1 //===- MachOUniversal.cpp - Mach-O universal binary -------------*- C++ -*-===//
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 // This file defines the MachOUniversalBinary class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Object/MachOUniversal.h"
14 #include "llvm/Object/Archive.h"
15 #include "llvm/Object/MachO.h"
16 #include "llvm/Object/ObjectFile.h"
17 #include "llvm/Support/Casting.h"
18 #include "llvm/Support/Host.h"
19 #include "llvm/Support/MemoryBuffer.h"
20 
21 using namespace llvm;
22 using namespace object;
23 
24 static Error
25 malformedError(Twine Msg) {
26   std::string StringMsg = "truncated or malformed fat file (" + Msg.str() + ")";
27   return make_error<GenericBinaryError>(std::move(StringMsg),
28                                         object_error::parse_failed);
29 }
30 
31 template<typename T>
32 static T getUniversalBinaryStruct(const char *Ptr) {
33   T Res;
34   memcpy(&Res, Ptr, sizeof(T));
35   // Universal binary headers have big-endian byte order.
36   if (sys::IsLittleEndianHost)
37     swapStruct(Res);
38   return Res;
39 }
40 
41 MachOUniversalBinary::ObjectForArch::ObjectForArch(
42     const MachOUniversalBinary *Parent, uint32_t Index)
43     : Parent(Parent), Index(Index) {
44   // The iterators use Parent as a nullptr and an Index+1 == NumberOfObjects.
45   if (!Parent || Index >= Parent->getNumberOfObjects()) {
46     clear();
47   } else {
48     // Parse object header.
49     StringRef ParentData = Parent->getData();
50     if (Parent->getMagic() == MachO::FAT_MAGIC) {
51       const char *HeaderPos = ParentData.begin() + sizeof(MachO::fat_header) +
52                               Index * sizeof(MachO::fat_arch);
53       Header = getUniversalBinaryStruct<MachO::fat_arch>(HeaderPos);
54     } else { // Parent->getMagic() == MachO::FAT_MAGIC_64
55       const char *HeaderPos = ParentData.begin() + sizeof(MachO::fat_header) +
56                               Index * sizeof(MachO::fat_arch_64);
57       Header64 = getUniversalBinaryStruct<MachO::fat_arch_64>(HeaderPos);
58     }
59   }
60 }
61 
62 Expected<std::unique_ptr<MachOObjectFile>>
63 MachOUniversalBinary::ObjectForArch::getAsObjectFile() const {
64   if (!Parent)
65     report_fatal_error("MachOUniversalBinary::ObjectForArch::getAsObjectFile() "
66                        "called when Parent is a nullptr");
67 
68   StringRef ParentData = Parent->getData();
69   StringRef ObjectData;
70   uint32_t cputype;
71   if (Parent->getMagic() == MachO::FAT_MAGIC) {
72     ObjectData = ParentData.substr(Header.offset, Header.size);
73     cputype = Header.cputype;
74   } else { // Parent->getMagic() == MachO::FAT_MAGIC_64
75     ObjectData = ParentData.substr(Header64.offset, Header64.size);
76     cputype = Header64.cputype;
77   }
78   StringRef ObjectName = Parent->getFileName();
79   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
80   return ObjectFile::createMachOObjectFile(ObjBuffer, cputype, Index);
81 }
82 
83 Expected<std::unique_ptr<Archive>>
84 MachOUniversalBinary::ObjectForArch::getAsArchive() const {
85   if (!Parent)
86     report_fatal_error("MachOUniversalBinary::ObjectForArch::getAsArchive() "
87                        "called when Parent is a nullptr");
88 
89   StringRef ParentData = Parent->getData();
90   StringRef ObjectData;
91   if (Parent->getMagic() == MachO::FAT_MAGIC)
92     ObjectData = ParentData.substr(Header.offset, Header.size);
93   else // Parent->getMagic() == MachO::FAT_MAGIC_64
94     ObjectData = ParentData.substr(Header64.offset, Header64.size);
95   StringRef ObjectName = Parent->getFileName();
96   MemoryBufferRef ObjBuffer(ObjectData, ObjectName);
97   return Archive::create(ObjBuffer);
98 }
99 
100 void MachOUniversalBinary::anchor() { }
101 
102 Expected<std::unique_ptr<MachOUniversalBinary>>
103 MachOUniversalBinary::create(MemoryBufferRef Source) {
104   Error Err = Error::success();
105   std::unique_ptr<MachOUniversalBinary> Ret(
106       new MachOUniversalBinary(Source, Err));
107   if (Err)
108     return std::move(Err);
109   return std::move(Ret);
110 }
111 
112 MachOUniversalBinary::MachOUniversalBinary(MemoryBufferRef Source, Error &Err)
113     : Binary(Binary::ID_MachOUniversalBinary, Source), Magic(0),
114       NumberOfObjects(0) {
115   ErrorAsOutParameter ErrAsOutParam(&Err);
116   if (Data.getBufferSize() < sizeof(MachO::fat_header)) {
117     Err = make_error<GenericBinaryError>("File too small to be a Mach-O "
118                                          "universal file",
119                                          object_error::invalid_file_type);
120     return;
121   }
122   // Check for magic value and sufficient header size.
