1 //===- FuzzerInterface.h - Interface header for the Fuzzer ------*- 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 // Define the interface between libFuzzer and the library being tested.
9 //===----------------------------------------------------------------------===//
10 
11 // NOTE: the libFuzzer interface is thin and in the majority of cases
12 // you should not include this file into your target. In 95% of cases
13 // all you need is to define the following function in your file:
14 // extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
15 
16 // WARNING: keep the interface in C.
17 
18 #ifndef LLVM_FUZZER_INTERFACE_H
19 #define LLVM_FUZZER_INTERFACE_H
20 
21 #include <stddef.h>
22 #include <stdint.h>
23 
24 #ifdef __cplusplus
25 extern "C" {
26 #endif  // __cplusplus
27 
28 // Define FUZZER_INTERFACE_VISIBILITY to set default visibility in a way that
29 // doesn't break MSVC.
30 #if defined(_WIN32)
31 #define FUZZER_INTERFACE_VISIBILITY __declspec(dllexport)
32 #else
33 #define FUZZER_INTERFACE_VISIBILITY __attribute__((visibility("default")))
34 #endif
35 
36 // Mandatory user-provided target function.
37 // Executes the code under test with [Data, Data+Size) as the input.
38 // libFuzzer will invoke this function *many* times with different inputs.
39 // Must return 0.
40 FUZZER_INTERFACE_VISIBILITY int
41 LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
42 
43 // Optional user-provided initialization function.
44 // If provided, this function will be called by libFuzzer once at startup.
45 // It may read and modify argc/argv.
46 // Must return 0.
47 FUZZER_INTERFACE_VISIBILITY int LLVMFuzzerInitialize(int *argc, char ***argv);
48 
49 // Optional user-provided custom mutator.
50 // Mutates raw data in [Data, Data+Size) inplace.
51 // Returns the new size, which is not greater than MaxSize.
52 // Given the same Seed produces the same mutation.
53 FUZZER_INTERFACE_VISIBILITY size_t
54 LLVMFuzzerCustomMutator(uint8_t *Data, size_t Size, size_t MaxSize,
55                         unsigned int Seed);
56 
57 // Optional user-provided custom cross-over function.
58 // Combines pieces of Data1 & Data2 together into Out.
59 // Returns the new size, which is not greater than MaxOutSize.
60 // Should produce the same mutation given the same Seed.
61 FUZZER_INTERFACE_VISIBILITY size_t
62 LLVMFuzzerCustomCrossOver(const uint8_t *Data1, size_t Size1,
63                           const uint8_t *Data2, size_t Size2, uint8_t *Out,
64                           size_t MaxOutSize, unsigned int Seed);
65 
66 // Experimental, may go away in future.
67 // libFuzzer-provided function to be used inside LLVMFuzzerCustomMutator.
68 // Mutates raw data in [Data, Data+Size) inplace.
69 // Returns the new size, which is not greater than MaxSize.
70 FUZZER_INTERFACE_VISIBILITY size_t
71 LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize);
72 
73 #undef FUZZER_INTERFACE_VISIBILITY
74 
75 #ifdef __cplusplus
76 }  // extern "C"
77 #endif  // __cplusplus
78 
79 #endif  // LLVM_FUZZER_INTERFACE_H
80