strans/ibus.c

#include "dat.h"
#include "fn.h"

#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>
#include <poll.h>
#include <dbus/dbus.h>
#include <xkbcommon/xkbcommon.h>

enum
{
	Maxwatches	= 2*Maxclients + 1,
	/* Toolkits keep one context per widget that ever took focus. */
	Maxcontexts	= 1024,
	Relmask		= 1<<30,
	/* IBus wire constants; the daemon does not link libibus. */
	Ibuscappreedit	= 1<<0,
	Ibusattrunderline = 1,
	Ibusunderlinesingle = 1,
	Ibuspreeditclear = 0,
	Maxpost		= 3,
};

/*
 * A client in IBus's synchronous mode (GTK 4) cannot take signals while
 * it waits for its ProcessKeyEvent reply: it asks afterwards, through the
 * PostProcessKeyEvent property, for what the key produced, as typed
 * (yv) pairs — 'c' a commit, 'u' or 'm' a preedit and then its
 * "cursor,visible[,mode]".
 */
typedef struct Post Post;
struct Post
{
	char	type;
	char	text[Maxutf];
	char	pos[32];
};

typedef struct Ictx Ictx;
struct Ictx
{
	DBusConnection	*conn;
	char	path[64];
	int	focused;
	u32int	cap;
	u32int	purpose;
	int	clientcommitpreedit;
	int	postprocess;
	int	keying;		/* inside ProcessKeyEvent: hold signals for the post */
	int	npost;
	Post	post[Maxpost];
	Caret	caret;
};

static DBusWatch *watches[Maxwatches];
static int nwatches;
static DBusConnection *conns[Maxclients];
static int nconns;
static DBusServer *srv;
static Ictx contexts[Maxcontexts];
static char addrfile[512];
static dev_t addrdev;
static ino_t addrino;
static int icctr;
static int busctr;
static Channel *replyc;
static const char ibusowner[] = ":1.0";
static Ictx *preowner;

/* Removes the address file only while it is still the one we wrote. */
static void
unlinkaddr(void)
{
	struct stat st;

	if(addrfile[0] != '\0' && lstat(addrfile, &st) == 0 &&
	   st.st_dev == addrdev && st.st_ino == addrino)
		unlink(addrfile);
	addrfile[0] = '\0';
	addrdev = 0;
	addrino = 0;
}

static int
addrnote(void*, char *note)
{
	if(notefatal(note))
		unlinkaddr();
	return 0;
}

static void
machineidfiles(char *buf, int sz, char **path, int npath)
{
	int fd, i, n;

	for(i = 0; i < npath; i++){
		fd = open(path[i], 0);
		if(fd < 0)
			continue;
		n = read(fd, buf, sz - 1);
		close(fd);
		if(n <= 0)
			continue;
		buf[n] = '\0';
		while(n > 0 && (buf[n-1] == '\n' || buf[n-1] == '\r'))
			buf[--n] = '\0';
		if(n > 0)
			return;
	}
	buf[0] = '\0';
}

/* libibus reads the D-Bus file first and calls it "machine-id" if neither is there. */
static void
machineid(char *buf, int sz)
{
	char *path[] = {
		"/var/lib/dbus/machine-id",
		"/etc/machine-id",
	};

	machineidfiles(buf, sz, path, nelem(path));
	if(buf[0] == '\0')
		snprintf(buf, sz, "machine-id");
}

static void
copyfield(char *dst, int sz, char *src, int n)
{
	if(n >= sz)
		n = sz - 1;
	memcpy(dst, src, n);
	dst[n] = '\0';
}

/*
 * The display libibus names the file after: the whole WAYLAND_DISPLAY,
 * else DISPLAY's host and number, else unix and 0.
 */
static void
xdisplay(char *host, int hsz, char *num, int nsz)
{
	char *d, *colon, *dot, *p;

	copyfield(host, hsz, "unix", 4);
	copyfield(num, nsz, "0", 1);
	d = getenv("WAYLAND_DISPLAY");
	if(d != nil && d[0] != '\0'){
		copyfield(num, nsz, d, strlen(d));
		return;
	}
	d = getenv("DISPLAY");
	if(d == nil || d[0] == '\0')
		return;
	colon = strchr(d, ':');
	if(colon == nil)
		return;
	if(colon > d)
		copyfield(host, hsz, d, colon - d);
	p = colon + 1;
	dot = strchr(p, '.');
	copyfield(num, nsz, p, dot ? dot - p : (int)strlen(p));
}

