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AK+Userland: Extend the compiletime format string check to other func…
…tions Thanks to @trflynn89 for the neat implicit consteval ctor trick! This allows us to basically slap `CheckedFormatString` on any formatting function, and have its format argument checked at compiletime. Note that there is a validator bug where it doesn't parse inner replaced fields like `{:~>{}}` correctly (what should be 'left align with next argument as size' is parsed as `{:~>{` following a literal closing brace), so the compiletime checks are disabled on these temporarily by forcing them to be StringViews. This commit also removes the now unused `AK::StringLiteral` type (which was introduced for use with NTTP strings).
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/* | ||
* Copyright (c) 2021, the SerenityOS developers. | ||
* All rights reserved. | ||
* | ||
* Redistribution and use in source and binary forms, with or without | ||
* modification, are permitted provided that the following conditions are met: | ||
* | ||
* 1. Redistributions of source code must retain the above copyright notice, this | ||
* list of conditions and the following disclaimer. | ||
* | ||
* 2. Redistributions in binary form must reproduce the above copyright notice, | ||
* this list of conditions and the following disclaimer in the documentation | ||
* and/or other materials provided with the distribution. | ||
* | ||
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | ||
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE | ||
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | ||
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
*/ | ||
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#pragma once | ||
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#include <AK/AllOf.h> | ||
#include <AK/AnyOf.h> | ||
#include <AK/StdLibExtras.h> | ||
#include <AK/StringView.h> | ||
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#ifndef DBGLN_NO_COMPILETIME_FORMAT_CHECK | ||
// FIXME: Seems like clang doesn't like calling 'consteval' functions inside 'consteval' functions quite the same way as GCC does, | ||
// it seems to entirely forget that it accepted that parameters to a 'consteval' function to begin with. | ||
# ifdef __clang__ | ||
# define DBGLN_NO_COMPILETIME_FORMAT_CHECK | ||
# endif | ||
#endif | ||
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#ifndef DBGLN_NO_COMPILETIME_FORMAT_CHECK | ||
namespace AK::Format::Detail { | ||
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// We have to define a local "purely constexpr" Array that doesn't lead back to us (via e.g. ASSERT) | ||
template<typename T, size_t Size> | ||
struct Array { | ||
constexpr static size_t size() { return Size; } | ||
constexpr const T& operator[](size_t index) const { return __data[index]; } | ||
constexpr T& operator[](size_t index) { return __data[index]; } | ||
using ConstIterator = SimpleIterator<const Array, const T>; | ||
using Iterator = SimpleIterator<Array, T>; | ||
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constexpr ConstIterator begin() const { return ConstIterator::begin(*this); } | ||
constexpr Iterator begin() { return Iterator::begin(*this); } | ||
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constexpr ConstIterator end() const { return ConstIterator::end(*this); } | ||
constexpr Iterator end() { return Iterator::end(*this); } | ||
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T __data[Size]; | ||
}; | ||
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template<typename... Args> | ||
void compiletime_fail(Args...); | ||
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template<size_t N> | ||
consteval auto extract_used_argument_index(const char (&fmt)[N], size_t specifier_start_index, size_t specifier_end_index, size_t& next_implicit_argument_index) | ||
{ | ||
struct { | ||
size_t index_value { 0 }; | ||
bool saw_explicit_index { false }; | ||
} state; | ||
for (size_t i = specifier_start_index; i < specifier_end_index; ++i) { | ||
auto c = fmt[i]; | ||
if (c > '9' || c < '0') | ||
break; | ||
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state.index_value *= 10; | ||
state.index_value += c - '0'; | ||
state.saw_explicit_index = true; | ||
} | ||
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if (!state.saw_explicit_index) | ||
return next_implicit_argument_index++; | ||
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return state.index_value; | ||
} | ||
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// FIXME: We should rather parse these format strings at compile-time if possible. | ||
template<size_t N> | ||
consteval auto count_fmt_params(const char (&fmt)[N]) | ||
{ | ||
struct { | ||
// FIXME: Switch to variable-sized storage whenever we can come up with one :) | ||
Array<size_t, 128> used_arguments { 0 }; | ||
size_t total_used_argument_count { 0 }; | ||
size_t next_implicit_argument_index { 0 }; | ||
bool has_explicit_argument_references { false }; | ||
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size_t unclosed_braces { 0 }; | ||
size_t extra_closed_braces { 0 }; | ||
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Array<size_t, 4> last_format_specifier_start { 0 }; | ||
size_t total_used_last_format_specifier_start_count { 0 }; | ||
} result; | ||
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for (size_t i = 0; i < N; ++i) { | ||
auto ch = fmt[i]; | ||
switch (ch) { | ||
case '{': | ||
if (i + 1 < N && fmt[i + 1] == '{') { | ||
++i; | ||
continue; | ||
} | ||
