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      1 //===-- ArchiveWriter.cpp - Write LLVM archive files ----------------------===//
      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 // Builds up an LLVM archive file (.a) containing LLVM bitcode.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "ArchiveInternals.h"
     15 #include "llvm/Module.h"
     16 #include "llvm/ADT/OwningPtr.h"
     17 #include "llvm/Bitcode/ReaderWriter.h"
     18 #include "llvm/Support/FileSystem.h"
     19 #include "llvm/Support/MemoryBuffer.h"
     20 #include "llvm/Support/Process.h"
     21 #include "llvm/Support/Signals.h"
     22 #include "llvm/Support/system_error.h"
     23 #include <fstream>
     24 #include <ostream>
     25 #include <iomanip>
     26 using namespace llvm;
     27 
     28 // Write an integer using variable bit rate encoding. This saves a few bytes
     29 // per entry in the symbol table.
     30 static inline void writeInteger(unsigned num, std::ofstream& ARFile) {
     31   while (1) {
     32     if (num < 0x80) { // done?
     33       ARFile << (unsigned char)num;
     34       return;
     35     }
     36 
     37     // Nope, we are bigger than a character, output the next 7 bits and set the
     38     // high bit to say that there is more coming...
     39     ARFile << (unsigned char)(0x80 | ((unsigned char)num & 0x7F));
     40     num >>= 7;  // Shift out 7 bits now...
     41   }
     42 }
     43 
     44 // Compute how many bytes are taken by a given VBR encoded value. This is needed
     45 // to pre-compute the size of the symbol table.
     46 static inline unsigned numVbrBytes(unsigned num) {
     47 
     48   // Note that the following nested ifs are somewhat equivalent to a binary
     49   // search. We split it in half by comparing against 2^14 first. This allows
     50   // most reasonable values to be done in 2 comparisons instead of 1 for
     51   // small ones and four for large ones. We expect this to access file offsets
     52   // in the 2^10 to 2^24 range and symbol lengths in the 2^0 to 2^8 range,
     53   // so this approach is reasonable.
     54   if (num < 1<<14) {
     55     if (num < 1<<7)
     56       return 1;
     57     else
     58       return 2;
     59   }
     60   if (num < 1<<21)
     61     return 3;
     62 
     63   if (num < 1<<28)
     64     return 4;
     65   return 5; // anything >= 2^28 takes 5 bytes
     66 }
     67 
     68 // Create an empty archive.
     69 Archive* Archive::CreateEmpty(const sys::Path& FilePath, LLVMContext& C) {
     70   Archive* result = new Archive(FilePath, C);
     71   return result;
     72 }
     73 
     74 // Fill the ArchiveMemberHeader with the information from a member. If
     75 // TruncateNames is true, names are flattened to 15 chars or less. The sz field
     76 // is provided here instead of coming from the mbr because the member might be
     77 // stored compressed and the compressed size is not the ArchiveMember's size.
     78 // Furthermore compressed files have negative size fields to identify them as
     79 // compressed.
     80 bool
     81 Archive::fillHeader(const ArchiveMember &mbr, ArchiveMemberHeader& hdr,
     82                     int sz, bool TruncateNames) const {
     83 
     84   // Set the permissions mode, uid and gid
     85   hdr.init();
     86   char buffer[32];
     87   sprintf(buffer, "%-8o", mbr.getMode());
     88   memcpy(hdr.mode,buffer,8);
     89   sprintf(buffer,  "%-6u", mbr.getUser());
     90   memcpy(hdr.uid,buffer,6);
     91   sprintf(buffer,  "%-6u", mbr.getGroup());
     92   memcpy(hdr.gid,buffer,6);
     93 
     94   // Set the last modification date
     95   uint64_t secondsSinceEpoch = mbr.getModTime().toEpochTime();
     96   sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch));
     97   memcpy(hdr.date,buffer,12);
     98 
     99   // Get rid of trailing blanks in the name
    100   std::string mbrPath = mbr.getPath().str();
    101   size_t mbrLen = mbrPath.length();
    102   while (mbrLen > 0 && mbrPath[mbrLen-1] == ' ') {
    103     mbrPath.erase(mbrLen-1,1);
    104     mbrLen--;
    105   }
    106 
    107   // Set the name field in one of its various flavors.
