liberty-xui: circumvent an Nvidia issue

They can be missing in bare configurations, such as Sway + XWayland.

liberty-proto.c

@@ -1594,6 +1594,8 @@ mpd_client_parse_kv (char *line, char **value)
 static void
 mpd_client_update_poller (struct mpd_client *self)
 {
+	if (self->state != MPD_CONNECTED)
+		return;
 	poller_fd_set (&self->socket_event,
 		self->write_buffer.len ? (POLLIN | POLLOUT) : POLLIN);
 }

liberty-xdg.c

@@ -86,24 +86,30 @@ xdg_xsettings_update (struct xdg_xsettings *self, Display *dpy)
 	// TODO: We're supposed to lock the server.
 	// TODO: We're supposed to trap X errors.
 	char *selection = xstrdup_printf ("_XSETTINGS_S%d", DefaultScreen (dpy));
-	Window owner
-		= XGetSelectionOwner (dpy, XInternAtom (dpy, selection, True));
+	Atom selection_atom = XInternAtom (dpy, selection, True);
 	free (selection);
+	if (!selection_atom)
+		return;
+
+	Window owner = XGetSelectionOwner (dpy, selection_atom);
 	if (!owner)
 		return;
 
+	Atom xsettings_atom = XInternAtom (dpy, "_XSETTINGS_SETTINGS", True);
+	if (!xsettings_atom)
+		return;
+
 	Atom actual_type = None;
 	int actual_format = 0;
 	unsigned long nitems = 0, bytes_after = 0;
 	unsigned char *buffer = NULL;
-	Atom xsettings = XInternAtom (dpy, "_XSETTINGS_SETTINGS", True);
 	int status = XGetWindowProperty (dpy,
 		owner,
-		xsettings,
+		xsettings_atom,
 		0L,
 		LONG_MAX,
 		False,
-		xsettings,
+		xsettings_atom,
 		&actual_type,
 		&actual_format,
 		&nitems,
@@ -112,7 +118,7 @@ xdg_xsettings_update (struct xdg_xsettings *self, Display *dpy)
 	if (status != Success || !buffer)
 		return;
 
-	if (actual_type != xsettings
+	if (actual_type != xsettings_atom
 	 || actual_format != 8
 	 || nitems < 12)
 		goto fail;

liberty-xui.c

@@ -1269,14 +1269,21 @@ x11_render_label (struct widget *self)
 	XRenderColor solid = *x11_fg (self), colors[3] = { solid, solid, solid };
 	colors[2].alpha = 0;
 
-	double portion = MIN (1, 2.0 * font->list->font->height / space);
+	// Nvidia's XRender appears to not add (x, y) to (srcx, srcy),
+	// and works correctly if we pass self->x as srcx further on.
+	//
+	// Instead of special-casing nvidia_drv.so, let's have the gradient
+	// also extend to the left, in order to make text legible at all.
+	//
+	// We could also detect the behaviour experimentally in run-time.
+	double portion = MIN (1, 2. * font->list->font->height / (self->x + space));
 	XFixed stops[3] = { 0, XDoubleToFixed (1 - portion), XDoubleToFixed (1) };
-	XLinearGradient gradient = { {}, { XDoubleToFixed (space), 0 } };
+	XLinearGradient gradient = { {}, { XDoubleToFixed (self->x + space), 0 } };
 
