Add fuzzing to to_chars for floats

fuzzing/fuzz_to_chars_float.cpp

@@ -0,0 +1,57 @@
+// Copyright 2024 Matt Borland
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/charconv.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <iostream>
+#include <exception>
+
+extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data, std::size_t size)
+{
+    try
+    {
+        auto c_data = reinterpret_cast<const char*>(data);
+
+        const auto formats = {boost::charconv::chars_format::general,
+                                                   boost::charconv::chars_format::fixed,
+                                                   boost::charconv::chars_format::scientific,
+                                                   boost::charconv::chars_format::hex};
+
+        for (const auto format : formats)
+        {
+            char buffer[20]; // Small enough it should encounter overflows
+
+            float f_val {};
+            boost::charconv::from_chars(c_data, c_data + size, f_val, format);
+            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), f_val, format);
+
+            double val {};
+            boost::charconv::from_chars(c_data, c_data + size, val, format);
+            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), val, format);
+
+            #if BOOST_CHARCONV_LDBL_BITS == 64
+            long double ld_val {};
+            boost::charconv::from_chars(c_data, c_data + size, ld_val, format);
+            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), ld_val, format);
+            #endif
+
+            // Also try with precisions
+            for (int precision = -1; precision < 10; ++precision)
+            {
+                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), f_val, format, precision);
+                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), val, format, precision);
+                #if BOOST_CHARCONV_LDBL_BITS == 64
+                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), ld_val, format, precision);
+                #endif
+            }
+        }
+    }
+    catch(...)
+    {
+        std::cerr << "Error with: " << data << std::endl;
+        std::terminate();
+    }
+
+    return 0;
+}

fuzzing/old_crashes/fuzz_to_chars_float/crash-09c8b86a9193e576c2b40b72af22cf35dabd240b

@@ -0,0 +1 @@
+BBBBBÿÿÿBBBBBBBBÿÿÿÿÿÿÿÿBBBBBBÿ

fuzzing/old_crashes/fuzz_to_chars_float/crash-09cd68a2a77b22a312dded612dd0d9988685189f

@@ -0,0 +1 @@
+es

fuzzing/old_crashes/fuzz_to_chars_float/crash-10a020de5380904a3affe37886c7c20196fd5acd

@@ -0,0 +1 @@
+1999
009

fuzzing/old_crashes/fuzz_to_chars_float/crash-285945accb992ef55b4a3413e89e2012e2f43aa7

@@ -0,0 +1 @@
+333333333333333ÿ

fuzzing/old_crashes/fuzz_to_chars_float/crash-a005df23eaa03d6a4009401ca46e71c068741754

@@ -0,0 +1 @@
+111111111111111!1111111111111111111[ß

fuzzing/old_crashes/fuzz_to_chars_float/crash-ee9bf16bb7c75a0dc9e898ceb5f713f9ba471e77

@@ -0,0 +1 @@
+3333;;33

fuzzing/old_crashes/fuzz_to_chars_float/crash-fff9981a80eb8a852ac0e8e7387f23a43d5cf76a

@@ -0,0 +1 @@
+66666666666666666666;;