/* The IBus address file lives where libibus looks: config/ibus/bus/. */
static int
buildaddrpath(char *buf, int sz)
{
	char mid[64], host[64], num[64], dir[512];
	char *cfg, *home, *explicit, *p;
	int n;

	explicit = getenv("IBUS_ADDRESS_FILE");
	if(explicit != nil){
		n = snprintf(buf, sz, "%s", explicit);
		return explicit[0] == '\0' || n < 0 || n >= sz ? -1 : 0;
	}
	machineid(mid, sizeof(mid));
	xdisplay(host, sizeof(host), num, sizeof(num));
	cfg = getenv("XDG_CONFIG_HOME");
	if(cfg != nil && cfg[0] != '\0')
		n = snprintf(dir, sizeof(dir), "%s/ibus/bus", cfg);
	else{
		home = getenv("HOME");
		if(home == nil)
			return -1;
		n = snprintf(dir, sizeof(dir), "%s/.config/ibus/bus", home);
	}
	if(n < 0 || n >= (int)sizeof dir)
		return -1;
	for(p = dir+1; *p; p++)
		if(*p == '/'){
			*p = '\0';
			mkdir(dir, 0700);
			*p = '/';
		}
	mkdir(dir, 0700);
	n = snprintf(buf, sz, "%s/%s-%s-%s", dir, mid, host, num);
	return n < 0 || n >= sz ? -1 : 0;
}

/* Publishes the address atomically and remembers the file's identity. */
static int
writeaddr(char *path, char *addr)
{
	char tmp[576], text[256];
	struct stat st;
	int fd, n, ok;

	n = snprintf(tmp, sizeof tmp, "%s.tmp.XXXXXX", path);
	if(n < 0 || n >= (int)sizeof tmp)
		return -1;
	n = snprintf(text, sizeof text, "IBUS_ADDRESS=%s\nIBUS_DAEMON_PID=%d\n",
		addr, (int)getpid());
	if(n < 0 || n >= (int)sizeof text)
		return -1;
	fd = mkstemp(tmp);
	if(fd < 0)
		return -1;
	ok = write(fd, text, n) == n && fsync(fd) == 0 &&
		fstat(fd, &st) == 0;
	close(fd);
	if(!ok || rename(tmp, path) < 0){
		unlink(tmp);
		return -1;
	}
	addrdev = st.st_dev;
	addrino = st.st_ino;
	return 0;
}

static dbus_bool_t
addwatch(DBusWatch *w, void*)
{
	int i;

	for(i = 0; i < nwatches; i++)
		if(watches[i] == nil){
			watches[i] = w;
			return TRUE;
		}
	if(nwatches >= Maxwatches)
		return FALSE;
	watches[nwatches++] = w;
	return TRUE;
}

static void
removewatch(DBusWatch *w, void*)
{
	int i;

	for(i = 0; i < nwatches; i++)
		if(watches[i] == w){
			watches[i] = nil;
			return;
		}
}

static Ictx*
findcontext(DBusConnection *conn, const char *path)
{
	int i;

	for(i = 0; i < nelem(contexts); i++)
		if(contexts[i].conn == conn && strcmp(contexts[i].path, path) == 0)
			return &contexts[i];
	return nil;
}

static Ictx*
newcontext(DBusConnection *conn, const char *path)
{
	int i;

	for(i = 0; i < nelem(contexts); i++)
		if(contexts[i].conn == nil){
			memset(&contexts[i], 0, sizeof contexts[i]);
			contexts[i].conn = conn;
			strncpy(contexts[i].path, path, sizeof contexts[i].path);
			contexts[i].path[sizeof contexts[i].path-1] = '\0';
			return &contexts[i];
		}
	return nil;
}

static int
clientpreedit(Ictx *ctx)
{
	return (ctx->cap & Ibuscappreedit) != 0;
}

static void
sendrequest(Ictx *ctx, int op, u32int ks, u32int mod, Keyres *res)
{
	Keyreq kr;

	memset(&kr, 0, sizeof kr);
	kr.owner = ctx;
	kr.clientpre = clientpreedit(ctx);
	kr.op = op;
	kr.ks = ks;
	kr.mod = mod;
	kr.caret = ctx->caret;
	kr.reply = replyc;
	chansend(keyc, &kr);
	chanrecv(replyc, res);
}

static int
hidden(Ictx *ctx)
{
	return ctx->purpose == Purposepassword ||
		ctx->purpose == Purposepin;
}

static void
setcursor(Ictx *ctx, int x, int y, int h)
{
	Keyres res;

	ctx->caret.valid = 1;
	ctx->caret.x = x;
	ctx->caret.y = y;
	ctx->caret.h = h;
	if(ctx->focused)
		sendrequest(ctx, Keycaret, 0, 0, &res);
}

/* Every IBus serializable carries an (empty) attachment dictionary. */
static void
emptydict(DBusMessageIter *it)
{
	DBusMessageIter d;

	dbus_message_iter_open_container(it, DBUS_TYPE_ARRAY, "{sv}", &d);
	dbus_message_iter_close_container(it, &d);
}

