1 //===- ArchiveWriter.cpp - ar File Format implementation --------*- 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 writeArchive function.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Object/ArchiveWriter.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/IR/LLVMContext.h"
18 #include "llvm/Object/Archive.h"
19 #include "llvm/Object/ObjectFile.h"
20 #include "llvm/Object/SymbolicFile.h"
21 #include "llvm/Support/EndianStream.h"
22 #include "llvm/Support/Errc.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/Format.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/ToolOutputFile.h"
27 #include "llvm/Support/raw_ostream.h"
28 
29 #if !defined(_MSC_VER) && !defined(__MINGW32__)
30 #include <unistd.h>
31 #else
32 #include <io.h>
33 #endif
34 
35 using namespace llvm;
36 
37 NewArchiveMember::NewArchiveMember(MemoryBufferRef BufRef)
38     : Buf(MemoryBuffer::getMemBuffer(BufRef, false)) {}
39 
40 Expected<NewArchiveMember>
41 NewArchiveMember::getOldMember(const object::Archive::Child &OldMember,
42                                bool Deterministic) {
43   Expected<llvm::MemoryBufferRef> BufOrErr = OldMember.getMemoryBufferRef();
44   if (!BufOrErr)
45     return BufOrErr.takeError();
46 
47   NewArchiveMember M;
48   M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
49   if (!Deterministic) {
50     Expected<sys::TimeValue> ModTimeOrErr = OldMember.getLastModified();
51     if (!ModTimeOrErr)
52       return ModTimeOrErr.takeError();
53     M.ModTime = ModTimeOrErr.get();
54     Expected<unsigned> UIDOrErr = OldMember.getUID();
55     if (!UIDOrErr)
56       return UIDOrErr.takeError();
57     M.UID = UIDOrErr.get();
58     Expected<unsigned> GIDOrErr = OldMember.getGID();
59     if (!GIDOrErr)
60       return GIDOrErr.takeError();
61     M.GID = GIDOrErr.get();
62     Expected<sys::fs::perms> AccessModeOrErr = OldMember.getAccessMode();
63     if (!AccessModeOrErr)
64       return AccessModeOrErr.takeError();
65     M.Perms = AccessModeOrErr.get();
66   }
67   return std::move(M);
68 }
69 
70 Expected<NewArchiveMember> NewArchiveMember::getFile(StringRef FileName,
71                                                      bool Deterministic) {
72   sys::fs::file_status Status;
73   int FD;
74   if (auto EC = sys::fs::openFileForRead(FileName, FD))
75     return errorCodeToError(EC);
76   assert(FD != -1);
77 
78   if (auto EC = sys::fs::status(FD, Status))
79     return errorCodeToError(EC);
80 
81   // Opening a directory doesn't make sense. Let it fail.
82   // Linux cannot open directories with open(2), although
83   // cygwin and *bsd can.
84   if (Status.type() == sys::fs::file_type::directory_file)
85     return errorCodeToError(make_error_code(errc::is_a_directory));
86 
87   ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
88       MemoryBuffer::getOpenFile(FD, FileName, Status.getSize(), false);
89   if (!MemberBufferOrErr)
90     return errorCodeToError(MemberBufferOrErr.getError());
91 
92   if (close(FD) != 0)
93     return errorCodeToError(std::error_code(errno, std::generic_category()));
94 
95   NewArchiveMember M;
96   M.Buf = std::move(*MemberBufferOrErr);
97   if (!Deterministic) {
98     M.ModTime = Status.getLastModificationTime();
99     M.UID = Status.getUser();
100     M.GID = Status.getGroup();
101     M.Perms = Status.permissions();
102   }
103   return std::move(M);
104 }
105 
106 template <typename T>
107 static void printWithSpacePadding(raw_fd_ostream &OS, T Data, unsigned Size,
108                                   bool MayTruncate = false) {
109   uint64_t OldPos = OS.tell();
110   OS << Data;
111   unsigned SizeSoFar = OS.tell() - OldPos;
112   if (Size > SizeSoFar) {
113     OS.indent(Size - SizeSoFar);
114   } else if (Size < SizeSoFar) {
115     assert(MayTruncate && "Data doesn't fit in Size");
116     // Some of the data this is used for (like UID) can be larger than the
117     // space available in the archive format. Truncate in that case.
