Tidy up and improve target (-t) argument parsing:

- move the code back into cmd.c and merge with the existing functions where
  possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
  look for it as an fnmatch pattern and then as the start of a name - if more
  that one session matches an error is given; so if there is one session called
  "mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
  is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
  name match, try it against the window names as an fnmatch pattern and a
  prefix.

8 files changed, 406 insertions, 298 deletions

diff --git a/Makefile b/Makefile
index 774e8341..4630160c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # $OpenBSD$
 
 PROG=	tmux
-SRCS=	arg.c attributes.c buffer-poll.c buffer.c cfg.c client-fn.c \
+SRCS=	attributes.c buffer-poll.c buffer.c cfg.c client-fn.c \
 	client-msg.c client.c clock.c cmd-attach-session.c cmd-bind-key.c \
 	cmd-break-pane.c cmd-choose-session.c cmd-choose-window.c \
 	cmd-clear-history.c cmd-clock-mode.c cmd-command-prompt.c \
diff --git a/arg.c b/arg.c
deleted file mode 100644
index 6fe36a15..00000000
--- a/arg.c
+++ /dev/null
@@ -1,194 +0,0 @@
-/* $OpenBSD$ */
-
-/*
- * Copyright (c) 2008 Nicholas Marriott <nicm@users.sourceforge.net>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
- * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
- * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include <sys/types.h>
-
-#include <fnmatch.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "tmux.h"
-
-struct client	*arg_lookup_client(const char *);
-struct session	*arg_lookup_session(const char *);
-
-struct client *
-arg_lookup_client(const char *name)
-{
-	struct client	*c;
-	u_int		 i;
-
-	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
-		c = ARRAY_ITEM(&clients, i);
-		if (c != NULL && strcmp(name, c->tty.path) == 0)
-			return (c);
-	}
-
-	return (NULL);
-}
-
-struct session *
-arg_lookup_session(const char *name)
-{
-	struct session	*s, *newest = NULL;
-	struct timeval	*tv;
-	u_int		 i;
-
-	tv = NULL;
-	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
-		s = ARRAY_ITEM(&sessions, i);
-		if (s == NULL || fnmatch(name, s->name, 0) != 0)
-			continue;
-
-		if (tv == NULL || timercmp(&s->tv, tv, >)) {
-			newest = s;
-			tv = &s->tv;
-		}
-	}
-
-	return (newest);
-}
-
-struct client *
-arg_parse_client(const char *arg)
-{
-	struct client	*c;
-	char		*arg2;
-	size_t		 n;
-
-	if (arg != NULL && (arg[0] != ':' || arg[1] != '\0')) {
-		arg2 = xstrdup(arg);
-
-		/* Trim a trailing : if any from the argument. */
-		n = strlen(arg2);
-		if (n && arg2[n - 1] == ':')
-			arg2[n - 1] = '\0';
-
-		/* Try and look up the client name. */
-		c = arg_lookup_client(arg2);
-		xfree(arg2);
-		return (c);
-	}
-
-	return (NULL);
-}
-
-struct session *
-arg_parse_session(const char *arg)
-{
-	struct session	*s;
-	struct client	*c;
-	char		*arg2;
-	size_t		 n;
-
-	if (arg != NULL && (arg[0] != ':' || arg[1] != '\0')) {
-		arg2 = xstrdup(arg);
-
-		/* Trim a trailing : if any from the argument. */
-		n = strlen(arg2);
-		if (n && arg2[n - 1] == ':')
-			arg2[n - 1] = '\0';
-
-		/* See if the argument matches a session. */
-		if ((s = arg_lookup_session(arg2)) != NULL) {
-			xfree(arg2);
-			return (s);
-		}
-
-		/* If not try a client. */
-		if ((c = arg_lookup_client(arg2)) != NULL) {
-			xfree(arg2);
-			return (c->session);
-		}
-
-		xfree(arg2);
-	}
-
-	return (NULL);
-}
-
-int
-arg_parse_window(const char *arg, struct session **s, int *idx)
-{
-	char		*arg2, *ptr;
-	const char	*errstr;
-
-	*idx = -1;
-
-	/* Handle no argument or a single :. */
-	if (arg == NULL || (arg[0] == ':' && arg[1] == '\0')) {
-		*s = arg_parse_session(NULL);
-		return (0);
-	}
-
-	/* Find the separator if any. */
-	arg2 = xstrdup(arg);
-	ptr = strrchr(arg2, ':');
-
-	/*
-	 * If it is first, this means no session name, so use current session
-	 * and try to convert the rest as index.
-	 */
-	if (ptr == arg2) {
-		*idx = strtonum(ptr + 1, 0, INT_MAX, &errstr);
-		if (errstr != NULL) {
-			xfree(arg2);
-			return (1);
-		}
-
-		xfree(arg2);
-		*s = arg_parse_session(NULL);
-		return (0);
-	}
-
-	/* If missing, try as an index, else look up immediately. */
-	if (ptr == NULL) {
-		*idx = strtonum(arg2, 0, INT_MAX, &errstr);
-		if (errstr == NULL) {
-			/* This is good as an index; use current session. */
-			xfree(arg2);
-			*s = arg_parse_session(NULL);
-			return (0);
-		}
-
-		*idx = -1;
-		goto lookup;
-	}
-
-	/* If last, strip it and look up as a session. */
-	if (ptr[1] == '\0') {
-		*ptr = '\0';
-		goto lookup;
-	}
-
-	/* Present but not first and not last. Break and convert both. */
-	*ptr = '\0';
-	*idx = strtonum(ptr + 1, 0, INT_MAX, &errstr);
-	if (errstr != NULL) {
-		xfree(arg2);
-		return (1);
-	}
-
-lookup:
-	/* Look up as session. */
-	*s = arg_parse_session(arg2);
-	xfree(arg2);
-	if (*s == NULL)
-		return (1);
-	return (0);
-}
diff --git a/cmd-link-window.c b/cmd-link-window.c
index 143e3cf0..4e1ada81 100644
--- a/cmd-link-window.c
+++ b/cmd-link-window.c
@@ -52,19 +52,8 @@ cmd_link_window_exec(struct cmd *self, struct cmd_ctx *ctx)
 
