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 static Error
26 malformedError(Twine Msg) {
27   std::string StringMsg = "truncated or malformed fat file (" + Msg.str() + ")";
28   return make_error<GenericBinaryError>(std::move(StringMsg),
29                                         object_error::parse_failed);
30 }
31 
32 template<typename T>
33 static T getUniversalBinaryStruct(const char *Ptr) {
34   T Res;
35   memcpy(&Res, Ptr, sizeof(T));
36   // Universal binary headers have big-endian byte order.
37   if (sys::IsLittleEndianHost)
38     swapStruct(Res);
39   return Res;
40 }
41 
42 MachOUniversalBinary::ObjectForArch::ObjectForArch(
43     const MachOUniversalBinary *Parent, uint32_t Index)
44     : Parent(Parent), Index(Index) {
45   // The iterators use Parent as a nullptr and an Index+1 == NumberOfObjects.
46   if (!Parent || Index >= Parent->getNumberOfObjects()) {
47     clear();
48   } else {
49     // Parse object header.
50     StringRef ParentData = Parent->getData();
51     if (Parent->getMagic() == MachO::FAT_MAGIC) {
52       const char *HeaderPos = ParentData.begin() + sizeof(MachO::fat_header) +
53                               Index * sizeof(MachO::fat_arch);
54       Header = getUniversalBinaryStruct<MachO::fat_arch>(HeaderPos);
55     } else { // Parent->getMagic() == MachO::FAT_MAGIC_64
56       const char *HeaderPos = ParentData.begin() + sizeof(MachO::fat_header) +
57                               Index * sizeof(MachO::fat_arch_64);
58       Header64 = getUniversalBinaryStruct<MachO::fat_arch_64>(HeaderPos);
59     }
60   }
61 }
62 
63 Expected<std::unique_ptr<MachOObjectFile>>
64 MachOUniversalBinary::ObjectForArch::getAsObjectFile() const {
65   if (!Parent)
66     report_fatal_error("MachOUniversalBinary::ObjectForArch::getAsObjectFile() "
67                        "called when Parent is a nullptr");
68 
69   StringRef ParentData = Parent->getData();
70   StringRef ObjectData;
71   uint32_t cputype;
72   if (Parent->getMagic() == MachO::FAT_MAGIC) {
73     ObjectData = ParentData.substr(Header.offset, Header.size);
74     cputype = Header.cputype;
75   } else { // Parent->getMagic() == MachO::FAT_MAGIC_64
76     ObjectData = ParentData.substr(Header64.offset, Header64.size);
77     cputype = Header64.cputype;
78   }
79   StringRef ObjectName = Parent->getFileName();
80   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
81   return ObjectFile::createMachOObjectFile(ObjBuffer, cputype, Index);
82 }
83 
84 Expected<std::unique_ptr<Archive>>
85 MachOUniversalBinary::ObjectForArch::getAsArchive() const {
86   if (!Parent)
87     report_fatal_error("MachOUniversalBinary::ObjectForArch::getAsArchive() "
88                        "called when Parent is a nullptr");
89 
90   StringRef ParentData = Parent->getData();
91   StringRef ObjectData;
92   if (Parent->getMagic() == MachO::FAT_MAGIC)
93     ObjectData = ParentData.substr(Header.offset, Header.size);
94   else // Parent->getMagic() == MachO::FAT_MAGIC_64
95     ObjectData = ParentData.substr(Header64.offset, Header64.size);
96   StringRef ObjectName = Parent->getFileName();
97   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
98   return Archive::create(ObjBuffer);
99 }
100 
101 void MachOUniversalBinary::anchor() { }
102 
103 Expected<std::unique_ptr<MachOUniversalBinary>>
104 MachOUniversalBinary::create(MemoryBufferRef Source) {
105   Error Err = Error::success();
106   std::unique_ptr<MachOUniversalBinary> Ret(
107       new MachOUniversalBinary(Source, Err));
108   if (Err)
109     return std::move(Err);
110   return std::move(Ret);
111 }
112 
113 MachOUniversalBinary::MachOUniversalBinary(MemoryBufferRef Source, Error &Err)
114     : Binary(Binary::ID_MachOUniversalBinary, Source), Magic(0),
115       NumberOfObjects(0) {
116   ErrorAsOutParameter ErrAsOutParam(&Err);
117   if (Data.getBufferSize() < sizeof(MachO::fat_header)) {
118     Err = make_error<GenericBinaryError>("File too small to be a Mach-O "
119                                          "universal file",
120                                          object_error::invalid_file_type);
121     return;
122   }
123   // Check for magic value and sufficient header size.
