uniform XML boolean attribute access

Replace 'attribute(...).has_value("yes")`
with 'attribute_value(..., false)'.

This allows for boolean configuration to be set with values such as
"true", "false", "yes", "no", or "1", "0".

Fixes #2002

repos/dde_bsd/src/drivers/audio/main.cc

@@ -466,15 +466,6 @@ class Audio_in::Root : public Audio_in::Root_component
  ** Main **
  **********/
 
-static bool check(Genode::Xml_node   config,
-                  char const * const attr,
-                  char const * const value)
-{
-	try         { return config.attribute(attr).has_value(value); }
-	catch (...) { return false; }
-}
-
-
 struct Main
 {
 	Genode::Env        &env;
@@ -502,7 +493,7 @@ struct Main
 		}
 
 		/* playback */
-		if (!check(config.xml(), "playback", "no")) {
+		if (config.xml().attribute_value("playback", true)) {
 			static Audio_out::Out out(ep);
 			Audio::play_sigh(out.sigh());
 			static Audio_out::Root out_root(ep, heap, out.data_avail());
@@ -512,7 +503,7 @@ struct Main
 		}
 
 		/* recording */
-		if (check(config.xml(), "recording", "yes")) {
+		if (config.xml().attribute_value("recording", true)) {
 			static Audio_in::In in(ep);
 			Audio::record_sigh(in.sigh());
 			static Audio_in::Root in_root(ep, heap,

repos/dde_linux/src/drivers/wifi/main.cc

@@ -232,9 +232,7 @@ struct Main
 		_ep(ep)
 	{
 		Genode::Xml_node config = Genode::config()->xml_node();
-		try {
-			config_verbose = config.attribute("verbose").has_value("yes");
-		} catch (...) { }
+		config_verbose = config.attribute_value("verbose", config_verbose);
 
 		_wpa = new (Genode::env()->heap()) Wpa_thread(wpa_startup_lock(), config_verbose);
 

repos/dde_linux/src/lib/usb/include/platform.h

@@ -58,7 +58,7 @@ struct Services
 				Genode::Xml_node node_screen = node_hid.sub_node("touchscreen");
 				node_screen.attribute("width").value(&screen_width);
 				node_screen.attribute("height").value(&screen_height);
-				multitouch = node_screen.attribute("multitouch").has_value("yes");
+				multitouch = node_screen.attribute_value("multitouch", false);
 			} catch (...) {
 				screen_width = screen_height = 0;
 				PDBG("Could not read screen resolution in config node");
@@ -87,32 +87,26 @@ struct Services
 
 			try {
 				Genode::Xml_node node_report = node_raw.sub_node("report");
-				raw_report_device_list = node_report.attribute("devices").has_value("yes");
+				raw_report_device_list = node_report.attribute_value("devices", false);
 			} catch (...) { }
 		} catch (Xml_node::Nonexistent_sub_node) {
 			PDBG("No <raw> config node found - not starting external USB service");
 		}
 
-		try {
-			if (!config()->xml_node().attribute("uhci").has_value("yes"))
-				throw -1;
+		if (config()->xml_node().attribute_value("uhci", false)) {
 			uhci = true;
 			PINF("Enabled UHCI (USB 1.0/1.1) support");
-		} catch (...) { }
+		}
 
-		try {
-			if (!config()->xml_node().attribute("ehci").has_value("yes"))
-				throw -1;
+		if (config()->xml_node().attribute_value("ehci", false)) {
 			ehci = true;
 			PINF("Enabled EHCI (USB 2.0) support");
-		} catch (...) { }
+		}
 
-		try {
-			if (!config()->xml_node().attribute("xhci").has_value("yes"))
-				throw -1;
+		if (config()->xml_node().attribute_value("xhci", false)) {
 			xhci = true;
 			PINF("Enabled XHCI (USB 3.0) support");
-		} catch (...) { }
+		}
 
 		if (!(uhci | ehci | xhci))
 			PWRN("Warning: No USB controllers enabled.\n"

repos/dde_linux/src/lib/usb/spec/x86/pci_driver.cc

@@ -152,18 +152,12 @@ extern "C" int pci_register_driver(struct pci_driver *driver)
 		/* register driver at the 'pci_dev' struct */
 		pci_dev->dev.driver = &driver->driver;
 
