diff --git a/include/fmt/os.h b/include/fmt/os.h
index a679de09..1a8833de 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -136,6 +136,8 @@ template <typename Char> struct formatter<std::error_code, Char> {
};
#ifdef _WIN32
+FMT_API const std::error_category& system_category() FMT_NOEXCEPT;
+
namespace detail {
// A converter from UTF-16 to UTF-8.
// It is only provided for Windows since other systems support UTF-8 natively.
@@ -202,6 +204,10 @@ std::system_error windows_error(int error_code, string_view message,
// Can be used to report errors from destructors.
FMT_API void report_windows_error(int error_code,
const char* message) FMT_NOEXCEPT;
+#else
+inline const std::error_category& system_category() FMT_NOEXCEPT {
+ return std::system_category();
+}
#endif // _WIN32
// std::system is not available on some platforms such as iOS (#2248).
diff --git a/src/os.cc b/src/os.cc
index 3fd043c7..6474d455 100644
--- a/src/os.cc
+++ b/src/os.cc
@@ -100,35 +100,78 @@ int detail::utf16_to_utf8::convert(wstring_view s) {
return 0;
}
+namespace detail {
+
+class system_message {
+ system_message(const system_message&) = delete;
+ void operator=(const system_message&) = delete;
+
+ unsigned long result_;
+ wchar_t* message_;
+
+ static bool is_whitespace(wchar_t c) FMT_NOEXCEPT {
+ return c == L' ' || c == L'\n' || c == L'\r' || c == L'\t' || c == L'\0';
+ }
+
+ public:
+ explicit system_message(unsigned long error_code)
+ : result_(0), message_(nullptr) {
+ result_ = FormatMessageW(
+ FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
+ FORMAT_MESSAGE_IGNORE_INSERTS,
+ nullptr, error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+ reinterpret_cast<wchar_t*>(&message_), 0, nullptr);
+ if (result_ != 0) {
+ while (result_ != 0 && is_whitespace(message_[result_ - 1])) {
+ --result_;
+ }
+ }
+ }
+ ~system_message() { LocalFree(message_); }
+ explicit operator bool() const FMT_NOEXCEPT { return result_ != 0; }
+ operator wstring_view() const FMT_NOEXCEPT {
+ return wstring_view(message_, result_);
+ }
+};
+
+class utf8_system_category final : public std::error_category {
+ public:
+ const char* name() const FMT_NOEXCEPT override { return "system"; }
+ std::string message(int error_code) const override {
+ system_message msg(error_code);
+ if (msg) {
+ utf16_to_utf8 utf8_message;
+ if (utf8_message.convert(msg) == ERROR_SUCCESS) {
+ return utf8_message.str();
+ }
+ }
+ return "unknown error";
+ }
+};
+
+} // namespace detail
+
+FMT_API const std::error_category& system_category() FMT_NOEXCEPT {
+ static const detail::utf8_system_category category;
+ return category;
+}
+
std::system_error vwindows_error(int err_code, string_view format_str,
format_args args) {
- auto ec = std::error_code(err_code, std::system_category());
+ auto ec = std::error_code(err_code, system_category());
throw std::system_error(ec, vformat(format_str, args));
}
void detail::format_windows_error(detail::buffer<char>& out, int error_code,
const char* message) FMT_NOEXCEPT {
FMT_TRY {
- wmemory_buffer buf;
- buf.resize(inline_buffer_size);
- for (;;) {
- wchar_t* system_message = &buf[0];
- int result = FormatMessageW(
- FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
- error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), system_message,
- static_cast<uint32_t>(buf.size()), nullptr);
- if (result != 0) {
- utf16_to_utf8 utf8_message;
- if (utf8_message.convert(system_message) == ERROR_SUCCESS) {
- format_to(buffer_appender<char>(out), "{}: {}", message,
- utf8_message);
- return;
- }
- break;
+ system_message msg(error_code);
+ if (msg) {
+ utf16_to_utf8 utf8_message;
+ if (utf8_message.convert(msg) == ERROR_SUCCESS) {
+ format_to(buffer_appender<char>(out), "{}: {}", message, utf8_message);
+ return;
}
- if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
- break; // Can't get error message, report error code instead.
