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add buffer flush before direct write
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Roman-Koshelev authored and vitaut committed Oct 24, 2023
1 parent e9bbd40 commit 3b7f58a
Showing 1 changed file with 7 additions and 9 deletions.
16 changes: 7 additions & 9 deletions include/fmt/format-inl.h
Original file line number Diff line number Diff line change
Expand Up @@ -73,9 +73,8 @@ FMT_FUNC void report_error(format_func func, int error_code,
}

// A wrapper around fwrite that throws on error.
inline void fwrite_fully(const void* ptr, size_t size, size_t count,
FILE* stream) {
size_t written = std::fwrite(ptr, size, count, stream);
inline void fwrite_fully(const void* ptr, size_t count, FILE* stream) {
size_t written = std::fwrite(ptr, 1, count, stream);
if (written < count)
FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
}
Expand Down Expand Up @@ -1433,13 +1432,12 @@ extern "C" __declspec(dllimport) int __stdcall WriteConsoleW( //
void*, const void*, dword, dword*, void*);

FMT_FUNC bool write_console(std::FILE* f, string_view text) {
auto fd = _fileno(f);
int fd = _fileno(f);
if (!_isatty(fd)) return false;
std::fflush(f);

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@dimztimz

dimztimz Oct 25, 2023

Contributor

Adding fflush here is not correct. This function write_console() is called either from the C stream print() or the C++ iostream print(). In the latter case, fflush should not be called at all, instead the ostream flush should be invoked.

auto u16 = utf8_to_utf16(text);
auto written = dword();
return WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)), u16.c_str(),
static_cast<uint32_t>(u16.size()), &written,
nullptr) != 0;
static_cast<dword>(u16.size()), nullptr, nullptr) != 0;
}
#endif

Expand All @@ -1448,12 +1446,12 @@ FMT_FUNC bool write_console(std::FILE* f, string_view text) {
FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args) {
auto buffer = memory_buffer();
detail::vformat_to(buffer, fmt, args);
fwrite_fully(buffer.data(), 1, buffer.size(), f);
fwrite_fully(buffer.data(), buffer.size(), f);
}
#endif

FMT_FUNC void print(std::FILE* f, string_view text) {
if (!write_console(f, text)) fwrite_fully(text.data(), 1, text.size(), f);
if (!write_console(f, text)) fwrite_fully(text.data(), text.size(), f);
}
} // namespace detail

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