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// Note: There's no compile-time throw, so we have to abuse a compile-time string to store errors. | ||
if (result.total_used_last_format_specifier_start_count >= result.last_format_specifier_start.size() - 1) | ||
compiletime_fail("Format-String Checker internal error: Format specifier nested too deep"); | ||
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result.last_format_specifier_start[result.total_used_last_format_specifier_start_count++] = i + 1; | ||
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++result.unclosed_braces; | ||
break; | ||
case '}': | ||
if (i + 1 < N && fmt[i + 1] == '}') { | ||
++i; | ||
continue; | ||
} | ||
if (result.unclosed_braces) { | ||
--result.unclosed_braces; | ||
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if (result.total_used_last_format_specifier_start_count == 0) | ||
compiletime_fail("Format-String Checker internal error: Expected location information"); | ||
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const auto specifier_start_index = result.last_format_specifier_start[--result.total_used_last_format_specifier_start_count]; | ||
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if (result.total_used_argument_count >= result.used_arguments.size()) | ||
compiletime_fail("Format-String Checker internal error: Too many format arguments in format string"); | ||
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auto used_argument_index = extract_used_argument_index<N>(fmt, specifier_start_index, i, result.next_implicit_argument_index); | ||
if (used_argument_index + 1 != result.next_implicit_argument_index) | ||
result.has_explicit_argument_references = true; | ||
result.used_arguments[result.total_used_argument_count++] = used_argument_index; | ||
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} else { | ||
++result.extra_closed_braces; | ||
} | ||
break; | ||
default: | ||
continue; | ||
} | ||
} | ||
return result; | ||
} | ||
} | ||
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#endif | ||
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namespace AK::Format::Detail { | ||
template<typename... Args> | ||
struct CheckedFormatString { | ||
template<size_t N> | ||
consteval CheckedFormatString(const char (&fmt)[N]) | ||
: m_string { fmt } | ||
{ | ||
#ifndef DBGLN_NO_COMPILETIME_FORMAT_CHECK | ||
check_format_parameter_consistency<N, sizeof...(Args)>(fmt); | ||
#endif | ||
} | ||
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template<typename T> | ||
CheckedFormatString(const T& unchecked_fmt) requires(requires(T t) { StringView { t }; }) | ||
: m_string(unchecked_fmt) | ||
{ | ||
} | ||
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auto view() const { return m_string; } | ||
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private: | ||
#ifndef DBGLN_NO_COMPILETIME_FORMAT_CHECK | ||
template<size_t N, size_t param_count> | ||
consteval static bool check_format_parameter_consistency(const char (&fmt)[N]) | ||
{ | ||
auto check = count_fmt_params<N>(fmt); | ||
if (check.unclosed_braces != 0) | ||
compiletime_fail("Extra unclosed braces in format string"); | ||
if (check.extra_closed_braces != 0) | ||
compiletime_fail("Extra closing braces in format string"); | ||
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{ | ||
auto begin = check.used_arguments.begin(); | ||
auto end = check.used_arguments.begin() + check.total_used_argument_count; | ||
auto has_all_referenced_arguments = !AK::any_of(begin, end, [](auto& entry) { return entry >= param_count; }); | ||
if (!has_all_referenced_arguments) | ||
compiletime_fail("Format string references nonexistent parameter"); | ||
} | ||
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if (!check.has_explicit_argument_references && check.total_used_argument_count != param_count) | ||
compiletime_fail("Format string does not reference all passed parameters"); | ||
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// Ensure that no passed parameter is ignored or otherwise not referenced in the format | ||
// As this check is generally pretty expensive, try to avoid it where it cannot fail. | ||
// We will only do this check if the format string has explicit argument refs | ||
// otherwise, the check above covers this check too, as implicit refs | ||
// monotonically increase, and cannot have 'gaps'. | ||
if (check.has_explicit_argument_references) { | ||
auto all_parameters = iota_array<size_t, param_count>(0); | ||
constexpr auto contains = [](auto begin, auto end, auto entry) { | ||
for (; begin != end; begin++) { | ||
if (*begin == entry) | ||
return true; | ||
} | ||
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return false; | ||
}; | ||
auto references_all_arguments = AK::all_of( | ||
all_parameters.begin(), | ||
all_parameters.end(), | ||
[&](auto& entry) { | ||
return contains( | ||
check.used_arguments.begin(), | ||
check.used_arguments.begin() + check.total_used_argument_count, | ||
entry); | ||
}); | ||
if (!references_all_arguments) | ||
compiletime_fail("Format string does not reference all passed parameters"); | ||
} | ||
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return true; | ||
} | ||
#endif | ||
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StringView m_string; | ||
}; | ||
} | ||
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namespace AK { | ||
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template<typename... Args> | ||
using CheckedFormatString = Format::Detail::CheckedFormatString<typename IdentityType<Args>::Type...>; | ||
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} |
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