123   StringRef Buf = getData();
124   MachO::fat_header H =
125       getUniversalBinaryStruct<MachO::fat_header>(Buf.begin());
126   Magic = H.magic;
127   NumberOfObjects = H.nfat_arch;
128   if (NumberOfObjects == 0) {
129     Err = malformedError("contains zero architecture types");
130     return;
131   }
132   uint32_t MinSize = sizeof(MachO::fat_header);
133   if (Magic == MachO::FAT_MAGIC)
134     MinSize += sizeof(MachO::fat_arch) * NumberOfObjects;
135   else if (Magic == MachO::FAT_MAGIC_64)
136     MinSize += sizeof(MachO::fat_arch_64) * NumberOfObjects;
137   else {
138     Err = malformedError("bad magic number");
139     return;
140   }
141   if (Buf.size() < MinSize) {
142     Err = malformedError("fat_arch" +
143                          Twine(Magic == MachO::FAT_MAGIC ? "" : "_64") +
144                          " structs would extend past the end of the file");
145     return;
146   }
147   for (uint32_t i = 0; i < NumberOfObjects; i++) {
148     ObjectForArch A(this, i);
149     uint64_t bigSize = A.getOffset();
150     bigSize += A.getSize();
151     if (bigSize > Buf.size()) {
152       Err = malformedError("offset plus size of cputype (" +
153         Twine(A.getCPUType()) + ") cpusubtype (" +
154         Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
155         ") extends past the end of the file");
156       return;
157     }
158 
159     if (A.getAlign() > MaxSectionAlignment) {
160       Err = malformedError("align (2^" + Twine(A.getAlign()) +
161                            ") too large for cputype (" + Twine(A.getCPUType()) +
162                            ") cpusubtype (" +
163                            Twine(A.getCPUSubType() & ~MachO::CPU_SUBTYPE_MASK) +
164                            ") (maximum 2^" + Twine(MaxSectionAlignment) + ")");
165       return;
166     }
167     if(A.getOffset() % (1ull << 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<MachOUniversalBinary::ObjectForArch>
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   for (const auto &Obj : objects())
221     if (Obj.getArchFlagName() == ArchName)
222       return Obj;
223   return make_error<GenericBinaryError>("fat file does not "
224                                         "contain " +
225                                             ArchName,
226                                         object_error::arch_not_found);
227 }
228 
229 Expected<std::unique_ptr<MachOObjectFile>>
230 MachOUniversalBinary::getMachOObjectForArch(StringRef ArchName) const {
231   Expected<ObjectForArch> O = getObjectForArch(ArchName);
232   if (!O)
233     return O.takeError();
234   return O->getAsObjectFile();
235 }
236 
237 Expected<std::unique_ptr<Archive>>
238 MachOUniversalBinary::getArchiveForArch(StringRef ArchName) const {
239   Expected<ObjectForArch> O = getObjectForArch(ArchName);
240   if (!O)
241     return O.takeError();
242   return O->getAsArchive();
243 }
244