142 lines · cpp
1//===-- printf_float_conv_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-exception6//7//===----------------------------------------------------------------------===//8///9/// Fuzzing test for llvm-libc printf %f/e/g/a implementations.10///11//===----------------------------------------------------------------------===//12#include "src/stdio/snprintf.h"13 14#include "src/__support/FPUtil/FPBits.h"15 16#include <stddef.h>17#include <stdint.h>18 19#include "utils/MPFRWrapper/mpfr_inc.h"20 21constexpr int MAX_SIZE = 10000;22 23inline bool simple_streq(char *first, char *second, int length) {24 for (int i = 0; i < length; ++i) {25 if (first[i] != second[i]) {26 return false;27 }28 }29 return true;30}31 32inline int simple_strlen(const char *str) {33 int i = 0;34 for (; *str; ++str, ++i) {35 ;36 }37 return i;38}39 40enum class TestResult {41 Success,42 BufferSizeFailed,43 LengthsDiffer,44 StringsNotEqual,45};46 47template <typename F>48inline TestResult test_vals(const char *fmt, F num, int prec, int width) {49 // Call snprintf on a nullptr to get the buffer size.50 int buffer_size = LIBC_NAMESPACE::snprintf(nullptr, 0, fmt, width, prec, num);51 52 if (buffer_size < 0) {53 return TestResult::BufferSizeFailed;54 }55 56 char *test_buff = new char[buffer_size + 1];57 char *reference_buff = new char[buffer_size + 1];58 59 int test_result = 0;60 int reference_result = 0;61 62 test_result = LIBC_NAMESPACE::snprintf(test_buff, buffer_size + 1, fmt, width,63 prec, num);64 reference_result =65 mpfr_snprintf(reference_buff, buffer_size + 1, fmt, width, prec, num);66 67 // All of these calls should return that they wrote the same amount.68 if (test_result != reference_result || test_result != buffer_size) {69 return TestResult::LengthsDiffer;70 }71 72 if (!simple_streq(test_buff, reference_buff, buffer_size)) {73 return TestResult::StringsNotEqual;74 }75 76 delete[] test_buff;77 delete[] reference_buff;78 return TestResult::Success;79}80 81constexpr char const *fmt_arr[] = {82 "%*.*f", "%*.*e", "%*.*g", "%*.*a", "%*.*Lf", "%*.*Le", "%*.*Lg", "%*.*La",83};84 85extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {86 // const uint8_t raw_data[] = {0x30,0x27,0x1,0x0,0x0,0x0,0x0,0x0,0x24};87 // data = raw_data;88 // size = sizeof(raw_data);89 double num = 0.0;90 int prec = 0;91 int width = 0;92 93 LIBC_NAMESPACE::fputil::FPBits<double>::StorageType raw_num = 0;94 95 // Copy as many bytes of data as will fit into num, prec, and with. Any extras96 // are ignored.97 for (size_t cur = 0; cur < size; ++cur) {98 if (cur < sizeof(raw_num)) {99 raw_num = (raw_num << 8) + data[cur];100 } else if (cur < sizeof(raw_num) + sizeof(prec)) {101 prec = (prec << 8) + data[cur];102 } else if (cur < sizeof(raw_num) + sizeof(prec) + sizeof(width)) {103 width = (width << 8) + data[cur];104 }105 }106 107 num = LIBC_NAMESPACE::fputil::FPBits<double>(raw_num).get_val();108 109 // While we could create a "ld_raw_num" from additional bytes, it's much110 // easier to stick with simply casting num to long double. This avoids the111 // issues around 80 bit long doubles, especially unnormal and pseudo-denormal112 // numbers, which MPFR doesn't handle well.113 long double ld_num = static_cast<long double>(num);114 115 if (width > MAX_SIZE) {116 width = MAX_SIZE;117 } else if (width < -MAX_SIZE) {118 width = -MAX_SIZE;119 }120 121 if (prec > MAX_SIZE) {122 prec = MAX_SIZE;123 } else if (prec < -MAX_SIZE) {124 prec = -MAX_SIZE;125 }126 127 for (size_t cur_fmt = 0; cur_fmt < sizeof(fmt_arr) / sizeof(char *);128 ++cur_fmt) {129 int fmt_len = simple_strlen(fmt_arr[cur_fmt]);130 TestResult result;131 if (fmt_arr[cur_fmt][fmt_len - 2] == 'L') {132 result = test_vals<long double>(fmt_arr[cur_fmt], ld_num, prec, width);133 } else {134 result = test_vals<double>(fmt_arr[cur_fmt], num, prec, width);135 }136 if (result != TestResult::Success) {137 __builtin_trap();138 }139 }140 return 0;141}142