lib/Support/FileUtilities.cpp

   1 //===- Support/FileUtilities.cpp - File System Utilities ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements a family of utility functions which are useful for doing
  10 // various things with files.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/FileUtilities.h"
  15 #include "llvm/ADT/ScopeExit.h"
  16 #include "llvm/ADT/SmallString.h"
  17 #include "llvm/Support/Error.h"
  18 #include "llvm/Support/ErrorOr.h"
  19 #include "llvm/Support/MemoryBuffer.h"
  20 #include "llvm/Support/Path.h"
  21 #include "llvm/Support/raw_ostream.h"
  22 #include <cctype>
  23 #include <cmath>
  24 #include <cstdint>
  25 #include <cstdlib>
  26 #include <cstring>
  27 #include <memory>
  28 #include <system_error>
  29
  30 using namespace llvm;
  31
  32 static bool isSignedChar(char C) {
  33   return (C == '+' || C == '-');
  34 }
  35
  36 static bool isExponentChar(char C) {
  37   switch (C) {
  38   case 'D':  // Strange exponential notation.
  39   case 'd':  // Strange exponential notation.
  40   case 'e':
  41   case 'E': return true;
  42   default: return false;
  43   }
  44 }
  45
  46 static bool isNumberChar(char C) {
  47   switch (C) {
  48   case '0': case '1': case '2': case '3': case '4':
  49   case '5': case '6': case '7': case '8': case '9':
  50   case '.': return true;
  51   default: return isSignedChar(C) || isExponentChar(C);
  52   }
  53 }
  54
  55 static const char *BackupNumber(const char *Pos, const char *FirstChar) {
  56   // If we didn't stop in the middle of a number, don't backup.
  57   if (!isNumberChar(*Pos)) return Pos;
  58
  59   // Otherwise, return to the start of the number.
  60   bool HasPeriod = false;
  61   while (Pos > FirstChar && isNumberChar(Pos[-1])) {
  62     // Backup over at most one period.
  63     if (Pos[-1] == '.') {
  64       if (HasPeriod)
  65         break;
  66       HasPeriod = true;
  67     }
  68
  69     --Pos;
  70     if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
  71       break;
  72   }
  73   return Pos;
  74 }
  75
  76 /// EndOfNumber - Return the first character that is not part of the specified
  77 /// number.  This assumes that the buffer is null terminated, so it won't fall
  78 /// off the end.
  79 static const char *EndOfNumber(const char *Pos) {
  80   while (isNumberChar(*Pos))
  81     ++Pos;
  82   return Pos;
  83 }
  84
  85 /// CompareNumbers - compare two numbers, returning true if they are different.
  86 static bool CompareNumbers(const char *&F1P, const char *&F2P,
  87                            const char *F1End, const char *F2End,
  88                            double AbsTolerance, double RelTolerance,
  89                            std::string *ErrorMsg) {
  90   const char *F1NumEnd, *F2NumEnd;
  91   double V1 = 0.0, V2 = 0.0;
  92
  93   // If one of the positions is at a space and the other isn't, chomp up 'til
  94   // the end of the space.
  95   while (isspace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
  96     ++F1P;
  97   while (isspace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
  98     ++F2P;
  99
 100   // If we stop on numbers, compare their difference.
 101   if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
 102     // The diff failed.
 103     F1NumEnd = F1P;
 104     F2NumEnd = F2P;
 105   } else {
 106     // Note that some ugliness is built into this to permit support for numbers
 107     // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
 108     // occurs in 200.sixtrack in spec2k.
 109     V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
 110     V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
 111
 112     if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
 113       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 114       SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
 115       // Strange exponential notation!
 116       StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
 117
 118       V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
 119       F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
 120     }
 121
 122     if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
 123       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 124       SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
 125       // Strange exponential notation!
