windows: Trick to get UTF-8 encoded argv in main entry point

- Adapt exifprint to the new wmain strategy
- Delete have_unicode_path
- wmain does not work with MSYS & MinGW
- cmake: entry point via cmake instead of pragma
- cmake: better doc for MSVC flags
- Fix entry point in sample apps
- Adapt CMake code to work with MSVC & MinGW

CMakeLists.txt

@@ -9,7 +9,7 @@ project(exiv2          # use TWEAK to categorize the build
                        # 1.00.0.20 = RC2 Preview
                        # 1.00.0.29 = RC2 Development
     DESCRIPTION    "Exif/IPTC/Xmp C++ metadata library and tools plus ICC Profiles, Previews and more."
-    LANGUAGES CXX
+    LANGUAGES C CXX
 )
 
 if(NOT CMAKE_BUILD_TYPE)

cmake/compilerFlags.cmake

@@ -167,13 +167,7 @@ if(MSVC)
         string(REGEX REPLACE "/W[0-4]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     endif ()
 
-    # Object Level Parallelism
-    add_compile_options(/MP)
+    add_compile_options(/MP)    # Object Level Parallelism
+    add_compile_options(/utf-8) # Set source and execution character sets to UTF-8
     add_definitions(-DNOMINMAX) # This definition is not only needed for Exiv2 but also for xmpsdk
-    
-    # https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
-    if (MSVC_VERSION GREATER_EQUAL "1910") # VS2017 and up
-        add_compile_options("/Zc:__cplusplus")
-    endif()
-
 endif()

samples/CMakeLists.txt

@@ -114,6 +114,15 @@ list(APPEND APPLICATIONS remotetest)
 # ******************************************************************************
 foreach(application ${APPLICATIONS})
     target_link_libraries(${application} PRIVATE exiv2lib)
+    if(MSVC)
+        target_link_libraries(${application} PRIVATE wmain)
+        target_link_options(${application} PRIVATE "/ENTRY:wWinMainCRTStartup")
+    endif()
+    if (MINGW)
+        target_link_libraries(${application} PRIVATE wmain)
+        target_compile_options(${application} PRIVATE -municode)
+        target_link_options(${application} PRIVATE -municode)
+    endif()
     if( EXIV2_ENABLE_PNG )
         target_link_libraries(${application} PRIVATE ${ZLIB_LIBRARIES} )
         if (MSVC)

samples/exifprint.cpp

@@ -25,25 +25,6 @@
 #include <cassert>
 #include <regex>
 
-// https://github.com/Exiv2/exiv2/issues/468
-#if defined(EXV_UNICODE_PATH) && defined(__MINGW__)
-#undef  EXV_UNICODE_PATH
-#endif
-
-#ifdef  EXV_UNICODE_PATH
-#define _tchar      wchar_t
-#define _tstrcmp    wcscmp
-#define _t(s)       L##s
-#define _tcout      wcout
-#define _tmain      wmain
-#else
-#define _tchar      char
-#define _tstrcmp    strcmp
-#define _t(s)       s
-#define _tcout      cout
-#define _tmain      main
-#endif
-
 // copied from src/tiffvisitor_int.cpp
 static const Exiv2::TagInfo* findTag(const Exiv2::TagInfo* pList,uint16_t tag)
 {
@@ -52,31 +33,32 @@ static const Exiv2::TagInfo* findTag(const Exiv2::TagInfo* pList,uint16_t tag)
 }
 
 
-int _tmain(int argc, _tchar* const argv[])
+int main(int argc, char* const argv[])
 try {
+    setlocale(LC_CTYPE, ".utf8");
     Exiv2::XmpParser::initialize();
     ::atexit(Exiv2::XmpParser::terminate);
 #ifdef EXV_ENABLE_BMFF
     Exiv2::enableBMFF();
 #endif
 
-    const _tchar* prog = argv[0];
+    const char* prog = argv[0];
     if (argc == 1) {
-        std::_tcout << _t("Usage: ") << prog << _t(" [ [--lint] path | --version | --version-test ]") << std::endl;
+        std::cout << "Usage: " << prog << " [ [--lint] path | --version | --version-test ]" << std::endl;
         return 1;
     }
 
     int    rc          = 0      ;
-    const _tchar* file = argv[1];
-    bool   bLint       = _tstrcmp(file,_t("--lint")) == 0 && argc == 3;
+    const char* file = argv[1];
+    bool   bLint       = strcmp(file, "--lint") == 0 && argc == 3;
     if (   bLint ) file= argv[2];
 
