llvm/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/SmallString.h"
  16 #include "llvm/ADT/StringExtras.h"
  17 #include "llvm/Support/Error.h"
  18 #include "llvm/Support/ErrorOr.h"
  19 #include "llvm/Support/MemoryBuffer.h"
  20 #include "llvm/Support/Process.h"
  21 #include "llvm/Support/raw_ostream.h"
  22 #include <cmath>
  23 #include <cstdint>
  24 #include <cstdlib>
  25 #include <cstring>
  26 #include <memory>
  27 #include <system_error>
  28
  29 using namespace llvm;
  30
  31 static bool isSignedChar(char C) {
  32   return (C == '+' || C == '-');
  33 }
  34
  35 static bool isExponentChar(char C) {
  36   switch (C) {
  37   case 'D':  // Strange exponential notation.
  38   case 'd':  // Strange exponential notation.
  39   case 'e':
  40   case 'E': return true;
  41   default: return false;
  42   }
  43 }
  44
  45 static bool isNumberChar(char C) {
  46   switch (C) {
  47   case '0': case '1': case '2': case '3': case '4':
  48   case '5': case '6': case '7': case '8': case '9':
  49   case '.': return true;
  50   default: return isSignedChar(C) || isExponentChar(C);
  51   }
  52 }
  53
  54 static const char *BackupNumber(const char *Pos, const char *FirstChar) {
  55   // If we didn't stop in the middle of a number, don't backup.
  56   if (!isNumberChar(*Pos)) return Pos;
  57
  58   // Otherwise, return to the start of the number.
  59   bool HasPeriod = false;
  60   while (Pos > FirstChar && isNumberChar(Pos[-1])) {
  61     // Backup over at most one period.
  62     if (Pos[-1] == '.') {
  63       if (HasPeriod)
  64         break;
  65       HasPeriod = true;
  66     }
  67
  68     --Pos;
  69     if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
  70       break;
  71   }
  72   return Pos;
  73 }
  74
  75 /// EndOfNumber - Return the first character that is not part of the specified
  76 /// number.  This assumes that the buffer is null terminated, so it won't fall
  77 /// off the end.
  78 static const char *EndOfNumber(const char *Pos) {
  79   while (isNumberChar(*Pos))
  80     ++Pos;
  81   return Pos;
  82 }
  83
  84 /// CompareNumbers - compare two numbers, returning true if they are different.
  85 static bool CompareNumbers(const char *&F1P, const char *&F2P,
  86                            const char *F1End, const char *F2End,
  87                            double AbsTolerance, double RelTolerance,
  88                            std::string *ErrorMsg) {
  89   const char *F1NumEnd, *F2NumEnd;
  90   double V1 = 0.0, V2 = 0.0;
  91
  92   // If one of the positions is at a space and the other isn't, chomp up 'til
  93   // the end of the space.
  94   while (isSpace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
  95     ++F1P;
  96   while (isSpace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
  97     ++F2P;
  98
  99   // If we stop on numbers, compare their difference.
 100   if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
 101     // The diff failed.
 102     F1NumEnd = F1P;
 103     F2NumEnd = F2P;
 104   } else {
 105     // Note that some ugliness is built into this to permit support for numbers
 106     // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
 107     // occurs in 200.sixtrack in spec2k.
 108     V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
 109     V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
 110
 111     if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
 112       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 113       SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
 114       // Strange exponential notation!
 115       StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
 116
 117       V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
 118       F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
 119     }
 120
 121     if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
 122       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 123       SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
 124       // Strange exponential notation!
 125       StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
 126
 127       V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
 128       F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
 129     }
 130   }
 131
 132   if (F1NumEnd == F1P || F2NumEnd == F2P) {
 133     if (ErrorMsg) {
 134       *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
 135       *ErrorMsg += F1P[0];
 136       *ErrorMsg += "' and '";
 137       *ErrorMsg += F2P[0];
 138       *ErrorMsg += "'";
 139     }
 140     return true;
 141   }
 142
 143   // Check to see if these are inside the absolute tolerance
 144   if (AbsTolerance < std::abs(V1-V2)) {
 145     // Nope, check the relative tolerance...