-		bool bios_handoff = true;
-		try {
-			if (config()->xml_node().attribute("bios_handoff").has_value("no"))
-				bios_handoff = false;
-		} catch (...) { }
-
 		/*
 		 * This quirk handles device handoff from BIOS, since the BIOS may still
 		 * access the USB controller after bootup. For this the ext cap register of
 		 * the PCI config space is checked
 		 */
-		if (bios_handoff)
+		if (config()->xml_node().attribute_value("bios_handoff", true))
 			__pci_fixup_quirk_usb_early_handoff(pci_dev);
 
 		/* call probe function of the Linux driver */

repos/dde_linux/src/lib/wifi/init.cc

@@ -139,8 +139,7 @@ void wifi_init(Server::Entrypoint &ep, Genode::Lock &lock)
 	 * For testing testing only the wireless stack with wpa_supplicant,
 	 * amongst other on linux, we do not want to load the iwlwifi drivers.
 	 */
-	if (Genode::config()->xml_node().has_attribute("mac80211_only"))
-		mac80211_only = Genode::config()->xml_node().attribute("mac80211_only").has_value("yes");
+	mac80211_only = Genode::config()->xml_node().attribute_value("mac80211_only", mac80211_only);
 	if (mac80211_only)
 		PINF("Initalizing only mac80211 stack without any driver!");
 

repos/dde_rump/src/server/rump_fs/main.cc

@@ -410,9 +410,7 @@ class File_system::Root : public Root_component<Session_component>
 				/*
 				 * Determine if write access is permitted for the session.
 				 */
-				try {
-					writeable = policy.attribute("writeable").has_value("yes");
-				} catch (Xml_node::Nonexistent_attribute) { }
+				writeable = policy.attribute_value("writeable", false);
 
 			} catch (Session_policy::No_policy_defined) {
 				PERR("Invalid session request, no matching policy");

repos/gems/src/app/backdrop/main.cc

@@ -259,8 +259,7 @@ void Backdrop::Main::apply_image(Xml_node operation)
 
 	Point const pos = Point(anchored_xpos, anchored_ypos) + offset;
 
-	bool const tiled = operation.has_attribute("tiled")
-	                && operation.attribute("tiled").has_value("yes");
+	bool const tiled = operation.attribute_value("tiled", false);
 
 	unsigned alpha = Decorator::attribute(operation, "alpha", 256U);
 

repos/gems/src/app/decorator/window.cc

@@ -193,16 +193,6 @@ void Decorator::Window::draw(Decorator::Canvas_base &canvas,
 }
 
 
-/**
- * Return true if specified XML attribute has the given value
- */
-static bool attribute_has_value(Genode::Xml_node node,
-                                char const *attr, char const *value)
-{
-	return node.has_attribute(attr) && node.attribute(attr).has_value(value);
-}
-
-
 bool Decorator::Window::update(Genode::Xml_node window_node)
 {
 	bool updated = false;
@@ -234,8 +224,8 @@ bool Decorator::Window::update(Genode::Xml_node window_node)
 		updated |= true;
 	}
 
-	_focused   = attribute_has_value(window_node, "focused",   "yes");
-	_has_alpha = attribute_has_value(window_node, "has_alpha", "yes");
+	_focused   = window_node.attribute_value(  "focused", false);
+	_has_alpha = window_node.attribute_value("has_alpha", false);
 
 	Window_title title = Decorator::string_attribute(window_node, "title",
 	                                                 Window_title("<untitled>"));
@@ -268,7 +258,7 @@ bool Decorator::Window::update(Genode::Xml_node window_node)
 				char const * const attr =
 					Control::type_name(window_control.type());
 
