1 //===- FuzzerDataFlowTrace.cpp - DataFlowTrace                ---*- C++ -* ===//
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 // fuzzer::DataFlowTrace
9 //===----------------------------------------------------------------------===//
10 
11 #include "FuzzerDataFlowTrace.h"
12 #include "FuzzerIO.h"
13 
14 #include <cstdlib>
15 #include <fstream>
16 #include <string>
17 #include <vector>
18 
19 namespace fuzzer {
20 
21 void DataFlowTrace::Init(const std::string &DirPath,
22                          const std::string &FocusFunction) {
23   if (DirPath.empty()) return;
24   const char *kFunctionsTxt = "functions.txt";
25   Printf("INFO: DataFlowTrace: reading from '%s'\n", DirPath.c_str());
26   Vector<SizedFile> Files;
27   GetSizedFilesFromDir(DirPath, &Files);
28   std::string L;
29 
30   // Read functions.txt
31   std::ifstream IF(DirPlusFile(DirPath, kFunctionsTxt));
32   size_t FocusFuncIdx = SIZE_MAX;
33   size_t NumFunctions = 0;
34   while (std::getline(IF, L, '\n')) {
35     NumFunctions++;
36     if (FocusFunction == L)
37       FocusFuncIdx = NumFunctions - 1;
38   }
39   if (!NumFunctions || FocusFuncIdx == SIZE_MAX || Files.size() <= 1)
40     return;
41   // Read traces.
42   size_t NumTraceFiles = 0;
43   size_t NumTracesWithFocusFunction = 0;
44   for (auto &SF : Files) {
45     auto Name = Basename(SF.File);
46     if (Name == kFunctionsTxt) continue;
47     auto ParseError = [&](const char *Err) {
48       Printf("DataFlowTrace: parse error: %s\n  File: %s\n  Line: %s\n", Err,
49              Name.c_str(), L.c_str());
50     };
51     NumTraceFiles++;
52     // Printf("=== %s\n", Name.c_str());
53     std::ifstream IF(SF.File);
54     while (std::getline(IF, L, '\n')) {
55       if (!L.empty() && L[0] == 'C')
56         continue; // Ignore coverage.
57       size_t SpacePos = L.find(' ');
58       if (SpacePos == std::string::npos)
59         return ParseError("no space in the trace line");
60       if (L.empty() || L[0] != 'F')
61         return ParseError("the trace line doesn't start with 'F'");
62       size_t N = std::atol(L.c_str() + 1);
63       if (N >= NumFunctions)
64         return ParseError("N is greater than the number of functions");
65       if (N == FocusFuncIdx) {
66         NumTracesWithFocusFunction++;
67         const char *Beg = L.c_str() + SpacePos + 1;
68         const char *End = L.c_str() + L.size();
69         assert(Beg < End);
70         size_t Len = End - Beg;
71         Vector<uint8_t> V(Len);
72         for (size_t I = 0; I < Len; I++) {
73           if (Beg[I] != '0' && Beg[I] != '1')
74             ParseError("the trace should contain only 0 or 1");
75           V[I] = Beg[I] == '1';
76         }
77         Traces[Name] = V;
78         // Print just a few small traces.
79         if (NumTracesWithFocusFunction <= 3 && Len <= 16)
80           Printf("%s => |%s|\n", Name.c_str(), L.c_str() + SpacePos + 1);
81         break;  // No need to parse the following lines.
82       }
83     }
84   }
85   assert(NumTraceFiles == Files.size() - 1);
86   Printf("INFO: DataFlowTrace: %zd trace files, %zd functions, "
87          "%zd traces with focus function\n",
88          NumTraceFiles, NumFunctions, NumTracesWithFocusFunction);
89 }
90 
91 }  // namespace fuzzer
92 
93