 void SwapStruct(MachO::fat_arch &H) {
     36   sys::swapByteOrder(H.cputype);
     37   sys::swapByteOrder(H.cpusubtype);
     38   sys::swapByteOrder(H.offset);
     39   sys::swapByteOrder(H.size);
     40   sys::swapByteOrder(H.align);
     41 }
     42 
     43 template<typename T>
     44 static T getUniversalBinaryStruct(const char *Ptr) {
     45   T Res;
     46   memcpy(&Res, Ptr, sizeof(T));
     47   // Universal binary headers have big-endian byte order.
     48   if (sys::IsLittleEndianHost)
     49     SwapStruct(Res);
     50   return Res;
     51 }
     52 
     53 MachOUniversalBinary::ObjectForArch::ObjectForArch(
     54     const MachOUniversalBinary *Parent, uint32_t Index)
     55     : Parent(Parent), Index(Index) {
     56   if (!Parent || Index >= Parent->getNumberOfObjects()) {
     57     clear();
     58   } else {
     59     // Parse object header.
     60     StringRef ParentData = Parent->getData();
     61     const char *HeaderPos = ParentData.begin() + sizeof(MachO::fat_header) +
     62                             Index * sizeof(MachO::fat_arch);
     63     Header = getUniversalBinaryStruct<MachO::fat_arch>(HeaderPos);
     64     if (ParentData.size() < Header.offset + Header.size) {
     65       clear();
     66     }
     67   }
     68 }
     69 
     70 ErrorOr<std::unique_ptr<MachOObjectFile>>
     71 MachOUniversalBinary::ObjectForArch::getAsObjectFile() const {
     72   if (!Parent)
     73     return object_error::parse_failed;
     74 
     75   StringRef ParentData = Parent->getData();
     76   StringRef ObjectData = ParentData.substr(Header.offset, Header.size);
     77   StringRef ObjectName = Parent->getFileName();
     78   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
     79   return ObjectFile::createMachOObjectFile(ObjBuffer);
     80 }
     81 
     82 ErrorOr<std::unique_ptr<Archive>>
     83 MachOUniversalBinary::ObjectForArch::getAsArchive() const {
     84   if (!Parent)
     85     return object_error::parse_failed;
     86 
     87   StringRef ParentData = Parent->getData();
     88   StringRef ObjectData = ParentData.substr(Header.offset, Header.size);
     89   StringRef ObjectName = Parent->getFileName();
     90   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
     91   return Archive::create(ObjBuffer);
     92 }
     93 
     94 void MachOUniversalBinary::anchor() { }
     95 
     96 ErrorOr<std::unique_ptr<MachOUniversalBinary>>
     97 MachOUniversalBinary::create(MemoryBufferRef Source) {
     98   std::error_code EC;
     99   std::unique_ptr<MachOUniversalBinary> Ret(
    100       new MachOUniversalBinary(Source, EC));
    101   if (EC)
    102     return EC;
    103   return std::move(Ret);
    104 }
    105 
    106 MachOUniversalBinary::MachOUniversalBinary(MemoryBufferRef Source,
    107                                            std::error_code &ec)
    108     : Binary(Binary::ID_MachOUniversalBinary, Source), NumberOfObjects(0) {
    109   if (Data.getBufferSize() < sizeof(MachO::fat_header)) {
    110     ec = object_error::invalid_file_type;
    111     return;
    112   }
    113   // Check for magic value and sufficient header size.
    114   StringRef Buf = getData();
    115   MachO::fat_header H= getUniversalBinaryStruct<MachO::fat_header>(Buf.begin());
    116   NumberOfObjects = H.nfat_arch;
    117   uint32_t MinSize = sizeof(MachO::fat_header) +
    118                      sizeof(MachO::fat_arch) * NumberOfObjects;
    119   if (H.magic != MachO::FAT_MAGIC || Buf.size() < MinSize) {
    120     ec = object_error::parse_failed;
    121     return;
    122   }
    123   ec = std::error_code();
    124 }
    125 
    126 ErrorOr<std::unique_ptr<MachOObjectFile>>
    127 MachOUniversalBinary::getObjectForArch(StringRef ArchName) const {
    128   if (Triple(ArchName).getArch() == Triple::ArchType::UnknownArch)
    129     return object_error::arch_not_found;
    130 
    131   for (object_iterator I = begin_objects(), E = end_objects(); I != E; ++I) {
    132     if (I->getArchTypeName() == ArchName)
    133       return I->getAsObjectFile();
    134   }
    135   return object_error::arch_not_found;
    136 }
    137