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llvm-mirror/lib/Object/ArchiveWriter.cpp
Rafael Espindola 282d12d41c llvm-ar: Pad the symbol table to 4 bytes. 
It looks like ld64 requires it. With this we seem to be able to bootstrap using
llvm-ar+/usr/bin/true instead of ar+ranlib (currently on stage2).

llvm-svn: 241842
2015-07-09 19:48:06 +00:00

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//===- ArchiveWriter.cpp - ar File Format implementation --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the writeArchive function.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/ArchiveWriter.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Object/Archive.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Object/SymbolicFile.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/raw_ostream.h"
#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#else
#include <io.h>
#endif
using namespace llvm;
NewArchiveIterator::NewArchiveIterator(object::Archive::child_iterator I,
StringRef Name)
: IsNewMember(false), Name(Name), OldI(I) {}
NewArchiveIterator::NewArchiveIterator(StringRef NewFilename, StringRef Name)
: IsNewMember(true), Name(Name), NewFilename(NewFilename) {}
StringRef NewArchiveIterator::getName() const { return Name; }
bool NewArchiveIterator::isNewMember() const { return IsNewMember; }
object::Archive::child_iterator NewArchiveIterator::getOld() const {
assert(!IsNewMember);
return OldI;
}
StringRef NewArchiveIterator::getNew() const {
assert(IsNewMember);
return NewFilename;
}
llvm::ErrorOr<int>
NewArchiveIterator::getFD(sys::fs::file_status &NewStatus) const {
assert(IsNewMember);
int NewFD;
if (auto EC = sys::fs::openFileForRead(NewFilename, NewFD))
return EC;
assert(NewFD != -1);
if (auto EC = sys::fs::status(NewFD, NewStatus))
return EC;
// Opening a directory doesn't make sense. Let it fail.
// Linux cannot open directories with open(2), although
// cygwin and *bsd can.
if (NewStatus.type() == sys::fs::file_type::directory_file)
return make_error_code(errc::is_a_directory);
return NewFD;
}
template <typename T>
static void printWithSpacePadding(raw_fd_ostream &OS, T Data, unsigned Size,
bool MayTruncate = false) {
uint64_t OldPos = OS.tell();
OS << Data;
unsigned SizeSoFar = OS.tell() - OldPos;
if (Size > SizeSoFar) {
OS.indent(Size - SizeSoFar);
} else if (Size < SizeSoFar) {
assert(MayTruncate && "Data doesn't fit in Size");
// Some of the data this is used for (like UID) can be larger than the
// space available in the archive format. Truncate in that case.
OS.seek(OldPos + Size);
}
}
static void print32(raw_ostream &Out, object::Archive::Kind Kind,
uint32_t Val) {
if (Kind == object::Archive::K_GNU)
support::endian::Writer<support::big>(Out).write(Val);
else
support::endian::Writer<support::little>(Out).write(Val);
}
static void printRestOfMemberHeader(raw_fd_ostream &Out,
const sys::TimeValue &ModTime, unsigned UID,
unsigned GID, unsigned Perms,
unsigned Size) {
printWithSpacePadding(Out, ModTime.toEpochTime(), 12);
printWithSpacePadding(Out, UID, 6, true);
printWithSpacePadding(Out, GID, 6, true);
printWithSpacePadding(Out, format("%o", Perms), 8);
printWithSpacePadding(Out, Size, 10);
Out << "`\n";
}
static void printGNUSmallMemberHeader(raw_fd_ostream &Out, StringRef Name,
const sys::TimeValue &ModTime,
unsigned UID, unsigned GID,
unsigned Perms, unsigned Size) {
printWithSpacePadding(Out, Twine(Name) + "/", 16);
printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
}
static void printBSDMemberHeader(raw_fd_ostream &Out, StringRef Name,
const sys::TimeValue &ModTime, unsigned UID,
unsigned GID, unsigned Perms, unsigned Size) {
uint64_t PosAfterHeader = Out.tell() + 60 + Name.size();
// Pad so that even 64 bit object files are aligned.