-				if (attribute_has_value(window_node, attr, "yes"))
+				if (window_node.attribute_value(attr, false))
 					new_controls.add(window_control);
 				break;
 			}

repos/gems/src/app/floating_window_layouter/main.cc

@@ -385,12 +385,9 @@ void Floating_window_layouter::Main::import_window_list(Xml_node window_list_xml
 
 			win->size(initial_size);
 			win->title(string_attribute(node, "title", Window::Title("")));
-			win->has_alpha(node.has_attribute("has_alpha")
-			            && node.attribute("has_alpha").has_value("yes"));
-			win->hidden(node.has_attribute("hidden")
-			         && node.attribute("hidden").has_value("yes"));
-			win->resizeable(node.has_attribute("resizeable")
-			             && node.attribute("resizeable").has_value("yes"));
+			win->has_alpha( node.attribute_value("has_alpha",  false));
+			win->hidden(    node.attribute_value("hidden",     false));
+			win->resizeable(node.attribute_value("resizeable", false));
 		}
 	} catch (...) { }
 }

repos/gems/src/app/menu_view/main.cc

@@ -174,8 +174,7 @@ void Menu_view::Main::handle_config(unsigned)
 
 	try {
 		hover_reporter.enabled(config()->xml_node().sub_node("report")
-		                                           .attribute("hover")
-		                                           .has_value("yes"));
+		                                           .attribute_value("hover", false));
 	} catch (...) {
 		hover_reporter.enabled(false);
 	}

repos/gems/src/app/menu_view/widgets.h

@@ -656,7 +656,7 @@ struct Menu_view::Button_widget : Widget, Animator::Item
 
 	static bool _enabled(Xml_node node, char const *attr)
 	{
-		return node.has_attribute(attr) && node.attribute(attr).has_value("yes");
+		return node.attribute_value(attr, false);
 	}
 
 	Button_widget(Widget_factory &factory, Xml_node node, Unique_id unique_id)

repos/libports/src/drivers/framebuffer/vesa/main.cc

@@ -63,14 +63,7 @@ unsigned long session_arg(const char *attr_name, const char *args,
 
 bool config_attribute(const char *attr_name)
 {
-
-	bool result  = false;
-
-	try {
-		result = Genode::config()->xml_node().attribute(attr_name).has_value("yes"); }
-	catch (...) {}
-
-	return result;
+	return Genode::config()->xml_node().attribute_value(attr_name, false);
 }
 
 

repos/libports/src/lib/libc_lwip_nic_dhcp/init.cc

@@ -52,10 +52,7 @@ void __attribute__((constructor)) init_nic_dhcp(void)
 	try {
 		Genode::Xml_node libc_node = Genode::config()->xml_node().sub_node("libc");
 
-		try {
-			if (libc_node.attribute("resolv").has_value("no"))
-				provide_etc_resolv_conf = false;
-		} catch(...) { }
+		provide_etc_resolv_conf = libc_node.attribute_value("resolv", provide_etc_resolv_conf);
 
 		try {
 			libc_node.attribute("ip_addr").value(ip_addr_str, sizeof(ip_addr_str));

repos/libports/src/lib/qt5/qtbase/src/plugins/platforms/nitpicker/qgenodeclipboard.cpp

@@ -31,29 +31,25 @@ static constexpr bool verbose = false;
 QGenodeClipboard::QGenodeClipboard(Genode::Signal_receiver &sig_rcv)
 : _clipboard_signal_dispatcher(sig_rcv, *this, &QGenodeClipboard::_handle_clipboard)
 {
-	try {
+	if (Genode::config()->xml_node().attribute_value("clipboard", false)) {
 
-		if (Genode::config()->xml_node().attribute("clipboard").has_value("yes")) {
+		try {
 
-			try {
+			_clipboard_ds = new (Genode::env()->heap())
+				Genode::Attached_rom_dataspace("clipboard");
 
-				_clipboard_ds = new (Genode::env()->heap())
-					Genode::Attached_rom_dataspace("clipboard");
+			_clipboard_ds->sigh(_clipboard_signal_dispatcher);
+			_clipboard_ds->update();
 
-				_clipboard_ds->sigh(_clipboard_signal_dispatcher);
-				_clipboard_ds->update();
+		} catch (...) { }
 
-			} catch (...) { }
+		try {
+			_clipboard_reporter = new (Genode::env()->heap())
+				Genode::Reporter("clipboard");
+			_clipboard_reporter->enabled(true);
+		} catch (...) {	}
 
-			try {
-				_clipboard_reporter = new (Genode::env()->heap())
-					Genode::Reporter("clipboard");
-				_clipboard_reporter->enabled(true);
-			} catch (...) {	}
-
-		}
-
-	} catch (...) { }
+	}
 }
 