 	if ((wl_src = cmd_find_window(ctx, data->src, NULL)) == NULL)
 		return (-1);
-
-	if (arg_parse_window(data->dst, &dst, &idx) != 0) {
-		ctx->error(ctx, "bad window: %s", data->dst);
-		return (-1);
-	}
-	if (dst == NULL)
-		dst = ctx->cursession;
-	if (dst == NULL)
-		dst = cmd_current_session(ctx);
-	if (dst == NULL) {
-		ctx->error(ctx, "session not found: %s", data->dst);
+	if ((idx = cmd_find_index(ctx, data->dst, &dst)) == -2)
 		return (-1);
-	}
 
 	wl_dst = NULL;
 	if (idx != -1)
diff --git a/cmd-move-window.c b/cmd-move-window.c
index 9f356a64..c9117c4b 100644
--- a/cmd-move-window.c
+++ b/cmd-move-window.c
@@ -54,19 +54,8 @@ cmd_move_window_exec(struct cmd *self, struct cmd_ctx *ctx)
 
 	if ((wl_src = cmd_find_window(ctx, data->src, &src)) == NULL)
 		return (-1);
-
-	if (arg_parse_window(data->dst, &dst, &idx) != 0) {
-		ctx->error(ctx, "bad window: %s", data->dst);
-		return (-1);
-	}
-	if (dst == NULL)
-		dst = ctx->cursession;
-	if (dst == NULL)
-		dst = cmd_current_session(ctx);
-	if (dst == NULL) {
-		ctx->error(ctx, "session not found: %s", data->dst);
+	if ((idx = cmd_find_index(ctx, data->dst, &dst)) == -2)
 		return (-1);
-	}
 
 	wl_dst = NULL;
 	if (idx != -1)
diff --git a/cmd-new-window.c b/cmd-new-window.c
index 30b84ac3..ee8cd8b7 100644
--- a/cmd-new-window.c
+++ b/cmd-new-window.c
@@ -126,18 +126,8 @@ cmd_new_window_exec(struct cmd *self, struct cmd_ctx *ctx)
 	if (data == NULL)
 		return (0);
 
