LLVM API Documentation
00001 //===-- ArchiveWriter.cpp - Write LLVM archive files ----------------------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by Reid Spencer and is distributed under the 00006 // University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // Builds up an LLVM archive file (.a) containing LLVM bytecode. 00011 // 00012 //===----------------------------------------------------------------------===// 00013 00014 #include "ArchiveInternals.h" 00015 #include "llvm/Bytecode/Reader.h" 00016 #include "llvm/Support/Compressor.h" 00017 #include "llvm/System/Signals.h" 00018 #include "llvm/System/Process.h" 00019 #include <fstream> 00020 #include <iostream> 00021 #include <iomanip> 00022 00023 using namespace llvm; 00024 00025 // Write an integer using variable bit rate encoding. This saves a few bytes 00026 // per entry in the symbol table. 00027 inline void writeInteger(unsigned num, std::ofstream& ARFile) { 00028 while (1) { 00029 if (num < 0x80) { // done? 00030 ARFile << (unsigned char)num; 00031 return; 00032 } 00033 00034 // Nope, we are bigger than a character, output the next 7 bits and set the 00035 // high bit to say that there is more coming... 00036 ARFile << (unsigned char)(0x80 | ((unsigned char)num & 0x7F)); 00037 num >>= 7; // Shift out 7 bits now... 00038 } 00039 } 00040 00041 // Compute how many bytes are taken by a given VBR encoded value. This is needed 00042 // to pre-compute the size of the symbol table. 00043 inline unsigned numVbrBytes(unsigned num) { 00044 00045 // Note that the following nested ifs are somewhat equivalent to a binary 00046 // search. We split it in half by comparing against 2^14 first. This allows 00047 // most reasonable values to be done in 2 comparisons instead of 1 for 00048 // small ones and four for large ones. We expect this to access file offsets 00049 // in the 2^10 to 2^24 range and symbol lengths in the 2^0 to 2^8 range, 00050 // so this approach is reasonable. 00051 if (num < 1<<14) 00052 if (num < 1<<7) 00053 return 1; 00054 else 00055 return 2; 00056 if (num < 1<<21) 00057 return 3; 00058 00059 if (num < 1<<28) 00060 return 4; 00061 return 5; // anything >= 2^28 takes 5 bytes 00062 } 00063 00064 // Create an empty archive. 00065 Archive* 00066 Archive::CreateEmpty(const sys::Path& FilePath ) { 00067 Archive* result = new Archive(FilePath,false); 00068 return result; 00069 } 00070 00071 // Fill the ArchiveMemberHeader with the information from a member. If 00072 // TruncateNames is true, names are flattened to 15 chars or less. The sz field 00073 // is provided here instead of coming from the mbr because the member might be 00074 // stored compressed and the compressed size is not the ArchiveMember's size. 00075 // Furthermore compressed files have negative size fields to identify them as 00076 // compressed. 00077 bool 00078 Archive::fillHeader(const ArchiveMember &mbr, ArchiveMemberHeader& hdr, 00079 int sz, bool TruncateNames) const { 00080 00081 // Set the permissions mode, uid and gid 00082 hdr.init(); 00083 char buffer[32]; 00084 sprintf(buffer, "%-8o", mbr.getMode()); 00085 memcpy(hdr.mode,buffer,8); 00086 sprintf(buffer, "%-6u", mbr.getUser()); 00087 memcpy(hdr.uid,buffer,6); 00088 sprintf(buffer, "%-6u", mbr.getGroup()); 00089 memcpy(hdr.gid,buffer,6); 00090 00091 // Set the last modification date 00092 uint64_t secondsSinceEpoch = mbr.getModTime().toEpochTime(); 00093 sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch)); 00094 memcpy(hdr.date,buffer,12); 00095 00096 // Get rid of trailing blanks in the name 00097 std::string mbrPath = mbr.getPath().toString(); 00098 size_t mbrLen = mbrPath.length(); 00099 while (mbrLen > 0 && mbrPath[mbrLen-1] == ' ') { 00100 mbrPath.erase(mbrLen-1,1); 00101 mbrLen--; 00102 } 00103 00104 // Set the name field in one of its various flavors. 