 126       StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
 127
 128       V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
 129       F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
 130     }
 131   }
 132
 133   if (F1NumEnd == F1P || F2NumEnd == F2P) {
 134     if (ErrorMsg) {
 135       *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
 136       *ErrorMsg += F1P[0];
 137       *ErrorMsg += "' and '";
 138       *ErrorMsg += F2P[0];
 139       *ErrorMsg += "'";
 140     }
 141     return true;
 142   }
 143
 144   // Check to see if these are inside the absolute tolerance
 145   if (AbsTolerance < std::abs(V1-V2)) {
 146     // Nope, check the relative tolerance...
 147     double Diff;
 148     if (V2)
 149       Diff = std::abs(V1/V2 - 1.0);
 150     else if (V1)
 151       Diff = std::abs(V2/V1 - 1.0);
 152     else
 153       Diff = 0;  // Both zero.
 154     if (Diff > RelTolerance) {
 155       if (ErrorMsg) {
 156         raw_string_ostream(*ErrorMsg)
 157           << "Compared: " << V1 << " and " << V2 << '\n'
 158           << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
 159           << "Out of tolerance: rel/abs: " << RelTolerance << '/'
 160           << AbsTolerance;
 161       }
 162       return true;
 163     }
 164   }
 165
 166   // Otherwise, advance our read pointers to the end of the numbers.
 167   F1P = F1NumEnd;  F2P = F2NumEnd;
 168   return false;
 169 }
 170
 171 /// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
 172 /// files match, 1 if they are different, and 2 if there is a file error.  This
 173 /// function differs from DiffFiles in that you can specify an absolete and
 174 /// relative FP error that is allowed to exist.  If you specify a string to fill
 175 /// in for the error option, it will set the string to an error message if an
 176 /// error occurs, allowing the caller to distinguish between a failed diff and a
 177 /// file system error.
 178 ///
 179 int llvm::DiffFilesWithTolerance(StringRef NameA,
 180                                  StringRef NameB,
 181                                  double AbsTol, double RelTol,
 182                                  std::string *Error) {
 183   // Now its safe to mmap the files into memory because both files
 184   // have a non-zero size.
 185   ErrorOr<std::unique_ptr<MemoryBuffer>> F1OrErr = MemoryBuffer::getFile(NameA);
 186   if (std::error_code EC = F1OrErr.getError()) {
 187     if (Error)
 188       *Error = EC.message();
 189     return 2;
 190   }
 191   MemoryBuffer &F1 = *F1OrErr.get();
 192
 193   ErrorOr<std::unique_ptr<MemoryBuffer>> F2OrErr = MemoryBuffer::getFile(NameB);
 194   if (std::error_code EC = F2OrErr.getError()) {
 195     if (Error)
 196       *Error = EC.message();
 197     return 2;
 198   }
 199   MemoryBuffer &F2 = *F2OrErr.get();
 200
 201   // Okay, now that we opened the files, scan them for the first difference.
 202   const char *File1Start = F1.getBufferStart();
 203   const char *File2Start = F2.getBufferStart();
 204   const char *File1End = F1.getBufferEnd();
 205   const char *File2End = F2.getBufferEnd();
 206   const char *F1P = File1Start;
 207   const char *F2P = File2Start;
 208   uint64_t A_size = F1.getBufferSize();
 209   uint64_t B_size = F2.getBufferSize();
 210
 211   // Are the buffers identical?  Common case: Handle this efficiently.
 212   if (A_size == B_size &&
 213       std::memcmp(File1Start, File2Start, A_size) == 0)
 214     return 0;
 215
 216   // Otherwise, we are done a tolerances are set.
 217   if (AbsTol == 0 && RelTol == 0) {
 218     if (Error)
 219       *Error = "Files differ without tolerance allowance";
 220     return 1;   // Files different!
 221   }
 222
 223   bool CompareFailed = false;
 224   while (true) {
 225     // Scan for the end of file or next difference.
 226     while (F1P < File1End && F2P < File2End && *F1P == *F2P) {
 227       ++F1P;
 228       ++F2P;
 229     }
 230
 231     if (F1P >= File1End || F2P >= File2End) break;
 232
 233     // Okay, we must have found a difference.  Backup to the start of the
 234     // current number each stream is at so that we can compare from the
 235     // beginning.
