lib/Support/FileUtilities.cpp

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