1 //===- Support/FileUtilities.cpp - File System Utilities ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements a family of utility functions which are useful for doing
10 // various things with files.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Support/FileUtilities.h"
15 #include "llvm/ADT/ScopeExit.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/Support/Error.h"
18 #include "llvm/Support/ErrorOr.h"
19 #include "llvm/Support/MemoryBuffer.h"
20 #include "llvm/Support/Path.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include <cctype>
23 #include <cmath>
24 #include <cstdint>
25 #include <cstdlib>
26 #include <cstring>
27 #include <memory>
28 #include <system_error>
29 
30 using namespace llvm;
31 
32 static bool isSignedChar(char C) {
33   return (C == '+' || C == '-');
34 }
35 
36 static bool isExponentChar(char C) {
37   switch (C) {
38   case 'D':  // Strange exponential notation.
39   case 'd':  // Strange exponential notation.
40   case 'e':
41   case 'E': return true;
42   default: return false;
43   }
44 }
45 
46 static bool isNumberChar(char C) {
47   switch (C) {
48   case '0': case '1': case '2': case '3': case '4':
49   case '5': case '6': case '7': case '8': case '9':
50   case '.': return true;
51   default: return isSignedChar(C) || isExponentChar(C);
52   }
53 }
54 
55 static const char *BackupNumber(const char *Pos, const char *FirstChar) {
56   // If we didn't stop in the middle of a number, don't backup.
57   if (!isNumberChar(*Pos)) return Pos;
58 
59   // Otherwise, return to the start of the number.
60   bool HasPeriod = false;
61   while (Pos > FirstChar && isNumberChar(Pos[-1])) {
62     // Backup over at most one period.
63     if (Pos[-1] == '.') {
64       if (HasPeriod)
65         break;
66       HasPeriod = true;
67     }
68 
69     --Pos;
70     if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
71       break;
72   }
73   return Pos;
74 }
75 
76 /// EndOfNumber - Return the first character that is not part of the specified
77 /// number.  This assumes that the buffer is null terminated, so it won't fall
78 /// off the end.
79 static const char *EndOfNumber(const char *Pos) {
80   while (isNumberChar(*Pos))
81     ++Pos;
82   return Pos;
83 }
84 
85 /// CompareNumbers - compare two numbers, returning true if they are different.
86 static bool CompareNumbers(const char *&F1P, const char *&F2P,
87                            const char *F1End, const char *F2End,
88                            double AbsTolerance, double RelTolerance,
89                            std::string *ErrorMsg) {
90   const char *F1NumEnd, *F2NumEnd;
91   double V1 = 0.0, V2 = 0.0;
92 
93   // If one of the positions is at a space and the other isn't, chomp up 'til
94   // the end of the space.
95   while (isspace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
96     ++F1P;
97   while (isspace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
98     ++F2P;
99 
100   // If we stop on numbers, compare their difference.
101   if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
102     // The diff failed.
103     F1NumEnd = F1P;
104     F2NumEnd = F2P;
105   } else {
106     // Note that some ugliness is built into this to permit support for numbers
107     // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
108     // occurs in 200.sixtrack in spec2k.
109     V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
110     V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
111 
112     if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
113       // Copy string into tmp buffer to replace the 'D' with an 'e'.
114       SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
115       // Strange exponential notation!
116       StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
117 
118       V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
119       F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
120     }
121 
122     if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
123       // Copy string into tmp buffer to replace the 'D' with an 'e'.
124       SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
125       // Strange exponential notation!
126       StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
127 
128       V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
129       F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
130     }
131   }
132 
133   if (F1NumEnd == F1P || F2NumEnd == F2P) {
134     if (ErrorMsg) {
135       *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
136       *ErrorMsg += F1P[0];
137       *ErrorMsg += "' and '";
138       *ErrorMsg += F2P[0];
139       *ErrorMsg += "'";
140     }
141     return true;
142   }
143 
144   // Check to see if these are inside the absolute tolerance
145   if (AbsTolerance < std::abs(V1-V2)) {
146     // Nope, check the relative tolerance...
147     double Diff;
148     if (V2)
149       Diff = std::abs(V1/V2 - 1.0);
150     else if (V1)
151       Diff = std::abs(V2/V1 - 1.0);
152     else
153       Diff = 0;  // Both zero.
154     if (Diff > RelTolerance) {
155       if (ErrorMsg) {
156         raw_string_ostream(*ErrorMsg)
157           << "Compared: " << V1 << " and " << V2 << '\n'
158           << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
159           << "Out of tolerance: rel/abs: " << RelTolerance << '/'
160           << AbsTolerance;
161       }
162       return true;
163     }
164   }
165 
166   // Otherwise, advance our read pointers to the end of the numbers.
167   F1P = F1NumEnd;  F2P = F2NumEnd;
168   return false;
169 }
170 
171 /// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
172 /// files match, 1 if they are different, and 2 if there is a file error.  This
173 /// function differs from DiffFiles in that you can specify an absolete and
174 /// relative FP error that is allowed to exist.  If you specify a string to fill
175 /// in for the error option, it will set the string to an error message if an
176 /// error occurs, allowing the caller to distinguish between a failed diff and a
177 /// file system error.
178 ///
179 int llvm::DiffFilesWithTolerance(StringRef NameA,
180                                  StringRef NameB,
181                                  double AbsTol, double RelTol,
182                                  std::string *Error) {
183   // Now its safe to mmap the files into memory because both files
184   // have a non-zero size.
