frontend: Use short-form names for shell argument

Instead of passing --shell=foo-shell.so, just pass --shell=foo, whilst
accepting the old form for compatibility.

Whilst we're at it, document the --shell argument in the manpage and
README.

Signed-off-by: Daniel Stone <daniels@collabora.com>

README.md

@@ -68,6 +68,12 @@ from a text console, it will take over that console. When launched from inside
 an existing Wayland or X11 session, it will start a 'nested' instance of Weston
 inside a window in that session.
 
+By default, Weston will start with a skeletal desktop-like environment called
+`desktop-shell`. Other shells are available; for example, to load the `kiosk`
+shell designed for single-application environments, you can start with:
+
+    $ weston --shell=kiosk
+
 Help is available by running `weston --help`, or `man weston`, which will list
 the available configuration options and display backends. It can also be
 configured through a file on disk; more information on this can be found through

compositor/main.c

@@ -670,7 +670,7 @@ usage(int error_code)
 #if defined(BUILD_X11_COMPOSITOR)
 			"\t\t\t\tx11\n"
 #endif
-		"  --shell=MODULE\tShell module, defaults to desktop-shell.so\n"
+		"  --shell=NAME\tShell to load, defaults to desktop\n"
 		"  -S, --socket=NAME\tName of socket to listen on\n"
 		"  -i, --idle-time=SECS\tIdle time in seconds\n"
 #if defined(BUILD_XWAYLAND)
@@ -922,12 +922,21 @@ wet_load_module(struct weston_compositor *compositor,
 
 static int
 wet_load_shell(struct weston_compositor *compositor,
-	       const char *name, int *argc, char *argv[])
+	       const char *_name, int *argc, char *argv[])
 {
+	char *name;
 	int (*shell_init)(struct weston_compositor *ec,
 			  int *argc, char *argv[]);
 
+	if (strstr(_name, "-shell.so"))
+		name = strdup(_name);
+	else
+		str_printf(&name, "%s-shell.so", _name);
+	assert(name);
+
 	shell_init = weston_load_module(name, "wet_shell_init", MODULEDIR);
+	free(name);
+
 	if (!shell_init)
 		return -1;
 	if (shell_init(compositor, argc, argv) < 0)
@@ -3893,7 +3902,7 @@ wet_main(int argc, char *argv[], const struct weston_testsuite_data *test_data)
 
 	if (!shell)
 		weston_config_section_get_string(section, "shell", &shell,
-						 "desktop-shell.so");
+						 "desktop");
 
 	if (wet_load_shell(wet.compositor, shell, &argc, argv) < 0)
 		goto out;

man/weston.ini.man

@@ -96,7 +96,7 @@ The
 .B core
 section is used to select the startup compositor modules and general options.
 .TP 7
-.BI "shell=" desktop-shell.so
+.BI "shell=" desktop
 specifies a shell to load (string). This can be used to load your own
 implemented shell or one with Weston as default. Available shells
 in the
@@ -105,7 +105,7 @@ directory are:
 .PP
 .RS 10
 .nf
-.BR desktop-shell.so
+.BR desktop
 .fi
 .RE
 .TP 7
@@ -660,7 +660,7 @@ sets the path to the xserver to run (string).
 .SH "SCREEN-SHARE SECTION"
 .TP 7
 .BI "command=" "@weston_bindir@/weston --backend=rdp \
---shell=fullscreen-shell.so --no-clients-resize --no-config"
+--shell=fullscreen --no-clients-resize --no-config"
 sets the command to start a fullscreen-shell server for screen sharing (string).
 .TP 7
 .BI "start-on-startup=" "false"

man/weston.man

@@ -188,6 +188,9 @@ Do not read
 for the compositor. Avoids e.g. loading compositor modules via the
 configuration file, which is useful for unit tests.
 .TP
+\fB\-\-shell\fR=\fIshell\fR
+Select which shell to load to provide Weston's user interface. See
+.BR ENVIRONMENT "."
 .TP
 \fB\-\^S\fR\fIname\fR, \fB\-\-socket\fR=\fIname\fR
 Weston will listen in the Wayland socket called

tests/weston-test-fixture-compositor.c

@@ -248,10 +248,10 @@ static const char *
 shell_to_str(enum shell_type t)
 {
 	static const char * const names[] = {
-		[SHELL_TEST_DESKTOP] = "weston-test-desktop-shell.so",
-		[SHELL_DESKTOP] = "desktop-shell.so",
-		[SHELL_FULLSCREEN] = "fullscreen-shell.so",
-		[SHELL_IVI] = "ivi-shell.so",
+		[SHELL_TEST_DESKTOP] = "weston-test-desktop",
+		[SHELL_DESKTOP] = "desktop",
+		[SHELL_FULLSCREEN] = "fullscreen",
+		[SHELL_IVI] = "ivi",
 	};
 	assert(t >= 0 && t < ARRAY_LENGTH(names));
 	return names[t];

weston.ini.in

@@ -1,7 +1,7 @@
 [core]
 #modules=cms-colord.so
 #xwayland=true
-#shell=desktop-shell.so
+#shell=desktop
 #gbm-format=xrgb2101010
 #require-input=true
 
@@ -82,7 +82,7 @@ path=@libexecdir@/weston-keyboard
 #max_accel_factor = 1.0
 
 [screen-share]
-command=@bindir@/weston --backend=rdp --shell=fullscreen-shell.so --no-clients-resize
+command=@bindir@/weston --backend=rdp --shell=fullscreen --no-clients-resize
 #start-on-startup=false
 
 #[xwayland]