 
-    if ( _tstrcmp(file,_t("--version")) == 0 ) {
+    if ( strcmp(file,"--version") == 0 ) {
         std::vector<std::regex> keys;
         Exiv2::dumpLibraryInfo(std::cout,keys);
         return rc;
-    } else if ( _tstrcmp(file,_t("--version-test")) == 0 ) {
+    } else if ( strcmp(file,"--version-test") == 0 ) {
         // verifies/test macro EXIV2_TEST_VERSION
         // described in include/exiv2/version.hpp
         std::cout << "EXV_PACKAGE_VERSION             " << EXV_PACKAGE_VERSION             << std::endl

src/CMakeLists.txt

@@ -287,6 +287,23 @@ if(EXIV2_BUILD_EXIV2_COMMAND)
         target_include_directories(exiv2 PRIVATE ${Intl_INCLUDE_DIRS})
     endif()
 
+    if(MSVC OR MINGW)
+        # Trick to get properly UTF-8 encoded argv 
+        # More info at: https://github.com/huangqinjin/wmain
+        add_library(wmain STATIC wmain.c)
+        target_link_libraries(exiv2 PRIVATE wmain)
+    endif()
+
+    if (MSVC)
+        target_link_options(wmain INTERFACE /WHOLEARCHIVE:$<TARGET_FILE:wmain>)
+        target_link_options(exiv2 PRIVATE "/ENTRY:wWinMainCRTStartup")
+    endif()
+
+    if (MINGW)
+        target_compile_options(exiv2 PRIVATE -municode)
+        target_link_options(exiv2 PRIVATE -municode)
+    endif()
+
     if (USING_CONAN AND WIN32 AND EXISTS ${PROJECT_BINARY_DIR}/conanDlls)
         # In case of using conan recipes with their 'shared' option turned on, we will have dlls of
         # the 3rd party dependencies in the conanDlls folder.

src/exiv2.cpp

@@ -120,6 +120,8 @@ namespace {
 // Main
 int main(int argc, char* const argv[])
 {
+    setlocale(LC_CTYPE, ".utf8");
+
     Exiv2::XmpParser::initialize();
     ::atexit(Exiv2::XmpParser::terminate);
 #ifdef EXV_ENABLE_BMFF

src/version.cpp

@@ -332,7 +332,6 @@ void Exiv2::dumpLibraryInfo(std::ostream& os,const std::vector<std::regex>& keys
     int have_strings     =0;
     int have_sys_types   =0;
     int have_unistd      =0;
-    int have_unicode_path=0;
 
     int enable_bmff      =0;
     int enable_webready  =0;
@@ -512,7 +511,6 @@ void Exiv2::dumpLibraryInfo(std::ostream& os,const std::vector<std::regex>& keys
     output(os,keys,"have_strings"      ,have_strings     );
     output(os,keys,"have_sys_types"    ,have_sys_types   );
     output(os,keys,"have_unistd"       ,have_unistd      );
-    output(os,keys,"have_unicode_path" ,have_unicode_path);
     output(os,keys,"enable_bmff"       ,enable_bmff      );
     output(os,keys,"enable_webready"   ,enable_webready  );
     output(os,keys,"enable_nls"        ,enable_nls       );

src/wmain.c

@@ -0,0 +1,40 @@
+#include <windows.h>
+
+extern int __cdecl main();
+
+int wmain(int argc, wchar_t* argv[])
+{
+    char** args;
+    int nbytes = sizeof(char*) * (argc + 1);
+    HANDLE heap = GetProcessHeap();
+
+    for (int i = 0; i < argc; ++i)
+        nbytes += WideCharToMultiByte(CP_UTF8, 0, argv[i], -1, NULL, 0, NULL, NULL);
+
+    args = HeapAlloc(heap, 0, nbytes);
+    args[0] = (char*)(args + argc + 1);
+    
+    for (int i = 0; i < argc; ++i)
+        args[i+1] = args[i] + WideCharToMultiByte(CP_UTF8, 0, argv[i], -1, args[i], nbytes, NULL, NULL);
+    
+    args[argc] = NULL;
+
+    argc = main(argc, args);
+    HeapFree(heap, 0, args);
+    return argc;
+}
+
+int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow)
+{
+    (void) hInstance;
+    (void) hPrevInstance;
+    (void) lpCmdLine;
+    (void) nCmdShow;
+
+    int argc;
+    wchar_t** argv;
+    argv = CommandLineToArgvW(GetCommandLineW(), &argc);
+    argc = wmain(argc, argv);
+    LocalFree(argv);
+    return argc;
+}