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/FileUtilities.h" 00017 #include "llvm/Support/Compressor.h" 00018 #include "llvm/System/Signals.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().get(); 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.get().find('/') != std::string::npos; 00166 if (hasSlash) 00167 flags |= ArchiveMember::HasPathFlag; 00168 if (hasSlash || filePath.get().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.get() + "(" + member.getPath().get() 00216 + ")"; 00217 ModuleProvider* MP = GetBytecodeSymbols( 00218 (const unsigned char*)data,fSize,FullMemberName, symbols); 00219 00220 // If the bytecode parsed successfully 00221 if ( MP ) { 00222 for (std::vector<std::string>::iterator SI = symbols.begin(), 00223 SE = symbols.end(); SI != SE; ++SI) { 00224 00225 std::pair<SymTabType::iterator,bool> Res = 00226 symTab.insert(std::make_pair(*SI,filepos)); 00227 00228 if (Res.second) { 00229 symTabSize += SI->length() + 00230 numVbrBytes(SI->length()) + 00231 numVbrBytes(filepos); 00232 } 00233 } 00234 // We don't need this module any more. 00235 delete MP; 00236 } else { 00237 throw std::string("Can't parse bytecode member: ") + 00238 member.getPath().get(); 00239 } 00240 } 00241 00242 // Determine if we actually should compress this member 00243 bool willCompress = 00244 (ShouldCompress && 00245 !member.isCompressed() && 00246 !member.isCompressedBytecode() && 00247 !member.isLLVMSymbolTable() && 00248 !member.isSVR4SymbolTable() && 00249 !member.isBSD4SymbolTable()); 00250 00251 // Perform the compression. Note that if the file is uncompressed bytecode 00252 // then we turn the file into compressed bytecode rather than treating it as 00253 // compressed data. This is necessary since it allows us to determine that the 00254 // file contains bytecode instead of looking like a regular compressed data 00255 // member. A compressed bytecode file has its content compressed but has a 00256 // magic number of "llvc". This acounts for the +/-4 arithmetic in the code 00257 // below. 00258 int hdrSize; 00259 if (willCompress) { 00260 char* output = 0; 00261 if (member.isBytecode()) { 00262 data +=4; 00263 fSize -= 4; 00264 } 00265 fSize = Compressor::compressToNewBuffer(data,fSize,output); 00266 data = output; 00267 if (member.isBytecode()) 00268 hdrSize = -fSize-4; 00269 else 00270 hdrSize = -fSize; 00271 } else { 00272 hdrSize = fSize; 00273 } 00274 00275 // Compute the fields of the header 00276 ArchiveMemberHeader Hdr; 00277 bool writeLongName = fillHeader(member,Hdr,hdrSize,TruncateNames); 00278 00279 // Write header to archive file 00280 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00281 00282 // Write the long filename if its long 00283 if (writeLongName) { 00284 ARFile.write(member.getPath().get().data(),member.getPath().get().length()); 00285 } 00286 00287 // Make sure we write the compressed bytecode magic number if we should. 00288 if (willCompress && member.isBytecode()) 00289 ARFile.write("llvc",4); 00290 00291 // Write the (possibly compressed) member's content to the file. 00292 ARFile.write(data,fSize); 00293 00294 // Make sure the member is an even length 00295 if (ARFile.tellp() & 1 == 1) 00296 ARFile << ARFILE_PAD; 00297 00298 // Free the compressed data, if necessary 00299 if (willCompress) { 00300 free((void*)data); 00301 } 00302 00303 // Close the mapped file if it was opened 00304 if (mFile != 0) { 00305 mFile->unmap(); 00306 delete mFile; 00307 } 00308 } 00309 00310 // Write out the LLVM symbol table as an archive member to the file. 00311 void 00312 Archive::writeSymbolTable(std::ofstream& ARFile) { 00313 00314 // Construct the symbol table's header 00315 ArchiveMemberHeader Hdr; 00316 Hdr.init(); 00317 memcpy(Hdr.name,ARFILE_LLVM_SYMTAB_NAME,16); 00318 uint64_t secondsSinceEpoch = sys::TimeValue::now().toEpochTime(); 00319 char buffer[32]; 00320 sprintf(buffer,"%-12u", unsigned(secondsSinceEpoch)); 00321 memcpy(Hdr.date,buffer,12); 00322 sprintf(buffer,"%-10u",symTabSize); 00323 memcpy(Hdr.size,buffer,10); 00324 00325 // Write the header 00326 ARFile.write((char*)&Hdr, sizeof(Hdr)); 00327 00328 // Save the starting position of the symbol tables data content. 