    108   bool writeLongName = false;
    109   if (mbr.isStringTable()) {
    110     memcpy(hdr.name,ARFILE_STRTAB_NAME,16);
    111   } else if (mbr.isSVR4SymbolTable()) {
    112     memcpy(hdr.name,ARFILE_SVR4_SYMTAB_NAME,16);
    113   } else if (mbr.isBSD4SymbolTable()) {
    114     memcpy(hdr.name,ARFILE_BSD4_SYMTAB_NAME,16);
    115   } else if (mbr.isLLVMSymbolTable()) {
    116     memcpy(hdr.name,ARFILE_LLVM_SYMTAB_NAME,16);
    117   } else if (TruncateNames) {
    118     const char* nm = mbrPath.c_str();
    119     unsigned len = mbrPath.length();
    120     size_t slashpos = mbrPath.rfind('/');
    121     if (slashpos != std::string::npos) {
    122       nm += slashpos + 1;
    123       len -= slashpos +1;
    124     }
    125     if (len > 15)
    126       len = 15;
    127     memcpy(hdr.name,nm,len);
    128     hdr.name[len] = '/';
    129   } else if (mbrPath.length() < 16 && mbrPath.find('/') == std::string::npos) {
    130     memcpy(hdr.name,mbrPath.c_str(),mbrPath.length());
    131     hdr.name[mbrPath.length()] = '/';
    132   } else {
    133     std::string nm = "#1/";
    134     nm += utostr(mbrPath.length());
    135     memcpy(hdr.name,nm.data(),nm.length());
    136     if (sz < 0)
    137       sz -= mbrPath.length();
    138     else
    139       sz += mbrPath.length();
    140     writeLongName = true;
    141   }
    142 
    143   // Set the size field
    144   if (sz < 0) {
    145     buffer[0] = '-';
    146     sprintf(&buffer[1],"%-9u",(unsigned)-sz);
    147   } else {
    148     sprintf(buffer, "%-10u", (unsigned)sz);
    149   }
    150   memcpy(hdr.size,buffer,10);
    151 
    152   return writeLongName;
    153 }
    154 
    155 // Insert a file into the archive before some other member. This also takes care
    156 // of extracting the necessary flags and information from the file.
    157 bool
    158 Archive::addFileBefore(const sys::Path& filePath, iterator where,
    159                         std::string* ErrMsg) {
    160   bool Exists;
    161   if (sys::fs::exists(filePath.str(), Exists) || !Exists) {
    162     if (ErrMsg)
    163       *ErrMsg = "Can not add a non-existent file to archive";
    164     return true;
    165   }
    166 
    167   ArchiveMember* mbr = new ArchiveMember(this);
    168 
    169   mbr->data = 0;
    170   mbr->path = filePath;
    171   const sys::FileStatus *FSInfo = mbr->path.getFileStatus(false, ErrMsg);
    172   if (!FSInfo) {
    173     delete mbr;
    174     return true;
    175   }
    176   mbr->info = *FSInfo;
    177 
    178   unsigned flags = 0;
    179   bool hasSlash = filePath.str().find('/') != std::string::npos;
    180   if (hasSlash)
    181     flags |= ArchiveMember::HasPathFlag;
    182   if (hasSlash || filePath.str().length() > 15)
    183     flags |= ArchiveMember::HasLongFilenameFlag;
    184 
    185   sys::LLVMFileType type;
    186   if (sys::fs::identify_magic(mbr->path.str(), type))
    187     type = sys::Unknown_FileType;
    188   switch (type) {
    189     case sys::Bitcode_FileType:
    190       flags |= ArchiveMember::BitcodeFlag;
    191       break;
    192     default:
    193       break;
    194   }
    195   mbr->flags = flags;
    196   members.insert(where,mbr);
    197   return false;
    198 }
    199 
    200 // Write one member out to the file.
