[libcalamaresui] Read emergency setting from module.desc

- Read setting from the module descriptor
 - Document optional settings
 - Add EMERGENCY keyword to the CMake helper functions

CMakeModules/CalamaresAddPlugin.cmake

@@ -38,6 +38,7 @@
 #   RESOURCES resource-file
 #   [NO_INSTALL]
 #   [SHARED_LIB]
+#   [EMERGENCY]
 # )
 
 include( CMakeParseArguments )
@@ -47,7 +48,7 @@ include( CMakeColors )
 function( calamares_add_plugin )
     # parse arguments ( name needs to be saved before passing ARGN into the macro )
     set( NAME ${ARGV0} )
-    set( options NO_INSTALL SHARED_LIB )
+    set( options NO_INSTALL SHARED_LIB EMERGENCY )
     set( oneValueArgs NAME TYPE EXPORT_MACRO RESOURCES )
     set( multiValueArgs SOURCES UI LINK_LIBRARIES LINK_PRIVATE_LIBRARIES COMPILE_DEFINITIONS )
     cmake_parse_arguments( PLUGIN "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN} )
@@ -132,6 +133,9 @@ function( calamares_add_plugin )
         set( _type ${PLUGIN_TYPE} )
         file( WRITE  ${_file} "# AUTO-GENERATED metadata file\n# Syntax is YAML 1.2\n---\n" )
         file( APPEND ${_file} "type: \"${_type}\"\nname: \"${PLUGIN_NAME}\"\ninterface: \"qtplugin\"\nload: \"lib${target}.so\"\n" )
+        if ( PLUGIN_EMERGENCY )
+            file( APPEND ${_file} "emergency: true\n" )
+        endif()
     endif()
 
     install( FILES ${CMAKE_CURRENT_BINARY_DIR}/${PLUGIN_DESC_FILE}

src/libcalamaresui/modulesystem/Module.cpp

@@ -290,6 +290,12 @@ void
 Module::initFrom( const QVariantMap& moduleDescriptor )
 {
     m_name = moduleDescriptor.value( "name" ).toString();
+
+    auto em = QStringLiteral( "emergency" );
+    if ( moduleDescriptor.contains( em ) )
+    {
+        m_emergency = moduleDescriptor[ em ].toBool();
+    }
 }
 
 } //ns

src/libcalamaresui/modulesystem/Module.h

@@ -182,9 +182,11 @@ public:
 protected:
     explicit Module();
     virtual void initFrom( const QVariantMap& moduleDescriptor );
-    bool m_loaded;
     QVariantMap m_configurationMap;
 
+    bool m_loaded = false;
+    bool m_emergency = false;
+
 private:
     void loadConfigurationFile( const QString& configFileName ); //throws YAML::Exception
 
@@ -193,8 +195,6 @@ private:
     QString m_directory;
     QString m_instanceId;
 
-    bool m_emergency;
-
     friend void ::operator>>( const QVariantMap& moduleDescriptor,
                               Calamares::Module* m );
 };

src/modules/README.md

@@ -43,15 +43,21 @@ module's name, type, interface and possibly other properties. The name
 of the module as defined in `module.desc` must be the same as the name
 of the module's directory.
 
-Module descriptors must have the following keys:
+Module descriptors **must** have the following keys:
 - *name* (an identifier; must be the same as the directory name)
 - *type* ("job" or "view")
 - *interface* (see below for the different interfaces; generally we
   refer to the kinds of modules by their interface)
 
+Module descriptors **may** have the following keys:
+- *required* **unimplemented** (a list of modules which are required for this module
+  to operate properly)
+- *emergency* (a boolean value, set to true to mark the module
+  as an emergency module)
+
 ## Module-specific configuration
 
-A Calamares module *may* read a module configuration file,
+A Calamares module **may** read a module configuration file,
 named `<modulename>.conf`. If such a file is present in the
 module's directory, it is shipped as a *default* configuration file.
 The module configuration file, if it exists, is a YAML 1.2 document
@@ -125,3 +131,17 @@ while the module type must be "job" or "jobmodule".
 The key *command* should have a string as value, which is passed to the
 shell -- remember to quote it properly.
 
+## Emergency Modules
+
+Only C++ modules and job modules may be emergency modules. If, during an
+*exec* step in the sequence, a module fails, installation as a whole fails
+and the install is aborted. If there are emergency modules in the **same**
+exec block, those will be executed before the installation is aborted.
+Non-emergency modules are not executed.
+
+If an emergency-module fails while processing emergency-modules for
+another failed module, that failure is ignored and emergency-module
+processing continues.
+
+Use the EMERGENCY keyword in the CMake description of a C++ module
+to generate a suitable `module.desc`.