00105 bool writeLongName = false; 00106 if (mbr.isStringTable()) { 00107 memcpy(hdr.name,ARFILE_STRTAB_NAME,16); 00108 } else if (mbr.isSVR4SymbolTable()) { 00109 memcpy(hdr.name,ARFILE_SVR4_SYMTAB_NAME,16); 00110 } else if (mbr.isBSD4SymbolTable()) { 00111 memcpy(hdr.name,ARFILE_BSD4_SYMTAB_NAME,16); 00112 } else if (mbr.isLLVMSymbolTable()) { 00113 memcpy(hdr.name,ARFILE_LLVM_SYMTAB_NAME,16); 00114 } else if (TruncateNames) { 00115 const char* nm = mbrPath.c_str(); 00116 unsigned len = mbrPath.length(); 00117 size_t slashpos = mbrPath.rfind('/'); 00118 if (slashpos != std::string::npos) { 00119 nm += slashpos + 1; 00120 len -= slashpos +1; 00121 } 00122 if (len > 15) 00123 len = 15; 00124 memcpy(hdr.name,nm,len); 00125 hdr.name[len] = '/'; 00126 } else if (mbrPath.length() < 16 && mbrPath.find('/') == std::string::npos) { 00127 memcpy(hdr.name,mbrPath.c_str(),mbrPath.length()); 00128 hdr.name[mbrPath.length()] = '/'; 00129 } else { 00130 std::string nm = "#1/"; 00131 nm += utostr(mbrPath.length()); 00132 memcpy(hdr.name,nm.data(),nm.length()); 00133 if (sz < 0) 00134 sz -= mbrPath.length(); 00135 else 00136 sz += mbrPath.length(); 00137 writeLongName = true; 00138 } 00139 00140 // Set the size field 00141 if (sz < 0) { 00142 buffer[0] = '-'; 00143 sprintf(&buffer[1],"%-9u",(unsigned)-sz); 00144 } else { 00145 sprintf(buffer, "%-10u", (unsigned)sz); 00146 } 00147 memcpy(hdr.size,buffer,10); 00148 00149 return writeLongName; 00150 } 00151 00152 // Insert a file into the archive before some other member. This also takes care 00153 // of extracting the necessary flags and information from the file. 00154 void 00155 Archive::addFileBefore(const sys::Path& filePath, iterator where) { 00156 assert(filePath.exists() && "Can't add a non-existent file"); 00157 00158 ArchiveMember* mbr = new ArchiveMember(this); 00159 00160 mbr->data = 0; 00161 mbr->path = filePath; 00162 mbr->path.getStatusInfo(mbr->info); 00163 00164 unsigned flags = 0; 00165 bool hasSlash = filePath.toString().find('/') != std::string::npos; 00166 if (hasSlash) 00167 flags |= ArchiveMember::HasPathFlag; 00168 if (hasSlash || filePath.toString().length() > 15) 00169 flags |= ArchiveMember::HasLongFilenameFlag; 00170 std::string magic; 00171 mbr->path.getMagicNumber(magic,4); 00172 switch (sys::IdentifyFileType(magic.c_str(),4)) { 00173 case sys::BytecodeFileType: 00174 flags |= ArchiveMember::BytecodeFlag; 00175 break; 00176 case sys::CompressedBytecodeFileType: 00177 flags |= ArchiveMember::CompressedBytecodeFlag; 00178 break; 00179 default: 00180 break; 00181 } 00182 mbr->flags = flags; 00183 members.insert(where,mbr); 00184 } 00185 00186 // Write one member out to the file. 00187 void 00188 Archive::writeMember( 00189 const ArchiveMember& member, 00190 std::ofstream& ARFile, 00191 bool CreateSymbolTable, 00192 bool TruncateNames, 00193 bool ShouldCompress 00194 ) { 00195 00196 unsigned filepos = ARFile.tellp(); 00197 filepos -= 8; 00198 00199 // Get the data and its size either from