- buf.resize(buf.size() * 2);
}
}
FMT_CATCH(...) {}
diff --git a/test/os-test.cc b/test/os-test.cc
index 8cf3c5e8..09115b77 100644
--- a/test/os-test.cc
+++ b/test/os-test.cc
@@ -45,7 +45,6 @@ void check_utf_conversion_error(
fmt::basic_string_view<Char> str = fmt::basic_string_view<Char>(0, 1)) {
fmt::memory_buffer out;
fmt::detail::format_windows_error(out, ERROR_INVALID_PARAMETER, message);
- out.resize(out.size() - 2); // Remove newline.
auto error = std::system_error(std::error_code());
try {
(Converter)(str);
@@ -74,10 +73,10 @@ TEST(os_test, format_std_error_code) {
std::error_code(42, std::generic_category())));
EXPECT_EQ("system:42",
fmt::format(FMT_STRING("{0}"),
- std::error_code(42, std::system_category())));
+ std::error_code(42, fmt::system_category())));
EXPECT_EQ("system:-42",
fmt::format(FMT_STRING("{0}"),
- std::error_code(-42, std::system_category())));
+ std::error_code(-42, fmt::system_category())));
}
TEST(os_test, format_std_error_code_wide) {
@@ -86,10 +85,10 @@ TEST(os_test, format_std_error_code_wide) {
std::error_code(42, std::generic_category())));
EXPECT_EQ(L"system:42",
fmt::format(FMT_STRING(L"{0}"),
- std::error_code(42, std::system_category())));
+ std::error_code(42, fmt::system_category())));
EXPECT_EQ(L"system:-42",
fmt::format(FMT_STRING(L"{0}"),
- std::error_code(-42, std::system_category())));
+ std::error_code(-42, fmt::system_category())));
}
TEST(os_test, format_windows_error) {
@@ -99,7 +98,8 @@ TEST(os_test, format_windows_error) {
FORMAT_MESSAGE_IGNORE_INSERTS,
0, ERROR_FILE_EXISTS, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
reinterpret_cast<LPWSTR>(&message), 0, 0);
- fmt::detail::utf16_to_utf8 utf8_message(message);
+ fmt::detail::utf16_to_utf8 utf8_message(
+ fmt::wstring_view(message, result - 2));
LocalFree(message);
fmt::memory_buffer actual_message;
fmt::detail::format_windows_error(actual_message, ERROR_FILE_EXISTS, "test");
@@ -120,8 +120,12 @@ TEST(os_test, format_long_windows_error) {
0, static_cast<DWORD>(provisioning_not_allowed),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
reinterpret_cast<LPWSTR>(&message), 0, 0);
- EXPECT_NE(result, 0);
- fmt::detail::utf16_to_utf8 utf8_message(message);
+ if (result == 0) {
+ LocalFree(message);
+ return;
+ }
+ fmt::detail::utf16_to_utf8 utf8_message(
+ fmt::wstring_view(message, result - 2));
LocalFree(message);
fmt::memory_buffer actual_message;
fmt::detail::format_windows_error(actual_message, provisioning_not_allowed,
@@ -139,7 +143,6 @@ TEST(os_test, windows_error) {
}
fmt::memory_buffer message;
fmt::detail::format_windows_error(message, ERROR_FILE_EXISTS, "test error");
- message.resize(message.size() - 2);
EXPECT_THAT(error.what(), HasSubstr(to_string(message)));
EXPECT_EQ(ERROR_FILE_EXISTS, error.code().value());
}
diff --git a/test/posix-mock-test.cc b/test/posix-mock-test.cc
index f669f13a..191d7aef 100644
--- a/test/posix-mock-test.cc
+++ b/test/posix-mock-test.cc
@@ -272,7 +272,7 @@ TEST(file_test, size) {
}
fstat_sim = none;
EXPECT_EQ(error_code,
- std::error_code(ERROR_ACCESS_DENIED, std::system_category()));
+ std::error_code(ERROR_ACCESS_DENIED, fmt::system_category()));
# else
f.close();
EXPECT_SYSTEM_ERROR(f.size(), EBADF, "cannot get file attributes");