 	// Note that this masking is a very expensive operation.
 	Picture source =
 		XRenderCreateLinearGradient (g_xui.dpy, &gradient, stops, colors, 3);
-	x11_font_render (font, PictOpOver, source, -self->x, 0, self->x, self->y,
+	x11_font_render (font, PictOpOver, source, 0, 0, self->x, self->y,
 		self->text);
 	XRenderFreePicture (g_xui.dpy, source);
 }
@@ -1884,6 +1891,8 @@ x11_init (struct poller *poller, struct attrs *app_attrs, size_t app_attrs_len)
 	if (!(g_xui.dpy = XkbOpenDisplay
 		(NULL, &g_xui.xkb_base_event_code, NULL, NULL, NULL, NULL)))
 		exit_fatal ("cannot open display");
+	if (!XftInit (NULL))
+		print_warning ("Fontconfig initialization failed");
 	if (!XftDefaultHasRender (g_xui.dpy))
 		exit_fatal ("XRender is not supported");
 	if (!(g_xui.x11_im = XOpenIM (g_xui.dpy, NULL, NULL, NULL)))
@@ -1912,8 +1921,6 @@ x11_init (struct poller *poller, struct attrs *app_attrs, size_t app_attrs_len)
 	g_xui.x11_xsettings = xdg_xsettings_make ();
 	xdg_xsettings_update (&g_xui.x11_xsettings, g_xui.dpy);
 
-	if (!FcInit ())
-		print_warning ("Fontconfig initialization failed");
 	if (!(g_xui.xft_fonts = x11_font_open (0)))
 		exit_fatal ("cannot open a font");
 

liberty.c

@@ -1209,7 +1209,10 @@ async_make (struct async_manager *manager)
 }
 
 /// Only allowed from the main thread once the job has been started but before
-/// the results have been dispatched
+/// the results have been dispatched.
+///
+/// Note that it may in practice lead to memory leakage, although that's
+/// an implementation issue: https://eissing.org/icing/posts/rip_pthread_cancel/
 static void
 async_cancel (struct async *self)
 {

libertyxdr.adoc

@@ -93,10 +93,12 @@ and always-present field, which must be a tag *enum*:
  case CAR:   void;
  case LORRY: i8 axles;
  case PLANE: i8 engines;
+ default:    void;
  };
 
-All possible enumeration values must be named, and there is no *case*
-fall-through.
+There is no *case* fall-through.
+Unless *default* is present, only the listed enumeration values are valid.
+Any *default* must currently be empty.
 
 Framing
 -------

libertyxdr.vim

@@ -8,7 +8,7 @@ syn region libertyxdrBlockComment start=+/[*]+ end=+[*]/+
 syn match libertyxdrComment "//.*"
 syn match libertyxdrIdentifier "\<[[:alpha:]][[:alnum:]_]*\>"
 syn match libertyxdrNumber "\<0\>\|\(-\|\<\)[1-9][[:digit:]]*\>"
-syn keyword libertyxdrKeyword const enum struct union switch case
+syn keyword libertyxdrKeyword const enum struct union switch case default
 syn keyword libertyxdrType bool u8 u16 u32 u64 i8 i16 i32 i64 string void
 
 let b:current_syntax = "libertyxdr"

tests/lxdrgen.lxdr

@@ -25,5 +25,7 @@ struct Struct {
 	union Onion switch (Enum tag) {
 	case NOTHING:
 		void;
+	default:
+		void;
 	} o;
 };

tools/lxdrgen.awk

@@ -1,6 +1,6 @@
 # lxdrgen.awk: an XDR-derived code generator for network protocols.
 #
-# Copyright (c) 2022 - 2023, Přemysl Eric Janouch <p@janouch.name>
+# Copyright (c) 2022 - 2025, Přemysl Eric Janouch <p@janouch.name>
 # SPDX-License-Identifier: 0BSD
 #
 # Usage: env LC_ALL=C awk -f lxdrgen.awk -f lxdrgen-{c,go,mjs}.awk \
@@ -218,7 +218,7 @@ function defstruct(    name, d, cg) {
 }
 
