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llvm-project/llvm/lib/Object/ArchiveWriter.cpp

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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;
NewArchiveMember::NewArchiveMember(MemoryBufferRef BufRef)
: Buf(MemoryBuffer::getMemBuffer(BufRef, false)) {}
Expected<NewArchiveMember>
NewArchiveMember::getOldMember(const object::Archive::Child &OldMember,
bool Deterministic) {
Expected<llvm::MemoryBufferRef> BufOrErr = OldMember.getMemoryBufferRef();
if (!BufOrErr)
return BufOrErr.takeError();
NewArchiveMember M;
assert(M.IsNew == false);
M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
if (!Deterministic) {
auto ModTimeOrErr = OldMember.getLastModified();
if (!ModTimeOrErr)
return ModTimeOrErr.takeError();
M.ModTime = ModTimeOrErr.get();
Expected<unsigned> UIDOrErr = OldMember.getUID();
if (!UIDOrErr)
return UIDOrErr.takeError();
M.UID = UIDOrErr.get();
Expected<unsigned> GIDOrErr = OldMember.getGID();
if (!GIDOrErr)
return GIDOrErr.takeError();
M.GID = GIDOrErr.get();
Expected<sys::fs::perms> AccessModeOrErr = OldMember.getAccessMode();
if (!AccessModeOrErr)
return AccessModeOrErr.takeError();
M.Perms = AccessModeOrErr.get();
}
return std::move(M);
}
Expected<NewArchiveMember> NewArchiveMember::getFile(StringRef FileName,
bool Deterministic) {
sys::fs::file_status Status;
int FD;
if (auto EC = sys::fs::openFileForRead(FileName, FD))
return errorCodeToError(EC);
assert(FD != -1);
if (auto EC = sys::fs::status(FD, Status))
return errorCodeToError(EC);
// Opening a directory doesn't make sense. Let it fail.
// Linux cannot open directories with open(2), although
// cygwin and *bsd can.
if (Status.type() == sys::fs::file_type::directory_file)
return errorCodeToError(make_error_code(errc::is_a_directory));
ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
MemoryBuffer::getOpenFile(FD, FileName, Status.getSize(), false);
if (!MemberBufferOrErr)
return errorCodeToError(MemberBufferOrErr.getError());
if (close(FD) != 0)
return errorCodeToError(std::error_code(errno, std::generic_category()));
NewArchiveMember M;
M.IsNew = true;
M.Buf = std::move(*MemberBufferOrErr);
if (!Deterministic) {
M.ModTime = std::chrono::time_point_cast<std::chrono::seconds>(
Status.getLastModificationTime());
M.UID = Status.getUser();
M.GID = Status.getGroup();
M.Perms = Status.permissions();
}
return std::move(M);
}
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::TimePoint<std::chrono::seconds> &ModTime,
unsigned UID, unsigned GID, unsigned Perms, unsigned Size) {
printWithSpacePadding(Out, sys::toTimeT(ModTime), 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::TimePoint<std::chrono::seconds> &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::TimePoint<std::chrono::seconds> &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 bool useStringTable(bool Thin, StringRef Name) {
return Thin || Name.size() >= 16;
}
static void
printMemberHeader(raw_fd_ostream &Out, object::Archive::Kind Kind, bool Thin,
StringRef Name,
std::vector<unsigned>::iterator &StringMapIndexIter,
const sys::TimePoint<std::chrono::seconds> &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 (!useStringTable(Thin, Name))
return printGNUSmallMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
Out << '/';
printWithSpacePadding(Out, *StringMapIndexIter++, 15);
printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
}
// Compute the relative path from From to To.
static std::string computeRelativePath(StringRef From, StringRef To) {
if (sys::path::is_absolute(From) || sys::path::is_absolute(To))
return To;
StringRef DirFrom = sys::path::parent_path(From);
auto FromI = sys::path::begin(DirFrom);
auto ToI = sys::path::begin(To);
while (*FromI == *ToI) {
++FromI;
++ToI;
}
SmallString<128> Relative;
for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI)
sys::path::append(Relative, "..");
for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI)
sys::path::append(Relative, *ToI);
#ifdef LLVM_ON_WIN32
// Replace backslashes with slashes so that the path is portable between *nix
// and Windows.