/* IBusText: (sa{sv}sv) holding an IBusAttrList of IBusAttributes. */
static void
appendibustext(DBusMessageIter *it, const char *s, int underline)
{
	DBusMessageIter v, st, alv, ali, alist, av, ai;
	const char *name = "IBusText";
	const char *aname = "IBusAttrList";
	const char *iname = "IBusAttribute";
	dbus_uint32_t type, value, start, end;

	dbus_message_iter_open_container(it, DBUS_TYPE_VARIANT, "(sa{sv}sv)", &v);
	dbus_message_iter_open_container(&v, DBUS_TYPE_STRUCT, nil, &st);
	dbus_message_iter_append_basic(&st, DBUS_TYPE_STRING, &name);
	emptydict(&st);
	dbus_message_iter_append_basic(&st, DBUS_TYPE_STRING, &s);
	dbus_message_iter_open_container(&st, DBUS_TYPE_VARIANT, "(sa{sv}av)", &alv);
	dbus_message_iter_open_container(&alv, DBUS_TYPE_STRUCT, nil, &ali);
	dbus_message_iter_append_basic(&ali, DBUS_TYPE_STRING, &aname);
	emptydict(&ali);
	dbus_message_iter_open_container(&ali, DBUS_TYPE_ARRAY, "v", &alist);
	if(underline && s[0] != '\0'){
		type = Ibusattrunderline;
		value = Ibusunderlinesingle;
		start = 0;
		end = utflen((char*)s);
		dbus_message_iter_open_container(&alist, DBUS_TYPE_VARIANT,
			"(sa{sv}uuuu)", &av);
		dbus_message_iter_open_container(&av, DBUS_TYPE_STRUCT, nil, &ai);
		dbus_message_iter_append_basic(&ai, DBUS_TYPE_STRING, &iname);
		emptydict(&ai);
		dbus_message_iter_append_basic(&ai, DBUS_TYPE_UINT32, &type);
		dbus_message_iter_append_basic(&ai, DBUS_TYPE_UINT32, &value);
		dbus_message_iter_append_basic(&ai, DBUS_TYPE_UINT32, &start);
		dbus_message_iter_append_basic(&ai, DBUS_TYPE_UINT32, &end);
		dbus_message_iter_close_container(&av, &ai);
		dbus_message_iter_close_container(&alist, &av);
	}
	dbus_message_iter_close_container(&ali, &alist);
	dbus_message_iter_close_container(&alv, &ali);
	dbus_message_iter_close_container(&st, &alv);
	dbus_message_iter_close_container(&v, &st);
	dbus_message_iter_close_container(it, &v);
}

static DBusMessage*
newsignal(const char *path, const char *name)
{
	DBusMessage *sig;

	sig = dbus_message_new_signal(path, "org.freedesktop.IBus.InputContext",
		name);
	if(sig == nil)
		die("ibus: out of memory");
	dbus_message_set_sender(sig, ibusowner);
	return sig;
}

static int
postpush(Ictx *ctx, char type, const char *text, const char *pos)
{
	Post *p;

	if(!ctx->postprocess || !ctx->keying)
		return 0;
	if(ctx->npost < Maxpost){
		p = &ctx->post[ctx->npost++];
		p->type = type;
		strcpy(p->text, text);
		strcpy(p->pos, pos);
	}
	return 1;
}

static void
emitcommit(Ictx *ctx, const char *text)
{
	DBusMessage *sig;
	DBusMessageIter it;

	if(postpush(ctx, 'c', text, ""))
		return;
	sig = newsignal(ctx->path, "CommitText");
	dbus_message_iter_init_append(sig, &it);
	appendibustext(&it, text, 0);
	dbus_connection_send(ctx->conn, sig, nil);
	dbus_message_unref(sig);
}

/* preowner is the one context showing a preedit; clearing anyone else's is moot. */
static void
emitpreedit(Ictx *ctx, const char *text)
{
	DBusMessage *sig;
	DBusMessageIter it;
	dbus_uint32_t cursor, mode;
	dbus_bool_t visible;
	char pos[32];

