Support international paths on Windows in app (#1319)

* Add support for wide paths to RequestFile in the rest library.

* Write to UTF16 filename for log files.

Author: jonsimantov

app/rest/request_file.cc

@@ -30,15 +30,31 @@
 #if FIREBASE_PLATFORM_WINDOWS
 #define fseeko _fseeki64
 #define ftello _ftelli64
+
+// Also include files needed for path conversion.
+#include <wchar.h>  // NOLINT
+
+#include <codecvt>
+#include <locale>
+#include <string>
 #endif  // FIREBASE_PLATFORM_WINDOWS
 
 namespace firebase {
 namespace rest {
 
 // Create a request that will read from the specified file.
 // This file isn't opened until the first call to ReadBody().
-RequestFile::RequestFile(const char* filename, size_t offset)
-    : file_(fopen(filename, "rb")), file_size_(0) {
+// Note that on Windows, the filename will be UTF-8 encoded
+// and needs to be converted to utf16.
+RequestFile::RequestFile(const char* filename, size_t offset) : file_size_(0) {
+#if FIREBASE_PLATFORM_WINDOWS
+  std::string filename_utf8(filename);
+  std::wstring_convert<std::codecvt_utf8<wchar_t>> utf8_to_utf16;
+  std::wstring filename_utf16 = utf8_to_utf16.from_bytes(filename_utf8);
+  file_ = _wfopen(filename_utf16.c_str(), L"rb");
+#else
+  file_ = fopen(filename, "rb");
+#endif
   options_.stream_post_fields = true;
   // If the file exists, seek to the end of the file and get the size.
   if (file_ && fseeko(file_, 0, SEEK_END) == 0) {

app/src/log.cc

@@ -23,6 +23,7 @@
 
 #include "app/src/assert.h"
 #include "app/src/include/firebase/internal/mutex.h"
+#include "app/src/include/firebase/internal/platform.h"
 
 #if !defined(FIREBASE_LOG_DEBUG)
 #define FIREBASE_LOG_DEBUG 0
@@ -86,6 +87,8 @@ static void DefaultLogCallback(LogLevel log_level, const char* message,
 // Log a message to a log file.
 static void LogToFile(LogLevel log_level, const char* format, va_list args) {
 #define FIREBASE_LOG_FILENAME "firebase.log"
+// Wide string version for Windows.
+#define FIREBASE_LOG_FILENAME_W L"firebase.log"
   static FILE* log_file = nullptr;
   static bool attempted_to_open_log_file = false;
   static const char* kLogLevelToPrefixString[] = {
@@ -109,7 +112,11 @@ static void LogToFile(LogLevel log_level, const char* format, va_list args) {
   } else {
     MutexLock lock(*g_log_mutex);
     if (!log_file) {
+#if FIREBASE_PLATFORM_WINDOWS
+      log_file = _wfopen(FIREBASE_LOG_FILENAME_W, L"wt");
+#else
       log_file = fopen(FIREBASE_LOG_FILENAME, "wt");
+#endif
       if (!log_file) {
         g_log_callback(kLogLevelError,
                        "Unable to open log file " FIREBASE_LOG_FILENAME,