118     OS.seek(OldPos + Size);
119   }
120 }
121 
122 static void print32(raw_ostream &Out, object::Archive::Kind Kind,
123                     uint32_t Val) {
124   if (Kind == object::Archive::K_GNU)
125     support::endian::Writer<support::big>(Out).write(Val);
126   else
127     support::endian::Writer<support::little>(Out).write(Val);
128 }
129 
130 static void printRestOfMemberHeader(raw_fd_ostream &Out,
131                                     const sys::TimeValue &ModTime, unsigned UID,
132                                     unsigned GID, unsigned Perms,
133                                     unsigned Size) {
134   printWithSpacePadding(Out, ModTime.toEpochTime(), 12);
135   printWithSpacePadding(Out, UID, 6, true);
136   printWithSpacePadding(Out, GID, 6, true);
137   printWithSpacePadding(Out, format("%o", Perms), 8);
138   printWithSpacePadding(Out, Size, 10);
139   Out << "`\n";
140 }
141 
142 static void printGNUSmallMemberHeader(raw_fd_ostream &Out, StringRef Name,
143                                       const sys::TimeValue &ModTime,
144                                       unsigned UID, unsigned GID,
145                                       unsigned Perms, unsigned Size) {
146   printWithSpacePadding(Out, Twine(Name) + "/", 16);
147   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
148 }
149 
150 static void printBSDMemberHeader(raw_fd_ostream &Out, StringRef Name,
151                                  const sys::TimeValue &ModTime, unsigned UID,
152                                  unsigned GID, unsigned Perms, unsigned Size) {
153   uint64_t PosAfterHeader = Out.tell() + 60 + Name.size();
154   // Pad so that even 64 bit object files are aligned.
155   unsigned Pad = OffsetToAlignment(PosAfterHeader, 8);
156   unsigned NameWithPadding = Name.size() + Pad;
157   printWithSpacePadding(Out, Twine("#1/") + Twine(NameWithPadding), 16);
158   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms,
159                           NameWithPadding + Size);
160   Out << Name;
161   assert(PosAfterHeader == Out.tell());
162   while (Pad--)
163     Out.write(uint8_t(0));
164 }
165 
166 static bool useStringTable(bool Thin, StringRef Name) {
167   return Thin || Name.size() >= 16;
168 }
169 
170 static void
171 printMemberHeader(raw_fd_ostream &Out, object::Archive::Kind Kind, bool Thin,
172                   StringRef Name,
173                   std::vector<unsigned>::iterator &StringMapIndexIter,
174                   const sys::TimeValue &ModTime, unsigned UID, unsigned GID,
175                   unsigned Perms, unsigned Size) {
176   if (Kind == object::Archive::K_BSD)
177     return printBSDMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
178   if (!useStringTable(Thin, Name))
179     return printGNUSmallMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
180   Out << '/';
181   printWithSpacePadding(Out, *StringMapIndexIter++, 15);
182   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
183 }
184 
185 // Compute the relative path from From to To.
186 static std::string computeRelativePath(StringRef From, StringRef To) {
187   if (sys::path::is_absolute(From) || sys::path::is_absolute(To))
188     return To;
189 
190   StringRef DirFrom = sys::path::parent_path(From);
191   auto FromI = sys::path::begin(DirFrom);
192   auto ToI = sys::path::begin(To);
193   while (*FromI == *ToI) {
194     ++FromI;
195     ++ToI;
196   }
197 
198   SmallString<128> Relative;
199   for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI)
200     sys::path::append(Relative, "..");
201 
202   for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI)
203     sys::path::append(Relative, *ToI);
204 
205   return Relative.str();
206 }
207 
208 static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
209                              ArrayRef<NewArchiveMember> Members,
210                              std::vector<unsigned> &StringMapIndexes,
211                              bool Thin) {
212   unsigned StartOffset = 0;
213   for (const NewArchiveMember &M : Members) {
214     StringRef Path = M.Buf->getBufferIdentifier();
215     StringRef Name = sys::path::filename(Path);
216     if (!useStringTable(Thin, Name))
217       continue;
218     if (StartOffset == 0) {
219       printWithSpacePadding(Out, "//", 58);
220       Out << "`\n";
221       StartOffset = Out.tell();
222     }
223     StringMapIndexes.push_back(Out.tell() - StartOffset);
224 
225     if (Thin)
226       Out << computeRelativePath(ArcName, Path);
227     else
228       Out << Name;
229 
230     Out << "/\n";
231   }
232   if (StartOffset == 0)
233     return;
234   if (Out.tell() % 2)
235     Out << '\n';
236   int Pos = Out.tell();
237   Out.seek(StartOffset - 12);
238   printWithSpacePadding(Out, Pos - StartOffset, 10);
239   Out.seek(Pos);
240 }
241 
242 static sys::TimeValue now(bool Deterministic) {
243   if (!Deterministic)
244     return sys::TimeValue::now();
245   sys::TimeValue TV;
246   TV.fromEpochTime(0);
247   return TV;
248 }
249 
250 // Returns the offset of the first reference to a member offset.
