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 bool 00188 Archive::writeMember( 00189 const ArchiveMember& member, 00190 std::ofstream& ARFile, 00191 bool CreateSymbolTable, 00192 bool TruncateNames, 00193 bool ShouldCompress, 00194 std::string* error 00195 ) { 00196 00197 unsigned filepos = ARFile.tellp(); 00198 filepos -= 8; 00199 00200 // Get the data and its size either from the 00201 // member's in-memory data or directly from the file. 00202 size_t fSize = member.getSize(); 00203 const char* data = (const char*)member.getData(); 00204 sys::MappedFile* mFile = 0; 00205 if (!data) { 00206 mFile = new sys::MappedFile(member.getPath()); 00207 data = (const char*) mFile->map(); 00208 fSize = mFile->size(); 00209 } 00210 00211 // Now that we have the data in memory, update the 00212 // symbol table if its a bytecode file. 00213 if (CreateSymbolTable && 00214 (member.isBytecode() || member.isCompressedBytecode())) { 00215 std::vector<std::string> symbols; 00216 std::string FullMemberName = archPath.toString() + "(" + 00217 member.getPath().toString() 00218 + ")"; 00219 ModuleProvider* MP = GetBytecodeSymbols( 00220 (const unsigned char*)data,fSize,FullMemberName, symbols); 00221 00222 // If the bytecode parsed successfully 00223 if ( MP ) { 00224 for (std::vector<std::string>::iterator SI = symbols.begin(), 00225 SE = symbols.end(); SI != SE; ++SI) { 00226 00227 std::pair<SymTabType::iterator,bool> Res = 00228 symTab.insert(std::make_pair(*SI,filepos)); 00229 00230 if (Res.second) { 00231 symTabSize += SI->length() + 00232 numVbrBytes(SI->length()) + 00233 numVbrBytes(filepos); 00234 } 00235 } 00236 // We don't need this module any more. 00237 delete MP; 00238 } else { 00239 if (mFile != 0) { 00240 mFile->close(); 00241 delete mFile; 00242 } 00243 if (error) 00244 *error = "Can't parse bytecode member: " + member.getPath().toString(); 00245 } 00246 } 00247 00248 // Determine if we actually should compress this member 00249 bool willCompress = 00250 (ShouldCompress && 00251 !member.isCompressed() && 00252 !member.isCompressedBytecode() && 00253 !member.isLLVMSymbolTable() && 00254 !member.isSVR4SymbolTable() && 00255 !member.isBSD4SymbolTable()); 00256 00257 // Perform the compression. Note that if the file is uncompressed bytecode 00258 // then we turn the file into compressed bytecode rather than treating it as 00259 // compressed data. This is necessary since it allows us to determine that the 00260 // file contains bytecode instead of looking like a regular compressed data 00261 // member. A compressed bytecode file has its content compressed but has a 00262 // magic number of "llvc". This acounts for the +/-4 arithmetic in the code 00263 // below. 00264 int hdrSize; 00265 if (willCompress) { 00266 char* output = 0; 00267 if (member.isBytecode()) { 00268 data +=4; 00269 fSize -= 4; 00270 } 00271 fSize = Compressor::compressToNewBuffer(data,fSize,output,error); 00272 if (fSize == 0) 00273 return false; 00274 data = output; 00275 if (member.isBytecode()) 00276 hdrSize = -fSize-4; 00277 else 00278 hdrSize = -fSize; 00279 } else { 00280 hdrSize = fSize; 00281 } 00282 00283 // Compute the fields of the header 00284 ArchiveMemberHeader Hdr; 00285 bool writeLongName = fillHeader(member,Hdr,hdrSize,TruncateNames); 00286 00287 // Write header to archive file 00288 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00289 00290 // Write the long filename if its long 00291 if (writeLongName) { 00292 ARFile.write(member.getPath().toString().data(), 00293 member.getPath().toString().length()); 00294 } 00295 00296 // Make sure we write the compressed bytecode magic number if we should. 