 function defunion(    name, tag, tagtype, tagvalue, cg, scg, d, a, i,
-		unseen, exhaustive) {
+		unseen, defaulted, exhaustive) {
 	delete cg[0]
 	delete scg[0]
 	delete d[0]
@@ -249,9 +249,22 @@ function defunion(    name, tag, tagtype, tagvalue, cg, scg, d, a, i,
 			if (!unseen[tagvalue]--)
 				fatal("no such value or duplicate case: " tagtype "." tagvalue)
 			codegen_struct_tag(tag, scg)
+		} else if (accept("default")) {
+			if (tagvalue)
+				codegen_union_struct(name, tagvalue, cg, scg)
+
+			expect(accept(":"))
+			if (defaulted)
+				fatal("duplicate default")
+
+			tagvalue = ""
+			defaulted = 1
 		} else if (tagvalue) {
 			if (readfield(d))
 				codegen_struct_field(d, scg)
+		} else if (defaulted) {
+			if (readfield(d))
+				fatal("default must not contain fields")
 		} else {
 			fatal("union fields must fall under a case")
 		}
@@ -259,11 +272,17 @@ function defunion(    name, tag, tagtype, tagvalue, cg, scg, d, a, i,
 	if (tagvalue)
 		codegen_union_struct(name, tagvalue, cg, scg)
 
-	# Unseen cases are simply not recognized/allowed.
+	# Unseen cases are only recognized/allowed when default is present.
 	exhaustive = 1
 	for (i in unseen)
-		if (i && unseen[i])
-			exhaustive = 0
+		if (i && unseen[i]) {
+			if (defaulted) {
+				codegen_struct_tag(tag, scg)
+				codegen_union_struct(name, i, cg, scg)
+			} else {
+				exhaustive = 0
+			}
+		}
 
 	Types[name] = "union"
 	codegen_union(name, cg, exhaustive)

tools/wdye/CMakeLists.txt

@@ -22,7 +22,7 @@ option (WITH_CURSES "Offer terminal sequences using Curses" "${CURSES_FOUND}")
 # -liconv may or may not be a part of libc
 find_path (iconv_INCLUDE_DIRS iconv.h)
 
-include_directories ("${PROJECT_BINARY_DIR}" ${iconv_INCLUDE_DIRS})
+include_directories (BEFORE "${PROJECT_BINARY_DIR}" ${iconv_INCLUDE_DIRS})
 file (CONFIGURE OUTPUT "${PROJECT_BINARY_DIR}/config.h" CONTENT [[
 #define PROGRAM_NAME "${PROJECT_NAME}"
 #define PROGRAM_VERSION "${PROJECT_VERSION}"
@@ -38,5 +38,5 @@ if (WITH_CURSES)
 	target_link_libraries (wdye PUBLIC ${CURSES_LIBRARIES})
 endif ()
 
-add_test (NAME simple COMMAND wdye "${PROJECT_SOURCE_DIR}/test.lua")
+add_test (NAME wdye COMMAND wdye "${PROJECT_SOURCE_DIR}/test.lua")
 include (CTest)

tools/wdye/test.lua

@@ -25,7 +25,9 @@ cat:send("Closing...\r"):send("\004")
 local v = expect(cat:eof {true},
 	cat:default {.5, function (p) error "expected EOF, got a timeout" end})
 
+assert(cat.pid > 0, "process has no ID")
 local s1, exit, signal = cat:wait ()
 assert(s1 == 0 and exit == 0 and not signal, "unexpected exit status")
+assert(cat.pid < 0, "process still has an ID")
 local s2 = cat:wait (true)
 assert(s1 == s2, "exit status not remembered")

tools/wdye/wdye.adoc

@@ -31,7 +31,7 @@ The *env* map may be used to override environment variables, notably _TERM_.
 Variables evaluating to _false_ will be removed from the environment.
 