251 static ErrorOr<unsigned>
252 writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
253                  ArrayRef<NewArchiveMember> Members,
254                  std::vector<unsigned> &MemberOffsetRefs, bool Deterministic) {
255   unsigned HeaderStartOffset = 0;
256   unsigned BodyStartOffset = 0;
257   SmallString<128> NameBuf;
258   raw_svector_ostream NameOS(NameBuf);
259   LLVMContext Context;
260   for (unsigned MemberNum = 0, N = Members.size(); MemberNum < N; ++MemberNum) {
261     MemoryBufferRef MemberBuffer = Members[MemberNum].Buf->getMemBufferRef();
262     Expected<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
263         object::SymbolicFile::createSymbolicFile(
264             MemberBuffer, sys::fs::file_magic::unknown, &Context);
265     if (!ObjOrErr) {
266       // FIXME: check only for "not an object file" errors.
267       consumeError(ObjOrErr.takeError());
268       continue;
269     }
270     object::SymbolicFile &Obj = *ObjOrErr.get();
271 
272     if (!HeaderStartOffset) {
273       HeaderStartOffset = Out.tell();
274       if (Kind == object::Archive::K_GNU)
275         printGNUSmallMemberHeader(Out, "", now(Deterministic), 0, 0, 0, 0);
276       else
277         printBSDMemberHeader(Out, "__.SYMDEF", now(Deterministic), 0, 0, 0, 0);
278       BodyStartOffset = Out.tell();
279       print32(Out, Kind, 0); // number of entries or bytes
280     }
281 
282     for (const object::BasicSymbolRef &S : Obj.symbols()) {
283       uint32_t Symflags = S.getFlags();
284       if (Symflags & object::SymbolRef::SF_FormatSpecific)
285         continue;
286       if (!(Symflags & object::SymbolRef::SF_Global))
287         continue;
288       if (Symflags & object::SymbolRef::SF_Undefined)
289         continue;
290 
291       unsigned NameOffset = NameOS.tell();
292       if (auto EC = S.printName(NameOS))
293         return EC;
294       NameOS << '\0';
295       MemberOffsetRefs.push_back(MemberNum);
296       if (Kind == object::Archive::K_BSD)
297         print32(Out, Kind, NameOffset);
298       print32(Out, Kind, 0); // member offset
299     }
300   }
301 
302   if (HeaderStartOffset == 0)
303     return 0;
304 
305   StringRef StringTable = NameOS.str();
306   if (Kind == object::Archive::K_BSD)
307     print32(Out, Kind, StringTable.size()); // byte count of the string table
308   Out << StringTable;
309 
310   // ld64 requires the next member header to start at an offset that is
311   // 4 bytes aligned.
312   unsigned Pad = OffsetToAlignment(Out.tell(), 4);
313   while (Pad--)
314     Out.write(uint8_t(0));
315 
316   // Patch up the size of the symbol table now that we know how big it is.
317   unsigned Pos = Out.tell();
318   const unsigned MemberHeaderSize = 60;
319   Out.seek(HeaderStartOffset + 48); // offset of the size field.
320   printWithSpacePadding(Out, Pos - MemberHeaderSize - HeaderStartOffset, 10);
321 
322   // Patch up the number of symbols.
