From d3a53a702ecbc36ebfb7192a91be4a7e608a5d69 Mon Sep 17 00:00:00 2001
From: Janek Bevendorff <janek@jbev.net>
Date: Thu, 25 Apr 2019 09:28:48 +0200
Subject: [PATCH] Set console code page to CP_UTF8 on Windows if supported.
 (#3050)

Previously, we enforced code page 850 for all console input and output,
which breaks with non-western scripts. Since more recent Windows shells
are able to display Unicode properly, this patch now enforces UTF-8 and
falls back to code page 850 only if UTF-8 is unsupported.

Non-Windows systems default to UTF-8, but can override the codec
by setting the LANG environment variable to something other than C.

Resolves #3049.
---
 src/cli/TextStream.cpp | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/cli/TextStream.cpp b/src/cli/TextStream.cpp
index d75cb74a..938fd629 100644
--- a/src/cli/TextStream.cpp
+++ b/src/cli/TextStream.cpp
@@ -19,6 +19,9 @@
 
 #include <QProcessEnvironment>
 #include <QTextCodec>
+#ifdef Q_OS_WIN
+#include <windows.h>
+#endif
 
 TextStream::TextStream()
 {
@@ -59,12 +62,26 @@ void TextStream::detectCodec()
 {
     QString codecName = "UTF-8";
     auto env = QProcessEnvironment::systemEnvironment();
+
 #ifdef Q_OS_WIN
-    if (!env.contains("SHELL")) {
-        // native shell (no Msys or cygwin)
+    WINBOOL success = false;
+#ifdef CP_UTF8
+    success = SetConsoleOutputCP(CP_UTF8);
+#endif
+    if (!success && !env.contains("SHELL")) {
+        // Fall back to cp850 if this is Windows without CP_UTF8 and we
+        // are running in a native shell (i.e., no Msys or Cygwin).
         codecName = "Windows-850";
     }
+#else
+    if (env.contains("LANG") && !env.value("LANG").isEmpty() && env.value("LANG") != "C") {
+        // Only override codec if LANG is set, otherwise Qt will assume
+        // US-ASCII, which is almost always wrong and results in
+        // Unicode passwords being displayed as question marks.
+        codecName = QTextCodec::codecForLocale()->name();
+    }
 #endif
+
     codecName = env.value("ENCODING_OVERRIDE", codecName);
     auto* codec = QTextCodec::codecForName(codecName.toLatin1());
     if (codec) {