the 00200 // member's in-memory data or directly from the file. 00201 size_t fSize = member.getSize(); 00202 const char* data = (const char*)member.getData(); 00203 sys::MappedFile* mFile = 0; 00204 if (!data) { 00205 mFile = new sys::MappedFile(member.getPath()); 00206 data = (const char*) mFile->map(); 00207 fSize = mFile->size(); 00208 } 00209 00210 // Now that we have the data in memory, update the 00211 // symbol table if its a bytecode file. 00212 if (CreateSymbolTable && 00213 (member.isBytecode() || member.isCompressedBytecode())) { 00214 std::vector<std::string> symbols; 00215 std::string FullMemberName = archPath.toString() + "(" + 00216 member.getPath().toString() 00217 + ")"; 00218 ModuleProvider* MP = GetBytecodeSymbols( 00219 (const unsigned char*)data,fSize,FullMemberName, symbols); 00220 00221 // If the bytecode parsed successfully 00222 if ( MP ) { 00223 for (std::vector<std::string>::iterator SI = symbols.begin(), 00224 SE = symbols.end(); SI != SE; ++SI) { 00225 00226 std::pair<SymTabType::iterator,bool> Res = 00227 symTab.insert(std::make_pair(*SI,filepos)); 00228 00229 if (Res.second) { 00230 symTabSize += SI->length() + 00231 numVbrBytes(SI->length()) + 00232 numVbrBytes(filepos); 00233 } 00234 } 00235 // We don't need this module any more. 00236 delete MP; 00237 } else { 00238 throw std::string("Can't parse bytecode member: ") + 00239 member.getPath().toString(); 00240 } 00241 } 00242 00243 // Determine if we actually should compress this member 00244 bool willCompress = 00245 (ShouldCompress && 00246 !member.isCompressed() && 00247 !member.isCompressedBytecode() && 00248 !member.isLLVMSymbolTable() && 00249 !member.isSVR4SymbolTable() && 00250 !member.isBSD4SymbolTable()); 00251 00252 // Perform the compression. Note that if the file is uncompressed bytecode 00253 // then we turn the file into compressed bytecode rather than treating it as 00254 // compressed data. This is necessary since it allows us to determine that the 00255 // file contains bytecode instead of looking like a regular compressed data 00256 // member. A compressed bytecode file has its content compressed but has a 00257 // magic number of "llvc". This acounts for the +/-4 arithmetic in the code 00258 // below. 00259 int hdrSize; 00260 if (willCompress) { 00261 char* output = 0; 00262 if (member.isBytecode()) { 00263 data +=4; 00264 fSize -= 4; 00265 } 00266 fSize = Compressor::compressToNewBuffer(data,fSize,output); 00267 data = output; 00268 if (member.isBytecode()) 00269 hdrSize = -fSize-4; 00270 else 00271 hdrSize = -fSize; 00272 } else { 00273 hdrSize = fSize; 00274 } 00275 00276 // Compute the fields of the header 00277 ArchiveMemberHeader Hdr; 00278 bool writeLongName = fillHeader(member,Hdr,hdrSize,TruncateNames); 00279 00280 // Write header to archive file 00281 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00282 00283 // Write the long filename if its long 00284 if (writeLongName) { 00285 ARFile.write(member.getPath().toString().data(), 00286 member.getPath().toString().length()); 00287 } 00288 00289 // Make sure we write the compressed bytecode magic number if we should. 