 The program's whole process group receives SIGKILL when the _process_
-is garbage-collected.
+is garbage-collected, unless *wait* has collected the process group leader.
 
 wdye.expect ([pattern1, ...])
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -57,6 +57,10 @@ PROCESS.buffer
 ~~~~~~~~~~~~~~
 A string with the _process_' current read buffer contents.
 
+PROCESS.pid
+~~~~~~~~~~~
+An integer with the _process_' process ID, or -1 if *wait* has collected it.
+
 PROCESS.term
 ~~~~~~~~~~~~
 A table with the _process_' *terminfo*(5) capabilities,
@@ -126,6 +130,12 @@ Example
  rot13:send "Hello\r"
  expect(rot13:exact {"Uryyb\r"})
 
+Environment
+-----------
+*WDYE_LOGGING*::
+	When this environment variable is present, *wdye* produces asciicast v2
+	files for every spawned program, in the current working directory.
+
 Reporting bugs
 --------------
 Use https://git.janouch.name/p/liberty to report bugs, request features,

tools/wdye/wdye.c

@@ -175,7 +175,7 @@ pty_fork (int *ptrfdm, char **slave_name,
 	char *pts_name = NULL;
 	if ((fdm = ptym_open (&pts_name)) < 0)
 	{
-		error_set (e, "can’t open master pty: %s", strerror (errno));
+		error_set (e, "can't open master pty: %s", strerror (errno));
 		return -1;
 	}
 	if (slave_name != NULL)
@@ -194,7 +194,7 @@ pty_fork (int *ptrfdm, char **slave_name,
 		if (setsid () < 0)
 			exit_fatal ("setsid: %s", strerror (errno));
 		if ((fds = ptys_open (pts_name)) < 0)
-			exit_fatal ("can’t open slave pty: %s", strerror (errno));
+			exit_fatal ("can't open slave pty: %s", strerror (errno));
 		xclose (fdm);
 
 #if defined BSD
@@ -222,6 +222,45 @@ pty_fork (int *ptrfdm, char **slave_name,
 	return pid;
 }
 
+// --- JSON --------------------------------------------------------------------
+
+static void
+write_json_string (FILE *output, const char *s, size_t len)
+{
+	fputc ('"', output);
+	for (const char *last = s, *end = s + len; s != end; last = s)
+	{
+		// Here is where you realize the asciicast format is retarded for using
+		// JSON at all.  (Consider multibyte characters at read() boundaries.)
+		int32_t codepoint = utf8_decode (&s, end - s);
+		if (codepoint < 0)
+		{
+			s++;
+			fprintf (output, "\\uFFFD");
+			continue;
+		}
+
+		switch (codepoint)
+		{
+		break; case '"':  fprintf (output, "\\\"");
+		break; case '\\': fprintf (output, "\\\\");
+		break; case '\b': fprintf (output, "\\b");
+		break; case '\f': fprintf (output, "\\f");
+		break; case '\n': fprintf (output, "\\n");
+		break; case '\r': fprintf (output, "\\r");
+		break; case '\t': fprintf (output, "\\t");
+		break; default:
+			if (!utf8_validate_cp (codepoint))
+				fprintf (output, "\\uFFFD");
+			else if (codepoint < 32)
+				fprintf (output, "\\u%04X", codepoint);
+			else
+				fwrite (last, 1, s - last, output);
+		}
+	}
+	fputc ('"', output);
+}
+
 // --- Global state ------------------------------------------------------------
 
 static struct
@@ -362,7 +401,7 @@ xlua_pattern_index (lua_State *L)
 		if (!strcmp (key, "process"))
 			lua_rawgeti (L, LUA_REGISTRYINDEX, self->ref_process);
 		else
-			return luaL_argerror (L, 2, "not a readable property");
+			return luaL_error (L, "not a readable property: %s", key);
 		return 1;
 	}
 
@@ -372,8 +411,8 @@ xlua_pattern_index (lua_State *L)
 	case PATTERN_REGEX:
 	{
 		const regmatch_t *m = self->matches + group;
-		if (group < 0 || group > self->regex->re_nsub
-		 || m->rm_so < 0 || m->rm_eo < 0 || m->rm_eo > self->input.len)
+		if (group < 0 || (size_t) group > self->regex->re_nsub
+		 || m->rm_so < 0 || m->rm_eo < 0 || (size_t) m->rm_eo > self->input.len)
 			lua_pushnil (L);
 		else
 			lua_pushlstring (L,
@@ -389,7 +428,7 @@ xlua_pattern_index (lua_State *L)
 			lua_pushlstring (L, self->input.str, self->input.len);
 		return 1;
 	default:
-		return luaL_argerror (L, 2, "indexing unavailable for this pattern");
+		return luaL_argerror (L, 1, "indexing unavailable for this pattern");
 	}
 }
 