	if(text[0] == '\0' && preowner != ctx)
		return;
	cursor = utflen((char*)text);
	visible = text[0] != '\0' ? TRUE : FALSE;
	mode = Ibuspreeditclear;
	if(ctx->clientcommitpreedit)
		snprintf(pos, sizeof pos, "%u,%u,%u", cursor, visible, mode);
	else
		snprintf(pos, sizeof pos, "%u,%u", cursor, visible);
	if(!postpush(ctx, ctx->clientcommitpreedit ? 'm' : 'u', text, pos)){
		sig = newsignal(ctx->path, ctx->clientcommitpreedit ?
			"UpdatePreeditTextWithMode" : "UpdatePreeditText");
		dbus_message_iter_init_append(sig, &it);
		appendibustext(&it, text, 1);
		dbus_message_iter_append_basic(&it, DBUS_TYPE_UINT32, &cursor);
		dbus_message_iter_append_basic(&it, DBUS_TYPE_BOOLEAN, &visible);
		if(ctx->clientcommitpreedit)
			dbus_message_iter_append_basic(&it, DBUS_TYPE_UINT32, &mode);
		dbus_connection_send(ctx->conn, sig, nil);
		dbus_message_unref(sig);
	}
	if(text[0] != '\0')
		preowner = ctx;
	else if(preowner == ctx)
		preowner = nil;
}

/* Another frontend may have taken the engine; then our preedit is stale. */
static void
checkpreowner(void)
{
	Ictx *ctx;
	Keyres res;

	ctx = preowner;
	if(ctx == nil)
		return;
	sendrequest(ctx, Keycap, 0, 0, &res);
	if(!res.eaten)
		emitpreedit(ctx, "");
}

/* A reset or a lost focus hands the pending text back as committed text. */
static void
flushcontext(Ictx *ctx, int op)
{
	Keyres res;
	char commit[Maxutf];

	sendrequest(ctx, op, 0, 0, &res);
	if(clientpreedit(ctx))
		emitpreedit(ctx, "");
	stoutf(&res.commit, commit, sizeof commit);
	if(commit[0] != '\0')
		emitcommit(ctx, commit);
}

/* Nobody is left to hand text to: the context or its connection is gone. */
static void
releasecontext(Ictx *ctx)
{
	Keyres res;

	if(ctx->focused)
		sendrequest(ctx, Keyrelease, 0, 0, &res);
	ctx->focused = 0;
	memset(&ctx->caret, 0, sizeof ctx->caret);
}

static void
dropcontext(Ictx *ctx)
{
	releasecontext(ctx);
	composedrop(Composeibus, ctx);
	if(preowner == ctx)
		preowner = nil;
	memset(ctx, 0, sizeof *ctx);
}

static void
dropconncontexts(DBusConnection *conn)
{
	int i;

	for(i = 0; i < nelem(contexts); i++)
		if(contexts[i].conn == conn)
			dropcontext(&contexts[i]);
}

/*
 * A key is proof of focus: some clients never send FocusIn, and the
 * focus events of two applications can cross.
 */
static int
processkey(Ictx *ctx, u32int sym, u32int state, char *text, int n, Keyres *res)
{
	text[0] = '\0';
	if(state & Relmask || hidden(ctx))
		return 0;
	ctx->focused = 1;
	/* An IBus client drops a dead key we do not take: compose it here. */
	if(composekey(Composeibus, ctx, sym, text, n))
		return -1;
	if(text[0] != '\0')
		/* Composed text follows whatever was pending. */
		sendrequest(ctx, Keyreset, 0, 0, res);
	else
		sendrequest(ctx, Keypress, ipckeysym(sym, xkb_keysym_to_utf32(sym)),
			ipcmod(state), res);
	if(preowner != nil && preowner != ctx)
		checkpreowner();
	return 1;
}


static DBusHandlerResult
handleerror(DBusConnection *c, DBusMessage *m, const char *name,
	const char *text)
{
	DBusMessage *r;

	r = dbus_message_new_error(m, name, text);
	if(r == nil)
		die("ibus: out of memory");
	dbus_connection_send(c, r, nil);
	dbus_message_unref(r);
	return DBUS_HANDLER_RESULT_HANDLED;
}

/* Replies with one argument of the given D-Bus type, or none. */
static DBusHandlerResult
reply(DBusConnection *c, DBusMessage *m, int type, void *v)
{
	DBusMessage *r;

	r = dbus_message_new_method_return(m);
	if(r == nil)
		die("ibus: out of memory");
	if(type != DBUS_TYPE_INVALID)
		dbus_message_append_args(r, type, v, DBUS_TYPE_INVALID);
	dbus_connection_send(c, r, nil);
	dbus_message_unref(r);
	return DBUS_HANDLER_RESULT_HANDLED;
}

static DBusHandlerResult
replybool(DBusConnection *c, DBusMessage *m, int value)
{
	dbus_bool_t b;

	b = value ? TRUE : FALSE;
	return reply(c, m, DBUS_TYPE_BOOLEAN, &b);
}

/* We are the bus as well as the engine: Hello names the caller. */
static DBusHandlerResult
handlehello(DBusConnection *c, DBusMessage *m)
{
	char name[32];
	const char *np;