00329 unsigned startpos = ARFile.tellp(); 00330 00331 // Write out the symbols sequentially 00332 for ( Archive::SymTabType::iterator I = symTab.begin(), E = symTab.end(); 00333 I != E; ++I) 00334 { 00335 // Write out the file index 00336 writeInteger(I->second, ARFile); 00337 // Write out the length of the symbol 00338 writeInteger(I->first.length(), ARFile); 00339 // Write out the symbol 00340 ARFile.write(I->first.data(), I->first.length()); 00341 } 00342 00343 // Now that we're done with the symbol table, get the ending file position 00344 unsigned endpos = ARFile.tellp(); 00345 00346 // Make sure that the amount we wrote is what we pre-computed. This is 00347 // critical for file integrity purposes. 00348 assert(endpos - startpos == symTabSize && "Invalid symTabSize computation"); 00349 00350 // Make sure the symbol table is even sized 00351 if (symTabSize % 2 != 0 ) 00352 ARFile << ARFILE_PAD; 00353 } 00354 00355 // Write the entire archive to the file specified when the archive was created. 00356 // This writes to a temporary file first. Options are for creating a symbol 00357 // table, flattening the file names (no directories, 15 chars max) and 00358 // compressing each archive member. 00359 void 00360 Archive::writeToDisk(bool CreateSymbolTable, bool TruncateNames, bool Compress){ 00361 00362 // Make sure they haven't opened up the file, not loaded it, 00363 // but are now trying to write it which would wipe out the file. 00364 assert(!(members.empty() && mapfile->size() > 8) && 00365 "Can't write an archive not opened for writing"); 00366 00367 // Create a temporary file to store the archive in 00368 sys::Path TmpArchive = archPath; 00369 TmpArchive.createTemporaryFile(); 00370 00371 // Make sure the temporary gets removed if we crash 00372 sys::RemoveFileOnSignal(TmpArchive); 00373 00374 // Ensure we can remove the temporary even in the face of an exception 00375 try { 00376 // Create archive file for output. 00377 std::ofstream ArchiveFile(TmpArchive.c_str()); 00378 00379 // Check for errors opening or creating archive file. 00380 if ( !ArchiveFile.is_open() || ArchiveFile.bad() ) { 00381 throw std::string("Error opening archive file: ") + archPath.get(); 00382 } 00383 00384 // If we're creating a symbol table, reset it now 00385 if (CreateSymbolTable) { 00386 symTabSize = 0; 00387 symTab.clear(); 00388 } 00389 00390 // Write magic string to archive. 00391 ArchiveFile << ARFILE_MAGIC; 00392 00393 // Loop over all member files, and write them out. Note that this also 00394 // builds the symbol table, symTab. 00395 for ( MembersList::iterator I = begin(), E = end(); I != E; ++I) { 00396 writeMember(*I,ArchiveFile,CreateSymbolTable,TruncateNames,Compress); 00397 } 00398 00399 // Close archive file. 00400 ArchiveFile.close(); 00401 00402 // Write the symbol table 00403 if (CreateSymbolTable) { 00404 // At this point we have written a file that is a legal archive but it 00405 // doesn't have a symbol table in it. To aid in faster reading and to 00406 // ensure compatibility with other archivers we need to put the symbol 00407 // table first in the file. Unfortunately, this means mapping the file 00408 // we just wrote back in and copying it to the destination file. 00409 00410 // Map in the archive we just wrote. 00411 sys::MappedFile arch(TmpArchive); 00412 const char* base = (const char*) arch.map(); 00413 00414 // Open the final file to write and check it. 00415 std::ofstream FinalFile(archPath.c_str()); 00416 if ( !FinalFile.is_open() || FinalFile.bad() ) { 00417 throw std::string("Error opening archive file: ") + archPath.get(); 00418 } 00419 00420 // Write the file magic number 00421 FinalFile << ARFILE_MAGIC; 00422 00423 // If there is a foreign symbol table, put it into the file now. Most 00424 // ar(1) implementations require the symbol table to be first but llvm-ar 00425 // can deal with it being after a foreign symbol table. This ensures 00426 // compatibility with other ar(1) implementations as well as allowing the 00427 // archive to store both native .o and LLVM .bc files, both indexed. 00428 if (foreignST) { 00429 writeMember(*foreignST, FinalFile, false, false, false); 00430 } 00431 00432 // Put out the LLVM symbol table now. 00433 writeSymbolTable(FinalFile); 00434 00435 // Copy the temporary file contents being sure to skip the file's magic 00436 // number. 00437 FinalFile.write(base + sizeof(ARFILE_MAGIC)-1, 00438 arch.size()-sizeof(ARFILE_MAGIC)+1); 00439 00440 // Close up shop 00441 FinalFile.close(); 00442 arch.unmap(); 00443 TmpArchive.destroyFile(); 00444 00445 } else { 00446 // We don't have to insert the symbol table, so just renaming the temp 00447 // file to the correct name will suffice. 00448 TmpArchive.renameFile(archPath); 00449 } 00450 } catch (...) { 00451 // Make sure we clean up. 00452 if (TmpArchive.exists()) 00453 TmpArchive.destroyFile(); 00454 throw; 00455 } 00456 }