@@ -435,6 +474,9 @@ struct process
 	int ref_term;                       ///< Terminal information
 	struct str buffer;                  ///< Terminal input buffer
 	int status;                         ///< Process status iff pid is -1
+
+	int64_t start;                      ///< Start timestamp (Unix msec)
+	FILE *asciicast;                    ///< asciicast script dump
 };
 
 static struct process *
@@ -462,6 +504,8 @@ xlua_process_gc (lua_State *L)
 		kill (-self->pid, SIGKILL);
 	luaL_unref (L, LUA_REGISTRYINDEX, self->ref_term);
 	str_free (&self->buffer);
+	if (self->asciicast)
+		fclose (self->asciicast);
 	return 0;
 }
 
@@ -475,10 +519,12 @@ xlua_process_index (lua_State *L)
 
 	if (!strcmp (key, "buffer"))
 		lua_pushlstring (L, self->buffer.str, self->buffer.len);
+	else if (!strcmp (key, "pid"))
+		lua_pushinteger (L, self->pid);
 	else if (!strcmp (key, "term"))
 		lua_rawgeti (L, LUA_REGISTRYINDEX, self->ref_term);
 	else
-		return luaL_argerror (L, 2, "not a readable property");
+		return luaL_error (L, "not a readable property: %s", key);
 	return 1;
 }
 
@@ -498,8 +544,16 @@ xlua_process_send (lua_State *L)
 		ssize_t written = write (self->terminal_fd, arg, len);
 		if (written == -1)
 			return luaL_error (L, "write failed: %s", strerror (errno));
-		else if (written != len)
+		else if (written != (ssize_t) len)
 			return luaL_error (L, "write failed: %s", "short write");
+
+		if (self->asciicast)
+		{
+			double timestamp = (clock_msec () - self->start) / 1000.;
+			fprintf (self->asciicast, "[%f, \"i\", ", timestamp);
+			write_json_string (self->asciicast, arg, len);
+			fprintf (self->asciicast, "]\n");
+		}
 	}
 	lua_pushvalue (L, 1);
 	return 1;
@@ -508,7 +562,7 @@ xlua_process_send (lua_State *L)
 static int
 xlua_process_regex (lua_State *L)
 {
-	struct process *self = luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
+	(void) luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
 	luaL_checktype (L, 2, LUA_TTABLE);
 	if (lua_gettop (L) != 2)
 		return luaL_error (L, "too many arguments");
@@ -541,7 +595,7 @@ xlua_process_regex (lua_State *L)
 static int
 xlua_process_exact (lua_State *L)
 {
-	struct process *self = luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
+	(void) luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
 	luaL_checktype (L, 2, LUA_TTABLE);
 	if (lua_gettop (L) != 2)
 		return luaL_error (L, "too many arguments");
@@ -566,7 +620,7 @@ xlua_process_exact (lua_State *L)
 static int
 xlua_process_eof (lua_State *L)
 {
-	struct process *self = luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
+	(void) luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
 	luaL_checktype (L, 2, LUA_TTABLE);
 	if (lua_gettop (L) != 2)
 		return luaL_error (L, "too many arguments");
@@ -582,7 +636,7 @@ xlua_process_eof (lua_State *L)
 static int
 xlua_process_default (lua_State *L)
 {
-	struct process *self = luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
+	(void) luaL_checkudata (L, 1, XLUA_PROCESS_METATABLE);
 	luaL_checktype (L, 2, LUA_TTABLE);
 	if (lua_gettop (L) != 2)
 		return luaL_error (L, "too many arguments");
@@ -667,6 +721,14 @@ process_feed (struct process *self)
 		return false;
 	}
 