185   ErrorOr<std::unique_ptr<MemoryBuffer>> F1OrErr = MemoryBuffer::getFile(NameA);
186   if (std::error_code EC = F1OrErr.getError()) {
187     if (Error)
188       *Error = EC.message();
189     return 2;
190   }
191   MemoryBuffer &F1 = *F1OrErr.get();
192 
193   ErrorOr<std::unique_ptr<MemoryBuffer>> F2OrErr = MemoryBuffer::getFile(NameB);
194   if (std::error_code EC = F2OrErr.getError()) {
195     if (Error)
196       *Error = EC.message();
197     return 2;
198   }
199   MemoryBuffer &F2 = *F2OrErr.get();
200 
201   // Okay, now that we opened the files, scan them for the first difference.
202   const char *File1Start = F1.getBufferStart();
203   const char *File2Start = F2.getBufferStart();
204   const char *File1End = F1.getBufferEnd();
205   const char *File2End = F2.getBufferEnd();
206   const char *F1P = File1Start;
207   const char *F2P = File2Start;
208   uint64_t A_size = F1.getBufferSize();
209   uint64_t B_size = F2.getBufferSize();
210 
211   // Are the buffers identical?  Common case: Handle this efficiently.
212   if (A_size == B_size &&
213       std::memcmp(File1Start, File2Start, A_size) == 0)
214     return 0;
215 
216   // Otherwise, we are done a tolerances are set.
217   if (AbsTol == 0 && RelTol == 0) {
218     if (Error)
219       *Error = "Files differ without tolerance allowance";
220     return 1;   // Files different!
221   }
222 
223   bool CompareFailed = false;
224   while (true) {
225     // Scan for the end of file or next difference.
226     while (F1P < File1End && F2P < File2End && *F1P == *F2P) {
227       ++F1P;
228       ++F2P;
229     }
230 
231     if (F1P >= File1End || F2P >= File2End) break;
232 
233     // Okay, we must have found a difference.  Backup to the start of the
234     // current number each stream is at so that we can compare from the
235     // beginning.
236     F1P = BackupNumber(F1P, File1Start);
237     F2P = BackupNumber(F2P, File2Start);
238 
239     // Now that we are at the start of the numbers, compare them, exiting if
240     // they don't match.
241     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
242       CompareFailed = true;
243       break;
244     }
245   }
246 
247   // Okay, we reached the end of file.  If both files are at the end, we
248   // succeeded.
249   bool F1AtEnd = F1P >= File1End;
250   bool F2AtEnd = F2P >= File2End;
251   if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
252     // Else, we might have run off the end due to a number: backup and retry.
253     if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
254     if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
255     F1P = BackupNumber(F1P, File1Start);
256     F2P = BackupNumber(F2P, File2Start);
257 
258     // Now that we are at the start of the numbers, compare them, exiting if
259     // they don't match.
260     if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
261       CompareFailed = true;
262 
263     // If we found the end, we succeeded.
264     if (F1P < File1End || F2P < File2End)
265       CompareFailed = true;
266   }
267 
268   return CompareFailed;
269 }
270 
271 void llvm::AtomicFileWriteError::log(raw_ostream &OS) const {
272   OS << "atomic_write_error: ";
273   switch (Error) {
274   case atomic_write_error::failed_to_create_uniq_file:
275     OS << "failed_to_create_uniq_file";
276     return;
277   case atomic_write_error::output_stream_error:
278     OS << "output_stream_error";
279     return;
280   case atomic_write_error::failed_to_rename_temp_file:
281     OS << "failed_to_rename_temp_file";
282     return;
283   }
284   llvm_unreachable("unknown atomic_write_error value in "
285                    "failed_to_rename_temp_file::log()");
286 }
287 
288 llvm::Error llvm::writeFileAtomically(StringRef TempPathModel,
289                                       StringRef FinalPath, StringRef Buffer) {
290   return writeFileAtomically(TempPathModel, FinalPath,
291                              [&Buffer](llvm::raw_ostream &OS) {
292                                OS.write(Buffer.data(), Buffer.size());
293                                return llvm::Error::success();
294                              });
295 }
296 
297 llvm::Error llvm::writeFileAtomically(
298     StringRef TempPathModel, StringRef FinalPath,
299     std::function<llvm::Error(llvm::raw_ostream &)> Writer) {
300   SmallString<128> GeneratedUniqPath;
301   int TempFD;
302   if (sys::fs::createUniqueFile(TempPathModel.str(), TempFD,
303                                 GeneratedUniqPath)) {
304     return llvm::make_error<AtomicFileWriteError>(
305         atomic_write_error::failed_to_create_uniq_file);
306   }
307   llvm::FileRemover RemoveTmpFileOnFail(GeneratedUniqPath);
308 
309   raw_fd_ostream OS(TempFD, /*shouldClose=*/true);
310   if (llvm::Error Err = Writer(OS)) {
311     return Err;
312   }
313 
314   OS.close();
315   if (OS.has_error()) {
316     OS.clear_error();
317     return llvm::make_error<AtomicFileWriteError>(
318         atomic_write_error::output_stream_error);
319   }
320 
321   if (const std::error_code Error =
322           sys::fs::rename(/*from=*/GeneratedUniqPath.c_str(),
323                           /*to=*/FinalPath.str().c_str())) {
324     return llvm::make_error<AtomicFileWriteError>(
325         atomic_write_error::failed_to_rename_temp_file);
326   }
327 
328   RemoveTmpFileOnFail.releaseFile();
329   return Error::success();
330 }
331 
332 char llvm::AtomicFileWriteError::ID;
333