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/Support/MemoryBuffer.h"
  17 #include "llvm/Support/raw_ostream.h"
  18 #include "llvm/Support/Path.h"
  19 #include "llvm/Support/system_error.h"
  20 #include "llvm/ADT/OwningPtr.h"
  21 #include "llvm/ADT/SmallString.h"
  22 #include <cstdlib>
  23 #include <cstring>
  24 #include <cctype>
  25 using namespace llvm;
  26
  27 static bool isSignedChar(char C) {
  28   return (C == '+' || C == '-');
  29 }
  30
  31 static bool isExponentChar(char C) {
  32   switch (C) {
  33   case 'D':  // Strange exponential notation.
  34   case 'd':  // Strange exponential notation.
  35   case 'e':
  36   case 'E': return true;
  37   default: return false;
  38   }
  39 }
  40
  41 static bool isNumberChar(char C) {
  42   switch (C) {
  43   case '0': case '1': case '2': case '3': case '4':
  44   case '5': case '6': case '7': case '8': case '9':
  45   case '.': return true;
  46   default: return isSignedChar(C) || isExponentChar(C);
  47   }
  48 }
  49
  50 static const char *BackupNumber(const char *Pos, const char *FirstChar) {
  51   // If we didn't stop in the middle of a number, don't backup.
  52   if (!isNumberChar(*Pos)) return Pos;
  53
  54   // Otherwise, return to the start of the number.
  55   bool HasPeriod = false;
  56   while (Pos > FirstChar && isNumberChar(Pos[-1])) {
  57     // Backup over at most one period.
  58     if (Pos[-1] == '.') {
  59       if (HasPeriod)
  60         break;
  61       HasPeriod = true;
  62     }
  63
  64     --Pos;
  65     if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
  66       break;
  67   }
  68   return Pos;
  69 }
  70
  71 /// EndOfNumber - Return the first character that is not part of the specified
  72 /// number.  This assumes that the buffer is null terminated, so it won't fall
  73 /// off the end.
  74 static const char *EndOfNumber(const char *Pos) {
  75   while (isNumberChar(*Pos))
  76     ++Pos;
  77   return Pos;
  78 }
  79
  80 /// CompareNumbers - compare two numbers, returning true if they are different.
  81 static bool CompareNumbers(const char *&F1P, const char *&F2P,
  82                            const char *F1End, const char *F2End,
  83                            double AbsTolerance, double RelTolerance,
  84                            std::string *ErrorMsg) {
  85   const char *F1NumEnd, *F2NumEnd;
  86   double V1 = 0.0, V2 = 0.0;
  87
  88   // If one of the positions is at a space and the other isn't, chomp up 'til
  89   // the end of the space.
  90   while (isspace(*F1P) && F1P != F1End)
  91     ++F1P;
  92   while (isspace(*F2P) && F2P != F2End)
  93     ++F2P;
  94
  95   // If we stop on numbers, compare their difference.
  96   if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
  97     // The diff failed.
  98     F1NumEnd = F1P;
  99     F2NumEnd = F2P;
 100   } else {
 101     // Note that some ugliness is built into this to permit support for numbers
 102     // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
 103     // occurs in 200.sixtrack in spec2k.
 104     V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
 105     V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
 106
 107     if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
 108       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 109       SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
 110       // Strange exponential notation!
 111       StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
 112
 113       V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
 114       F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
 115     }
 116
 117     if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
 118       // Copy string into tmp buffer to replace the 'D' with an 'e'.
 119       SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
 120       // Strange exponential notation!
 121       StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
 122
 123       V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
 124       F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
 125     }
 126   }
 127
 128   if (F1NumEnd == F1P || F2NumEnd == F2P) {
 129     if (ErrorMsg) {
 130       *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
 131       *ErrorMsg += F1P[0];
 132       *ErrorMsg += "' and '";
 133       *ErrorMsg += F2P[0];
 134       *ErrorMsg += "'";
 135     }
 136     return true;
 137   }
 138
 139   // Check to see if these are inside the absolute tolerance
 140   if (AbsTolerance < std::abs(V1-V2)) {
 141     // Nope, check the relative tolerance...
 142     double Diff;
 143     if (V2)
 144       Diff = std::abs(V1/V2 - 1.0);
 145     else if (V1)
 146       Diff = std::abs(V2/V1 - 1.0);
 147     else
 148       Diff = 0;  // Both zero.
 149     if (Diff > RelTolerance) {
 150       if (ErrorMsg) {
 151         raw_string_ostream(*ErrorMsg)
 152           << "Compared: " << V1 << " and " << V2 << '\n'
 153           << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
 154           << "Out of tolerance: rel/abs: " << RelTolerance << '/'
 155           << AbsTolerance;
 156       }
 157       return true;
 158     }
 159   }
 160
 161   // Otherwise, advance our read pointers to the end of the numbers.