 

repos/libports/src/server/ffat_fs/main.cc

@@ -946,9 +946,7 @@ namespace File_system {
 					/*
 					 * Determine if write access is permitted for the session.
 					 */
-					try {
-						writeable = policy.attribute("writeable").has_value("yes");
-					} catch (Xml_node::Nonexistent_attribute) { }
+					writeable = policy.attribute_value("writeable", false);
 
 				} catch (Session_policy::No_policy_defined) {
 					PERR("Invalid session request, no matching policy");

repos/libports/src/server/fuse_fs/fuse_fs_main.cc

@@ -477,10 +477,9 @@ class File_system::Root : public Root_component<Session_component>
 				/*
 				 * Determine if write access is permitted for the session.
 				 */
-				try {
-					writeable = policy.attribute("writeable").has_value("yes");
+				writeable = policy.attribute_value("writeable", false);
+				if (writeable)
 					PWRN("WARNING: write support in fuse_fs is considered experimental, data-loss may occur.");
-				} catch (Xml_node::Nonexistent_attribute) { }
 
 			} catch (Session_policy::No_policy_defined) {
 				PERR("Invalid session request, no matching policy");

repos/os/include/init/child.h

@@ -431,7 +431,7 @@ class Init::Child : Genode::Child_policy
 						try {
 							if (rsc.attribute("name").has_value("RAM")) {
 								rsc.attribute("quantum").value(&ram_bytes);
-								constrain_phys = rsc.attribute("constrain_phys").has_value("yes");
+								constrain_phys = rsc.attribute_value("constrain_phys", false);
 							} else if (rsc.attribute("name").has_value("CPU")) {
 								rsc.attribute("quantum").value(&cpu_quota_pc); }
 						} catch (...) { }
@@ -817,7 +817,7 @@ class Init::Child : Genode::Child_policy
 		void exit(int exit_value) override
 		{
 			try {
-				if (_start_node.sub_node("exit").attribute("propagate").has_value("yes")) {
+				if (_start_node.sub_node("exit").attribute_value("propagate", false)) {
 					Genode::env()->parent()->exit(exit_value);
 					return;
 				}

repos/os/src/app/trace_subject_reporter/main.cc

@@ -162,7 +162,7 @@ struct Server::Main
 	{
 		try {
 			return Genode::config()->xml_node().sub_node("report")
-			                                   .attribute(attr).has_value("yes");
+			                                   .attribute_value(attr, false);
 		} catch (...) { return false; }
 	}
 

repos/os/src/drivers/framebuffer/spec/imx53/main.cc

@@ -114,12 +114,7 @@ class Framebuffer::Session_component :
 
 static bool config_attribute(const char *attr_name)
 {
-	bool result = false;
-	try {
-		result =
-			Genode::config()->xml_node().attribute(attr_name).has_value("yes"); }
-	catch (...) {}
-	return result;
+	return Genode::config()->xml_node().attribute_value(attr_name, false);
 }
 
 

repos/os/src/drivers/framebuffer/spec/omap4/main.cc

@@ -143,12 +143,7 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 
 static bool config_attribute(const char *attr_name)
 {
-	bool result = false;
-	try {
-		result =
-			Genode::config()->xml_node().attribute(attr_name).has_value("yes"); }
-	catch (...) {}
-	return result;
+	return Genode::config()->xml_node().attribute_value(attr_name, false);
 }
 
 

repos/os/src/drivers/framebuffer/spec/rpi/main.cc

@@ -110,11 +110,7 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 
 static bool config_is_buffered()
 {
-	try {
-		return Genode::config()->xml_node().attribute("buffered").has_value("yes");
-	} catch (...) {
-		return false;
-	}
+	return Genode::config()->xml_node().attribute_value("buffered", false);
 }
 
 

repos/os/src/drivers/input/spec/ps2/pl050/main.cc

@@ -44,11 +44,9 @@ struct Main
 	Irq_handler  ps2_mouse_irq;
 	Irq_handler  ps2_keybd_irq;
 
-	bool _check_verbose(const char * verbose) {
-		using namespace Genode;
-		try {
-			return config()->xml_node().attribute(verbose).has_value("yes");
-		} catch (...) { return false; }
+	bool _check_verbose(const char * verbose)
+	{
+		return Genode::config()->xml_node().attribute_value(verbose, false);
 	}
 
