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