-	if (arg_parse_window(data->target, &s, &idx) != 0) {
-		ctx->error(ctx, "bad window: %s", data->target);
+	if ((idx = cmd_find_index(ctx, data->target, &s)) == -2)
 		return (-1);
-	}
-	if (s == NULL)
-		s = ctx->cursession;
-	if (s == NULL)
-		s = cmd_current_session(ctx);
-	if (s == NULL) {
-		ctx->error(ctx, "session not found: %s", data->target);
-		return (-1);
-	}
 
 	wl = NULL;
 	if (idx != -1)
diff --git a/cmd.c b/cmd.c
index 7e98f8cc..a2264081 100644
--- a/cmd.c
+++ b/cmd.c
@@ -19,6 +19,8 @@
 #include <sys/types.h>
 #include <sys/time.h>
 
+#include <fnmatch.h>
+#include <paths.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -100,6 +102,11 @@ const struct cmd_entry *cmd_table[] = {
 	NULL
 };
 
+struct session	*cmd_newest_session(void);
+struct client	*cmd_lookup_client(const char *);
+struct session	*cmd_lookup_session(const char *, int *);
+struct winlink	*cmd_lookup_window(struct session *, const char *, int *);
+
 struct cmd *
 cmd_parse(int argc, char **argv, char **cause)
 {
@@ -294,106 +301,421 @@ cmd_recv_string(struct buffer *b)
 	return (s);
 }
 
+/*
+ * Figure out the current session. Use: 1) the current session, if the command
+ * context has one; 2) the session specified in the TMUX variable from the
+ * environment (as passed from the client); 3) the newest session.
+ */
 struct session *
 cmd_current_session(struct cmd_ctx *ctx)
 {
 	struct msg_command_data	*data = ctx->msgdata;
-	struct timeval		*tv;
-	struct session		*s, *newest = NULL;
-	u_int			 i;
+	struct session		*s;
 
 	if (ctx->cursession != NULL)
 		return (ctx->cursession);
 
 	if (data != NULL && data->pid != -1) {
-		if (data->pid != getpid()) {
-			ctx->error(ctx, "wrong server: %ld", (long) data->pid);
+		if (data->pid != getpid())
 			return (NULL);
-		}
-		if (data->idx > ARRAY_LENGTH(&sessions)) {
-			ctx->error(ctx, "index out of range: %d", data->idx);
+		if (data->idx > ARRAY_LENGTH(&sessions))
 			return (NULL);
-		}
-		if ((s = ARRAY_ITEM(&sessions, data->idx)) == NULL) {
-			ctx->error(ctx, "session doesn't exist: %u", data->idx);
+		if ((s = ARRAY_ITEM(&sessions, data->idx)) == NULL)
 			return (NULL);
-		}
 		return (s);
 	}
 
-	tv = NULL;
+	return (cmd_newest_session());
+}
+
+/* Find the newest session. */
+struct session *
+cmd_newest_session(void)
+{
+	struct session	*s, *snewest;
+	struct timeval	*tv = NULL;
+	u_int		 i;
+
+	snewest = NULL;
 	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {
-		s = ARRAY_ITEM(&sessions, i);
-		if (s != NULL && (tv == NULL || timercmp(&s->tv, tv, >))) {
-			newest = ARRAY_ITEM(&sessions, i);
+		if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
+			continue;
+
+		if (tv == NULL || timercmp(&s->tv, tv, >)) {
+			snewest = s;
 			tv = &s->tv;
 		}
 	}
-	return (newest);
+
+	return (snewest);
 }
 
+/* Find the target client or report an error and return NULL. */
 struct client *
 cmd_find_client(struct cmd_ctx *ctx, const char *arg)
 {
 	struct client	*c;
+	char		*tmparg;
+	size_t		 arglen;
 
