Added user input validation for default filenames

 - fixes #5123 partially

src/core/control/Control.cpp

@@ -4,6 +4,7 @@
 #include <cstdlib>    // for size_t
 #include <exception>  // for exce...
 #include <iterator>   // for end
+#include <locale>
 #include <memory>     // for make...
 #include <numeric>    // for accu...
 #include <optional>   // for opti...
@@ -2876,11 +2877,18 @@ void Control::closeDocument() {
 }
 
 void Control::applyPreferredLanguage() {
+    auto const& lang = this->settings->getPreferredLocale();
 #ifdef _WIN32
-    _putenv_s("LANGUAGE", this->settings->getPreferredLocale().c_str());
+    _putenv_s("LANGUAGE", lang.c_str());
 #else
-    setenv("LANGUAGE", this->settings->getPreferredLocale().c_str(), 1);
+    setenv("LANGUAGE", lang.c_str(), 1);
 #endif
+    try {
+        auto glob = std::locale{std::locale(".UTF-8"), lang, std::locale::all};
+        std::locale::global(glob);
+    } catch (std::runtime_error const& e) {
+        g_warning("Failed to set locale %s: %s", lang.c_str(), e.what());
+    }
 }
 
 void Control::initButtonTool() {

src/core/control/XournalMain.cpp

@@ -96,7 +96,7 @@ void initLocalisation() {
 
     // Not working on GNU g++(mingww) forWindows! Only working on Linux/macOS and with msvc
     try {
-        std::locale::global(std::locale(""));  // "" - system default locale
+        std::locale::global(std::locale(".UTF-8"));  // "" - system default locale
     } catch (const std::runtime_error& e) {
         g_warning("XournalMain: System default locale could not be set.\n - Caused by: %s\n - Note that it is not "
                   "supported to set the locale using mingw-w64 on windows.\n - This could be solved by compiling "

src/core/gui/dialog/LanguageConfigGui.cpp

@@ -57,16 +57,18 @@ LanguageConfigGui::LanguageConfigGui(GladeSearchpath* gladeSearchPath, GtkWidget
 
 
     // Set the current locale if previously selected
-    auto prefPos = availableLocales.begin();
-    if (auto preferred = settings->getPreferredLocale(); !preferred.empty()) {
-        prefPos = std::find(availableLocales.begin(), availableLocales.end(), preferred);
-        if (*prefPos != preferred) {
+    auto prefPos = [&]() {
+        if (auto preferred = settings->getPreferredLocale(); !preferred.empty()) {
+            if (auto &&endi = availableLocales.end(), prefPos = std::find(availableLocales.begin(), endi, preferred);
+                prefPos != endi) {
+                return prefPos;
+            }
             XojMsgBox::showErrorToUser(nullptr, _("Previously selected language not available anymore!"));
-
-            // Use system default
-            prefPos = availableLocales.begin();
         }
-    }
+        // Use system default
+        return availableLocales.begin();
+    }();
+
     gtk_combo_box_set_active(GTK_COMBO_BOX(dropdown), prefPos - availableLocales.begin());
 }
 

src/core/model/Document.cpp

@@ -1,6 +1,9 @@
 #include "Document.h"
 
+#include <array>
 #include <ctime>    // for size_t, localtime, strf...
+#include <iomanip>
+#include <sstream>
 #include <string>   // for string
 #include <utility>  // for move, pair
 
@@ -131,6 +134,7 @@ auto Document::createSaveFolder(fs::path lastSavePath) -> fs::path {
 }
 
 auto Document::createSaveFilename(DocumentType type, const std::string& defaultSaveName, const std::string& defaultPdfName) -> fs::path {
+    constexpr static std::string_view forbiddenChars = {"\\/:*?\"<>|"};
     std::string wildcardString;
     if (type != Document::PDF) {
         if (!filepath.empty()) {
@@ -152,17 +156,23 @@ auto Document::createSaveFilename(DocumentType type, const std::string& defaultS
 
     const char* format = wildcardString.empty() ? defaultSaveName.c_str() : wildcardString.c_str();
 
+    // Todo (cpp20): use <format>
+    std::ostringstream ss;
+    ss.imbue(std::locale());
     time_t curtime = time(nullptr);
-    char stime[128];
-    strftime(stime, sizeof(stime), format, localtime(&curtime));
-
-    // Remove the extension, file format is handled by the filter combo box
-    fs::path p = stime;
+    ss << std::put_time(localtime(&curtime), format);
+    auto filename = ss.str();
+    // Todo (cpp20): use <ranges>
+    for (auto& c: filename) {
+        if ((c < 32 && c > 0) || c == 127 || forbiddenChars.find(c) != std::string::npos) {
+            c = '_';
+        }
+    }
+    fs::path p = filename;
     Util::clearExtensions(p);
     return p;
 }
 
-
 auto Document::getPreview() const -> cairo_surface_t* { return this->preview; }
 
 void Document::setPreview(cairo_surface_t* preview) {

ui/settings.glade

@@ -572,19 +572,20 @@ If the file was not yet saved you can find it in ~/.cache/xournalpp/autosaves&lt
 %H		Hour in 24h format (00-23)
 %I		Hour in 12h format (01-12)
 %j		Day of the year (001-366)
-%m	Month as a decimal number (01-12)
-%M	Minute (00-59)
+%m		Month as a decimal number (01-12)
+%M		Minute (00-59)
 %p		AM or PM designation (e.g. PM)
 %S		Second (00-61)
 %U		Week number with the first Sunday as the first day of week one (00-53)
 %w		Weekday as a decimal number with Sunday as 0 (0-6)
-%W	Week number with the first Monday as the first day of week one (00-53)
+%W		Week number with the first Monday as the first day of week one (00-53)
 %x		Date representation (e.g. 08/23/01)
 %X		Time representation (e.g. 14:55:02)
 %y		Year, last two digits (00-99)
 %Y		Year (e.g. 2001)
 %Z		Timezone name or abbreviation (e.g. CDT)
-%%	A % sign</property>
+%%		%
+Illegal characters are replaced with "_"</property>
                                                 <property name="xalign">0</property>
                                               </object>
                                             </child>
@@ -743,19 +744,20 @@ If the file was not yet saved you can find it in ~/.cache/xournalpp/autosaves&lt
 %H			Hour in 24h format (00-23)
 %I			Hour in 12h format (01-12)
 %j			Day of the year (001-366)
-%m		Month as a decimal number (01-12)
-%M		Minute (00-59)
+%m			Month as a decimal number (01-12)
+%M			Minute (00-59)
 %p			AM or PM designation (e.g. PM)
 %S			Second (00-61)
 %U			Week number with the first Sunday as the first day of week one (00-53)
 %w			Weekday as a decimal number with Sunday as 0 (0-6)
-%W		Week number with the first Monday as the first day of week one (00-53)
+%W			Week number with the first Monday as the first day of week one (00-53)
 %x			Date representation (e.g. 08/23/01)
 %X			Time representation (e.g. 14:55:02 or 2:55:02 PM)
 %y			Year, last two digits (00-99)
 %Y			Year (e.g. 2001)
 %Z			Timezone name or abbreviation (e.g. CDT)
-%%		A % sign</property>
+%%			%
+Illegal characters are replaced with "_"</property>
                                             <property name="xalign">0</property>
                                           </object>
                                         </child>