From fba8bc3975704f4622e35d7846170bc6dfa511ae Mon Sep 17 00:00:00 2001
From: Gleb Mazovetskiy <glex.spb@gmail.com>
Date: Sat, 2 Jul 2022 11:30:43 +0100
Subject: [PATCH] Optional Win9x support

Adds optional support for Windows 9x/ME and the original Xbox (nxdk).

Most of libfmt is available except functions that depend on `fileno`,
such as file descriptor duplication.

For now, support must be enabled explicitly by defining `FMT_WIN9X`.
---
 CMakeLists.txt           | 5 +++++
 include/fmt/chrono.h     | 8 ++++----
 include/fmt/core.h       | 8 ++++++++
 include/fmt/format-inl.h | 8 ++++----
 include/fmt/os.h         | 6 +++++-
 src/os.cc                | 6 +++++-
 6 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b096e4e2..ecf529df 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -268,6 +268,11 @@ target_include_directories(fmt-header-only ${FMT_SYSTEM_HEADERS_ATTRIBUTE} INTER
   $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
   $<INSTALL_INTERFACE:${FMT_INC_DIR}>)
 
+if (FMT_WIN98X)
+  target_compile_definitions(fmt PUBLIC FMT_WIN98X=1)
+  target_compile_definitions(fmt-header-only INTERFACE FMT_WIN98X=1)
+endif()
+
 # Install targets.
 if (FMT_INSTALL)
   include(CMakePackageConfigHelpers)
diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 11565d63..ca198379 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -46,8 +46,8 @@ FMT_BEGIN_NAMESPACE
 #  if FMT_HAS_INCLUDE("winapifamily.h")
 #    include <winapifamily.h>
 #  endif
-#  if defined(_WIN32) && (!defined(WINAPI_FAMILY) || \
-                          (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+#  if defined(_WIN32) && !FMT_WIN9X && \
+     (!defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
 #    define FMT_USE_TZSET 1
 #  else
 #    define FMT_USE_TZSET 0
@@ -488,7 +488,7 @@ inline std::tm localtime(std::time_t time) {
 
     bool fallback(int res) { return res == 0; }
 
-#if !FMT_MSC_VERSION
+#if !FMT_MSC_VERSION || FMT_WIN9X
     bool fallback(detail::null<>) {
       using namespace fmt::detail;
       std::tm* tm = std::localtime(&time_);
@@ -537,7 +537,7 @@ inline std::tm gmtime(std::time_t time) {
 
     bool fallback(int res) { return res == 0; }
 
-#if !FMT_MSC_VERSION
+#if !FMT_MSC_VERSION || FMT_WIN9X
     bool fallback(detail::null<>) {
       std::tm* tm = std::gmtime(&time_);
       if (tm) tm_ = *tm;
diff --git a/include/fmt/core.h b/include/fmt/core.h
index 27143856..90c55c42 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -257,6 +257,14 @@
 #  define FMT_UNICODE !FMT_MSC_VERSION
 #endif
 
+#ifndef FMT_WIN9X
+#  if defined(NXDK)
+#    define FMT_WIN9X 1
+#  else
+#    define FMT_WIN9X 0
+#  endif
+#endif
+
 #ifndef FMT_CONSTEVAL
 #  if ((FMT_GCC_VERSION >= 1000 || FMT_CLANG_VERSION >= 1101) && \
        (!defined(__apple_build_version__) ||                     \
diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
index ba1ab462..32fa426b 100644
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -22,7 +22,7 @@
 #  include <locale>
 #endif
 
-#ifdef _WIN32
+#if defined(_WIN32) && !FMT_WIN9X
 #  include <io.h>  // _isatty
 #endif
 
@@ -1453,7 +1453,7 @@ FMT_FUNC std::string vformat(string_view fmt, format_args args) {
 }
 
 namespace detail {
-#ifdef _WIN32
+#if defined(_WIN32) && !FMT_WIN9X
 using dword = conditional_t<sizeof(long) == 4, unsigned long, unsigned>;
 extern "C" __declspec(dllimport) int __stdcall WriteConsoleW(  //
     void*, const void*, dword, dword*, void*);
@@ -1478,7 +1478,7 @@ FMT_FUNC bool write_console(std::FILE* f, string_view text) {
 #endif
 
