Merge branch 'develop' into guard-page-tests

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

cmake/ci.cmake

@@ -485,13 +485,6 @@ add_custom_target(ci_clang_analyze
 # Check code with Cppcheck.
 ###############################################################################
 
-# default_defines.hpp expands the Hedley macros to the compiler's feature-test operators, which Cppcheck does not know.
-# Since Cppcheck 2.20, it rejects their invocations in #if conditions instead of evaluating them as 0.
-file(WRITE ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "")
-foreach(OPERATOR __has_attribute __has_builtin __has_cpp_attribute __has_declspec_attribute __has_extension __has_feature __has_include __has_warning)
-    file(APPEND ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "#define ${OPERATOR}(x) 0\n")
-endforeach()
-
 add_custom_target(ci_cppcheck
     COMMAND mkdir -p cppcheck
     COMMAND clang -dM -E -x c++ -std=c++11 ${CMAKE_SOURCE_DIR}/include/nlohmann/thirdparty/hedley/hedley.hpp > default_defines.hpp 2> /dev/null
@@ -500,7 +493,7 @@ add_custom_target(ci_cppcheck
     COMMAND venv_cppcheck/bin/cppcheck --enable=warning --check-level=exhaustive --inline-suppr --inconclusive --force
             --std=c++11 ${PROJECT_SOURCE_DIR}/include/nlohmann/json.hpp -I ${CMAKE_SOURCE_DIR}/include
             --error-exitcode=1 --relative-paths=${PROJECT_SOURCE_DIR} -j ${N} --include=default_defines.hpp
-            --include=${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp --cppcheck-build-dir=cppcheck
+            --cppcheck-build-dir=cppcheck
             -UJSON_CATCH_USER -UJSON_TRY_USER -UJSON_ASSERT -UJSON_INTERNAL_CATCH -UJSON_THROW
             -DJSON_HAS_CPP_11 -UJSON_HAS_CPP_14 -UJSON_HAS_CPP_17 -UJSON_HAS_CPP_20 -UJSON_HAS_THREE_WAY_COMPARISON
     COMMENT "Check code with Cppcheck"

cmake/requirements/requirements-cppcheck.txt

@@ -1 +1 @@
-cppcheck==1.5.2
+cppcheck==1.5.1

docs/mkdocs/docs/api/basic_json/array_t.md

@@ -27,7 +27,7 @@ To store objects in C++, a type is defined by the template parameters explained
 
 ### Default type
 
-With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default value for
+With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default type for
 `array_t` is:
 
 ```cpp

docs/mkdocs/docs/api/basic_json/boolean_t.md

@@ -23,7 +23,7 @@ To store boolean values in C++, a type is defined by the template parameter  `Bo
 
 ### Default type
 
-With the default values for `BooleanType` (`#!cpp bool`), the default value for `boolean_t` is `#!cpp bool`.
+With the default values for `BooleanType` (`#!cpp bool`), the default type for `boolean_t` is `#!cpp bool`.
 
 ### Storage
 

docs/mkdocs/docs/api/basic_json/number_float_t.md

@@ -35,7 +35,7 @@ type to use.
 
 ### Default type
 
-With the default values for `NumberFloatType` (`double`), the default value for `number_float_t` is `#!cpp double`.
+With the default values for `NumberFloatType` (`double`), the default type for `number_float_t` is `#!cpp double`.
 
 ### Default behavior
 
@@ -52,8 +52,9 @@ With the default values for `NumberFloatType` (`double`), the default value for
 > interoperability can be achieved by implementations that expect no more precision or range than these provide, in the
 > sense that implementations will approximate JSON numbers within the expected precision.
 
-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that
-numbers smaller than `-1.79769313486232e+308` or greater than `1.79769313486232e+308` are rejected during parsing with
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers by default.
+Note that with the default `double`, numbers smaller than `-1.79769313486232e+308` or greater than
+`1.79769313486232e+308` are rejected during parsing with
 [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can
 only be stored by assigning them directly and are serialized to `null`.
 

docs/mkdocs/docs/api/basic_json/number_integer_t.md

@@ -31,7 +31,7 @@ to use.
 
 ### Default type
 
-With the default values for `NumberIntegerType` (`std::int64_t`), the default value for `number_integer_t` is
+With the default values for `NumberIntegerType` (`std::int64_t`), the default type for `number_integer_t` is
 `#!cpp std::int64_t`.
 
 ### Default behavior

docs/mkdocs/docs/api/basic_json/number_unsigned_t.md

@@ -32,7 +32,7 @@ the type to use.
 
 ### Default type
 
-With the default values for `NumberUnsignedType` (`std::uint64_t`), the default value for `number_unsigned_t` is
+With the default values for `NumberUnsignedType` (`std::uint64_t`), the default type for `number_unsigned_t` is
 `#!cpp std::uint64_t`.
 
 ### Default behavior

docs/mkdocs/docs/api/basic_json/object_t.md

@@ -36,7 +36,7 @@ To store objects in C++, a type is defined by the template parameters described
 ### Default type
 
 With the default values for `ObjectType` (`std::map`), `StringType` (`std::string`), and `AllocatorType`
-(`std::allocator`), the default value for `object_t` is:
+(`std::allocator`), the default type for `object_t` is:
 