unsigned Pad = OffsetToAlignment(PosAfterHeader, 8);
unsigned NameWithPadding = Name.size() + Pad;
printWithSpacePadding(Out, Twine("#1/") + Twine(NameWithPadding), 16);
printRestOfMemberHeader(Out, ModTime, UID, GID, Perms,
NameWithPadding + Size);
Out << Name;
assert(PosAfterHeader == Out.tell());
while (Pad--)
Out.write(uint8_t(0));
}
static void
printMemberHeader(raw_fd_ostream &Out, object::Archive::Kind Kind,
StringRef Name,
std::vector<unsigned>::iterator &StringMapIndexIter,
const sys::TimeValue &ModTime, unsigned UID, unsigned GID,
unsigned Perms, unsigned Size) {
if (Kind == object::Archive::K_BSD)
return printBSDMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
if (Name.size() < 16)
return printGNUSmallMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
Out << '/';
printWithSpacePadding(Out, *StringMapIndexIter++, 15);
printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
}
static void writeStringTable(raw_fd_ostream &Out,
ArrayRef<NewArchiveIterator> Members,
std::vector<unsigned> &StringMapIndexes) {
unsigned StartOffset = 0;
for (ArrayRef<NewArchiveIterator>::iterator I = Members.begin(),
E = Members.end();
I != E; ++I) {
StringRef Name = I->getName();
if (Name.size() < 16)
continue;
if (StartOffset == 0) {
printWithSpacePadding(Out, "//", 58);
Out << "`\n";
StartOffset = Out.tell();
}
StringMapIndexes.push_back(Out.tell() - StartOffset);
Out << Name << "/\n";
}
if (StartOffset == 0)
return;
if (Out.tell() % 2)
Out << '\n';
int Pos = Out.tell();
Out.seek(StartOffset - 12);
printWithSpacePadding(Out, Pos - StartOffset, 10);
Out.seek(Pos);
}
// Returns the offset of the first reference to a member offset.
static ErrorOr<unsigned>
writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
ArrayRef<NewArchiveIterator> Members,
ArrayRef<MemoryBufferRef> Buffers,
std::vector<unsigned> &MemberOffsetRefs) {
unsigned HeaderStartOffset = 0;
unsigned BodyStartOffset = 0;
SmallString<128> NameBuf;
raw_svector_ostream NameOS(NameBuf);
LLVMContext Context;
for (unsigned MemberNum = 0, N = Members.size(); MemberNum < N; ++MemberNum) {
MemoryBufferRef MemberBuffer = Buffers[MemberNum];
ErrorOr<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
object::SymbolicFile::createSymbolicFile(
MemberBuffer, sys::fs::file_magic::unknown, &Context);
if (!ObjOrErr)
continue; // FIXME: check only for "not an object file" errors.
object::SymbolicFile &Obj = *ObjOrErr.get();
if (!HeaderStartOffset) {
HeaderStartOffset = Out.tell();
if (Kind == object::Archive::K_GNU)
printGNUSmallMemberHeader(Out, "", sys::TimeValue::now(), 0, 0, 0, 0);
else
printBSDMemberHeader(Out, "__.SYMDEF", sys::TimeValue::now(), 0, 0, 0,
0);
BodyStartOffset = Out.tell();
print32(Out, Kind, 0); // number of entries or bytes
}
for (const object::BasicSymbolRef &S : Obj.symbols()) {
uint32_t Symflags = S.getFlags();
if (Symflags & object::SymbolRef::SF_FormatSpecific)
continue;
if (!(Symflags & object::SymbolRef::SF_Global))
continue;
if (Symflags & object::SymbolRef::SF_Undefined)
continue;
unsigned NameOffset = NameOS.tell();
if (auto EC = S.printName(NameOS))
return EC;
NameOS << '\0';
MemberOffsetRefs.push_back(MemberNum);
if (Kind == object::Archive::K_BSD)
print32(Out, Kind, NameOffset);
print32(Out, Kind, 0); // member offset
}
}
if (HeaderStartOffset == 0)
return 0;
StringRef StringTable = NameOS.str();
if (Kind == object::Archive::K_BSD)
print32(Out, Kind, StringTable.size()); // byte count of the string table
Out << StringTable;
// ld64 requires the next member header to start at an offset that is
// 4 bytes aligned.
unsigned Pad = OffsetToAlignment(Out.tell(), 4);
while (Pad--)
Out.write(uint8_t(0));
// Patch up the size of the symbol table now that we know how big it is.
unsigned Pos = Out.tell();
const unsigned MemberHeaderSize = 60;
Out.seek(HeaderStartOffset + 48); // offset of the size field.
printWithSpacePadding(Out, Pos - MemberHeaderSize - HeaderStartOffset, 10);
// Patch up the number of symbols.