00297 if (willCompress && member.isBytecode()) 00298 ARFile.write("llvc",4); 00299 00300 // Write the (possibly compressed) member's content to the file. 00301 ARFile.write(data,fSize); 00302 00303 // Make sure the member is an even length 00304 if ((ARFile.tellp() & 1) == 1) 00305 ARFile << ARFILE_PAD; 00306 00307 // Free the compressed data, if necessary 00308 if (willCompress) { 00309 free((void*)data); 00310 } 00311 00312 // Close the mapped file if it was opened 00313 if (mFile != 0) { 00314 mFile->close(); 00315 delete mFile; 00316 } 00317 return true; 00318 } 00319 00320 // Write out the LLVM symbol table as an archive member to the file. 00321 void 00322 Archive::writeSymbolTable(std::ofstream& ARFile) { 00323 00324 // Construct the symbol table's header 00325 ArchiveMemberHeader Hdr; 00326 Hdr.init(); 00327 memcpy(Hdr.name,ARFILE_LLVM_SYMTAB_NAME,16); 00328 uint64_t secondsSinceEpoch = sys::TimeValue::now().toEpochTime(); 00329 char buffer[32]; 00330 sprintf(buffer, "%-8o", 0644); 00331 memcpy(Hdr.mode,buffer,8); 00332 sprintf(buffer, "%-6u", sys::Process::GetCurrentUserId()); 00333 memcpy(Hdr.uid,buffer,6); 00334 sprintf(buffer, "%-6u", sys::Process::GetCurrentGroupId()); 00335 memcpy(Hdr.gid,buffer,6); 00336 sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch)); 00337 memcpy(Hdr.date,buffer,12); 00338 sprintf(buffer,"%-10u",symTabSize); 00339 memcpy(Hdr.size,buffer,10); 00340 00341 // Write the header 00342 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00343 00344 // Save the starting position of the symbol tables data content. 00345 unsigned startpos = ARFile.tellp(); 00346 00347 // Write out the symbols sequentially 00348 for ( Archive::SymTabType::iterator I = symTab.begin(), E = symTab.end(); 00349 I != E; ++I) 00350 { 00351 // Write out the file index 00352 writeInteger(I->second, ARFile); 00353 // Write out the length of the symbol 00354 writeInteger(I->first.length(), ARFile); 00355 // Write out the symbol 00356 ARFile.write(I->first.data(), I->first.length()); 00357 } 00358 00359 // Now that we're done with the symbol table, get the ending file position 00360 unsigned endpos = ARFile.tellp(); 00361 00362 // Make sure that the amount we wrote is what we pre-computed. This is 00363 // critical for file integrity purposes. 00364 assert(endpos - startpos == symTabSize && "Invalid symTabSize computation"); 00365 00366 // Make sure the symbol table is even sized 00367 if (symTabSize % 2 != 0 ) 00368 ARFile << ARFILE_PAD; 00369 } 00370 00371 // Write the entire archive to the file specified when the archive was created. 00372 // This writes to a temporary file first. Options are for creating a symbol 00373 // table, flattening the file names (no directories, 15 chars max) and 00374 // compressing each archive member. 00375 bool 00376 Archive::writeToDisk(bool CreateSymbolTable, bool TruncateNames, bool Compress, 00377 std::string* error) 00378 { 00379 // Make sure they haven't opened up the file, not loaded it, 00380 // but are now trying to write it which would wipe out the file. 00381 assert(!(members.empty() && mapfile->size() > 8) && 00382 "Can't write an archive not opened for writing"); 00383 00384 // Create a temporary file to store the archive in 00385 sys::Path TmpArchive = archPath; 00386 TmpArchive.createTemporaryFileOnDisk(); 00387 00388 // Make sure the temporary gets removed if we crash 00389 sys::RemoveFileOnSignal(TmpArchive); 00390 00391 // Create archive file for output. 