+	/* A NULL argument means the current client. */
 	if (arg == NULL)
-		c = ctx->curclient;
-	else {
-		if ((c = arg_parse_client(arg)) == NULL) {
-			if (arg != NULL)
-				ctx->error(ctx, "client not found: %s", arg);
-			else
-				ctx->error(ctx, "no client found");
+		return (ctx->curclient);
+	tmparg = xstrdup(arg);
+
+	/* Trim a single trailing colon if any. */
+	arglen = strlen(tmparg);
+	if (arglen != 0 && tmparg[arglen - 1] == ':')
+		tmparg[arglen - 1] = '\0';
+
+	/* Find the client, if any. */
+	c = cmd_lookup_client(tmparg);
+
+	/* If no client found, report an error. */
+	if (c == NULL)
+		ctx->error(ctx, "client not found: %s", tmparg);
+
+	xfree(tmparg);
+	return (c);
+}
+
+/*
+ * Lookup a client by device path. Either of a full match and a match without a
+ * leading _PATH_DEV ("/dev/") is accepted.
+ */
+struct client *
+cmd_lookup_client(const char *name)
+{
+	struct client	*c;
+	const char	*path;
+	u_int		 i;
+
+	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
+		if ((c = ARRAY_ITEM(&clients, i)) == NULL)
+			continue;
+		path = c->tty.path;
+
+		/* Check for exact matches. */
+		if (strcmp(name, path) == 0)
+			return (c);
+
+		/* Check without leading /dev if present. */
+		if (strncmp(path, _PATH_DEV, (sizeof _PATH_DEV) - 1) != 0)
+			continue;
+		if (strcmp(name, path + (sizeof _PATH_DEV) - 1) == 0)
+			return (c);
+	}
+
+	return (NULL);
+}
+
+/* Lookup a session by name. If no session is found, NULL is returned. */
+struct session *
+cmd_lookup_session(const char *name, int *ambiguous)
+{
+	struct session	*s, *sfound;
+	u_int		 i;
+
+	*ambiguous = 0;
+
+	/*
+	 * Look for matches. Session names must be unique so an exact match
+	 * can't be ambigious and can just be returned.
+	 */
+	sfound = NULL;
+	for (i = 0; i < ARRAY_LENGTH(&sessions); i++) {	
+		if ((s = ARRAY_ITEM(&sessions, i)) == NULL)
+			continue;
+
+		/* Check for an exact match and return it if found. */
+		if (strcmp(name, s->name) == 0)
+			return (s);
+		
+		/* Then check for pattern matches. */
+		if (strncmp(name, s->name, strlen(name)) == 0 ||
+		    fnmatch(name, s->name, 0) == 0) {
+			if (sfound != NULL) {
+				*ambiguous = 1;
+				return (NULL);
+			}
+			sfound = s;
 		}
 	}
-	return (c);
+		
+ 	return (sfound);
 }
 
+/*
+ * Lookup a window or return -1 if not found or ambigious. First try as an index
+ * and if invalid, use fnmatch or leading prefix.
+ */
+struct winlink *
+cmd_lookup_window(struct session *s, const char *name, int *ambiguous)
+{
+	struct winlink	*wl, *wlfound;
+	struct window	*w;
+	const char	*errstr;
+	u_int		 idx;
+
+	*ambiguous = 0;
+
+	/* First see if this is a valid window index in this session. */
+	idx = strtonum(name, 0, INT_MAX, &errstr);
+	if (errstr == NULL) {
+		if ((wl = winlink_find_by_index(&s->windows, idx)) != NULL)
+			return (wl);
+	}
+		
+	/* Look for exact matches, error if more than one. */
+	wlfound = NULL;
+	RB_FOREACH(wl, winlinks, &s->windows) {
+		w = wl->window;
+		if (strcmp(name, w->name) == 0) {
+			if (wlfound != NULL) {
+				*ambiguous = 1;
+				return (NULL);
+			}
+			wlfound = wl;
+		}
+	}
+	if (wlfound != NULL)
+		return (wlfound);
+
+	/* Now look for pattern matches, again error if multiple. */
+	wlfound = NULL;
+	RB_FOREACH(wl, winlinks, &s->windows) {
+		w = wl->window;
+		if (strncmp(name, w->name, strlen(name)) == 0 ||
+		    fnmatch(name, w->name, 0) == 0) {
+			if (wlfound != NULL) {
+				*ambiguous = 1;
+				return (NULL);
+			}
+			wlfound = wl;
+		}
+	}	
+	if (wlfound != NULL)
+		return (wlfound);
+
+	return (NULL);
+}
+
+/* Find the target session or report an error and return NULL. */
 struct session *
 cmd_find_session(struct cmd_ctx *ctx, const char *arg)
 {
 	struct session	*s;
+	struct client	*c;
+	char		*tmparg;
+	size_t		 arglen;
+	int		 ambiguous;
 
