1 //===- MachOUniversalWriter.cpp - MachO universal binary writer---*- 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 // Defines the Slice class and writeUniversalBinary function for writing a MachO
10 // universal binary file.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Object/MachOUniversalWriter.h"
15 #include "llvm/ADT/Triple.h"
16 #include "llvm/Object/Archive.h"
17 #include "llvm/Object/Binary.h"
18 #include "llvm/Object/Error.h"
19 #include "llvm/Object/IRObjectFile.h"
20 #include "llvm/Object/MachO.h"
21 #include "llvm/Object/MachOUniversal.h"
22 #include "llvm/Support/SmallVectorMemoryBuffer.h"
23 
24 using namespace llvm;
25 using namespace object;
26 
27 // For compatibility with cctools lipo, a file's alignment is calculated as the
28 // minimum aligment of all segments. For object files, the file's alignment is
29 // the maximum alignment of its sections.
30 static uint32_t calculateFileAlignment(const MachOObjectFile &O) {
31   uint32_t P2CurrentAlignment;
32   uint32_t P2MinAlignment = MachOUniversalBinary::MaxSectionAlignment;
33   const bool Is64Bit = O.is64Bit();
34 
35   for (const auto &LC : O.load_commands()) {
36     if (LC.C.cmd != (Is64Bit ? MachO::LC_SEGMENT_64 : MachO::LC_SEGMENT))
37       continue;
38     if (O.getHeader().filetype == MachO::MH_OBJECT) {
39       unsigned NumberOfSections =
40           (Is64Bit ? O.getSegment64LoadCommand(LC).nsects
41                    : O.getSegmentLoadCommand(LC).nsects);
42       P2CurrentAlignment = NumberOfSections ? 2 : P2MinAlignment;
43       for (unsigned SI = 0; SI < NumberOfSections; ++SI) {
44         P2CurrentAlignment = std::max(P2CurrentAlignment,
45                                       (Is64Bit ? O.getSection64(LC, SI).align
46                                                : O.getSection(LC, SI).align));
47       }
48     } else {
49       P2CurrentAlignment =
50           countTrailingZeros(Is64Bit ? O.getSegment64LoadCommand(LC).vmaddr
51                                      : O.getSegmentLoadCommand(LC).vmaddr);
52     }
53     P2MinAlignment = std::min(P2MinAlignment, P2CurrentAlignment);
54   }
55   // return a value >= 4 byte aligned, and less than MachO MaxSectionAlignment
56   return std::max(
57       static_cast<uint32_t>(2),
58       std::min(P2MinAlignment, static_cast<uint32_t>(
59                                    MachOUniversalBinary::MaxSectionAlignment)));
60 }
61 
62 static uint32_t calculateAlignment(const MachOObjectFile &ObjectFile) {
63   switch (ObjectFile.getHeader().cputype) {
64   case MachO::CPU_TYPE_I386:
65   case MachO::CPU_TYPE_X86_64:
66   case MachO::CPU_TYPE_POWERPC:
67   case MachO::CPU_TYPE_POWERPC64:
68     return 12; // log2 value of page size(4k) for x86 and PPC
69   case MachO::CPU_TYPE_ARM:
70   case MachO::CPU_TYPE_ARM64:
71   case MachO::CPU_TYPE_ARM64_32:
72     return 14; // log2 value of page size(16k) for Darwin ARM
73   default:
74     return calculateFileAlignment(ObjectFile);
75   }
76 }
77 
78 Slice::Slice(const Archive &A, uint32_t CPUType, uint32_t CPUSubType,
79              std::string ArchName, uint32_t Align)
80     : B(&A), CPUType(CPUType), CPUSubType(CPUSubType),
81       ArchName(std::move(ArchName)), P2Alignment(Align) {}
82 
83 Slice::Slice(const MachOObjectFile &O, uint32_t Align)
84     : B(&O), CPUType(O.getHeader().cputype),
85       CPUSubType(O.getHeader().cpusubtype),
86       ArchName(std::string(O.getArchTriple().getArchName())),
87       P2Alignment(Align) {}
88 
89 Slice::Slice(const IRObjectFile &IRO, uint32_t CPUType, uint32_t CPUSubType,
90              std::string ArchName, uint32_t Align)