323   Out.seek(BodyStartOffset);
324   unsigned NumSyms = MemberOffsetRefs.size();
325   if (Kind == object::Archive::K_GNU)
326     print32(Out, Kind, NumSyms);
327   else
328     print32(Out, Kind, NumSyms * 8);
329 
330   Out.seek(Pos);
331   return BodyStartOffset + 4;
332 }
333 
334 std::pair<StringRef, std::error_code>
335 llvm::writeArchive(StringRef ArcName,
336                    std::vector<NewArchiveMember> &NewMembers,
337                    bool WriteSymtab, object::Archive::Kind Kind,
338                    bool Deterministic, bool Thin,
339                    std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
340   assert((!Thin || Kind == object::Archive::K_GNU) &&
341          "Only the gnu format has a thin mode");
342   SmallString<128> TmpArchive;
343   int TmpArchiveFD;
344   if (auto EC = sys::fs::createUniqueFile(ArcName + ".temp-archive-%%%%%%%.a",
345                                           TmpArchiveFD, TmpArchive))
346     return std::make_pair(ArcName, EC);
347 
348   tool_output_file Output(TmpArchive, TmpArchiveFD);
349   raw_fd_ostream &Out = Output.os();
350   if (Thin)
351     Out << "!<thin>\n";
352   else
353     Out << "!<arch>\n";
354 
355   std::vector<unsigned> MemberOffsetRefs;
356 
357   std::vector<std::unique_ptr<MemoryBuffer>> Buffers;
358   std::vector<MemoryBufferRef> Members;
359   std::vector<sys::fs::file_status> NewMemberStatus;
360 
361   unsigned MemberReferenceOffset = 0;
362   if (WriteSymtab) {
363     ErrorOr<unsigned> MemberReferenceOffsetOrErr = writeSymbolTable(
364         Out, Kind, NewMembers, MemberOffsetRefs, Deterministic);
365     if (auto EC = MemberReferenceOffsetOrErr.getError())
366       return std::make_pair(ArcName, EC);
367     MemberReferenceOffset = MemberReferenceOffsetOrErr.get();
368   }
369 
370   std::vector<unsigned> StringMapIndexes;
371   if (Kind != object::Archive::K_BSD)
372     writeStringTable(Out, ArcName, NewMembers, StringMapIndexes, Thin);
373 
374   std::vector<unsigned>::iterator StringMapIndexIter = StringMapIndexes.begin();
375   std::vector<unsigned> MemberOffset;
376   for (const NewArchiveMember &M : NewMembers) {
377     MemoryBufferRef File = M.Buf->getMemBufferRef();
378 
379     unsigned Pos = Out.tell();
380     MemberOffset.push_back(Pos);
381 
382     printMemberHeader(Out, Kind, Thin,
383                       sys::path::filename(M.Buf->getBufferIdentifier()),
384                       StringMapIndexIter, M.ModTime, M.UID, M.GID, M.Perms,
385                       M.Buf->getBufferSize());
386 
387     if (!Thin)
388       Out << File.getBuffer();
389 
390     if (Out.tell() % 2)
391       Out << '\n';
392   }
393 
394   if (MemberReferenceOffset) {
395     Out.seek(MemberReferenceOffset);
396     for (unsigned MemberNum : MemberOffsetRefs) {
397       if (Kind == object::Archive::K_BSD)
398         Out.seek(Out.tell() + 4); // skip over the string offset
399       print32(Out, Kind, MemberOffset[MemberNum]);
400     }
401   }
402 
403   Output.keep();
404   Out.close();
405 
406   // At this point, we no longer need whatever backing memory
407   // was used to generate the NewMembers. On Windows, this buffer
408   // could be a mapped view of the file we want to replace (if
409   // we're updating an existing archive, say). In that case, the
410   // rename would still succeed, but it would leave behind a
411   // temporary file (actually the original file renamed) because
412   // a file cannot be deleted while there's a handle open on it,
413   // only renamed. So by freeing this buffer, this ensures that
414   // the last open handle on the destination file, if any, is
415   // closed before we attempt to rename.
416   OldArchiveBuf.reset();
417 
418   sys::fs::rename(TmpArchive, ArcName);
419   return std::make_pair("", std::error_code());
420 }
421