 236     F1P = BackupNumber(F1P, File1Start);
 237     F2P = BackupNumber(F2P, File2Start);
 238
 239     // Now that we are at the start of the numbers, compare them, exiting if
 240     // they don't match.
 241     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
 242       CompareFailed = true;
 243       break;
 244     }
 245   }
 246
 247   // Okay, we reached the end of file.  If both files are at the end, we
 248   // succeeded.
 249   bool F1AtEnd = F1P >= File1End;
 250   bool F2AtEnd = F2P >= File2End;
 251   if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
 252     // Else, we might have run off the end due to a number: backup and retry.
 253     if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
 254     if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
 255     F1P = BackupNumber(F1P, File1Start);
 256     F2P = BackupNumber(F2P, File2Start);
 257
 258     // Now that we are at the start of the numbers, compare them, exiting if
 259     // they don't match.
 260     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
 261       CompareFailed = true;
 262
 263     // If we found the end, we succeeded.
 264     if (F1P < File1End || F2P < File2End)
 265       CompareFailed = true;
 266   }
 267
 268   return CompareFailed;
 269 }
 270
 271 void llvm::AtomicFileWriteError::log(raw_ostream &OS) const {
 272   OS << "atomic_write_error: ";
 273   switch (Error) {
 274   case atomic_write_error::failed_to_create_uniq_file:
 275     OS << "failed_to_create_uniq_file";
 276     return;
 277   case atomic_write_error::output_stream_error:
 278     OS << "output_stream_error";
 279     return;
 280   case atomic_write_error::failed_to_rename_temp_file:
 281     OS << "failed_to_rename_temp_file";
 282     return;
 283   }
 284   llvm_unreachable("unknown atomic_write_error value in "
 285                    "failed_to_rename_temp_file::log()");
 286 }
 287
 288 llvm::Error llvm::writeFileAtomically(StringRef TempPathModel,
 289                                       StringRef FinalPath, StringRef Buffer) {
 290   return writeFileAtomically(TempPathModel, FinalPath,
 291                              [&Buffer](llvm::raw_ostream &OS) {
 292                                OS.write(Buffer.data(), Buffer.size());
 293                                return llvm::Error::success();
 294                              });
 295 }
 296
 297 llvm::Error llvm::writeFileAtomically(
 298     StringRef TempPathModel, StringRef FinalPath,
 299     std::function<llvm::Error(llvm::raw_ostream &)> Writer) {
 300   SmallString<128> GeneratedUniqPath;
 301   int TempFD;
 302   if (sys::fs::createUniqueFile(TempPathModel.str(), TempFD,
 303                                 GeneratedUniqPath)) {
 304     return llvm::make_error<AtomicFileWriteError>(
 305         atomic_write_error::failed_to_create_uniq_file);
 306   }
 307   llvm::FileRemover RemoveTmpFileOnFail(GeneratedUniqPath);
 308
 309   raw_fd_ostream OS(TempFD, /*shouldClose=*/true);
 310   if (llvm::Error Err = Writer(OS)) {
 311     return Err;
 312   }
 313
 314   OS.close();
 315   if (OS.has_error()) {
 316     OS.clear_error();
 317     return llvm::make_error<AtomicFileWriteError>(
 318         atomic_write_error::output_stream_error);
 319   }
 320
 321   if (const std::error_code Error =
 322           sys::fs::rename(/*from=*/GeneratedUniqPath.c_str(),
 323                           /*to=*/FinalPath.str().c_str())) {
 324     return llvm::make_error<AtomicFileWriteError>(
 325         atomic_write_error::failed_to_rename_temp_file);
 326   }
 327
 328   RemoveTmpFileOnFail.releaseFile();
 329   return Error::success();
 330 }
 331
 332 char llvm::AtomicFileWriteError::ID;