91     : B(&IRO), CPUType(CPUType), CPUSubType(CPUSubType),
92       ArchName(std::move(ArchName)), P2Alignment(Align) {}
93 
94 Slice::Slice(const MachOObjectFile &O) : Slice(O, calculateAlignment(O)) {}
95 
96 using MachoCPUTy = std::pair<unsigned, unsigned>;
97 
98 static Expected<MachoCPUTy> getMachoCPUFromTriple(Triple TT) {
99   auto CPU = std::make_pair(MachO::getCPUType(TT), MachO::getCPUSubType(TT));
100   if (!CPU.first) {
101     return CPU.first.takeError();
102   }
103   if (!CPU.second) {
104     return CPU.second.takeError();
105   }
106   return std::make_pair(*CPU.first, *CPU.second);
107 }
108 
109 static Expected<MachoCPUTy> getMachoCPUFromTriple(StringRef TT) {
110   return getMachoCPUFromTriple(Triple{TT});
111 }
112 
113 Expected<Slice> Slice::create(const Archive &A, LLVMContext *LLVMCtx) {
114   Error Err = Error::success();
115   std::unique_ptr<MachOObjectFile> MFO = nullptr;
116   std::unique_ptr<IRObjectFile> IRFO = nullptr;
117   for (const Archive::Child &Child : A.children(Err)) {
118     Expected<std::unique_ptr<Binary>> ChildOrErr = Child.getAsBinary(LLVMCtx);
119     if (!ChildOrErr)
120       return createFileError(A.getFileName(), ChildOrErr.takeError());
121     Binary *Bin = ChildOrErr.get().get();
122     if (Bin->isMachOUniversalBinary())
123       return createStringError(std::errc::invalid_argument,
124                                ("archive member " + Bin->getFileName() +
125                                 " is a fat file (not allowed in an archive)")
126                                    .str()
127                                    .c_str());
128     if (Bin->isMachO()) {
129       MachOObjectFile *O = cast<MachOObjectFile>(Bin);
130       if (IRFO) {
131         return createStringError(
132             std::errc::invalid_argument,
133             "archive member %s is a MachO, while previous archive member "
134             "%s was an IR LLVM object",
135             O->getFileName().str().c_str(), IRFO->getFileName().str().c_str());
136       }
137       if (MFO &&
138           std::tie(MFO->getHeader().cputype, MFO->getHeader().cpusubtype) !=
139               std::tie(O->getHeader().cputype, O->getHeader().cpusubtype)) {
140         return createStringError(
141             std::errc::invalid_argument,
142             ("archive member " + O->getFileName() + " cputype (" +
143              Twine(O->getHeader().cputype) + ") and cpusubtype(" +
144              Twine(O->getHeader().cpusubtype) +
145              ") does not match previous archive members cputype (" +
146              Twine(MFO->getHeader().cputype) + ") and cpusubtype(" +
147              Twine(MFO->getHeader().cpusubtype) +
148              ") (all members must match) " + MFO->getFileName())
149                 .str()
150                 .c_str());
151       }
152       if (!MFO) {
153         ChildOrErr.get().release();
154         MFO.reset(O);
155       }
156     } else if (Bin->isIR()) {
157       IRObjectFile *O = cast<IRObjectFile>(Bin);
158       if (MFO) {
159         return createStringError(std::errc::invalid_argument,
160                                  "archive member '%s' is an LLVM IR object, "
161                                  "while previous archive member "
162                                  "'%s' was a MachO",
163                                  O->getFileName().str().c_str(),
164                                  MFO->getFileName().str().c_str());
165       }
166       if (IRFO) {
167         Expected<MachoCPUTy> CPUO = getMachoCPUFromTriple(O->getTargetTriple());
