Error writeArchive(StringRef ArcName, ArrayRef<NewArchiveMember> NewMembers,
bool WriteSymtab, object::Archive::Kind Kind,
bool Deterministic, bool Thin,
std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
assert((!Thin || !isBSDLike(Kind)) && "Only the gnu format has a thin mode");
SmallString<0> SymNamesBuf;
raw_svector_ostream SymNames(SymNamesBuf);
SmallString<0> StringTableBuf;
raw_svector_ostream StringTable(StringTableBuf);
Expected<std::vector<MemberData>> DataOrErr = computeMemberData(
StringTable, SymNames, Kind, Thin, Deterministic, NewMembers);
if (Error E = DataOrErr.takeError())
return E;
std::vector<MemberData> &Data = *DataOrErr;
if (!StringTableBuf.empty())
Data.insert(Data.begin(), computeStringTable(StringTableBuf));
// We would like to detect if we need to switch to a 64-bit symbol table.
if (WriteSymtab) {
uint64_t MaxOffset = 0;
uint64_t LastOffset = MaxOffset;
for (const auto &M : Data) {
// Record the start of the member's offset
LastOffset = MaxOffset;
// Account for the size of each part associated with the member.
MaxOffset += M.Header.size() + M.Data.size() + M.Padding.size();
// We assume 32-bit symbols to see if 32-bit symbols are possible or not.
MaxOffset += M.Symbols.size() * 4;
}
// The SYM64 format is used when an archive's member offsets are larger than
// 32-bits can hold. The need for this shift in format is detected by
// writeArchive. To test this we need to generate a file with a member that
// has an offset larger than 32-bits but this demands a very slow test. To
// speed the test up we use this environment variable to pretend like the
// cutoff happens before 32-bits and instead happens at some much smaller
// value.
const char *Sym64Env = std::getenv("SYM64_THRESHOLD");
int Sym64Threshold = 32;
if (Sym64Env)
StringRef(Sym64Env).getAsInteger(10, Sym64Threshold);
// If LastOffset isn't going to fit in a 32-bit varible we need to switch
// to 64-bit. Note that the file can be larger than 4GB as long as the last
// member starts before the 4GB offset.
if (LastOffset >= (1ULL << Sym64Threshold)) {
if (Kind == object::Archive::K_DARWIN)
Kind = object::Archive::K_DARWIN64;
else
Kind = object::Archive::K_GNU64;
}
}
Expected<sys::fs::TempFile> Temp =
sys::fs::TempFile::create(ArcName + ".temp-archive-%%%%%%%.a");
if (!Temp)
return Temp.takeError();
raw_fd_ostream Out(Temp->FD, false);
if (Thin)
Out << "!<thin>\n";
else
Out << "!<arch>\n";
if (WriteSymtab)
writeSymbolTable(Out, Kind, Deterministic, Data, SymNamesBuf);
for (const MemberData &M : Data)
Out << M.Header << M.Data << M.Padding;
Out.flush();
// 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();
return Temp->keep(ArcName);
}
