Added detection for corrupted PrusaSlicer.ini and fixed showing instr…

…uctions on how to recover from it (#8217).

Previously when PrusaSlicer.ini was just partly corrupted, it could happen that PrusaSlicer.ini wasn't detected as corrupted, and it could cause that instruction on how to recover from this state wasn't shown, and PrusaSlicer crashed because wrong data from PrusaSlicer.ini was read.

src/libslic3r/AppConfig.cpp

@@ -230,8 +230,13 @@ static std::string appconfig_md5_hash_line(const std::string_view data)
     return "# MD5 checksum " + md5_digest_str + "\n";
 };
 
+struct ConfigFileInfo {
+    bool correct_checksum {false};
+    bool contains_null {false};
+};
+
 // Assume that the last line with the comment inside the config file contains a checksum and that the user didn't modify the config file.
-static bool verify_config_file_checksum(boost::nowide::ifstream &ifs)
+static ConfigFileInfo check_config_file_and_verify_checksum(boost::nowide::ifstream &ifs)
 {
     auto read_whole_config_file = [&ifs]() -> std::string {
         std::stringstream ss;
@@ -240,7 +245,8 @@ static bool verify_config_file_checksum(boost::nowide::ifstream &ifs)
     };
 
     ifs.seekg(0, boost::nowide::ifstream::beg);
-    std::string whole_config = read_whole_config_file();
+    const std::string whole_config  = read_whole_config_file();
+    const bool        contains_null = whole_config.find_first_of('\0') != std::string::npos;
 
     // The checksum should be on the last line in the config file.
     if (size_t last_comment_pos = whole_config.find_last_of('#'); last_comment_pos != std::string::npos) {
@@ -249,9 +255,9 @@ static bool verify_config_file_checksum(boost::nowide::ifstream &ifs)
         // When the checksum isn't found, the checksum was not saved correctly, it was removed or it is an older config file without the checksum.
         // If the checksum is incorrect, then the file was either not saved correctly or modified.
         if (std::string_view(whole_config.c_str() + last_comment_pos, whole_config.size() - last_comment_pos) == appconfig_md5_hash_line({ whole_config.data(), last_comment_pos }))
-            return true;
+            return {true, contains_null};
     }
-    return false;
+    return {false, contains_null};
 }
 #endif
 
@@ -269,44 +275,55 @@ std::string AppConfig::load(const std::string &path)
         ifs.open(path);
 #ifdef WIN32
         // Verify the checksum of the config file without taking just for debugging purpose.
-        if (!verify_config_file_checksum(ifs))
-            BOOST_LOG_TRIVIAL(info) << "The configuration file " << path <<
-            " has a wrong MD5 checksum or the checksum is missing. This may indicate a file corruption or a harmless user edit.";
+        const ConfigFileInfo config_file_info = check_config_file_and_verify_checksum(ifs);
+        if (!config_file_info.correct_checksum)
+            BOOST_LOG_TRIVIAL(info)
+                << "The configuration file " << path
+                << " has a wrong MD5 checksum or the checksum is missing. This may indicate a file corruption or a harmless user edit.";
+
+        if (!config_file_info.correct_checksum && config_file_info.contains_null) {
+            BOOST_LOG_TRIVIAL(info) << "The configuration file " + path + " is corrupted, because it is contains null characters.";
+            throw Slic3r::CriticalException("The configuration file contains null characters.");
+        }
 
         ifs.seekg(0, boost::nowide::ifstream::beg);
 #endif
-        pt::read_ini(ifs, tree);
-    } catch (pt::ptree_error& ex) {
+        try {
+            pt::read_ini(ifs, tree);
+        } catch (pt::ptree_error &ex) {
+            throw Slic3r::CriticalException(ex.what());
+        }
+    } catch (Slic3r::CriticalException &ex) {
 #ifdef WIN32
         // The configuration file is corrupted, try replacing it with the backup configuration.
         ifs.close();
         std::string backup_path = (boost::format("%1%.bak") % path).str();
         if (boost::filesystem::exists(backup_path)) {
             // Compute checksum of the configuration backup file and try to load configuration from it when the checksum is correct.
             boost::nowide::ifstream backup_ifs(backup_path);
-            if (!verify_config_file_checksum(backup_ifs)) {
-                BOOST_LOG_TRIVIAL(error) << format("Both \"%1%\" and \"%2%\" are corrupted. It isn't possible to restore configuration from the backup.", path, backup_path);
+            if (const ConfigFileInfo config_file_info = check_config_file_and_verify_checksum(backup_ifs); !config_file_info.correct_checksum || config_file_info.contains_null) {
+                BOOST_LOG_TRIVIAL(error) << format(R"(Both "%1%" and "%2%" are corrupted. It isn't possible to restore configuration from the backup.)", path, backup_path);
                 backup_ifs.close();
                 boost::filesystem::remove(backup_path);
             } else if (std::string error_message; copy_file(backup_path, path, error_message, false) != SUCCESS) {
-                BOOST_LOG_TRIVIAL(error) << format("Configuration file \"%1%\" is corrupted. Failed to restore from backup \"%2%\": %3%", path, backup_path, error_message);
+                BOOST_LOG_TRIVIAL(error) << format(R"(Configuration file "%1%" is corrupted. Failed to restore from backup "%2%": %3%)", path, backup_path, error_message);
                 backup_ifs.close();
                 boost::filesystem::remove(backup_path);
             } else {
-                BOOST_LOG_TRIVIAL(info) << format("Configuration file \"%1%\" was corrupted. It has been succesfully restored from the backup \"%2%\".", path, backup_path);
+                BOOST_LOG_TRIVIAL(info) << format(R"(Configuration file "%1%" was corrupted. It has been successfully restored from the backup "%2%".)", path, backup_path);
                 // Try parse configuration file after restore from backup.
                 try {
                     ifs.open(path);
                     pt::read_ini(ifs, tree);
                     recovered = true;
                 } catch (pt::ptree_error& ex) {
-                    BOOST_LOG_TRIVIAL(info) << format("Failed to parse configuration file \"%1%\" after it has been restored from backup: %2%", path, ex.what());
+                    BOOST_LOG_TRIVIAL(info) << format(R"(Failed to parse configuration file "%1%" after it has been restored from backup: %2%)", path, ex.what());
                 }
             }
         } else
 #endif // WIN32
-            BOOST_LOG_TRIVIAL(info) << format("Failed to parse configuration file \"%1%\": %2%", path, ex.what());
-        if (! recovered) {
+            BOOST_LOG_TRIVIAL(info) << format(R"(Failed to parse configuration file "%1%": %2%)", path, ex.what());
+        if (!recovered) {
             // Report the initial error of parsing PrusaSlicer.ini.
             // Error while parsing config file. We'll customize the error message and rethrow to be displayed.
             // ! But to avoid the use of _utf8 (related to use of wxWidgets)