 ```cpp
 // until C++14

docs/mkdocs/docs/api/basic_json/string_t.md

@@ -32,7 +32,7 @@ JSON class into byte-sized characters during deserialization.
 
 ### Default type
 
-With the default values for `StringType` (`std::string`), the default value for `string_t` is `#!cpp std::string`.
+With the default values for `StringType` (`std::string`), the default type for `string_t` is `#!cpp std::string`.
 
 ### Encoding
 

docs/mkdocs/docs/features/types/index.md

@@ -120,7 +120,7 @@ requirements are collected in [Template Parameter Requirements](template_paramet
 
 ### Default type
 
-With the default values for *ObjectType* (`std::map`), *StringType* (`std::string`), and *AllocatorType* (`std::allocator`), the default value for `object_t` is:
+With the default values for *ObjectType* (`std::map`), *StringType* (`std::string`), and *AllocatorType* (`std::allocator`), the default type for `object_t` is:
 
 ```cpp
 std::map<
@@ -177,7 +177,7 @@ json j = m;
 
 ### Default type
 
-With the default values for *ArrayType* (`std::vector`) and *AllocatorType* (`std::allocator`), the default value for `array_t` is:
+With the default values for *ArrayType* (`std::vector`) and *AllocatorType* (`std::allocator`), the default type for `array_t` is:
 
 ```cpp
 std::vector<
@@ -209,7 +209,7 @@ Unicode values are split by the JSON class into byte-sized characters during des
 
 ### Default type
 
-With the default values for *StringType* (`std::string`), the default value for `string_t` is `#!cpp std::string`.
+With the default values for *StringType* (`std::string`), the default type for `string_t` is `#!cpp std::string`.
 
 ### Encoding
 
@@ -234,7 +234,7 @@ String values are stored as pointers in a `basic_json` type. That is, for any ac
 
 ### Default type
 
-With the default values for *BooleanType* (`#!cpp bool`), the default value for `boolean_t` is `#!cpp bool`.
+With the default values for *BooleanType* (`#!cpp bool`), the default type for `boolean_t` is `#!cpp bool`.
 
 ### Storage
 
@@ -252,9 +252,9 @@ This description includes both integer and floating-point numbers. However, C++
 
 ### Default types
 
-With the default values for *NumberIntegerType* (`std::int64_t`), the default value for `number_integer_t` is `std::int64_t`.
-With the default values for *NumberUnsignedType* (`std::uint64_t`), the default value for `number_unsigned_t` is `std::uint64_t`.
-With the default values for *NumberFloatType* (`#!cpp double`), the default value for `number_float_t` is `#!cpp double`.
+With the default values for *NumberIntegerType* (`std::int64_t`), the default type for `number_integer_t` is `std::int64_t`.
+With the default values for *NumberUnsignedType* (`std::uint64_t`), the default type for `number_unsigned_t` is `std::uint64_t`.
+With the default values for *NumberFloatType* (`#!cpp double`), the default type for `number_float_t` is `#!cpp double`.
 
 ### Default behavior
 
@@ -281,7 +281,7 @@ As this range is a subrange of the exactly supported range [`INT64_MIN`, `INT64_
 
 > This specification allows implementations to set limits on the range and precision of numbers accepted. Since software that implements IEEE 754-2008 binary64 (double precision) numbers is generally available and widely used, good interoperability can be achieved by implementations that expect no more precision or range than these provide, in the sense that implementations will approximate JSON numbers within the expected precision.
 