+	if (self->asciicast)
+	{
+		double timestamp = (clock_msec () - self->start) / 1000.;
+		fprintf (self->asciicast, "[%f, \"o\", ", timestamp);
+		write_json_string (self->asciicast, buf, n);
+		fprintf (self->asciicast, "]\n");
+	}
+
 	// TODO(p): Add match_max processing, limiting the buffer size.
 	str_append_data (&self->buffer, buf, n);
 	return n > 0;
@@ -828,10 +890,11 @@ environ_map_serialize (struct str_map *env, struct strv *envv)
 static int
 spawn_protected (lua_State *L)
 {
-	struct spawn_context *ctx = lua_touserdata (L, 1);
+	struct spawn_context *ctx = lua_touserdata (L, lua_upvalueindex (1));
+	luaL_checktype (L, 1, LUA_TTABLE);
 
 	// Step 1: Prepare process environment.
-	if (xlua_getfield (L, 2, "environ", LUA_TTABLE, true))
+	if (xlua_getfield (L, 1, "environ", LUA_TTABLE, true))
 	{
 		environ_map_update (&ctx->env, L);
 		lua_pop (L, 1);
@@ -851,11 +914,11 @@ spawn_protected (lua_State *L)
 #endif
 
 	// Step 3: Prepare process command line.
-	size_t argc = lua_rawlen (L, 2);
+	size_t argc = lua_rawlen (L, 1);
 	for (size_t i = 1; i <= argc; i++)
 	{
 		lua_pushinteger (L, i);
-		lua_rawget (L, 2);
+		lua_rawget (L, 1);
 		const char *arg = lua_tostring (L, -1);
 		if (!arg)
 			return luaL_error (L, "spawn arguments must be strings");
@@ -888,9 +951,17 @@ spawn_protected (lua_State *L)
 	}
 	process->ref_term = luaL_ref (L, LUA_REGISTRYINDEX);
 
+	struct winsize ws = { .ws_row = 24, .ws_col = 80 };
+	if ((entry = str_map_find (&ctx->term, "lines"))
+	 && entry->kind == TERMINFO_NUMERIC)
+		ws.ws_row = entry->numeric;
+	if ((entry = str_map_find (&ctx->term, "columns"))
+	 && entry->kind == TERMINFO_NUMERIC)
+		ws.ws_col = entry->numeric;
+
 	// Step 5: Spawn the process, which gets a new process group.
 	process->pid =
-		pty_fork (&process->terminal_fd, NULL, NULL, NULL, &ctx->error);
+		pty_fork (&process->terminal_fd, NULL, NULL, &ws, &ctx->error);
 	if (process->pid < 0)
 	{
 		return luaL_error (L, "failed to spawn %s: %s",
@@ -905,6 +976,28 @@ spawn_protected (lua_State *L)
 		_exit (EXIT_FAILURE);
 	}
 
+	// Step 6: Create a log file.
+	if (getenv ("WDYE_LOGGING"))
+	{
+		const char *name = ctx->argv.vector[0];
+		const char *last_slash = strrchr (name, '/');
+		if (last_slash)
+			name = last_slash + 1;
+
+		char *path = xstrdup_printf ("%s-%s.%d.cast",
+			PROGRAM_NAME, name, (int) process->pid);
+		if (!(process->asciicast = fopen (path, "w")))
+			print_warning ("%s: %s", path, strerror (errno));
+		free (path);
+	}
+	process->start = clock_msec ();
+	if (process->asciicast)
+	{
+		fprintf (process->asciicast, "{\"version\": 2, "
+			"\"width\": %u, \"height\": %u, \"env\": {\"TERM\": \"%s\"}}\n",
+			ws.ws_col, ws.ws_row, term);
+	}
+
 	set_cloexec (process->terminal_fd);
 	return 1;
 }
@@ -912,23 +1005,24 @@ spawn_protected (lua_State *L)
 static int
 xlua_spawn (lua_State *L)
 {
-	luaL_checktype (L, 1, LUA_TTABLE);
-
 	lua_pushcfunction (L, xlua_error_handler);
-	lua_pushcfunction (L, spawn_protected);
+	lua_insert (L, 1);
+
+	struct spawn_context ctx = {};
+	lua_pushlightuserdata (L, &ctx);
+	lua_pushcclosure (L, spawn_protected, 1);
+	lua_insert (L, 2);
 