00290 if (willCompress && member.isBytecode()) 00291 ARFile.write("llvc",4); 00292 00293 // Write the (possibly compressed) member's content to the file. 00294 ARFile.write(data,fSize); 00295 00296 // Make sure the member is an even length 00297 if ((ARFile.tellp() & 1) == 1) 00298 ARFile << ARFILE_PAD; 00299 00300 // Free the compressed data, if necessary 00301 if (willCompress) { 00302 free((void*)data); 00303 } 00304 00305 // Close the mapped file if it was opened 00306 if (mFile != 0) { 00307 mFile->close(); 00308 delete mFile; 00309 } 00310 } 00311 00312 // Write out the LLVM symbol table as an archive member to the file. 00313 void 00314 Archive::writeSymbolTable(std::ofstream& ARFile) { 00315 00316 // Construct the symbol table's header 00317 ArchiveMemberHeader Hdr; 00318 Hdr.init(); 00319 memcpy(Hdr.name,ARFILE_LLVM_SYMTAB_NAME,16); 00320 uint64_t secondsSinceEpoch = sys::TimeValue::now().toEpochTime(); 00321 char buffer[32]; 00322 sprintf(buffer, "%-8o", 0644); 00323 memcpy(Hdr.mode,buffer,8); 00324 sprintf(buffer, "%-6u", sys::Process::GetCurrentUserId()); 00325 memcpy(Hdr.uid,buffer,6); 00326 sprintf(buffer, "%-6u", sys::Process::GetCurrentGroupId()); 00327 memcpy(Hdr.gid,buffer,6); 00328 sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch)); 00329 memcpy(Hdr.date,buffer,12); 00330 sprintf(buffer,"%-10u",symTabSize); 00331 memcpy(Hdr.size,buffer,10); 00332 00333 // Write the header 00334 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00335 00336 // Save the starting position of the symbol tables data content. 00337 unsigned startpos = ARFile.tellp(); 00338 00339 // Write out the symbols sequentially 00340 for ( Archive::SymTabType::iterator I = symTab.begin(), E = symTab.end(); 00341 I != E; ++I) 00342 { 00343 // Write out the file index 00344 writeInteger(I->second, ARFile); 00345 // Write out the length of the symbol 00346 writeInteger(I->first.length(), ARFile); 00347 // Write out the symbol 00348 ARFile.write(I->first.data(), I->first.length()); 00349 } 00350 00351 // Now that we're done with the symbol table, get the ending file position 00352 unsigned endpos = ARFile.tellp(); 00353 00354 // Make sure that the amount we wrote is what we pre-computed. This is 00355 // critical for file integrity purposes. 00356 assert(endpos - startpos == symTabSize && "Invalid symTabSize computation"); 00357 00358 // Make sure the symbol table is even sized 00359 if (symTabSize % 2 != 0 ) 00360 ARFile << ARFILE_PAD; 00361 } 00362 00363 // Write the entire archive to the file specified when the archive was created. 00364 // This writes to a temporary file first. Options are for creating a symbol 00365 // table, flattening the file names (no directories, 15 chars max) and 00366 // compressing each archive member. 00367 void 00368 Archive::writeToDisk(bool CreateSymbolTable, bool TruncateNames, bool Compress){ 00369 00370 // Make sure they haven't opened up the file, not loaded it, 00371 // but are now trying to write it which would wipe out the file. 00372 assert(!(members.empty() && mapfile->size() > 8) && 00373 "Can't write an archive not opened for writing"); 00374 00375 // Create a temporary file to store the archive in 00376 sys::Path TmpArchive = archPath; 00377 TmpArchive.createTemporaryFileOnDisk(); 00378 00379 // Make sure the temporary gets removed if we crash 00380 sys::RemoveFileOnSignal(TmpArchive); 00381 00382 // Ensure we can remove the temporary even in the face of an exception 00383 try { 00384 // Create archive file for output. 