	if(!dbus_message_has_signature(m, ""))
		return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
			"Hello expects no arguments");
	busctr++;
	snprintf(name, sizeof(name), ":1.%d", busctr);
	np = name;
	return reply(c, m, DBUS_TYPE_STRING, &np);
}

static DBusHandlerResult
handlenameowner(DBusConnection *c, DBusMessage *m)
{
	const char *name, *owner;

	if(!dbus_message_get_args(m, nil, DBUS_TYPE_STRING, &name,
	   DBUS_TYPE_INVALID))
		return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
			"GetNameOwner expects one bus name");
	if(strcmp(name, "org.freedesktop.IBus") != 0)
		return handleerror(c, m, DBUS_ERROR_NAME_HAS_NO_OWNER,
			"bus name has no owner");
	owner = ibusowner;
	return reply(c, m, DBUS_TYPE_STRING, &owner);
}

static DBusHandlerResult
handlecreate(DBusConnection *c, DBusMessage *m)
{
	char path[64];
	const char *pp;
	Ictx *ctx;

	if(!dbus_message_has_signature(m, "s"))
		return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
			"CreateInputContext expects one client name");
	icctr++;
	snprintf(path, sizeof(path),
		"/org/freedesktop/IBus/InputContext_%d", icctr);
	ctx = newcontext(c, path);
	if(ctx == nil)
		return handleerror(c, m, DBUS_ERROR_LIMITS_EXCEEDED,
			"too many input contexts");
	pp = path;
	return reply(c, m, DBUS_TYPE_OBJECT_PATH, &pp);
}

static DBusHandlerResult
handlekey(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	dbus_uint32_t sym, code, state;
	Keyres res;
	char commit[Maxutf], preedit[Maxutf], text[Maxutf];
	int restart, rv;

	dbus_message_get_args(m, nil, DBUS_TYPE_UINT32, &sym,
		DBUS_TYPE_UINT32, &code, DBUS_TYPE_UINT32, &state,
		DBUS_TYPE_INVALID);
	rv = processkey(ctx, sym, state, text, sizeof text, &res);
	if(rv <= 0)	/* below zero: a sequence in the making */
		return replybool(c, m, rv < 0);
	stoutf(&res.commit, commit, sizeof commit);
	stoutf(&res.preedit, preedit, sizeof preedit);
	/* A commit ends the preedit around it, so clients place it right. */
	restart = clientpreedit(ctx) && commit[0] != '\0' && preowner == ctx;
	ctx->keying = 1;
	if(restart)
		emitpreedit(ctx, "");
	if(commit[0] != '\0')
		emitcommit(ctx, commit);
	if(text[0] != '\0')
		emitcommit(ctx, text);
	if(clientpreedit(ctx) && (!restart || preedit[0] != '\0'))
		emitpreedit(ctx, preedit);
	ctx->keying = 0;
	return replybool(c, m, res.eaten || text[0] != '\0');
}

/* Properties.Get PostProcessKeyEvent: what the last key produced. */
static DBusHandlerResult
handlepost(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	DBusMessage *r;
	DBusMessageIter it, v, a, st;
	Post *p;
	int i;

	r = dbus_message_new_method_return(m);
	if(r == nil)
		die("ibus: out of memory");
	dbus_message_iter_init_append(r, &it);
	dbus_message_iter_open_container(&it, DBUS_TYPE_VARIANT, "a(yv)", &v);
	dbus_message_iter_open_container(&v, DBUS_TYPE_ARRAY, "(yv)", &a);
	for(i = 0; i < ctx->npost; i++){
		p = &ctx->post[i];
		dbus_message_iter_open_container(&a, DBUS_TYPE_STRUCT, nil, &st);
		dbus_message_iter_append_basic(&st, DBUS_TYPE_BYTE, &p->type);
		appendibustext(&st, p->text, p->type != 'c');
		dbus_message_iter_close_container(&a, &st);
		if(p->type == 'c')
			continue;
		dbus_message_iter_open_container(&a, DBUS_TYPE_STRUCT, nil, &st);
		dbus_message_iter_append_basic(&st, DBUS_TYPE_BYTE, &p->type);
		appendibustext(&st, p->pos, 0);
		dbus_message_iter_close_container(&a, &st);
	}
	dbus_message_iter_close_container(&v, &a);
	dbus_message_iter_close_container(&it, &v);
	dbus_connection_send(c, r, nil);
	dbus_message_unref(r);
	ctx->npost = 0;
	return DBUS_HANDLER_RESULT_HANDLED;
}

static DBusHandlerResult
handlereset(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	flushcontext(ctx, Keyreset);
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

static DBusHandlerResult
handlefocusin(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	ctx->focused = 1;
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

static DBusHandlerResult
handlefocusout(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	if(ctx->focused)
		flushcontext(ctx, Keyrelease);
	ctx->focused = 0;
	memset(&ctx->caret, 0, sizeof ctx->caret);
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