-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that numbers smaller than `#!c -1.79769313486232e+308` or greater than `#!c 1.79769313486232e+308` are rejected during parsing with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can only be stored by assigning them directly and are serialized to `#!json null`.
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers by default (see *NumberFloatType* above). Note that with the default `#!cpp double`, numbers smaller than `#!c -1.79769313486232e+308` or greater than `#!c 1.79769313486232e+308` are rejected during parsing with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can only be stored by assigning them directly and are serialized to `#!json null`.
 
 ### Storage
 

include/nlohmann/detail/input/number_parse.hpp

@@ -704,7 +704,7 @@ inline void float_from_bits(std::uint64_t bits, float& value) noexcept
 {
     static_assert(sizeof(float) == sizeof(std::uint32_t), "float must have 32 bits");
     const auto bits32 = static_cast<std::uint32_t>(bits);
-    std::memcpy(&value, &bits32, sizeof(bits32));
+    std::memcpy(&value, &bits32, sizeof(value));
 }
 
 /// the powers of ten that are exact in binary64 (up to 10^22)

single_include/nlohmann/json.hpp

@@ -10151,7 +10151,7 @@ inline void float_from_bits(std::uint64_t bits, float& value) noexcept
 {
     static_assert(sizeof(float) == sizeof(std::uint32_t), "float must have 32 bits");
     const auto bits32 = static_cast<std::uint32_t>(bits);
-    std::memcpy(&value, &bits32, sizeof(bits32));
+    std::memcpy(&value, &bits32, sizeof(value));
 }
 
 /// the powers of ten that are exact in binary64 (up to 10^22)