 146     double Diff;
 147     if (V2)
 148       Diff = std::abs(V1/V2 - 1.0);
 149     else if (V1)
 150       Diff = std::abs(V2/V1 - 1.0);
 151     else
 152       Diff = 0;  // Both zero.
 153     if (Diff > RelTolerance) {
 154       if (ErrorMsg) {
 155         raw_string_ostream(*ErrorMsg)
 156           << "Compared: " << V1 << " and " << V2 << '\n'
 157           << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
 158           << "Out of tolerance: rel/abs: " << RelTolerance << '/'
 159           << AbsTolerance;
 160       }
 161       return true;
 162     }
 163   }
 164
 165   // Otherwise, advance our read pointers to the end of the numbers.
 166   F1P = F1NumEnd;  F2P = F2NumEnd;
 167   return false;
 168 }
 169
 170 /// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
 171 /// files match, 1 if they are different, and 2 if there is a file error.  This
 172 /// function differs from DiffFiles in that you can specify an absolute and
 173 /// relative FP error that is allowed to exist.  If you specify a string to fill
 174 /// in for the error option, it will set the string to an error message if an
 175 /// error occurs, allowing the caller to distinguish between a failed diff and a
 176 /// file system error.
 177 ///
 178 int llvm::DiffFilesWithTolerance(StringRef NameA,
 179                                  StringRef NameB,
 180                                  double AbsTol, double RelTol,
 181                                  std::string *Error) {
 182   // Now its safe to mmap the files into memory because both files
 183   // have a non-zero size.
 184   ErrorOr<std::unique_ptr<MemoryBuffer>> F1OrErr = MemoryBuffer::getFile(NameA);
 185   if (std::error_code EC = F1OrErr.getError()) {
 186     if (Error)
 187       *Error = EC.message();
 188     return 2;
 189   }
 190   MemoryBuffer &F1 = *F1OrErr.get();
 191
 192   ErrorOr<std::unique_ptr<MemoryBuffer>> F2OrErr = MemoryBuffer::getFile(NameB);
 193   if (std::error_code EC = F2OrErr.getError()) {
 194     if (Error)
 195       *Error = EC.message();
 196     return 2;
 197   }
 198   MemoryBuffer &F2 = *F2OrErr.get();
 199
 200   // Okay, now that we opened the files, scan them for the first difference.
 201   const char *File1Start = F1.getBufferStart();
 202   const char *File2Start = F2.getBufferStart();
 203   const char *File1End = F1.getBufferEnd();
 204   const char *File2End = F2.getBufferEnd();
 205   const char *F1P = File1Start;
 206   const char *F2P = File2Start;
 207   uint64_t A_size = F1.getBufferSize();
 208   uint64_t B_size = F2.getBufferSize();
 209
 210   // Are the buffers identical?  Common case: Handle this efficiently.
 211   if (A_size == B_size &&
 212       std::memcmp(File1Start, File2Start, A_size) == 0)
 213     return 0;
 214
 215   // Otherwise, we are done a tolerances are set.
 216   if (AbsTol == 0 && RelTol == 0) {
 217     if (Error)
 218       *Error = "Files differ without tolerance allowance";
 219     return 1;   // Files different!
 220   }
 221
 222   bool CompareFailed = false;
 223   while (true) {
 224     // Scan for the end of file or next difference.
 225     while (F1P < File1End && F2P < File2End && *F1P == *F2P) {
 226       ++F1P;
 227       ++F2P;
 228     }
 229
 230     if (F1P >= File1End || F2P >= File2End) break;
 231
 232     // Okay, we must have found a difference.  Backup to the start of the
 233     // current number each stream is at so that we can compare from the
 234     // beginning.