 	// There are way too many opportunities for Lua to throw,
 	// so maintain a context to clean up in one go.
-	struct spawn_context ctx = spawn_context_make ();
-	lua_pushlightuserdata (L, &ctx);
-	lua_rotate (L, 1, -1);
-	int result = lua_pcall (L, 2, 1, -4);
+	ctx = spawn_context_make ();
+	int result = lua_pcall (L, lua_gettop (L) - 2, 1, 1);
 	spawn_context_free (&ctx);
 	if (result)
 		return lua_error (L);
 
 	// Remove the error handler ("good programming practice").
-	lua_remove (L, -2);
+	lua_remove (L, 1);
 	return 1;
 }
 
@@ -991,7 +1085,7 @@ expect_prepare_pattern (struct expect_context *ctx, struct pattern *p)
 {
 	str_reset (&p->input);
 	if (p->kind == PATTERN_REGEX)
-		for (int i = 0; i <= p->regex->re_nsub; i++)
+		for (size_t i = 0; i <= p->regex->re_nsub; i++)
 			p->matches[i] = (regmatch_t) { .rm_so = -1, .rm_eo = -1 };
 
 	if (p->kind == PATTERN_REGEX
@@ -1078,7 +1172,7 @@ pattern_match (struct pattern *self)
 		if (regexec (self->regex, buffer->str,
 			self->regex->re_nsub + 1, self->matches, flags))
 		{
-			for (int i = 0; i <= self->regex->re_nsub; i++)
+			for (size_t i = 0; i <= self->regex->re_nsub; i++)
 				self->matches[i] = (regmatch_t) { .rm_so = -1, .rm_eo = -1 };
 			return false;
 		}
@@ -1284,9 +1378,9 @@ xlua_panic (lua_State *L)
 int
 main (int argc, char *argv[])
 {
-	if (argc != 2)
+	if (argc < 2)
 	{
-		fprintf (stderr, "Usage: %s program.lua\n", argv[0]);
+		fprintf (stderr, "Usage: %s program.lua [args...]\n", argv[0]);
 		return 1;
 	}
 
@@ -1307,16 +1401,20 @@ main (int argc, char *argv[])
 	luaL_setfuncs (g.L, xlua_pattern_table, 0);
 	lua_pop (g.L, 1);
 
-	const char *path = argv[1];
+	luaL_checkstack (g.L, argc, NULL);
+
 	lua_pushcfunction (g.L, xlua_error_handler);
-	if (luaL_loadfile (g.L, path)
-	 || lua_pcall (g.L, 0, 0, -2))
-	{
-		print_error ("%s", lua_tostring (g.L, -1));
-		lua_pop (g.L, 1);
-		lua_close (g.L);
-		return 1;
-	}
+	if (luaL_loadfile (g.L, strcmp (argv[1], "-") ? argv[1] : NULL))
+		goto error;
+	for (int i = 2; i < argc; i++)
+		lua_pushstring (g.L, argv[i]);
+	if (lua_pcall (g.L, argc - 2, 0, 1))
+		goto error;
 	lua_close (g.L);
 	return 0;
+
+error:
+	print_error ("%s", lua_tostring (g.L, -1));
+	lua_close (g.L);
+	return 1;
 }