tests/src/unit-guard-page.cpp

@@ -0,0 +1,447 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+// The fast paths for contiguous input (bulk string scanning, SWAR searches,
+// UTF-8 prefix validation, the 8-digit number loop, the 8-byte indentation
+// skip, the BSON/BON8 bulk string readers) load several bytes at a time. This
+// test places every input directly in front of (or directly behind) an
+// inaccessible page, so reading even one byte outside the input crashes, with
+// or without sanitizers. ASan alone misses over-reads into the slack of the
+// same heap allocation.
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstdint>
+#include <cstring>
+#include <string>
+#include <utility>
+#include <vector>
+
+#if defined(_WIN32)
+    #define JSON_TEST_GUARD_PAGE_WINDOWS
+    #ifndef NOMINMAX
+        #define NOMINMAX
+    #endif
+    #ifndef WIN32_LEAN_AND_MEAN
+        #define WIN32_LEAN_AND_MEAN
+    #endif
+    #include <windows.h>
+#elif defined(__unix__) || defined(__APPLE__)
+    #define JSON_TEST_GUARD_PAGE_POSIX
+    #include <sys/mman.h>
+    #include <unistd.h>
+#endif
+
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS) || defined(JSON_TEST_GUARD_PAGE_POSIX)
+
+namespace
+{
+// Three pages: an inaccessible one, a readable one, an inaccessible one. An
+// input is copied either to the end of the middle page (any read past its last
+// byte faults) or to its start (any read before its first byte faults).
+class guarded_buffer
+{
+  public:
+    guarded_buffer()
+        : page(page_size())
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        void* const p = VirtualAlloc(nullptr, 3 * page, MEM_RESERVE | MEM_COMMIT, PAGE_NOACCESS);
+        REQUIRE(p != nullptr);
+        base = static_cast<unsigned char*>(p);
+        DWORD old_protect = 0;
+        REQUIRE(VirtualProtect(base + page, page, PAGE_READWRITE, &old_protect) != 0);
+#else
+        void* const p = mmap(nullptr, 3 * page, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+        REQUIRE(p != MAP_FAILED);
+        base = static_cast<unsigned char*>(p);
+        REQUIRE(mprotect(base + page, page, PROT_READ | PROT_WRITE) == 0);
+#endif
+    }
+
+    ~guarded_buffer()
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        VirtualFree(base, 0, MEM_RELEASE);
+#else
+        munmap(base, 3 * page);
+#endif
+    }
+
+    guarded_buffer(const guarded_buffer&) = delete;
+    guarded_buffer& operator=(const guarded_buffer&) = delete;
+    guarded_buffer(guarded_buffer&&) = delete;
+    guarded_buffer& operator=(guarded_buffer&&) = delete;
+
+    // copies @a input so its last byte is the last readable byte
+    const std::uint8_t* at_end(const std::string& input)
+    {
+        REQUIRE(input.size() <= page);
+        unsigned char* const first = base + (2 * page) - input.size();
+        std::memcpy(first, input.data(), input.size());
+        return first;
+    }
+
+    // copies @a input so its first byte is the first readable byte
+    const std::uint8_t* at_start(const std::string& input)
+    {
+        REQUIRE(input.size() <= page);
+        unsigned char* const first = base + page;
+        std::memcpy(first, input.data(), input.size());
+        return first;
+    }
+
+  private:
+    static std::size_t page_size()
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        SYSTEM_INFO info;
+        GetSystemInfo(&info);
+        return static_cast<std::size_t>(info.dwPageSize);
+#else
+        return static_cast<std::size_t>(sysconf(_SC_PAGESIZE));
+#endif
+    }
+
+    std::size_t page = 0;
+    unsigned char* base = nullptr;
+};
+
+// the serialization of the result of @a f, or the exception message; @a f
+// takes the allow_exceptions flag, which is false without exceptions, where
+// an error yields a discarded value instead
+template<typename F>
+std::string outcome(F f)
+{
+#if defined(JSON_NOEXCEPTION)
+    return "value: " + f(false).dump(-1, ' ', false, json::error_handler_t::keep);
+#else
+    try
+    {
+        return "value: " + f(true).dump(-1, ' ', false, json::error_handler_t::keep);
+    }
+    catch (const json::exception& e)
+    {
+        return std::string("error: ") + e.what();
+    }
+#endif
+}
+
+// a SAX handler that only counts events, so sax_parse runs without a DOM
+struct counting_sax : nlohmann::json_sax<json>
+{
+    std::size_t events = 0;
+    std::string error{}; // NOLINT(readability-redundant-member-init)
+
+    bool null() override
+    {
+        return count();
+    }
+    bool boolean(bool /*val*/) override
+    {
+        return count();
+    }
+    bool number_integer(number_integer_t /*val*/) override
+    {
+        return count();
+    }
+    bool number_unsigned(number_unsigned_t /*val*/) override
+    {
+        return count();
+    }
+    bool number_float(number_float_t /*val*/, const string_t& /*s*/) override
+    {
+        return count();
+    }
+    bool string(string_t& /*val*/) override
+    {
+        return count();
+    }
+    bool binary(binary_t& /*val*/) override
+    {
+        return count();
+    }
+    bool start_object(std::size_t /*elements*/) override
+    {
+        return count();
+    }
+    bool key(string_t& /*val*/) override
+    {
+        return count();
