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//===- Support/FileUtilities.cpp - File System Utilities ------------------===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file implements a family of utility functions which are useful for doing
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// various things with files.
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/FileUtilities.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/system_error.h"
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#include "llvm/ADT/OwningPtr.h"
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#include "llvm/ADT/SmallString.h"
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static bool isSignedChar(char C) {
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return (C == '+' || C == '-');
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static bool isExponentChar(char C) {
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case 'D': // Strange exponential notation.
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case 'd': // Strange exponential notation.
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case 'E': return true;
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default: return false;
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static bool isNumberChar(char C) {
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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case '.': return true;
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default: return isSignedChar(C) || isExponentChar(C);
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static const char *BackupNumber(const char *Pos, const char *FirstChar) {
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// If we didn't stop in the middle of a number, don't backup.
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if (!isNumberChar(*Pos)) return Pos;
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// Otherwise, return to the start of the number.
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bool HasPeriod = false;
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while (Pos > FirstChar && isNumberChar(Pos[-1])) {
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// Backup over at most one period.
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if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
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/// EndOfNumber - Return the first character that is not part of the specified
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/// number. This assumes that the buffer is null terminated, so it won't fall
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static const char *EndOfNumber(const char *Pos) {
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while (isNumberChar(*Pos))
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/// CompareNumbers - compare two numbers, returning true if they are different.
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static bool CompareNumbers(const char *&F1P, const char *&F2P,
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const char *F1End, const char *F2End,
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double AbsTolerance, double RelTolerance,
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std::string *ErrorMsg) {
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const char *F1NumEnd, *F2NumEnd;
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double V1 = 0.0, V2 = 0.0;
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// If one of the positions is at a space and the other isn't, chomp up 'til
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// the end of the space.
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while (isspace(*F1P) && F1P != F1End)
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while (isspace(*F2P) && F2P != F2End)
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// If we stop on numbers, compare their difference.
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if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
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// Note that some ugliness is built into this to permit support for numbers
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// that use "D" or "d" as their exponential marker, e.g. "1.234D45". This
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// occurs in 200.sixtrack in spec2k.
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V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
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V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
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if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
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// Copy string into tmp buffer to replace the 'D' with an 'e'.
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SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
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// Strange exponential notation!
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StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
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V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
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F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
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if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
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// Copy string into tmp buffer to replace the 'D' with an 'e'.
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SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
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// Strange exponential notation!
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StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
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V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
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F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
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if (F1NumEnd == F1P || F2NumEnd == F2P) {
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*ErrorMsg = "FP Comparison failed, not a numeric difference between '";
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*ErrorMsg += "' and '";
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// Check to see if these are inside the absolute tolerance
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if (AbsTolerance < std::abs(V1-V2)) {
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// Nope, check the relative tolerance...
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Diff = std::abs(V1/V2 - 1.0);
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Diff = std::abs(V2/V1 - 1.0);
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Diff = 0; // Both zero.
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if (Diff > RelTolerance) {
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raw_string_ostream(*ErrorMsg)
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<< "Compared: " << V1 << " and " << V2 << '\n'
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<< "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
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<< "Out of tolerance: rel/abs: " << RelTolerance << '/'
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// Otherwise, advance our read pointers to the end of the numbers.
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F1P = F1NumEnd; F2P = F2NumEnd;
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/// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
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/// files match, 1 if they are different, and 2 if there is a file error. This
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/// function differs from DiffFiles in that you can specify an absolete and
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/// relative FP error that is allowed to exist. If you specify a string to fill
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/// in for the error option, it will set the string to an error message if an
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/// error occurs, allowing the caller to distinguish between a failed diff and a
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/// file system error.
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int llvm::DiffFilesWithTolerance(const sys::PathWithStatus &FileA,
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const sys::PathWithStatus &FileB,
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double AbsTol, double RelTol,
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std::string *Error) {
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const sys::FileStatus *FileAStat = FileA.getFileStatus(false, Error);
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const sys::FileStatus *FileBStat = FileB.getFileStatus(false, Error);
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// Check for zero length files because some systems croak when you try to
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// mmap an empty file.
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size_t A_size = FileAStat->getSize();
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size_t B_size = FileBStat->getSize();
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// If they are both zero sized then they're the same
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if (A_size == 0 && B_size == 0)
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// If only one of them is zero sized then they can't be the same
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if ((A_size == 0 || B_size == 0)) {
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*Error = "Files differ: one is zero-sized, the other isn't";
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// Now its safe to mmap the files into memory because both files
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// have a non-zero size.
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OwningPtr<MemoryBuffer> F1;
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if (error_code ec = MemoryBuffer::getFile(FileA.c_str(), F1)) {
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*Error = ec.message();
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OwningPtr<MemoryBuffer> F2;
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if (error_code ec = MemoryBuffer::getFile(FileB.c_str(), F2)) {
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*Error = ec.message();
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// Okay, now that we opened the files, scan them for the first difference.
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const char *File1Start = F1->getBufferStart();
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const char *File2Start = F2->getBufferStart();
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const char *File1End = F1->getBufferEnd();
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const char *File2End = F2->getBufferEnd();
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const char *F1P = File1Start;
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const char *F2P = File2Start;
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// Are the buffers identical? Common case: Handle this efficiently.
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if (A_size == B_size &&
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std::memcmp(File1Start, File2Start, A_size) == 0)
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// Otherwise, we are done a tolerances are set.
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if (AbsTol == 0 && RelTol == 0) {
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*Error = "Files differ without tolerance allowance";
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return 1; // Files different!
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bool CompareFailed = false;
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// Scan for the end of file or next difference.
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while (F1P < File1End && F2P < File2End && *F1P == *F2P)
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if (F1P >= File1End || F2P >= File2End) break;
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// Okay, we must have found a difference. Backup to the start of the
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// current number each stream is at so that we can compare from the
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F1P = BackupNumber(F1P, File1Start);
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F2P = BackupNumber(F2P, File2Start);
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// Now that we are at the start of the numbers, compare them, exiting if
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if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
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CompareFailed = true;
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// Okay, we reached the end of file. If both files are at the end, we
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bool F1AtEnd = F1P >= File1End;
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bool F2AtEnd = F2P >= File2End;
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if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
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// Else, we might have run off the end due to a number: backup and retry.
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if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
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if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
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F1P = BackupNumber(F1P, File1Start);
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F2P = BackupNumber(F2P, File2Start);
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// Now that we are at the start of the numbers, compare them, exiting if
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if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
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CompareFailed = true;
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// If we found the end, we succeeded.
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if (F1P < File1End || F2P < File2End)
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CompareFailed = true;
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return CompareFailed;