124   StringRef Buf = getData();
125   MachO::fat_header H =
126       getUniversalBinaryStruct<MachO::fat_header>(Buf.begin());
127   Magic = H.magic;
128   NumberOfObjects = H.nfat_arch;
129   if (NumberOfObjects == 0) {
130     Err = malformedError("contains zero architecture types");
131     return;
132   }
133   uint32_t MinSize = sizeof(MachO::fat_header);
134   if (Magic == MachO::FAT_MAGIC)
135     MinSize += sizeof(MachO::fat_arch) * NumberOfObjects;
136   else if (Magic == MachO::FAT_MAGIC_64)
137     MinSize += sizeof(MachO::fat_arch_64) * NumberOfObjects;
138   else {
139     Err = malformedError("bad magic number");
140     return;
141   }
142   if (Buf.size() < MinSize) {
143     Err = malformedError("fat_arch" +
144                          Twine(Magic == MachO::FAT_MAGIC ? "" : "_64") +
145                          " structs would extend past the end of the file");
146     return;
147   }
148   for (uint32_t i = 0; i < NumberOfObjects; i++) {
149     ObjectForArch A(this, i);
150     uint64_t bigSize = A.getOffset();
151     bigSize += A.getSize();
152     if (bigSize > Buf.size()) {
153       Err = malformedError("offset plus size of cputype (" +
154         Twine(A.getCPUType()) + ") cpusubtype (" +
155         Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
156         ") extends past the end of the file");
157       return;
158     }
159 #define MAXSECTALIGN 15 /* 2**15 or 0x8000 */
160     if (A.getAlign() > MAXSECTALIGN) {
161       Err = malformedError("align (2^" + Twine(A.getAlign()) + ") too large "
162         "for cputype (" + Twine(A.getCPUType()) + ") cpusubtype (" +
163         Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
164         ") (maximum 2^" + Twine(MAXSECTALIGN) + ")");
165       return;
166     }
167     if(A.getOffset() % (1 << A.getAlign()) != 0){
168       Err = malformedError("offset: " + Twine(A.getOffset()) +
169         " for cputype (" + Twine(A.getCPUType()) + ") cpusubtype (" +
170         Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
171         ") not aligned on it's alignment (2^" + Twine(A.getAlign()) + ")");
172       return;
173     }
174     if (A.getOffset() < MinSize) {
175       Err =  malformedError("cputype (" + Twine(A.getCPUType()) + ") "
176         "cpusubtype (" + Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
177         ") offset " + Twine(A.getOffset()) + " overlaps universal headers");
178       return;
179     }
180   }
181   for (uint32_t i = 0; i < NumberOfObjects; i++) {
182     ObjectForArch A(this, i);
183     for (uint32_t j = i + 1; j < NumberOfObjects; j++) {
184       ObjectForArch B(this, j);
185       if (A.getCPUType() == B.getCPUType() &&
186           (A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) ==
187           (B.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK)) {
188         Err = malformedError("contains two of the same architecture (cputype "
189           "(" + Twine(A.getCPUType()) + ") cpusubtype (" +
190           Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) + "))");
191         return;
192       }
193       if ((A.getOffset() >= B.getOffset() &&
194            A.getOffset() < B.getOffset() + B.getSize()) ||
195           (A.getOffset() + A.getSize() > B.getOffset() &&
196            A.getOffset() + A.getSize() < B.getOffset() + B.getSize()) ||
197           (A.getOffset() <= B.getOffset() &&
198            A.getOffset() + A.getSize() >= B.getOffset() + B.getSize())) {
199         Err =  malformedError("cputype (" + Twine(A.getCPUType()) + ") "
200           "cpusubtype (" + Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
201           ") at offset " + Twine(A.getOffset()) + " with a size of " +
202           Twine(A.getSize()) + ", overlaps cputype (" + Twine(B.getCPUType()) +
203           ") cpusubtype (" + Twine(B.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK)
204           + ") at offset " + Twine(B.getOffset()) + " with a size of "
205           + Twine(B.getSize()));
206         return;
207       }
208     }
209   }
210   Err = Error::success();
211 }
212 
213 Expected<std::unique_ptr<MachOObjectFile>>
214 MachOUniversalBinary::getObjectForArch(StringRef ArchName) const {
215   if (Triple(ArchName).getArch() == Triple::ArchType::UnknownArch)
216     return make_error<GenericBinaryError>("Unknown architecture "
217                                           "named: " +
218                                               ArchName,
219                                           object_error::arch_not_found);
220 
221   for (auto &Obj : objects())
222     if (Obj.getArchFlagName() == ArchName)
223       return Obj.getAsObjectFile();
224   return make_error<GenericBinaryError>("fat file does not "
225                                         "contain " +
226                                             ArchName,
227                                         object_error::arch_not_found);
228 }
229