static DBusHandlerResult
handlecap(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	dbus_uint32_t cap;
	Keyres res;
	char preedit[Maxutf];
	u32int old;

	dbus_message_get_args(m, nil, DBUS_TYPE_UINT32, &cap, DBUS_TYPE_INVALID);
	old = ctx->cap;
	ctx->cap = cap;
	if(ctx->focused){
		sendrequest(ctx, Keycap, 0, 0, &res);
		if((old & Ibuscappreedit) != (ctx->cap & Ibuscappreedit)){
			if((ctx->cap & Ibuscappreedit) && res.eaten){
				stoutf(&res.preedit, preedit, sizeof preedit);
				emitpreedit(ctx, preedit);
			}else if(!(ctx->cap & Ibuscappreedit))
				emitpreedit(ctx, "");
		}
	}
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

static int
getproperty(DBusMessage *m, const char **iface, const char **name,
	DBusMessageIter *value)
{
	DBusMessageIter it;

	if(!dbus_message_has_signature(m, "ssv") ||
	   !dbus_message_iter_init(m, &it))
		return 0;
	dbus_message_iter_get_basic(&it, iface);
	dbus_message_iter_next(&it);
	dbus_message_iter_get_basic(&it, name);
	dbus_message_iter_next(&it);
	dbus_message_iter_recurse(&it, value);
	return 1;
}

/* ContentType is (purpose, hints); only the purpose matters to us. */
static int
getcontent(DBusMessageIter *value, u32int *purpose)
{
	DBusMessageIter st;
	dbus_uint32_t p;

	if(dbus_message_iter_get_arg_type(value) != DBUS_TYPE_STRUCT)
		return 0;
	dbus_message_iter_recurse(value, &st);
	if(dbus_message_iter_get_arg_type(&st) != DBUS_TYPE_UINT32)
		return 0;
	dbus_message_iter_get_basic(&st, &p);
	if(!dbus_message_iter_next(&st) ||
	   dbus_message_iter_get_arg_type(&st) != DBUS_TYPE_UINT32)
		return 0;
	if(dbus_message_iter_next(&st))
		return 0;
	*purpose = p;
	return 1;
}

/* ContentType, ClientCommitPreedit, and EffectivePostProcessKeyEvent are settable. */
static DBusHandlerResult
handlepropertyset(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	const char *iface, *name;
	DBusMessageIter value, st;
	dbus_bool_t b;
	u32int purpose;
	int washidden;

	if(!getproperty(m, &iface, &name, &value))
		return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
			"Properties.Set expects interface, property, and value");
	if(strcmp(iface, "org.freedesktop.IBus.InputContext") != 0)
		return handleerror(c, m, DBUS_ERROR_UNKNOWN_INTERFACE,
			"unknown property interface");
	if(strcmp(name, "ContentType") == 0){
		if(!getcontent(&value, &purpose))
			return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
				"ContentType expects (uu)");
		washidden = hidden(ctx);
		ctx->purpose = purpose;
		if(ctx->focused && !washidden && hidden(ctx))
			flushcontext(ctx, Keyreset);
		return reply(c, m, DBUS_TYPE_INVALID, nil);
	}
	if(strcmp(name, "ClientCommitPreedit") == 0 ||
	   strcmp(name, "EffectivePostProcessKeyEvent") == 0){
		if(dbus_message_iter_get_arg_type(&value) != DBUS_TYPE_STRUCT)
			return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
				"the property expects (b)");
		dbus_message_iter_recurse(&value, &st);
		if(dbus_message_iter_get_arg_type(&st) != DBUS_TYPE_BOOLEAN)
			return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
				"the property expects (b)");
		dbus_message_iter_get_basic(&st, &b);
		if(dbus_message_iter_next(&st))
			return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
				"the property expects (b)");
		if(name[0] == 'C')
			ctx->clientcommitpreedit = b != FALSE;
		else
			ctx->postprocess = b != FALSE;
		return reply(c, m, DBUS_TYPE_INVALID, nil);
	}
	return handleerror(c, m, DBUS_ERROR_UNKNOWN_PROPERTY,
		"unknown input context property");
}

static DBusHandlerResult
handlepropertygetall(DBusConnection *c, DBusMessage *m)
{
	DBusMessage *r;
	DBusMessageIter it;
	const char *iface;

	if(!dbus_message_get_args(m, nil, DBUS_TYPE_STRING, &iface,
	   DBUS_TYPE_INVALID))
		return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
			"Properties.GetAll expects an interface name");
	if(strcmp(iface, "org.freedesktop.IBus.InputContext") != 0)
		return handleerror(c, m, DBUS_ERROR_UNKNOWN_INTERFACE,
			"unknown property interface");
	r = dbus_message_new_method_return(m);
	if(r == nil)
		die("ibus: out of memory");
	dbus_message_iter_init_append(r, &it);
	emptydict(&it);
	dbus_connection_send(c, r, nil);
	dbus_message_unref(r);
	return DBUS_HANDLER_RESULT_HANDLED;
}