+    }
+    bool end_object() override
+    {
+        return count();
+    }
+    bool start_array(std::size_t /*elements*/) override
+    {
+        return count();
+    }
+    bool end_array() override
+    {
+        return count();
+    }
+    bool parse_error(std::size_t position, const std::string& /*last_token*/, const nlohmann::detail::exception& ex) override
+    {
+        error = std::to_string(position) + " " + ex.what();
+        return false;
+    }
+
+  private:
+    bool count()
+    {
+        ++events;
+        return true;
+    }
+};
+
+// all prefixes of each seed, so the input ends at every byte of it
+std::vector<std::string> all_prefixes(const std::vector<std::string>& seeds)
+{
+    std::vector<std::string> result;
+    for (const auto& seed : seeds)
+    {
+        for (std::size_t n = 0; n <= seed.size(); ++n)
+        {
+            result.push_back(seed.substr(0, n));
+        }
+    }
+    return result;
+}
+
+std::vector<std::string> json_seeds()
+{
+    std::vector<std::string> seeds =
+    {
+        // string runs: ASCII, escapes, \u escapes, surrogate pairs
+        "\"abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ\"",
+        R"("ab\ncd\"ef\\gh\u00e4ij\uD83D\uDE00kl\u12")",
+        // 2-, 3- and 4-byte UTF-8 sequences, then invalid UTF-8
+        std::string("\"\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80") + "abcdefgh\"",
+        "\"abcdefgh\xC3\x28 \xED\xA0\x80 \xF4\x90\x80\x80 \xF8 \xC0\xAF\"",
+        std::string("\"abcdefg\x01") + "abcdefgh\"",
+        // numbers, so the 8-digit loop runs up to the end
+        "12345678",
+        "1234567890123456",
+        "12345678901234567890123",
+        "-0.000000001234567890123456789",
+        "3.14159265358979323846264338327950288e+100",
+        "-1.2345678901234567e-12",
+        "1E-5",
+        "[1.5,2e10,-3E-5,0.000000001,123456789012345678]",
+        // literals
+        "[true,false,null]",
+        // comments (only parsed with ignore_comments)
+        "/* comment */ [1, // line comment\n 2] /**/",
+        // a pretty-printed document
+        json::parse(R"({"a": [1, 2.5, "three", {"b": null, "c": [true, false]}], "d": {"e": {"f": {"g": "h"}}}})").dump(4),
+        json::parse(R"({"a": [1, 2.5, "three", {"b": null, "c": [true, false]}], "d": {"e": {"f": {"g": "h"}}}})").dump(8, '\t'),
+    };
+
+    // indentation runs of every length, with and without a closing bracket
+    for (std::size_t n = 0; n <= 20; ++n)
+    {
+        seeds.push_back("[\n" + std::string(n, ' ') + "1,\n" + std::string(n, ' ') + "2\n]");
+    }
+
+    return all_prefixes(seeds);
+}
+
+// a value whose binary serializations contain long strings and keys, numbers
+// of every width, and nested containers
+json binary_document()
+{
+    json j;
+    j["a key that is longer than eight bytes"] = "a string value that is longer than eight bytes";
+    j["\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80"] = "\xF0\x9F\x98\x80\xE2\x82\xAC\xC3\xA4 utf-8 0123456789";
+    j["numbers"] = {0, 1, -1, 255, -256, 65536, -2147483649LL, 4294967296ULL, 1.5, -2.25e100};
+    j["nested"] = {{"x", {{"y", {true, false, nullptr}}}}};
+    j["s"] = "";
+    return j;
+}
+
+// readers for check_binary(), callable with a container or an iterator range
+// followed by the allow_exceptions flag
+#define JSON_TEST_GUARD_PAGE_READER(name, from)                                     \
+    struct name                                                                     \
+    {                                                                               \
+        template<typename... Args>                                                  \
+        json operator()(bool allow_exceptions, Args&& ... args) const               \
+        {                                                                           \
+            return json::from(std::forward<Args>(args)..., true, allow_exceptions); \
+        }                                                                           \
+    };
+JSON_TEST_GUARD_PAGE_READER(read_bson, from_bson)
+JSON_TEST_GUARD_PAGE_READER(read_bon8, from_bon8)
+JSON_TEST_GUARD_PAGE_READER(read_cbor, from_cbor)
+JSON_TEST_GUARD_PAGE_READER(read_msgpack, from_msgpack)
+JSON_TEST_GUARD_PAGE_READER(read_ubjson, from_ubjson)
+JSON_TEST_GUARD_PAGE_READER(read_bjdata, from_bjdata)
+#undef JSON_TEST_GUARD_PAGE_READER
+
+// reads every prefix of @a bytes at both ends of the guarded page and from a
+// std::string, which must give the same outcome
+template<typename Reader>
+void check_binary(guarded_buffer& guard, const std::vector<std::uint8_t>& bytes, Reader parse)
+{
+    for (const auto& input : all_prefixes({std::string(bytes.begin(), bytes.end())}))
+    {
+        CAPTURE(input)
+        const std::string expected = outcome([&](bool allow)
+        {
+            return parse(allow, input);
+        });
+        for (int placement = 0; placement < 2; ++placement)
+        {
+            const std::uint8_t* const first = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+            CHECK(outcome([&](bool allow)
+            {
+                return parse(allow, first, first + input.size());
+            }) == expected);
