1//===-- printf_parser_fuzz.cpp --------------------------------------------===//
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/// Fuzzing test for llvm-libc qsort implementation.
10///
11//===----------------------------------------------------------------------===//
12
13#include "src/__support/arg_list.h"
14#include "src/stdio/printf_core/parser.h"
15
16#include <stdarg.h>
17#include <stdint.h>
18
19using namespace LIBC_NAMESPACE;
20
21// The design for the printf parser fuzzer is fairly simple. The parser uses a
22// mock arg list that will never fail, and is passed a randomized string. The
23// format sections it outputs are checked against a count of the number of '%'
24// signs are in the original string. This is a fairly basic test, and the main
25// intent is to run this under sanitizers, which will check for buffer overruns.
26extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
27 char *in_str = new char[size + 1];
28
29 for (size_t i = 0; i < size; ++i)
30 in_str[i] = data[i];
31
32 in_str[size] = '\0';
33
34 auto mock_arg_list = internal::MockArgList();
35
36 auto parser =
37 printf_core::Parser<internal::MockArgList>(in_str, mock_arg_list);
38
39 int str_percent_count = 0;
40
41 for (size_t i = 0; i < size && in_str[i] != '\0'; ++i) {
42 if (in_str[i] == '%') {
43 ++str_percent_count;
44 }
45 }
46
47 int section_percent_count = 0;
48
49 for (printf_core::FormatSection cur_section = parser.get_next_section();
50 !cur_section.raw_string.empty();
51 cur_section = parser.get_next_section()) {
52 if (cur_section.has_conv) {
53 ++section_percent_count;
54 if (cur_section.conv_name == '%') {
55 ++section_percent_count;
56 }
57 } else if (cur_section.raw_string[0] == '%') {
58 // If the conversion would be undefined, it's instead raw, but it still
59 // starts with a %.
60 ++section_percent_count;
61 }
62 }
63
64 if (str_percent_count != section_percent_count) {
65 __builtin_trap();
66 }
67
68 delete[] in_str;
69 return 0;
70}
71

source code of libc/fuzzing/stdio/printf_parser_fuzz.cpp