+	/* A NULL argument means the current session. */
 	if (arg == NULL)
-		s = cmd_current_session(ctx);
-	else {
-		if ((s = arg_parse_session(arg)) == NULL) {
-			if (arg != NULL)
-				ctx->error(ctx, "session not found: %s", arg);
-			else
-				ctx->error(ctx, "no session found");
-		}
+		return (cmd_current_session(ctx));
+	tmparg = xstrdup(arg);
+
+	/* Trim a single trailing colon if any. */
+	arglen = strlen(tmparg);
+	if (arglen != 0 && tmparg[arglen - 1] == ':')
+		tmparg[arglen - 1] = '\0';
+
+	/* Find the session, if any. */
+	s = cmd_lookup_session(tmparg, &ambiguous);
+
+	/* If it doesn't, try to match it as a client. */
+	if (s == NULL && (c = cmd_lookup_client(tmparg)) != NULL)
+		s = c->session;
+
+	/* If no session found, report an error. */
+	if (s == NULL) {
+		if (ambiguous)
+			ctx->error(ctx, "more than one session: %s", tmparg);
+		else
+			ctx->error(ctx, "session not found: %s", tmparg);
 	}
+
+	xfree(tmparg);
 	return (s);
 }
 
+/* Find the target session and window or report an error and return NULL. */
 struct winlink *
 cmd_find_window(struct cmd_ctx *ctx, const char *arg, struct session **sp)
 {
 	struct session	*s;
 	struct winlink	*wl;
-	int		 idx;
-
-	wl = NULL;
-	if (arg_parse_window(arg, &s, &idx) != 0) {
-		ctx->error(ctx, "bad window: %s", arg);
+	const char	*winptr;
+	char		*sessptr = NULL;
+	int		 ambiguous = 0;
+
+	/*
+	 * Find the current session. There must always be a current session, if
+	 * it can't be found, report an error.
+	 */
+	if ((s = cmd_current_session(ctx)) == NULL) {
+		ctx->error(ctx, "can't establish current session");
 		return (NULL);
 	}
-	if (s == NULL)
-		s = ctx->cursession;
-	if (s == NULL)
-		s = cmd_current_session(ctx);
-	if (s == NULL)
-		return (NULL);
+
+	/* A NULL argument means the current session and window. */
+	if (arg == NULL) {
+		if (sp != NULL)
+			*sp = s;
+		return (s->curw);
+	}
+
+	/* Time to look at the argument. If it is empty, that is an error. */
+	if (*arg == '\0')
+		goto not_found;
+
+	/* Find the separating colon. If none, assume the current session. */
+	winptr = strchr(arg, ':');
+	if (winptr == NULL)
+		winptr = xstrdup(arg);
+	else {
+		winptr++;	/* skip : */
+		sessptr = xstrdup(arg);
+		*strchr(sessptr, ':') = '\0';
+	}
+
+	log_debug("%s: winptr=%s, sessptr=%s", __func__, winptr, sessptr);
+
+	/* Try to lookup the session if present. */
+	if (sessptr != NULL && *sessptr != '\0') {
+		if  ((s = cmd_lookup_session(sessptr, &ambiguous)) == NULL)
+			goto no_session;
+	}
 	if (sp != NULL)
 		*sp = s;
 
