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