00385 std::ios::openmode io_mode = std::ios::out | std::ios::trunc | 00386 std::ios::binary; 00387 std::ofstream ArchiveFile(TmpArchive.c_str(), io_mode); 00388 00389 // Check for errors opening or creating archive file. 00390 if ( !ArchiveFile.is_open() || ArchiveFile.bad() ) { 00391 throw std::string("Error opening archive file: ") + archPath.toString(); 00392 } 00393 00394 // If we're creating a symbol table, reset it now 00395 if (CreateSymbolTable) { 00396 symTabSize = 0; 00397 symTab.clear(); 00398 } 00399 00400 // Write magic string to archive. 00401 ArchiveFile << ARFILE_MAGIC; 00402 00403 // Loop over all member files, and write them out. Note that this also 00404 // builds the symbol table, symTab. 00405 for ( MembersList::iterator I = begin(), E = end(); I != E; ++I) { 00406 writeMember(*I,ArchiveFile,CreateSymbolTable,TruncateNames,Compress); 00407 } 00408 00409 // Close archive file. 00410 ArchiveFile.close(); 00411 00412 // Write the symbol table 00413 if (CreateSymbolTable) { 00414 // At this point we have written a file that is a legal archive but it 00415 // doesn't have a symbol table in it. To aid in faster reading and to 00416 // ensure compatibility with other archivers we need to put the symbol 00417 // table first in the file. Unfortunately, this means mapping the file 00418 // we just wrote back in and copying it to the destination file. 00419 00420 // Map in the archive we just wrote. 00421 sys::MappedFile arch(TmpArchive); 00422 const char* base = (const char*) arch.map(); 00423 00424 // Open another temporary file in order to avoid invalidating the mmapped data 00425 sys::Path FinalFilePath = archPath; 00426 FinalFilePath.createTemporaryFileOnDisk(); 00427 sys::RemoveFileOnSignal(FinalFilePath); 00428 try { 00429 00430 00431 std::ofstream FinalFile(FinalFilePath.c_str(), io_mode); 00432 if ( !FinalFile.is_open() || FinalFile.bad() ) { 00433 throw std::string("Error opening archive file: ") + FinalFilePath.toString(); 00434 } 00435 00436 // Write the file magic number 00437 FinalFile << ARFILE_MAGIC; 00438 00439 // If there is a foreign symbol table, put it into the file now. Most 00440 // ar(1) implementations require the symbol table to be first but llvm-ar 00441 // can deal with it being after a foreign symbol table. This ensures 00442 // compatibility with other ar(1) implementations as well as allowing the 00443 // archive to store both native .o and LLVM .bc files, both indexed. 00444 if (foreignST) { 00445 writeMember(*foreignST, FinalFile, false, false, false); 00446 } 00447 00448 // Put out the LLVM symbol table now. 00449 writeSymbolTable(FinalFile); 00450 00451 // Copy the temporary file contents being sure to skip the file's magic 00452 // number. 00453 FinalFile.write(base + sizeof(ARFILE_MAGIC)-1, 00454 arch.size()-sizeof(ARFILE_MAGIC)+1); 00455 00456 // Close up shop 00457 FinalFile.close(); 00458 arch.close(); 00459 00460 // Move the final file over top of TmpArchive 00461 FinalFilePath.renamePathOnDisk(TmpArchive); 00462 } catch (...) { 00463 // Make sure we clean up. 00464 if (FinalFilePath.exists()) 00465 FinalFilePath.eraseFromDisk(); 00466 throw; 00467 } 00468 } 00469 00470 // Before we replace the actual archive, we need to forget all the 00471 // members, since they point to data in that old archive. We need to do 00472 // we cannot replace an open file on Windows. 00473 cleanUpMemory(); 00474 00475 TmpArchive.renamePathOnDisk(archPath); 00476 } catch (...) { 00477 // Make sure we clean up. 00478 if (TmpArchive.exists()) 00479 TmpArchive.eraseFromDisk(); 00480 throw; 00481 } 00482 }