LLVM API Documentation

FileUtilities.cpp

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00001 //===- Support/FileUtilities.cpp - File System Utilities ------------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements a family of utility functions which are useful for doing
00011 // various things with files.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #include "llvm/Support/FileUtilities.h"
00016 #include "llvm/System/Path.h"
00017 #include "llvm/System/MappedFile.h"
00018 #include "llvm/ADT/StringExtras.h"
00019 #include <cmath>
00020 #include <cstring>
00021 #include <cctype>
00022 using namespace llvm;
00023 
00024 static bool isNumberChar(char C) {
00025   switch (C) {
00026   case '0': case '1': case '2': case '3': case '4':
00027   case '5': case '6': case '7': case '8': case '9':
00028   case '.': case '+': case '-':
00029   case 'D':  // Strange exponential notation.
00030   case 'd':  // Strange exponential notation.
00031   case 'e':
00032   case 'E': return true;
00033   default: return false;
00034   }
00035 }
00036 
00037 static char *BackupNumber(char *Pos, char *FirstChar) {
00038   // If we didn't stop in the middle of a number, don't backup.
00039   if (!isNumberChar(*Pos)) return Pos;
00040 
00041   // Otherwise, return to the start of the number.
00042   while (Pos > FirstChar && isNumberChar(Pos[-1]))
00043     --Pos;
00044   return Pos;
00045 }
00046 
00047 /// CompareNumbers - compare two numbers, returning true if they are different.
00048 static bool CompareNumbers(char *&F1P, char *&F2P, char *F1End, char *F2End,
00049                            double AbsTolerance, double RelTolerance,
00050                            std::string *ErrorMsg) {
00051   char *F1NumEnd, *F2NumEnd;
00052   double V1 = 0.0, V2 = 0.0;
00053 
00054   // If one of the positions is at a space and the other isn't, chomp up 'til
00055   // the end of the space.
00056   while (isspace(*F1P) && F1P != F1End)
00057     ++F1P;
00058   while (isspace(*F2P) && F2P != F2End)
00059     ++F2P;
00060 
00061   // If we stop on numbers, compare their difference.  Note that some ugliness
00062   // is built into this to permit support for numbers that use "D" or "d" as
00063   // their exponential marker, e.g. "1.234D45".  This occurs in 200.sixtrack in
00064   // spec2k.
00065   if (isNumberChar(*F1P) && isNumberChar(*F2P)) {
00066     bool isDNotation;
00067     do {
00068       isDNotation = false;
00069       V1 = strtod(F1P, &F1NumEnd);
00070       V2 = strtod(F2P, &F2NumEnd);
00071 
00072       if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
00073         *F1NumEnd = 'e';  // Strange exponential notation!
00074         isDNotation = true;
00075       }
00076       if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
00077         *F2NumEnd = 'e';  // Strange exponential notation!
00078         isDNotation = true;
00079       }
00080     } while (isDNotation);
00081   } else {
00082     // Otherwise, the diff failed.
00083     F1NumEnd = F1P;
00084     F2NumEnd = F2P;
00085   }
00086 
00087   if (F1NumEnd == F1P || F2NumEnd == F2P) {
00088     if (ErrorMsg) *ErrorMsg = "Comparison failed, not a numeric difference.";
00089     return true;
00090   }
00091 
00092   // Check to see if these are inside the absolute tolerance
00093   if (AbsTolerance < std::abs(V1-V2)) {
00094     // Nope, check the relative tolerance...
00095     double Diff;
00096     if (V2)
00097       Diff = std::abs(V1/V2 - 1.0);
00098     else if (V1)
00099       Diff = std::abs(V2/V1 - 1.0);
00100     else
00101       Diff = 0;  // Both zero.
00102     if (Diff > RelTolerance) {
00103       if (ErrorMsg) {
00104         *ErrorMsg = "Compared: " + ftostr(V1) + " and " + ftostr(V2) +
00105                     ": diff = " + ftostr(Diff) + "\n";
00106         *ErrorMsg += "Out of tolerance: rel/abs: " + ftostr(RelTolerance) +
00107                      "/" + ftostr(AbsTolerance);
00108       }
00109       return true;
00110     }
00111   }
00112 
00113   // Otherwise, advance our read pointers to the end of the numbers.
00114   F1P = F1NumEnd;  F2P = F2NumEnd;
00115   return false;
00116 }
00117 
00118 // PadFileIfNeeded - If the files are not identical, we will have to be doing
00119 // numeric comparisons in here.  There are bad cases involved where we (i.e.,
00120 // strtod) might run off the beginning or end of the file if it starts or ends
00121 // with a number.  Because of this, if needed, we pad the file so that it starts
00122 // and ends with a null character.