 235     F1P = BackupNumber(F1P, File1Start);
 236     F2P = BackupNumber(F2P, File2Start);
 237
 238     // Now that we are at the start of the numbers, compare them, exiting if
 239     // they don't match.
 240     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
 241       CompareFailed = true;
 242       break;
 243     }
 244   }
 245
 246   // Okay, we reached the end of file.  If both files are at the end, we
 247   // succeeded.
 248   bool F1AtEnd = F1P >= File1End;
 249   bool F2AtEnd = F2P >= File2End;
 250   if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
 251     // Else, we might have run off the end due to a number: backup and retry.
 252     if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
 253     if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
 254     F1P = BackupNumber(F1P, File1Start);
 255     F2P = BackupNumber(F2P, File2Start);
 256
 257     // Now that we are at the start of the numbers, compare them, exiting if
 258     // they don't match.
 259     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
 260       CompareFailed = true;
 261
 262     // If we found the end, we succeeded.
 263     if (F1P < File1End || F2P < File2End)
 264       CompareFailed = true;
 265   }
 266
 267   return CompareFailed;
 268 }
 269
 270 Expected<FilePermissionsApplier>
 271 FilePermissionsApplier::create(StringRef InputFilename) {
 272   sys::fs::file_status Status;
 273
 274   if (InputFilename != "-") {
 275     if (auto EC = sys::fs::status(InputFilename, Status))
 276       return createFileError(InputFilename, EC);
 277   } else {
 278     Status.permissions(static_cast<sys::fs::perms>(0777));
 279   }
 280
 281   return FilePermissionsApplier(InputFilename, Status);
 282 }
 283
 284 Error FilePermissionsApplier::apply(
 285     StringRef OutputFilename, bool CopyDates,
 286     std::optional<sys::fs::perms> OverwritePermissions) {
 287   sys::fs::file_status Status = InputStatus;
 288
 289   if (OverwritePermissions)
 290     Status.permissions(*OverwritePermissions);
 291
 292   int FD = 0;
 293
 294   // Writing to stdout should not be treated as an error here, just
 295   // do not set access/modification times or permissions.
 296   if (OutputFilename == "-")
 297     return Error::success();
 298
 299   if (std::error_code EC = sys::fs::openFileForWrite(OutputFilename, FD,
 300                                                      sys::fs::CD_OpenExisting))
 301     return createFileError(OutputFilename, EC);
 302
 303   if (CopyDates)
 304     if (std::error_code EC = sys::fs::setLastAccessAndModificationTime(
 305             FD, Status.getLastAccessedTime(), Status.getLastModificationTime()))
 306       return createFileError(OutputFilename, EC);
 307
 308   sys::fs::file_status OStat;
 309   if (std::error_code EC = sys::fs::status(FD, OStat))
 310     return createFileError(OutputFilename, EC);
 311   if (OStat.type() == sys::fs::file_type::regular_file) {
 312 #ifndef _WIN32
 313     // Keep ownership if llvm-objcopy is called under root.
 314     if (OutputFilename == InputFilename && OStat.getUser() == 0)
 315       sys::fs::changeFileOwnership(FD, Status.getUser(), Status.getGroup());
 316 #endif
 317
 318     sys::fs::perms Perm = Status.permissions();
 319     if (OutputFilename != InputFilename)
 320       Perm = static_cast<sys::fs::perms>(Perm & ~sys::fs::getUmask() & ~06000);
 321 #ifdef _WIN32
 322     if (std::error_code EC = sys::fs::setPermissions(OutputFilename, Perm))
 323 #else
 324     if (std::error_code EC = sys::fs::setPermissions(FD, Perm))
 325 #endif
 326       return createFileError(OutputFilename, EC);
 327   }
 328
 329   if (std::error_code EC = sys::Process::SafelyCloseFileDescriptor(FD))
 330     return createFileError(OutputFilename, EC);
 331
 332   return Error::success();
 333 }