static DBusHandlerResult
handledestroy(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	dropcontext(ctx);
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

static DBusHandlerResult
handlecursor(DBusConnection *c, DBusMessage *m, Ictx *ctx)
{
	dbus_int32_t x, y, w, h;

	dbus_message_get_args(m, nil, DBUS_TYPE_INT32, &x, DBUS_TYPE_INT32, &y,
		DBUS_TYPE_INT32, &w, DBUS_TYPE_INT32, &h, DBUS_TYPE_INVALID);
	setcursor(ctx, x, y, h);
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

/*
 * Accepted and thrown away: there is one engine, so any name is fine,
 * and a relative cursor location is surface local, not a caret.
 */
static DBusHandlerResult
handleok(DBusConnection *c, DBusMessage *m, Ictx*)
{
	return reply(c, m, DBUS_TYPE_INVALID, nil);
}

/* The InputContext interface: member, argument signature, handler. */
static struct {
	char	*member;
	char	*sig;
	DBusHandlerResult (*fn)(DBusConnection*, DBusMessage*, Ictx*);
} ictab[] = {
	{"ProcessKeyEvent", "uuu", handlekey},
	{"FocusIn", "", handlefocusin},
	{"FocusOut", "", handlefocusout},
	{"Reset", "", handlereset},
	{"Destroy", "", handledestroy},
	{"SetCursorLocation", "iiii", handlecursor},
	{"SetCursorLocationRelative", "iiii", handleok},
	{"SetCapabilities", "u", handlecap},
	{"SetEngine", "s", handleok},
};

/*
 * One handler for everything a client sends: the tiny slice of the bus
 * that libibus needs, then the InputContext interface.  Unhandled calls
 * get libdbus's UnknownMethod error.
 */
static DBusHandlerResult
onmsg(DBusConnection *c, DBusMessage *m, void*)
{
	const char *iface, *member, *path;
	Ictx *ctx;
	int i;

	if(dbus_message_get_type(m) != DBUS_MESSAGE_TYPE_METHOD_CALL)
		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
	iface = dbus_message_get_interface(m);
	member = dbus_message_get_member(m);
	path = dbus_message_get_path(m);
	if(iface == nil || member == nil || path == nil)
		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
	if(strcmp(iface, "org.freedesktop.DBus") == 0){
		if(strcmp(member, "Hello") == 0)
			return handlehello(c, m);
		if(strcmp(member, "GetNameOwner") == 0)
			return handlenameowner(c, m);
		if(strcmp(member, "AddMatch") == 0
		|| strcmp(member, "RemoveMatch") == 0){
			if(!dbus_message_has_signature(m, "s"))
				return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
					"match rule must be one string");
			return reply(c, m, DBUS_TYPE_INVALID, nil);
		}
	}
	if(strcmp(iface, "org.freedesktop.IBus") == 0){
		if(strcmp(member, "CreateInputContext") == 0)
			return handlecreate(c, m);
	}
	if(strcmp(iface, "org.freedesktop.DBus.Properties") == 0){
		ctx = findcontext(c, path);
		if(ctx == nil)
			return handleerror(c, m, DBUS_ERROR_UNKNOWN_OBJECT,
				"unknown input context");
		if(strcmp(member, "Set") == 0)
			return handlepropertyset(c, m, ctx);
		if(strcmp(member, "Get") == 0){
			if(dbus_message_get_args(m, nil, DBUS_TYPE_STRING, &iface,
			   DBUS_TYPE_STRING, &member, DBUS_TYPE_INVALID) &&
			   strcmp(member, "PostProcessKeyEvent") == 0)
				return handlepost(c, m, ctx);
			return handleerror(c, m, DBUS_ERROR_UNKNOWN_PROPERTY,
				"unknown input context property");
		}
		if(strcmp(member, "GetAll") == 0)
			return handlepropertygetall(c, m);
	}
	/* libibus destroys a context through its Service base interface. */
	if(strcmp(iface, "org.freedesktop.IBus.Service") == 0 &&
	   strcmp(member, "Destroy") == 0)
		iface = "org.freedesktop.IBus.InputContext";
	if(strcmp(iface, "org.freedesktop.IBus.InputContext") == 0){
		ctx = findcontext(c, path);
		if(ctx == nil)
			return handleerror(c, m, DBUS_ERROR_UNKNOWN_OBJECT,
				"unknown input context");
		for(i = 0; i < nelem(ictab); i++){
			if(strcmp(member, ictab[i].member) != 0)
				continue;
			if(!dbus_message_has_signature(m, ictab[i].sig))
				return handleerror(c, m, DBUS_ERROR_INVALID_ARGS,
					"bad arguments");
			return ictab[i].fn(c, m, ctx);
		}
	}
	return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}