 	Main(Server::Entrypoint &ep)

repos/os/src/drivers/input/spec/ps2/x86/main.cc

@@ -52,11 +52,9 @@ struct Main
 
 	enum { REG_IOPORT_DATA = 0, REG_IOPORT_STATUS};
 
-	bool _check_verbose(const char * verbose) {
-		using namespace Genode;
-		try {
-			return config()->xml_node().attribute(verbose).has_value("yes");
-		} catch (...) { return false; }
+	bool _check_verbose(const char * verbose)
+	{
+		return Genode::config()->xml_node().attribute_value(verbose, false);
 	}
 
 	Main(Server::Entrypoint &ep)

repos/os/src/drivers/uart/uart_component.h

@@ -232,10 +232,7 @@ namespace Uart {
 						policy.attribute("baudrate").value(&baudrate);
 					} catch (Xml_node::Nonexistent_attribute) { }
 
-					bool detect_size = false;
-					try {
-						detect_size = policy.attribute("detect_size").has_value("yes");
-					} catch (Xml_node::Nonexistent_attribute) { }
+					bool detect_size = policy.attribute_value("detect_size", false);
 
 					return new (md_alloc())
 						Session_component(_driver_factory, index, baudrate, detect_size);

repos/os/src/init/main.cc

@@ -310,10 +310,8 @@ int main(int, char **)
 
 	for (;;) {
 
-		try {
-			config_verbose =
-				config()->xml_node().attribute("verbose").has_value("yes"); }
-		catch (...) { }
+		config_verbose =
+			config()->xml_node().attribute_value("verbose", false);
 
 		try { determine_parent_services(&parent_services); }
 		catch (...) { }

repos/os/src/server/clipboard/main.cc

@@ -78,8 +78,7 @@ struct Server::Main : Rom::Module::Read_policy, Rom::Module::Write_policy
 	bool _verbose_config()
 	{
 		char const *attr = "verbose";
-		return Genode::config()->xml_node().has_attribute(attr)
-		    && Genode::config()->xml_node().attribute(attr).has_value("yes");
+		return Genode::config()->xml_node().attribute_value(attr, false);
 	}
 
 	bool verbose = _verbose_config();
@@ -107,7 +106,7 @@ struct Server::Main : Rom::Module::Read_policy, Rom::Module::Write_policy
 		try {
 			Genode::Xml_node focus(_focus_ds.local_addr<char>(), _focus_ds.size());
 
-			if (focus.attribute("active").has_value("yes"))
+			if (focus.attribute_value("active", false))
 				_focused_domain = focus.attribute_value("domain", Domain());
 
 		} catch (...) { }

repos/os/src/server/dynamic_rom/main.cc

@@ -251,8 +251,7 @@ struct Dynamic_rom::Main
 	{
 		Xml_node config = Genode::config()->xml_node();
 
-		return config.has_attribute("verbose")
-		    && config.attribute("verbose").has_value("yes");
+		return config.attribute_value("verbose", false);
 	}
 
 	bool verbose = _verbose_config();

repos/os/src/server/lx_fs/main.cc

@@ -370,9 +370,7 @@ class File_system::Root : public Root_component<Session_component>
 				/*
 				 * Determine if write access is permitted for the session.
 				 */
-				try {
-					writeable = policy.attribute("writeable").has_value("yes");
-				} catch (Xml_node::Nonexistent_attribute) { }
+				writeable = policy.attribute_value("writeable", false);
 
 			} catch (Session_policy::No_policy_defined) {
 				PERR("Invalid session request, no matching policy");

repos/os/src/server/mixer/mixer.cc

@@ -444,8 +444,7 @@ class Audio_out::Mixer
 			config()->reload();
 
 			Xml_node config_node = config()->xml_node();
-			try { verbose = config_node.attribute("verbose").has_value("yes"); }
-			catch (...) { verbose = false; }
+			verbose = config_node.attribute_value("verbose", verbose);
 