    201 bool
    202 Archive::writeMember(
    203   const ArchiveMember& member,
    204   std::ofstream& ARFile,
    205   bool CreateSymbolTable,
    206   bool TruncateNames,
    207   bool ShouldCompress,
    208   std::string* ErrMsg
    209 ) {
    210 
    211   unsigned filepos = ARFile.tellp();
    212   filepos -= 8;
    213 
    214   // Get the data and its size either from the
    215   // member's in-memory data or directly from the file.
    216   size_t fSize = member.getSize();
    217   const char *data = (const char*)member.getData();
    218   MemoryBuffer *mFile = 0;
    219   if (!data) {
    220     OwningPtr<MemoryBuffer> File;
    221     if (error_code ec = MemoryBuffer::getFile(member.getPath().c_str(), File)) {
    222       if (ErrMsg)
    223         *ErrMsg = ec.message();
    224       return true;
    225     }
    226     mFile = File.take();
    227     data = mFile->getBufferStart();
    228     fSize = mFile->getBufferSize();
    229   }
    230 
    231   // Now that we have the data in memory, update the
    232   // symbol table if it's a bitcode file.
    233   if (CreateSymbolTable && member.isBitcode()) {
    234     std::vector<std::string> symbols;
    235     std::string FullMemberName = archPath.str() + "(" + member.getPath().str()
    236       + ")";
    237     Module* M =
    238       GetBitcodeSymbols(data, fSize, FullMemberName, Context, symbols, ErrMsg);
    239 
    240     // If the bitcode parsed successfully
    241     if ( M ) {
    242       for (std::vector<std::string>::iterator SI = symbols.begin(),
    243            SE = symbols.end(); SI != SE; ++SI) {
    244 
    245         std::pair<SymTabType::iterator,bool> Res =
    246           symTab.insert(std::make_pair(*SI,filepos));
    247 
    248         if (Res.second) {
    249           symTabSize += SI->length() +
    250                         numVbrBytes(SI->length()) +
    251                         numVbrBytes(filepos);
    252         }
    253       }
    254       // We don't need this module any more.
    255       delete M;
    256     } else {
    257       delete mFile;
    258       if (ErrMsg)
    259         *ErrMsg = "Can't parse bitcode member: " + member.getPath().str()
    260           + ": " + *ErrMsg;
    261       return true;
    262     }
    263   }
    264 
    265   int hdrSize = fSize;
    266 
    267   // Compute the fields of the header
    268   ArchiveMemberHeader Hdr;
    269   bool writeLongName = fillHeader(member,Hdr,hdrSize,TruncateNames);
    270 
    271   // Write header to archive file
    272   ARFile.write((char*)&Hdr, sizeof(Hdr));
    273 
    274   // Write the long filename if its long
    275   if (writeLongName) {
    276     ARFile.write(member.getPath().str().data(),
    277                  member.getPath().str().length());
    278   }
    279 
    280   // Write the (possibly compressed) member's content to the file.
    281   ARFile.write(data,fSize);
    282 
    283   // Make sure the member is an even length
    284   if ((ARFile.tellp() & 1) == 1)
    285     ARFile << ARFILE_PAD;
    286 
    287   // Close the mapped file if it was opened
    288   delete mFile;
    289   return false;
    290 }
    291 
    292 // Write out the LLVM symbol table as an archive member to the file.
