path: root/lib/Archive/ArchiveWriter.cpp

//===-- ArchiveWriter.cpp - Write LLVM archive files ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Builds up an LLVM archive file (.a) containing LLVM bitcode.
//
//===----------------------------------------------------------------------===//

#include "ArchiveInternals.h"
#include "llvm/Module.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/system_error.h"
#include <fstream>
#include <ostream>
#include <iomanip>
using namespace llvm;

// Write an integer using variable bit rate encoding. This saves a few bytes
// per entry in the symbol table.
static inline void writeInteger(unsigned num, std::ofstream& ARFile) {
  while (1) {
    if (num < 0x80) { // done?
      ARFile << (unsigned char)num;
      return;
    }

    // Nope, we are bigger than a character, output the next 7 bits and set the
    // high bit to say that there is more coming...
    ARFile << (unsigned char)(0x80 | ((unsigned char)num & 0x7F));
    num >>= 7;  // Shift out 7 bits now...
  }
}

// Compute how many bytes are taken by a given VBR encoded value. This is needed
// to pre-compute the size of the symbol table.
static inline unsigned numVbrBytes(unsigned num) {

  // Note that the following nested ifs are somewhat equivalent to a binary
  // search. We split it in half by comparing against 2^14 first. This allows
  // most reasonable values to be done in 2 comparisons instead of 1 for
  // small ones and four for large ones. We expect this to access file offsets
  // in the 2^10 to 2^24 range and symbol lengths in the 2^0 to 2^8 range,
  // so this approach is reasonable.
  if (num < 1<<14) {
    if (num < 1<<7)
      return 1;
    else
      return 2;
  }
  if (num < 1<<21)
    return 3;

  if (num < 1<<28)
    return 4;
  return 5; // anything >= 2^28 takes 5 bytes
}

// Create an empty archive.
Archive* Archive::CreateEmpty(const sys::Path& FilePath, LLVMContext& C) {
  Archive* result = new Archive(FilePath, C);
  return result;
}

// Fill the ArchiveMemberHeader with the information from a member. If
// TruncateNames is true, names are flattened to 15 chars or less. The sz field
// is provided here instead of coming from the mbr because the member might be
// stored compressed and the compressed size is not the ArchiveMember's size.
// Furthermore compressed files have negative size fields to identify them as
// compressed.
bool
Archive::fillHeader(const ArchiveMember &mbr, ArchiveMemberHeader& hdr,
                    int sz, bool TruncateNames) const {

  // Set the permissions mode, uid and gid
  hdr.init();
  char buffer[32];
  sprintf(buffer, "%-8o", mbr.getMode());
  memcpy(hdr.mode,buffer,8);
  sprintf(buffer,  "%-6u", mbr.getUser());
  memcpy(hdr.uid,buffer,6);
  sprintf(buffer,  "%-6u", mbr.getGroup());
  memcpy(hdr.gid,buffer,6);

  // Set the last modification date
  uint64_t secondsSinceEpoch = mbr.getModTime().toEpochTime();
  sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch));
  memcpy(hdr.date,buffer,12);

  // Get rid of trailing blanks in the name
  std::string mbrPath = mbr.getPath().str();
  size_t mbrLen = mbrPath.length();
  while (mbrLen > 0 && mbrPath[mbrLen-1] == ' ') {
    mbrPath.erase(mbrLen-1,1);
    mbrLen--;
  }

  // Set the name field in one of its various flavors.
  bool writeLongName = false;
  if (mbr.isStringTable()) {
    memcpy(hdr.name,ARFILE_STRTAB_NAME,16);
  } else if (mbr.isSVR4SymbolTable()) {
    memcpy(hdr.name,ARFILE_SVR4_SYMTAB_NAME,16);
  } else if (mbr.isBSD4SymbolTable()) {
    memcpy(hdr.name,ARFILE_BSD4_SYMTAB_NAME,16);
  } else if (mbr.isLLVMSymbolTable()) {
    memcpy(hdr.name,ARFILE_LLVM_SYMTAB_NAME,16);
  } else if (TruncateNames) {
    const char* nm = mbrPath.c_str();
    unsigned len = mbrPath.length();
    size_t slashpos = mbrPath.rfind('/');
    if (slashpos != std::string::npos) {
      nm += slashpos + 1;
      len -= slashpos +1;
    }
    if (len > 15)
      len = 15;
    memcpy(hdr.name,nm,len);
    hdr.name[len] = '/';
  } else if (mbrPath.length() < 16 && mbrPath.find('/') == std::string::npos) {
    memcpy(hdr.name,mbrPath.c_str(),mbrPath.length());
    hdr.name[mbrPath.length()] = '/';
  } else {
    std::string nm = "#1/";
    nm += utostr(mbrPath.length());
    memcpy(hdr.name,nm.data(),nm.length());
    if (sz < 0)
      sz -= mbrPath.length();
    else
      sz += mbrPath.length();
    writeLongName = true;
  }

  // Set the size field
  if (sz < 0) {
    buffer[0] = '-';
    sprintf(&buffer[1],"%-9u",(unsigned)-sz);
  } else {
    sprintf(buffer, "%-10u", (unsigned)sz);
  }
  memcpy(hdr.size,buffer,10);

  return writeLongName;
}

// Insert a file into the archive before some other member. This also takes care
// of extracting the necessary flags and information from the file.
bool
Archive::addFileBefore(const sys::Path& filePath, iterator where,
                        std::string* ErrMsg) {
  bool Exists;
  if (sys::fs::exists(filePath.str(), Exists) || !Exists) {
    if (ErrMsg)
      *ErrMsg = "Can not add a non-existent file to archive";
    return true;
  }

  ArchiveMember* mbr = new ArchiveMember(this);

  mbr->data = 0;
  mbr->path = filePath;
  const sys::FileStatus *FSInfo = mbr->path.getFileStatus(false, ErrMsg);
  if (!FSInfo) {
    delete mbr;
    return true;
  }
  mbr->info = *FSInfo;

  unsigned flags = 0;
  bool hasSlash = filePath.str().find('/') != std::string::npos;
  if (hasSlash)
    flags |= ArchiveMember::HasPathFlag;
  if (hasSlash || filePath.str().length() > 15)
    flags |= ArchiveMember::HasLongFilenameFlag;

  sys::LLVMFileType type;
  if (sys::fs::identify_magic(mbr->path.str(), type))
    type = sys::Unknown_FileType;
  switch (type) {
    case sys::Bitcode_FileType:
      flags |= ArchiveMember::BitcodeFlag;
      break;
    default:
      break;
  }
  mbr->flags = flags;
  members.insert(where,mbr);
  return false;
}

// Write one member out to the file.
bool
Archive::writeMember(
  const ArchiveMember& member,
  std::ofstream& ARFile,
  bool CreateSymbolTable,
  bool TruncateNames,
  bool ShouldCompress,
  std::string* ErrMsg
) {

  unsigned