 			_set_default_config(config_node);
 

repos/os/src/server/nitpicker/main.cc

@@ -1317,8 +1317,7 @@ static void configure_reporter(Genode::Reporter &reporter)
 	try {
 		Genode::Xml_node config_xml = Genode::config()->xml_node();
 		reporter.enabled(config_xml.sub_node("report")
-		                           .attribute(reporter.name().string())
-		                           .has_value("yes"));
+		                           .attribute_value(reporter.name().string(), false));
 	} catch (...) {
 		reporter.enabled(false);
 	}
@@ -1339,11 +1338,9 @@ void Nitpicker::Main::handle_config(unsigned)
 	} catch (...) { }
 
 	/* enable or disable redraw debug mode */
-	try {
-		tmp_fb = nullptr;
-		if (config()->xml_node().attribute("flash").has_value("yes"))
-			tmp_fb = &framebuffer;
-	} catch (...) { }
+	tmp_fb = config()->xml_node().attribute_value("flash", false)
+		? &framebuffer
+		: nullptr;
 
 	configure_reporter(pointer_reporter);
 	configure_reporter(hover_reporter);

repos/os/src/server/part_blk/main.cc

@@ -37,11 +37,7 @@ void Block::Driver::_ready_to_submit(unsigned) {
 
 static bool _use_gpt()
 {
-	try {
-		return Genode::config()->xml_node().attribute("use_gpt").has_value("yes");
-	} catch(...) { }
-
-	return false;
+	return Genode::config()->xml_node().attribute_value("use_gpt", false);
 }
 
 

repos/os/src/server/ram_fs/main.cc

@@ -469,9 +469,7 @@ namespace File_system {
 					/*
 					 * Determine if write access is permitted for the session.
 					 */
-					try {
-						writeable = policy.attribute("writeable").has_value("yes");
-					} catch (Xml_node::Nonexistent_attribute) { }
+					writeable = policy.attribute_value("writeable", false);
 
 				} catch (Session_policy::No_policy_defined) {
 					PERR("Invalid session request, no matching policy");

repos/os/src/test/resource_yield/main.cc

@@ -168,8 +168,7 @@ static inline unsigned long read_period_ms_from_config()
 
 Child::Child()
 :
-	_expand(Genode::config()->xml_node().has_attribute("expand")
-	     && Genode::config()->xml_node().attribute("expand").has_value("yes")),
+	_expand(Genode::config()->xml_node().attribute_value("expand", false)),
 	_periodic_timeout_dispatcher(_sig_rec, *this,
 	                             &Child::_dispatch_periodic_timeout),
 	_yield_dispatcher(_sig_rec, *this,
@@ -357,7 +356,7 @@ int main(int argc, char **argv)
 	 * the child or the parent role.
 	 */
 	bool const is_child = config()->xml_node().has_attribute("child")
-	                   && config()->xml_node().attribute("child").has_value("yes");
+	                   && config()->xml_node().attribute_value("child", false);
 
 	if (is_child) {
 		printf("--- test-resource_yield child role started ---\n");

repos/ports/src/app/vbox_pointer/main.cc

@@ -222,8 +222,7 @@ void Main::_handle_xray(unsigned)
 	try {
 		Genode::Xml_node node(_xray_ds.local_addr<char>());
 
-		bool xray = node.has_attribute("enabled")
-		         && node.attribute("enabled").has_value("yes");
+		bool xray = node.attribute_value("enabled", false);
 
 		/* update pointer if xray status changed */
 		if (xray != _xray) {

repos/ports/src/noux/main.cc

@@ -1144,12 +1144,8 @@ int main(int argc, char **argv)
 	static Genode::Cap_connection cap;
 
 	/* obtain global configuration */
-	try {
-		trace_syscalls = config()->xml_node().attribute("trace_syscalls").has_value("yes");
-	} catch (Xml_node::Nonexistent_attribute) { }
-	try {
-		verbose = config()->xml_node().attribute("verbose").has_value("yes");
-	} catch (Xml_node::Nonexistent_attribute) { }
+	trace_syscalls = config()->xml_node().attribute_value("trace_syscalls", trace_syscalls);
+	verbose        = config()->xml_node().attribute_value("verbose", verbose);
 
 	/* register additional file systems to the VFS */
 	Vfs::Global_file_system_factory &fs_factory = Vfs::global_file_system_factory();