    293 void
    294 Archive::writeSymbolTable(std::ofstream& ARFile) {
    295 
    296   // Construct the symbol table's header
    297   ArchiveMemberHeader Hdr;
    298   Hdr.init();
    299   memcpy(Hdr.name,ARFILE_LLVM_SYMTAB_NAME,16);
    300   uint64_t secondsSinceEpoch = sys::TimeValue::now().toEpochTime();
    301   char buffer[32];
    302   sprintf(buffer, "%-8o", 0644);
    303   memcpy(Hdr.mode,buffer,8);
    304   sprintf(buffer, "%-6u", sys::Process::GetCurrentUserId());
    305   memcpy(Hdr.uid,buffer,6);
    306   sprintf(buffer, "%-6u", sys::Process::GetCurrentGroupId());
    307   memcpy(Hdr.gid,buffer,6);
    308   sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch));
    309   memcpy(Hdr.date,buffer,12);
    310   sprintf(buffer,"%-10u",symTabSize);
    311   memcpy(Hdr.size,buffer,10);
    312 
    313   // Write the header
    314   ARFile.write((char*)&Hdr, sizeof(Hdr));
    315 
    316 #ifndef NDEBUG
    317   // Save the starting position of the symbol tables data content.
    318   unsigned startpos = ARFile.tellp();
    319 #endif
    320 
    321   // Write out the symbols sequentially
    322   for ( Archive::SymTabType::iterator I = symTab.begin(), E = symTab.end();
    323         I != E; ++I)
    324   {
    325     // Write out the file index
    326     writeInteger(I->second, ARFile);
    327     // Write out the length of the symbol
    328     writeInteger(I->first.length(), ARFile);
    329     // Write out the symbol
    330     ARFile.write(I->first.data(), I->first.length());
    331   }
    332 
    333 #ifndef NDEBUG
    334   // Now that we're done with the symbol table, get the ending file position
    335   unsigned endpos = ARFile.tellp();
    336 #endif
    337 
    338   // Make sure that the amount we wrote is what we pre-computed. This is
    339   // critical for file integrity purposes.
    340   assert(endpos - startpos == symTabSize && "Invalid symTabSize computation");
    341 
    342   // Make sure the symbol table is even sized
    343   if (symTabSize % 2 != 0 )
    344     ARFile << ARFILE_PAD;
    345 }
    346 
    347 // Write the entire archive to the file specified when the archive was created.
    348 // This writes to a temporary file first. Options are for creating a symbol
    349 // table, flattening the file names (no directories, 15 chars max) and
    350 // compressing each archive member.
    351 bool
    352 Archive::writeToDisk(bool CreateSymbolTable, bool TruncateNames, bool Compress,
    353                      std::string* ErrMsg)
    354 {
    355   // Make sure they haven't opened up the file, not loaded it,
    356   // but are now trying to write it which would wipe out the file.
    357   if (members.empty() && mapfile && mapfile->getBufferSize() > 8) {
    358     if (ErrMsg)
    359       *ErrMsg = "Can't write an archive not opened for writing";
    360     return true;
    361   }
    362 
    363   // Create a temporary file to store the archive in
    364   sys::Path TmpArchive = archPath;
    365   if (TmpArchive.createTemporaryFileOnDisk(ErrMsg))
    366     return true;
    367 
    368   // Make sure the temporary gets removed if we crash
    369   sys::RemoveFileOnSignal(TmpArchive);
    370 
    371   // Create archive file for output.
    372   std::ios::openmode io_mode = std::ios::out | std::ios::trunc |
    373                                std::ios::binary;
    374   std::ofstream ArchiveFile(TmpArchive.c_str(), io_mode);
    375 
    376   // Check for errors opening or creating archive file.
    377   if (!ArchiveFile.is_open() || ArchiveFile.bad()) {
    378     TmpArchive.eraseFromDisk();
    379     if (ErrMsg)
    380       *ErrMsg = "Error opening archive file: " + archPath.str();
    381     return true;
    382   }
    383 
    384   // If we're creating a symbol table, reset it now
    385   if (CreateSymbolTable) {
    386     symTabSize = 0;
    387     symTab.clear();
    388   }
    389 
    390   // Write magic string to archive.
    391   ArchiveFile << ARFILE_MAGIC;
    392 
    393   // Loop over all member files, and write them out. Note that this also
    394   // builds the symbol table, symTab.