std::replace(Relative.begin(), Relative.end(), '\\', '/');
#endif
return Relative.str();
}
static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
ArrayRef<NewArchiveMember> Members,
std::vector<unsigned> &StringMapIndexes,
bool Thin) {
unsigned StartOffset = 0;
for (const NewArchiveMember &M : Members) {
StringRef Path = M.Buf->getBufferIdentifier();
StringRef Name = sys::path::filename(Path);
if (!useStringTable(Thin, Name))
continue;
if (StartOffset == 0) {
printWithSpacePadding(Out, "//", 58);
Out << "`\n";
StartOffset = Out.tell();
}
StringMapIndexes.push_back(Out.tell() - StartOffset);
if (Thin) {
if (M.IsNew)
Out << computeRelativePath(ArcName, Path);
else
Out << M.Buf->getBufferIdentifier();
} else
Out << Name;
Out << "/\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);
}
static sys::TimePoint<std::chrono::seconds> now(bool Deterministic) {
using namespace std::chrono;
if (!Deterministic)
return time_point_cast<seconds>(system_clock::now());
return sys::TimePoint<seconds>();
}
// Returns the offset of the first reference to a member offset.
static ErrorOr<unsigned>
writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
ArrayRef<NewArchiveMember> Members,
std::vector<unsigned> &MemberOffsetRefs, bool Deterministic) {
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 = Members[MemberNum].Buf->getMemBufferRef();
Expected<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
object::SymbolicFile::createSymbolicFile(
MemberBuffer, sys::fs::file_magic::unknown, &Context);
if (!ObjOrErr) {
// FIXME: check only for "not an object file" errors.
consumeError(ObjOrErr.takeError());
continue;
}
object::SymbolicFile &Obj = *ObjOrErr.get();
if (!HeaderStartOffset) {
HeaderStartOffset = Out.tell();
if (Kind == object::Archive::K_GNU)
printGNUSmallMemberHeader(Out, "", now(Deterministic), 0, 0, 0, 0);
else
printBSDMemberHeader(Out, "__.SYMDEF", now(Deterministic), 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;
// ld64 prefers the cctools type archive which pads its string table to a
// boundary of sizeof(int32_t).
if (Kind == object::Archive::K_BSD)
for (unsigned P = OffsetToAlignment(NameOS.tell(), sizeof(int32_t)); P--;)
NameOS << '\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<NewArchiveMember> &NewMembers,
bool WriteSymtab, object::Archive::Kind Kind,
bool Deterministic, bool Thin,
std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
assert((!Thin || Kind == object::Archive::K_GNU) &&
"Only the gnu format has a thin mode");
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();
if (Thin)
Out << "!<thin>\n";
else
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;
unsigned MemberReferenceOffset = 0;
if (WriteSymtab) {
ErrorOr<unsigned> MemberReferenceOffsetOrErr = writeSymbolTable(
Out, Kind, NewMembers, MemberOffsetRefs, Deterministic);
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, ArcName, NewMembers, StringMapIndexes, Thin);
std::vector<unsigned>::iterator StringMapIndexIter = StringMapIndexes.begin();
std::vector<unsigned> MemberOffset;
for (const NewArchiveMember &M : NewMembers) {
MemoryBufferRef File = M.Buf->getMemBufferRef();
unsigned Padding = 0;
unsigned Pos = Out.tell();
MemberOffset.push_back(Pos);
// ld64 expects the members to be 8-byte aligned for 64-bit content and at
// least 4-byte aligned for 32-bit content. Opt for the larger encoding
// uniformly. This matches the behaviour with cctools and ensures that ld64
// is happy with archives that we generate.
if (Kind == object::Archive::K_BSD)
Padding = OffsetToAlignment(M.Buf->getBufferSize(), 8);
printMemberHeader(Out, Kind, Thin,
sys::path::filename(M.Buf->getBufferIdentifier()),
StringMapIndexIter, M.ModTime, M.UID, M.GID, M.Perms,
M.Buf->getBufferSize() + Padding);
if (!Thin)
Out << File.getBuffer();
while (Padding--)
Out << '\n';
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();
// At this point, we no longer need whatever backing memory
// was used to generate the NewMembers. On Windows, this buffer
// could be a mapped view of the file we want to replace (if
// we're updating an existing archive, say). In that case, the
// rename would still succeed, but it would leave behind a
// temporary file (actually the original file renamed) because
// a file cannot be deleted while there's a handle open on it,
// only renamed. So by freeing this buffer, this ensures that
// the last open handle on the destination file, if any, is
// closed before we attempt to rename.
OldArchiveBuf.reset();
sys::fs::rename(TmpArchive, ArcName);
return std::make_pair("", std::error_code());
}
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