 FMT_FUNC void print(std::FILE* f, string_view text) {
-#ifdef _WIN32
+#if defined(_WIN32) && !FMT_WIN9X
   if (write_console(f, text)) return;
 #endif
   detail::fwrite_fully(text.data(), 1, text.size(), f);
@@ -1491,7 +1491,7 @@ FMT_FUNC void vprint(std::FILE* f, string_view format_str, format_args args) {
   detail::print(f, {buffer.data(), buffer.size()});
 }
 
-#ifdef _WIN32
+#if defined(_WIN32) && !FMT_WIN9X
 // Print assuming legacy (non-Unicode) encoding.
 FMT_FUNC void detail::vprint_mojibake(std::FILE* f, string_view format_str,
                                       format_args args) {
diff --git a/include/fmt/os.h b/include/fmt/os.h
index e39f38cd..29413a5b 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -49,7 +49,7 @@
 #  define FMT_POSIX_CALL(call) FMT_SYSTEM(call)
 #else
 #  define FMT_SYSTEM(call) ::call
-#  ifdef _WIN32
+#  if defined(_WIN32) && !FMT_WIN9X
 // Fix warnings about deprecated symbols.
 #    define FMT_POSIX_CALL(call) ::_##call
 #  else
@@ -242,7 +242,9 @@ class buffered_file {
   // Returns the pointer to a FILE object representing this file.
   FILE* get() const noexcept { return file_; }
 
+#if !FMT_WIN9X
   FMT_API int descriptor() const;
+#endif
 
   void vprint(string_view format_str, format_args args) {
     fmt::vprint(file_, format_str, args);
@@ -318,6 +320,7 @@ class FMT_API file {
   // Attempts to write count bytes from the specified buffer to the file.
   size_t write(const void* buffer, size_t count);
 
+#if !FMT_WIN9X
   // Duplicates a file descriptor with the dup function and returns
   // the duplicate as a file object.
   static file dup(int fd);
@@ -333,6 +336,7 @@ class FMT_API file {
   // Creates a pipe setting up read_end and write_end file objects for reading
   // and writing respectively.
   static void pipe(file& read_end, file& write_end);
+#endif
 
   // Creates a buffered_file object associated with this file and detaches
   // this file object from the file.
diff --git a/src/os.cc b/src/os.cc
index 521b84de..fd27d622 100644
--- a/src/os.cc
+++ b/src/os.cc
@@ -71,7 +71,7 @@ inline std::size_t convert_rwcount(std::size_t count) { return count; }
 
 FMT_BEGIN_NAMESPACE
 
-#ifdef _WIN32
+#if defined(_WIN32) && !FMT_WIN9X
 detail::utf16_to_utf8::utf16_to_utf8(basic_string_view<wchar_t> s) {
   if (int error_code = convert(s)) {
     FMT_THROW(windows_error(error_code,
@@ -205,6 +205,7 @@ void buffered_file::close() {
     FMT_THROW(system_error(errno, FMT_STRING("cannot close file")));
 }
 
+#if !FMT_WIN9X
 int buffered_file::descriptor() const {
 #ifdef fileno  // fileno is a macro on OpenBSD so we cannot use FMT_POSIX_CALL.
   int fd = fileno(file_);
@@ -215,6 +216,7 @@ int buffered_file::descriptor() const {
     FMT_THROW(system_error(errno, FMT_STRING("cannot get file descriptor")));
   return fd;
 }
+#endif // !FMT_WIN9X
 
 #if FMT_USE_FCNTL
 #  ifdef _WIN32
@@ -295,6 +297,7 @@ std::size_t file::write(const void* buffer, std::size_t count) {
   return detail::to_unsigned(result);
 }
 
+#if !FMT_WIN9X
 file file::dup(int fd) {
   // Don't retry as dup doesn't return EINTR.
   // http://pubs.opengroup.org/onlinepubs/009695399/functions/dup.html
@@ -343,6 +346,7 @@ void file::pipe(file& read_end, file& write_end) {
   read_end = file(fds[0]);
   write_end = file(fds[1]);
 }
+#endif
 
 buffered_file file::fdopen(const char* mode) {
 // Don't retry as fdopen doesn't return EINTR.