168         Expected<MachoCPUTy> CPUFO =
169             getMachoCPUFromTriple(IRFO->getTargetTriple());
170         if (!CPUO)
171           return CPUO.takeError();
172         if (!CPUFO)
173           return CPUFO.takeError();
174         if (*CPUO != *CPUFO) {
175           return createStringError(
176               std::errc::invalid_argument,
177               ("archive member " + O->getFileName() + " cputype (" +
178                Twine(CPUO->first) + ") and cpusubtype(" + Twine(CPUO->second) +
179                ") does not match previous archive members cputype (" +
180                Twine(CPUFO->first) + ") and cpusubtype(" +
181                Twine(CPUFO->second) + ") (all members must match) " +
182                IRFO->getFileName())
183                   .str()
184                   .c_str());
185         }
186       } else {
187         ChildOrErr.get().release();
188         IRFO.reset(O);
189       }
190     } else
191       return createStringError(std::errc::invalid_argument,
192                                ("archive member " + Bin->getFileName() +
193                                 " is neither a MachO file or an LLVM IR file "
194                                 "(not allowed in an archive)")
195                                    .str()
196                                    .c_str());
197   }
198   if (Err)
199     return createFileError(A.getFileName(), std::move(Err));
200   if (!MFO && !IRFO)
201     return createStringError(
202         std::errc::invalid_argument,
203         ("empty archive with no architecture specification: " +
204          A.getFileName() + " (can't determine architecture for it)")
205             .str()
206             .c_str());
207 
208   if (MFO) {
209     Slice ArchiveSlice(*(MFO.get()), MFO->is64Bit() ? 3 : 2);
210     ArchiveSlice.B = &A;
211     return ArchiveSlice;
212   }
213 
214   // For IR objects
215   Expected<Slice> ArchiveSliceOrErr = Slice::create(*IRFO, 0);
216   if (!ArchiveSliceOrErr)
217     return createFileError(A.getFileName(), ArchiveSliceOrErr.takeError());
218   auto &ArchiveSlice = ArchiveSliceOrErr.get();
219   ArchiveSlice.B = &A;
220   return std::move(ArchiveSlice);
221 }
222 
223 Expected<Slice> Slice::create(const IRObjectFile &IRO, uint32_t Align) {
224   Expected<MachoCPUTy> CPUOrErr = getMachoCPUFromTriple(IRO.getTargetTriple());
225   if (!CPUOrErr)
226     return CPUOrErr.takeError();
227   unsigned CPUType, CPUSubType;
228   std::tie(CPUType, CPUSubType) = CPUOrErr.get();
229   // We don't directly use the architecture name of the target triple T, as,
230   // for instance, thumb is treated as ARM by the MachOUniversal object.
231   std::string ArchName(
232       MachOObjectFile::getArchTriple(CPUType, CPUSubType).getArchName());
233   return Slice{IRO, CPUType, CPUSubType, std::move(ArchName), Align};
234 }
235 
236 static Expected<SmallVector<MachO::fat_arch, 2>>
237 buildFatArchList(ArrayRef<Slice> Slices) {
238   SmallVector<MachO::fat_arch, 2> FatArchList;
239   uint64_t Offset =
240       sizeof(MachO::fat_header) + Slices.size() * sizeof(MachO::fat_arch);
241 
242   for (const auto &S : Slices) {
243     Offset = alignTo(Offset, 1ull << S.getP2Alignment());
244     if (Offset > UINT32_MAX)
245       return createStringError(
246           std::errc::invalid_argument,
247           ("fat file too large to be created because the offset "
248            "field in struct fat_arch is only 32-bits and the offset " +
249            Twine(Offset) + " for " + S.getBinary()->getFileName() +
250            " for architecture " + S.getArchString() + "exceeds that.")