    395   for (MembersList::iterator I = begin(), E = end(); I != E; ++I) {
    396     if (writeMember(*I, ArchiveFile, CreateSymbolTable,
    397                      TruncateNames, Compress, ErrMsg)) {
    398       TmpArchive.eraseFromDisk();
    399       ArchiveFile.close();
    400       return true;
    401     }
    402   }
    403 
    404   // Close archive file.
    405   ArchiveFile.close();
    406 
    407   // Write the symbol table
    408   if (CreateSymbolTable) {
    409     // At this point we have written a file that is a legal archive but it
    410     // doesn't have a symbol table in it. To aid in faster reading and to
    411     // ensure compatibility with other archivers we need to put the symbol
    412     // table first in the file. Unfortunately, this means mapping the file
    413     // we just wrote back in and copying it to the destination file.
    414     sys::Path FinalFilePath = archPath;
    415 
    416     // Map in the archive we just wrote.
    417     {
    418     OwningPtr<MemoryBuffer> arch;
    419     if (error_code ec = MemoryBuffer::getFile(TmpArchive.c_str(), arch)) {
    420       if (ErrMsg)
    421         *ErrMsg = ec.message();
    422       return true;
    423     }
    424     const char* base = arch->getBufferStart();
    425 
    426     // Open another temporary file in order to avoid invalidating the
    427     // mmapped data
    428     if (FinalFilePath.createTemporaryFileOnDisk(ErrMsg))
    429       return true;
    430     sys::RemoveFileOnSignal(FinalFilePath);
    431 
    432     std::ofstream FinalFile(FinalFilePath.c_str(), io_mode);
    433     if (!FinalFile.is_open() || FinalFile.bad()) {
    434       TmpArchive.eraseFromDisk();
    435       if (ErrMsg)
    436         *ErrMsg = "Error opening archive file: " + FinalFilePath.str();
    437       return true;
    438     }
    439 
    440     // Write the file magic number
    441     FinalFile << ARFILE_MAGIC;
    442 
    443     // If there is a foreign symbol table, put it into the file now. Most
    444     // ar(1) implementations require the symbol table to be first but llvm-ar
    445     // can deal with it being after a foreign symbol table. This ensures
    446     // compatibility with other ar(1) implementations as well as allowing the
    447     // archive to store both native .o and LLVM .bc files, both indexed.
    448     if (foreignST) {
    449       if (writeMember(*foreignST, FinalFile, false, false, false, ErrMsg)) {
    450         FinalFile.close();
    451         TmpArchive.eraseFromDisk();
    452         return true;
    453       }
    454     }
    455 
    456     // Put out the LLVM symbol table now.
    457     writeSymbolTable(FinalFile);
    458 
    459     // Copy the temporary file contents being sure to skip the file's magic
    460     // number.
    461     FinalFile.write(base + sizeof(ARFILE_MAGIC)-1,
    462       arch->getBufferSize()-sizeof(ARFILE_MAGIC)+1);
    463 
    464     // Close up shop
    465     FinalFile.close();
    466     } // free arch.
    467 
    468     // Move the final file over top of TmpArchive
    469     if (FinalFilePath.renamePathOnDisk(TmpArchive, ErrMsg))
    470       return true;
    471   }
    472 
    473   // Before we replace the actual archive, we need to forget all the
    474   // members, since they point to data in that old archive. We need to do
    475   // this because we cannot replace an open file on Windows.
    476   cleanUpMemory();
    477 
    478   if (TmpArchive.renamePathOnDisk(archPath, ErrMsg))
    479     return true;
    480 
    481   // Set correct read and write permissions after temporary file is moved
    482   // to final destination path.
    483   if (archPath.makeReadableOnDisk(ErrMsg))
    484     return true;
    485   if (archPath.makeWriteableOnDisk(ErrMsg))
    486     return true;
    487 
    488   return false;
    489 }
    490