 162   F1P = F1NumEnd;  F2P = F2NumEnd;
 163   return false;
 164 }
 165
 166 /// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
 167 /// files match, 1 if they are different, and 2 if there is a file error.  This
 168 /// function differs from DiffFiles in that you can specify an absolete and
 169 /// relative FP error that is allowed to exist.  If you specify a string to fill
 170 /// in for the error option, it will set the string to an error message if an
 171 /// error occurs, allowing the caller to distinguish between a failed diff and a
 172 /// file system error.
 173 ///
 174 int llvm::DiffFilesWithTolerance(const sys::PathWithStatus &FileA,
 175                                  const sys::PathWithStatus &FileB,
 176                                  double AbsTol, double RelTol,
 177                                  std::string *Error) {
 178   const sys::FileStatus *FileAStat = FileA.getFileStatus(false, Error);
 179   if (!FileAStat)
 180     return 2;
 181   const sys::FileStatus *FileBStat = FileB.getFileStatus(false, Error);
 182   if (!FileBStat)
 183     return 2;
 184
 185   // Check for zero length files because some systems croak when you try to
 186   // mmap an empty file.
 187   size_t A_size = FileAStat->getSize();
 188   size_t B_size = FileBStat->getSize();
 189
 190   // If they are both zero sized then they're the same
 191   if (A_size == 0 && B_size == 0)
 192     return 0;
 193
 194   // If only one of them is zero sized then they can't be the same
 195   if ((A_size == 0 || B_size == 0)) {
 196     if (Error)
 197       *Error = "Files differ: one is zero-sized, the other isn't";
 198     return 1;
 199   }
 200
 201   // Now its safe to mmap the files into memory because both files
 202   // have a non-zero size.
 203   error_code ec;
 204   OwningPtr<MemoryBuffer> F1;
 205   if (error_code ec = MemoryBuffer::getFile(FileA.c_str(), F1)) {
 206     if (Error)
 207       *Error = ec.message();
 208     return 2;
 209   }
 210   OwningPtr<MemoryBuffer> F2;
 211   if (error_code ec = MemoryBuffer::getFile(FileB.c_str(), F2)) {
 212     if (Error)
 213       *Error = ec.message();
 214     return 2;
 215   }
 216
 217   // Okay, now that we opened the files, scan them for the first difference.
 218   const char *File1Start = F1->getBufferStart();
 219   const char *File2Start = F2->getBufferStart();
 220   const char *File1End = F1->getBufferEnd();
 221   const char *File2End = F2->getBufferEnd();
 222   const char *F1P = File1Start;
 223   const char *F2P = File2Start;
 224
 225   // Are the buffers identical?  Common case: Handle this efficiently.
 226   if (A_size == B_size &&
 227       std::memcmp(File1Start, File2Start, A_size) == 0)
 228     return 0;
 229
 230   // Otherwise, we are done a tolerances are set.
 231   if (AbsTol == 0 && RelTol == 0) {
 232     if (Error)
 233       *Error = "Files differ without tolerance allowance";
 234     return 1;   // Files different!
 235   }
 236
 237   bool CompareFailed = false;
 238   while (1) {
 239     // Scan for the end of file or next difference.
 240     while (F1P < File1End && F2P < File2End && *F1P == *F2P)
 241       ++F1P, ++F2P;
 242
 243     if (F1P >= File1End || F2P >= File2End) break;
 244
 245     // Okay, we must have found a difference.  Backup to the start of the
 246     // current number each stream is at so that we can compare from the
 247     // beginning.
 248     F1P = BackupNumber(F1P, File1Start);
 249     F2P = BackupNumber(F2P, File2Start);
 250
 251     // Now that we are at the start of the numbers, compare them, exiting if
 252     // they don't match.
 253     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
 254       CompareFailed = true;
 255       break;
 256     }
 257   }
 258
 259   // Okay, we reached the end of file.  If both files are at the end, we
 260   // succeeded.
 261   bool F1AtEnd = F1P >= File1End;
 262   bool F2AtEnd = F2P >= File2End;
 263   if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
 264     // Else, we might have run off the end due to a number: backup and retry.
 265     if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
 266     if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
 267     F1P = BackupNumber(F1P, File1Start);
 268     F2P = BackupNumber(F2P, File2Start);
 269
 270     // Now that we are at the start of the numbers, compare them, exiting if
 271     // they don't match.
 272     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
 273       CompareFailed = true;
 274
 275     // If we found the end, we succeeded.
 276     if (F1P < File1End || F2P < File2End)
 277       CompareFailed = true;
 278   }
 279
 280   return CompareFailed;
 281 }