251               .str()
252               .c_str());
253 
254     MachO::fat_arch FatArch;
255     FatArch.cputype = S.getCPUType();
256     FatArch.cpusubtype = S.getCPUSubType();
257     FatArch.offset = Offset;
258     FatArch.size = S.getBinary()->getMemoryBufferRef().getBufferSize();
259     FatArch.align = S.getP2Alignment();
260     Offset += FatArch.size;
261     FatArchList.push_back(FatArch);
262   }
263   return FatArchList;
264 }
265 
266 static Error writeUniversalBinaryToStream(ArrayRef<Slice> Slices,
267                                           raw_ostream &Out) {
268   MachO::fat_header FatHeader;
269   FatHeader.magic = MachO::FAT_MAGIC;
270   FatHeader.nfat_arch = Slices.size();
271 
272   Expected<SmallVector<MachO::fat_arch, 2>> FatArchListOrErr =
273       buildFatArchList(Slices);
274   if (!FatArchListOrErr)
275     return FatArchListOrErr.takeError();
276   SmallVector<MachO::fat_arch, 2> FatArchList = *FatArchListOrErr;
277 
278   if (sys::IsLittleEndianHost)
279     MachO::swapStruct(FatHeader);
280   Out.write(reinterpret_cast<const char *>(&FatHeader),
281             sizeof(MachO::fat_header));
282 
283   if (sys::IsLittleEndianHost)
284     for (MachO::fat_arch &FA : FatArchList)
285       MachO::swapStruct(FA);
286   Out.write(reinterpret_cast<const char *>(FatArchList.data()),
287             sizeof(MachO::fat_arch) * FatArchList.size());
288 
289   if (sys::IsLittleEndianHost)
290     for (MachO::fat_arch &FA : FatArchList)
291       MachO::swapStruct(FA);
292 
293   size_t Offset =
294       sizeof(MachO::fat_header) + sizeof(MachO::fat_arch) * FatArchList.size();
295   for (size_t Index = 0, Size = Slices.size(); Index < Size; ++Index) {
296     MemoryBufferRef BufferRef = Slices[Index].getBinary()->getMemoryBufferRef();
297     assert((Offset <= FatArchList[Index].offset) && "Incorrect slice offset");
298     Out.write_zeros(FatArchList[Index].offset - Offset);
299     Out.write(BufferRef.getBufferStart(), BufferRef.getBufferSize());
300     Offset = FatArchList[Index].offset + BufferRef.getBufferSize();
301   }
302 
303   Out.flush();
304   return Error::success();
305 }
306 
307 Error object::writeUniversalBinary(ArrayRef<Slice> Slices,
308                                    StringRef OutputFileName) {
309   const bool IsExecutable = any_of(Slices, [](Slice S) {
310     return sys::fs::can_execute(S.getBinary()->getFileName());
311   });
312   unsigned Mode = sys::fs::all_read | sys::fs::all_write;
313   if (IsExecutable)
314     Mode |= sys::fs::all_exe;
315   Expected<sys::fs::TempFile> Temp = sys::fs::TempFile::create(
316       OutputFileName + ".temp-universal-%%%%%%", Mode);
317   if (!Temp)
318     return Temp.takeError();
319   raw_fd_ostream Out(Temp->FD, false);
320   if (Error E = writeUniversalBinaryToStream(Slices, Out)) {
321     if (Error DiscardError = Temp->discard())
322       return joinErrors(std::move(E), std::move(DiscardError));
323     return E;
324   }
325   return Temp->keep(OutputFileName);
326 }
327 
328 Expected<std::unique_ptr<MemoryBuffer>>
329 object::writeUniversalBinaryToBuffer(ArrayRef<Slice> Slices) {
330   SmallVector<char, 0> Buffer;
331   raw_svector_ostream Out(Buffer);
332 
333   if (Error E = writeUniversalBinaryToStream(Slices, Out))
334     return std::move(E);
335 
336   return std::make_unique<SmallVectorMemoryBuffer>(std::move(Buffer));
337 }
338