-	if (idx == -1)
+	/*
+	 * Then work out the window. An empty string is the current window,
+	 * otherwise try to look it up in the session.
+	 */
+	if (winptr == NULL || *winptr == '\0')
 		wl = s->curw;
-	else
-		wl = winlink_find_by_index(&s->windows, idx);
-	if (wl == NULL)
-		ctx->error(ctx, "window not found: %s:%d", s->name, idx);
+	else if ((wl = cmd_lookup_window(s, winptr, &ambiguous)) == NULL)
+		goto not_found;
+	
+	if (sessptr != NULL)
+		xfree(sessptr);
 	return (wl);
+
+no_session:
+	if (ambiguous)
+		ctx->error(ctx, "multiple sessions: %s", sessptr);
+	else
+		ctx->error(ctx, "session not found: %s", sessptr);
+	if (sessptr != NULL)
+		xfree(sessptr);
+	return (NULL);
+
+not_found:
+	if (ambiguous)
+		ctx->error(ctx, "multiple windows: %s", arg);
+	else
+		ctx->error(ctx, "window not found: %s", arg);
+	if (sessptr != NULL)
+		xfree(sessptr);
+	return (NULL);
+}
+
+/*
+ * Find the target session and window index, whether or not it exists in the
+ * session. Return -2 on error or -1 if no window index is specified. This is
+ * used when parsing an argument for a window target that may not be exist (for
+ * example it is going to be created).
+ */
+int
+cmd_find_index(struct cmd_ctx *ctx, const char *arg, struct session **sp)
+{
+	struct session	*s;
+	struct winlink	*wl;
+	const char	*winptr, *errstr;
+	char		*sessptr = NULL;
+	int		 idx, ambiguous = 0;
+
+	/*
+	 * Find the current session. There must always be a current session, if
+	 * it can't be found, report an error.
+	 */
+	if ((s = cmd_current_session(ctx)) == NULL) {
+		ctx->error(ctx, "can't establish current session");
+		return (NULL);
+	}
+
+	/* A NULL argument means the current session and "no window" (-1). */
+	if (arg == NULL) {
+		if (sp != NULL)
+			*sp = s;
+		return (-1);
+	}
+
+	/* Time to look at the argument. If it is empty, that is an error. */
+	if (*arg == '\0')
+		goto not_found;
+
+	/* Find the separating colon. If none, assume the current session. */
+	winptr = strchr(arg, ':');
+	if (winptr == NULL)
+		winptr = xstrdup(arg);
+	else {
+		winptr++;	/* skip : */
+		sessptr = xstrdup(arg);
+		*strchr(sessptr, ':') = '\0';
+	}
+
+	log_debug("%s: winptr=%s, sessptr=%s", __func__, winptr, sessptr);
+
+	/* Try to lookup the session if present. */
+	if (sessptr != NULL && *sessptr != '\0') {
+		if  ((s = cmd_lookup_session(sessptr, &ambiguous)) == NULL)
+			goto no_session;
+	}
+	if (sp != NULL)
+		*sp = s;
+
+	/*
+	 * Then work out the window. No : means "no window" (-1), an empty
+	 * string is the current window, otherwise try to look it up in the
+	 * session.
+	 */
+	if (winptr == NULL)
+		idx = -1;
+	else if (*winptr == '\0')
+		idx = s->curw->idx;
+	else if ((wl = cmd_lookup_window(s, winptr, &ambiguous)) == NULL) {
+		if (ambiguous)
+			goto not_found;
+		/* Don't care it doesn't exist if this is a valid index. */
+		idx = strtonum(winptr, 0, INT_MAX, &errstr);
+		if (errstr != NULL)  {
+			ctx->error(ctx, "index %s: %s", errstr, winptr);
+			idx = -2;
+		}
+	} else
+		idx = wl->idx;
+	
+	if (sessptr != NULL)
+		xfree(sessptr);
+	return (idx);
+
+no_session:
+	if (ambiguous)
+ 		ctx->error(ctx, "multiple sessions: %s", sessptr);
+	else
+		ctx->error(ctx, "session not found: %s", sessptr);
+	if (sessptr != NULL)
+		xfree(sessptr);
+	return (-2);
+
+not_found:
+	if (ambiguous)
+		ctx->error(ctx, "multiple windows: %s", arg);
+	else
+		ctx->error(ctx, "window not found: %s", arg);
+	if (sessptr != NULL)
+		xfree(sessptr);
+	return (-2);
 }
diff --git a/tmux.1 b/tmux.1