00123 static void PadFileIfNeeded(char *&FileStart, char *&FileEnd, char *&FP) {
00124   if (FileStart-FileEnd < 2 ||
00125       isNumberChar(FileStart[0]) || isNumberChar(FileEnd[-1])) {
00126     unsigned FileLen = FileEnd-FileStart;
00127     char *NewFile = new char[FileLen+2];
00128     NewFile[0] = 0;              // Add null padding
00129     NewFile[FileLen+1] = 0;      // Add null padding
00130     memcpy(NewFile+1, FileStart, FileLen);
00131     FP = NewFile+(FP-FileStart)+1;
00132     FileStart = NewFile+1;
00133     FileEnd = FileStart+FileLen;
00134   }
00135 }
00136 
00137 /// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
00138 /// files match, 1 if they are different, and 2 if there is a file error.  This
00139 /// function differs from DiffFiles in that you can specify an absolete and
00140 /// relative FP error that is allowed to exist.  If you specify a string to fill
00141 /// in for the error option, it will set the string to an error message if an
00142 /// error occurs, allowing the caller to distinguish between a failed diff and a
00143 /// file system error.
00144 ///
00145 int llvm::DiffFilesWithTolerance(const sys::Path &FileA,
00146                                  const sys::Path &FileB,
00147                                  double AbsTol, double RelTol,
00148                                  std::string *Error) {
00149   try {
00150     // Check for zero length files because some systems croak when you try to
00151     // mmap an empty file.
00152     size_t A_size = FileA.getSize();
00153     size_t B_size = FileB.getSize();
00154 
00155     // If they are both zero sized then they're the same
00156     if (A_size == 0 && B_size == 0)
00157       return 0;
00158     // If only one of them is zero sized then they can't be the same
00159     if ((A_size == 0 || B_size == 0))
00160       return 1;
00161 
00162     // Now its safe to mmap the files into memory becasue both files
00163     // have a non-zero size.
00164     sys::MappedFile F1(FileA);
00165     sys::MappedFile F2(FileB);
00166     F1.map();
00167     F2.map();
00168 
00169     // Okay, now that we opened the files, scan them for the first difference.
00170     char *File1Start = F1.charBase();
00171     char *File2Start = F2.charBase();
00172     char *File1End = File1Start+A_size;
00173     char *File2End = File2Start+B_size;
00174     char *F1P = File1Start;
00175     char *F2P = File2Start;
00176 
00177     if (A_size == B_size) {
00178       // Are the buffers identical?
00179       if (std::memcmp(File1Start, File2Start, A_size) == 0)
00180         return 0;
00181 
00182       if (AbsTol == 0 && RelTol == 0)
00183         return 1;   // Files different!
00184     }
00185 
00186     char *OrigFile1Start = File1Start;
00187     char *OrigFile2Start = File2Start;
00188 
00189     // If the files need padding, do so now.
00190     PadFileIfNeeded(File1Start, File1End, F1P);
00191     PadFileIfNeeded(File2Start, File2End, F2P);
00192 
00193     bool CompareFailed = false;
00194     while (1) {
00195       // Scan for the end of file or next difference.
00196       while (F1P < File1End && F2P < File2End && *F1P == *F2P)
00197         ++F1P, ++F2P;
00198 
00199       if (F1P >= File1End || F2P >= File2End) break;
00200 
00201       // Okay, we must have found a difference.  Backup to the start of the
00202       // current number each stream is at so that we can compare from the
00203       // beginning.
00204       F1P = BackupNumber(F1P, File1Start);
00205       F2P = BackupNumber(F2P, File2Start);
00206 
00207       // Now that we are at the start of the numbers, compare them, exiting if
00208       // they don't match.
00209       if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
00210         CompareFailed = true;
00211         break;
00212       }
00213     }
00214 
00215     // Okay, we reached the end of file.  If both files are at the end, we
00216     // succeeded.
00217     bool F1AtEnd = F1P >= File1End;
00218     bool F2AtEnd = F2P >= File2End;
00219     if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
00220       // Else, we might have run off the end due to a number: backup and retry.
00221       if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
00222       if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
00223       F1P = BackupNumber(F1P, File1Start);
00224       F2P = BackupNumber(F2P, File2Start);
00225 
00226       // Now that we are at the start of the numbers, compare them, exiting if
00227       // they don't match.
00228       if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
00229         CompareFailed = true;
00230 
00231       // If we found the end, we succeeded.
00232       if (F1P < File1End || F2P < File2End)
00233         CompareFailed = true;
00234     }
00235 
00236     if (OrigFile1Start != File1Start)
00237       delete[] (File1Start-1);   // Back up past null byte
00238     if (OrigFile2Start != File2Start)
00239       delete[] (File2Start-1);   // Back up past null byte
00240     return CompareFailed;
00241   } catch (const std::string &Msg) {
00242     if (Error) *Error = Msg;
00243     return 2;
00244   }
00245 }