Out.seek(BodyStartOffset);
unsigned NumSyms = MemberOffsetRefs.size();
if (Kind == object::Archive::K_GNU)
print32(Out, Kind, NumSyms);
else
print32(Out, Kind, NumSyms * 8);
Out.seek(Pos);
return BodyStartOffset + 4;
}
std::pair<StringRef, std::error_code>
llvm::writeArchive(StringRef ArcName,
std::vector<NewArchiveIterator> &NewMembers,
bool WriteSymtab, object::Archive::Kind Kind) {
SmallString<128> TmpArchive;
int TmpArchiveFD;
if (auto EC = sys::fs::createUniqueFile(ArcName + ".temp-archive-%%%%%%%.a",
TmpArchiveFD, TmpArchive))
return std::make_pair(ArcName, EC);
tool_output_file Output(TmpArchive, TmpArchiveFD);
raw_fd_ostream &Out = Output.os();
Out << "!<arch>\n";
std::vector<unsigned> MemberOffsetRefs;
std::vector<std::unique_ptr<MemoryBuffer>> Buffers;
std::vector<MemoryBufferRef> Members;
std::vector<sys::fs::file_status> NewMemberStatus;
for (unsigned I = 0, N = NewMembers.size(); I < N; ++I) {
NewArchiveIterator &Member = NewMembers[I];
MemoryBufferRef MemberRef;
if (Member.isNewMember()) {
StringRef Filename = Member.getNew();
NewMemberStatus.resize(NewMemberStatus.size() + 1);
sys::fs::file_status &Status = NewMemberStatus.back();
ErrorOr<int> FD = Member.getFD(Status);
if (auto EC = FD.getError())
return std::make_pair(Filename, EC);
ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
MemoryBuffer::getOpenFile(FD.get(), Filename, Status.getSize(),
false);
if (auto EC = MemberBufferOrErr.getError())
return std::make_pair(Filename, EC);
if (close(FD.get()) != 0)
return std::make_pair(Filename,
std::error_code(errno, std::generic_category()));
Buffers.push_back(std::move(MemberBufferOrErr.get()));
MemberRef = Buffers.back()->getMemBufferRef();
} else {
object::Archive::child_iterator OldMember = Member.getOld();
ErrorOr<MemoryBufferRef> MemberBufferOrErr =
OldMember->getMemoryBufferRef();
if (auto EC = MemberBufferOrErr.getError())
return std::make_pair("", EC);
MemberRef = MemberBufferOrErr.get();
}
Members.push_back(MemberRef);
}
unsigned MemberReferenceOffset = 0;
if (WriteSymtab) {
ErrorOr<unsigned> MemberReferenceOffsetOrErr =
writeSymbolTable(Out, Kind, NewMembers, Members, MemberOffsetRefs);
if (auto EC = MemberReferenceOffsetOrErr.getError())
return std::make_pair(ArcName, EC);
MemberReferenceOffset = MemberReferenceOffsetOrErr.get();
}
std::vector<unsigned> StringMapIndexes;
if (Kind != object::Archive::K_BSD)
writeStringTable(Out, NewMembers, StringMapIndexes);
unsigned MemberNum = 0;
unsigned NewMemberNum = 0;
std::vector<unsigned>::iterator StringMapIndexIter = StringMapIndexes.begin();
std::vector<unsigned> MemberOffset;
for (const NewArchiveIterator &I : NewMembers) {
MemoryBufferRef File = Members[MemberNum++];
unsigned Pos = Out.tell();
MemberOffset.push_back(Pos);
if (I.isNewMember()) {
StringRef FileName = I.getNew();
const sys::fs::file_status &Status = NewMemberStatus[NewMemberNum++];
printMemberHeader(Out, Kind, sys::path::filename(FileName),
StringMapIndexIter, Status.getLastModificationTime(),
Status.getUser(), Status.getGroup(),
Status.permissions(), Status.getSize());
} else {
object::Archive::child_iterator OldMember = I.getOld();
printMemberHeader(Out, Kind, I.getName(), StringMapIndexIter,
OldMember->getLastModified(), OldMember->getUID(),
OldMember->getGID(), OldMember->getAccessMode(),
OldMember->getSize());
}
Out << File.getBuffer();
if (Out.tell() % 2)
Out << '\n';
}
if (MemberReferenceOffset) {
Out.seek(MemberReferenceOffset);
for (unsigned MemberNum : MemberOffsetRefs) {
if (Kind == object::Archive::K_BSD)
Out.seek(Out.tell() + 4); // skip over the string offset
print32(Out, Kind, MemberOffset[MemberNum]);
}
}
Output.keep();
Out.close();
sys::fs::rename(TmpArchive, ArcName);
return std::make_pair("", std::error_code());
}
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