index e3965c7a..552907b0 100644
--- a/tmux.1
+++ b/tmux.1
@@ -500,8 +500,14 @@ These specify the client, session or window which a command should affect.
 .Ar target-client
 is the name of the
 .Xr pty 4
-file to which the client is connected, for example
+file to which the client is connected, for example either of
+.Pa /dev/ttyp1
+or
+.Pa ttyp1
+for the client attached to 
 .Pa /dev/ttyp1 .
+If no client is specified, the current client is chosen, if possible, or an
+error is reported.
 Clients may be listed with the
 .Ic list-clients
 command.
@@ -509,23 +515,32 @@ command.
 .Ar target-session
 is either the name of a session (as listed by the
 .Ic list-sessions
-command) or the name of a client,
+command) or the name of a client with the same syntax as
 .Ar target-client ,
 in which case the session attached to the client is used.
-An
+When looking for the session name, 
+.Nm
+initially searches for an exact match; if none is found, the session names
+are checked for any for which
+.Ar target-session
+is a prefix or for which it matches as an
 .Xr fnmatch 3
-pattern may be used to match the session name.
-If a session is omitted when required,
-.Nm tmux
-attempts to use the current session; if no current session is available, the
-most recently created is chosen.
-If no client is specified, the current client is chosen, if possible, or an
-error is reported.
+pattern.
+If a single match is found, it is used as the target session; multiple matches
+produce an error
+If a session is omitted, the current session is used if available; if no
+current session is available, the most recently created is chosen.
 .Pp
 .Ar target-window
 specifies a window in the form
-.Em session Ns \&: Ns Em index ,
-for example mysession:1.
+.Em session Ns \&: Ns Em window ,
+where
+.Em window
+is a window index, for example mysession:1, or a window name,
+.Xr fnmatch 3
+pattern, or prefix, such as mysession:mywin[0-3].
+If the latter, the window is looked up in a similar fashion to session name
+searches described above.
 The session is in the same form as for
 .Ar target-session .
 .Em session ,
@@ -536,7 +551,7 @@ If
 is omitted, the same rules as for
 .Ar target-session
 are followed; if
-.Em index
+.Em window
 is not present, the current window for the given session is used.
 When the argument does not contain a colon,
 .Nm
diff --git a/tmux.h b/tmux.h
index 481b0ca7..585daeb9 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1076,11 +1076,6 @@ int		 paste_replace(struct paste_stack *, u_int, char *);
 /* clock.c */
 void		 clock_draw(struct screen_write_ctx *, u_int, int);
 
-/* arg.c */
-struct client 	*arg_parse_client(const char *);
-struct session 	*arg_parse_session(const char *);
-int		 arg_parse_window(const char *, struct session **, int *);
-
 /* cmd.c */
 struct cmd	*cmd_parse(int, char **, char **);
 int		 cmd_exec(struct cmd *, struct cmd_ctx *);
@@ -1094,7 +1089,9 @@ struct session	*cmd_current_session(struct cmd_ctx *);
 struct client	*cmd_find_client(struct cmd_ctx *, const char *);
 struct session	*cmd_find_session(struct cmd_ctx *, const char *);
 struct winlink	*cmd_find_window(
-    		     struct cmd_ctx *, const char *, struct session **);
+		     struct cmd_ctx *, const char *, struct session **);
+int		 cmd_find_index(
+		     struct cmd_ctx *, const char *, struct session **);
 extern const struct cmd_entry *cmd_table[];
 extern const struct cmd_entry cmd_attach_session_entry;
 extern const struct cmd_entry cmd_bind_key_entry;