static void
newconn(DBusServer*, DBusConnection *c, void*)
{
	DBusObjectPathVTable vt;

	if(nconns >= Maxclients){
		fprint(2, "strans: ibus: rejecting client: %d-connection limit reached\n",
			Maxclients);
		dbus_connection_close(c);
		return;
	}
	if(!dbus_connection_set_watch_functions(c, addwatch, removewatch,
	   nil, nil, nil)){
		fprint(2, "strans: ibus: cannot watch client connection\n");
		dbus_connection_close(c);
		return;
	}
	memset(&vt, 0, sizeof(vt));
	vt.message_function = onmsg;
	if(!dbus_connection_register_fallback(c, "/", &vt, nil)){
		fprint(2, "strans: ibus: cannot register client handler\n");
		dbus_connection_set_watch_functions(c, nil, nil, nil, nil, nil);
		dbus_connection_close(c);
		return;
	}
	dbus_connection_ref(c);
	conns[nconns++] = c;
}

static void
pruneconns(void)
{
	int i, j;

	j = 0;
	for(i = 0; i < nconns; i++){
		if(dbus_connection_get_is_connected(conns[i])){
			conns[j++] = conns[i];
			continue;
		}
		dropconncontexts(conns[i]);
		dbus_connection_unref(conns[i]);
	}
	nconns = j;
}

static void
ibusinit(void)
{
	DBusError err;
	char addr[64], *full;

	if(buildaddrpath(addrfile, sizeof addrfile) < 0)
		die("ibus: cannot build address path");
	snprintf(addr, sizeof addr, "unix:abstract=strans-%d", (int)getpid());
	dbus_error_init(&err);
	srv = dbus_server_listen(addr, &err);
	if(srv == nil)
		die("ibus: listen: %s", err.message);
	dbus_server_set_new_connection_function(srv, newconn, nil, nil);
	if(!dbus_server_set_watch_functions(srv, addwatch, removewatch,
	   nil, nil, nil))
		die("ibus: cannot watch server");
	full = dbus_server_get_address(srv);
	if(full == nil)
		die("ibus: cannot get server address");
	atexit(unlinkaddr);
	threadnotify(addrnote, 1);
	if(writeaddr(addrfile, full) < 0)
		die("ibus: cannot write %s", addrfile);
	dbus_free(full);
}

void
ibusthread(void*)
{
	struct pollfd pfds[Maxwatches];
	DBusWatch *polled[Maxwatches];
	int wi[Maxwatches];
	int i, n, rv;
	unsigned int f;

	threadsetname("ibus");
	ibusinit();
	replyc = chancreate(sizeof(Keyres), 0);
	for(;;){
		if(!dbus_server_get_is_connected(srv))
			die("ibus: server disconnected");
		n = 0;
		for(i = 0; i < nwatches && n < Maxwatches; i++){
			if(watches[i] == nil)
				continue;
			if(!dbus_watch_get_enabled(watches[i]))
				continue;
			pfds[n].fd = dbus_watch_get_unix_fd(watches[i]);
			pfds[n].events = 0;
			f = dbus_watch_get_flags(watches[i]);
			if(f & DBUS_WATCH_READABLE) pfds[n].events |= POLLIN;
			if(f & DBUS_WATCH_WRITABLE) pfds[n].events |= POLLOUT;
			wi[n] = i;
			polled[n] = watches[i];
			n++;
		}
		rv = poll(pfds, n, preowner != nil ? Ownerpoll : -1);
		if(rv < 0 && errno == EINTR)
			continue;
		if(rv < 0)
			die("ibus: poll: %r");
		for(i = 0; i < n; i++){
			if(pfds[i].revents == 0)
				continue;
			if(watches[wi[i]] != polled[i])
				continue;
			f = 0;
			if(pfds[i].revents & POLLIN) f |= DBUS_WATCH_READABLE;
			if(pfds[i].revents & POLLOUT) f |= DBUS_WATCH_WRITABLE;
			if(pfds[i].revents & POLLHUP) f |= DBUS_WATCH_HANGUP;
			if(pfds[i].revents & POLLERR) f |= DBUS_WATCH_ERROR;
			dbus_watch_handle(polled[i], f);
		}
		for(i = 0; i < nconns; i++)
			while(dbus_connection_dispatch(conns[i]) == DBUS_DISPATCH_DATA_REMAINS)
				;
		pruneconns();
		checkpreowner();
	}
}