00392 std::ios::openmode io_mode = std::ios::out | std::ios::trunc | 00393 std::ios::binary; 00394 std::ofstream ArchiveFile(TmpArchive.c_str(), io_mode); 00395 00396 // Check for errors opening or creating archive file. 00397 if ( !ArchiveFile.is_open() || ArchiveFile.bad() ) { 00398 if (TmpArchive.exists()) 00399 TmpArchive.eraseFromDisk(); 00400 if (error) 00401 *error = "Error opening archive file: " + archPath.toString(); 00402 return false; 00403 } 00404 00405 // If we're creating a symbol table, reset it now 00406 if (CreateSymbolTable) { 00407 symTabSize = 0; 00408 symTab.clear(); 00409 } 00410 00411 // Write magic string to archive. 00412 ArchiveFile << ARFILE_MAGIC; 00413 00414 // Loop over all member files, and write them out. Note that this also 00415 // builds the symbol table, symTab. 00416 for ( MembersList::iterator I = begin(), E = end(); I != E; ++I) { 00417 if (!writeMember(*I,ArchiveFile,CreateSymbolTable, 00418 TruncateNames,Compress,error)) 00419 { 00420 if (TmpArchive.exists()) 00421 TmpArchive.eraseFromDisk(); 00422 ArchiveFile.close(); 00423 return false; 00424 } 00425 } 00426 00427 // Close archive file. 00428 ArchiveFile.close(); 00429 00430 // Write the symbol table 00431 if (CreateSymbolTable) { 00432 // At this point we have written a file that is a legal archive but it 00433 // doesn't have a symbol table in it. To aid in faster reading and to 00434 // ensure compatibility with other archivers we need to put the symbol 00435 // table first in the file. Unfortunately, this means mapping the file 00436 // we just wrote back in and copying it to the destination file. 00437 00438 // Map in the archive we just wrote. 00439 sys::MappedFile arch(TmpArchive); 00440 const char* base = (const char*) arch.map(); 00441 00442 // Open another temporary file in order to avoid invalidating the 00443 // mmapped data 00444 sys::Path FinalFilePath = archPath; 00445 FinalFilePath.createTemporaryFileOnDisk(); 00446 sys::RemoveFileOnSignal(FinalFilePath); 00447 00448 std::ofstream FinalFile(FinalFilePath.c_str(), io_mode); 00449 if ( !FinalFile.is_open() || FinalFile.bad() ) { 00450 if (TmpArchive.exists()) 00451 TmpArchive.eraseFromDisk(); 00452 if (error) 00453 *error = "Error opening archive file: " + FinalFilePath.toString(); 00454 return false; 00455 } 00456 00457 // Write the file magic number 00458 FinalFile << ARFILE_MAGIC; 00459 00460 // If there is a foreign symbol table, put it into the file now. Most 00461 // ar(1) implementations require the symbol table to be first but llvm-ar 00462 // can deal with it being after a foreign symbol table. This ensures 00463 // compatibility with other ar(1) implementations as well as allowing the 00464 // archive to store both native .o and LLVM .bc files, both indexed. 00465 if (foreignST) { 00466 if (!writeMember(*foreignST, FinalFile, false, false, false, error)) { 00467 FinalFile.close(); 00468 if (TmpArchive.exists()) 00469 TmpArchive.eraseFromDisk(); 00470 return false; 00471 } 00472 } 00473 00474 // Put out the LLVM symbol table now. 00475 writeSymbolTable(FinalFile); 00476 00477 // Copy the temporary file contents being sure to skip the file's magic 00478 // number. 00479 FinalFile.write(base + sizeof(ARFILE_MAGIC)-1, 00480 arch.size()-sizeof(ARFILE_MAGIC)+1); 00481 00482 // Close up shop 00483 FinalFile.close(); 00484 arch.close(); 00485 00486 // Move the final file over top of TmpArchive 00487 FinalFilePath.renamePathOnDisk(TmpArchive); 00488 } 00489 00490 // Before we replace the actual archive, we need to forget all the 00491 // members, since they point to data in that old archive. We need to do 00492 // this because we cannot replace an open file on Windows. 00493 cleanUpMemory(); 00494 00495 TmpArchive.renamePathOnDisk(archPath); 00496 00497 return true; 00498 }