+        }
+    }
+}
+} // namespace
+
+TEST_CASE("guard page")
+{
+    guarded_buffer guard;
+
+    SECTION("string scanning")
+    {
+        // fills that drive each function to a different stop
+        const std::vector<std::string> fills =
+        {
+            std::string(64, 'a'),
+            std::string(64, '"'),
+            std::string(64, '\\'),
+            std::string(64, '\x01'),
+            std::string(64, '\x7F'),
+            std::string(64, '\xFF'),
+        };
+        std::vector<std::string> patterns = fills;
+        {
+            std::string utf8;
+            while (utf8.size() < 64)
+            {
+                utf8 += "\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80" "ab";
+            }
+            patterns.push_back(utf8);
+        }
+        {
+            std::string bytes;
+            for (unsigned int i = 0; i < 64; ++i)
+            {
+                bytes.push_back(static_cast<char>((i * 37u) & 0xFFu));
+            }
+            patterns.push_back(bytes);
+        }
+
+        for (const auto& pattern : patterns)
+        {
+            for (std::size_t n = 0; n <= 64; ++n)
+            {
+                const std::string input = pattern.substr(0, n);
+                for (int placement = 0; placement < 2; ++placement)
+                {
+                    const unsigned char* const p = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+
+                    CHECK(nlohmann::detail::find_string_special(p, n) <= n);
+                    CHECK(nlohmann::detail::find_ascii_copyable_run(p, n) <= n);
+                    CHECK(nlohmann::detail::valid_utf8_prefix(p, n) <= n);
+#if defined(JSON_USE_SIMDUTF) && defined(JSON_HAS_CPP_17)
+                    CHECK(nlohmann::detail::find_string_delimiter(p, n) <= n);
+#endif
+                    CHECK(nlohmann::detail::string_bulk_run(p, n) <= n);
+                    CHECK(nlohmann::detail::scalar_string_bulk_run(p, n) <= n);
+                    for (std::size_t i = 0; i < n; ++i)
+                    {
+                        CHECK(nlohmann::detail::validate_one_utf8(p + i, n - i) <= n - i);
+                    }
+                }
+            }
+        }
+    }
+
+    SECTION("Eisel-Lemire")
+    {
+        const std::vector<std::string> numbers = all_prefixes(
+        {
+            "1234567812345678123456781234567812345678",
+            "-1.2345678901234567890123456789e-123",
+            "0.00000000000000000000000000000000000001",
+            "98765432.10987654",
+        });
+        for (const auto& number : numbers)
+        {
+            double out = 0;
+            const char* const end = reinterpret_cast<const char*>(guard.at_end(number));
+            static_cast<void>(nlohmann::detail::parse_float_eisel_lemire(end, end + number.size(), out));
+            const char* const start = reinterpret_cast<const char*>(guard.at_start(number));
+            static_cast<void>(nlohmann::detail::parse_float_eisel_lemire(start, start + number.size(), out));
+        }
+    }
+
+    SECTION("JSON")
+    {
+        for (const auto& input : json_seeds())
+        {
+            CAPTURE(input)
+            const std::string expected = outcome([&](bool allow)
+            {
+                return json::parse(input, nullptr, allow);
+            });
+            const std::string expected_comments = outcome([&](bool allow)
+            {
+                return json::parse(input, nullptr, allow, true);
+            });
+            const bool expected_accept = json::accept(input);
+            counting_sax expected_sax;
+            const bool expected_sax_result = json::sax_parse(input, &expected_sax);
+
+            for (int placement = 0; placement < 2; ++placement)
+            {
+                const std::uint8_t* const first = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+                const std::uint8_t* const last = first + input.size();
+
+                CHECK(outcome([&](bool allow)
+                {
+                    return json::parse(first, last, nullptr, allow);
+                }) == expected);
+                CHECK(outcome([&](bool allow)
+                {
+                    return json::parse(first, last, nullptr, allow, true);
+                }) == expected_comments);
+                CHECK(json::accept(first, last) == expected_accept);
+
+                counting_sax sax;
+                CHECK(json::sax_parse(first, last, &sax) == expected_sax_result);
+                CHECK(sax.events == expected_sax.events);
+                CHECK(sax.error == expected_sax.error);
+            }
+        }
+    }
+
+    SECTION("binary formats")
+    {
+        // every prefix ends inside a value, e.g., inside a BSON key or BON8
+        // string without its terminator
+        const json j = binary_document();
+        check_binary(guard, json::to_bson(j), read_bson());
+        check_binary(guard, json::to_bon8(j), read_bon8());
+        check_binary(guard, json::to_cbor(j), read_cbor());
+        check_binary(guard, json::to_msgpack(j), read_msgpack());
+        check_binary(guard, json::to_ubjson(j), read_ubjson());
+        check_binary(guard, json::to_bjdata(j), read_bjdata());
+    }
+}
+
+#endif