Add some missing const, from Jere Viikari.

usr.bin/tmux/environ.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: environ.c,v 1.30 2026/02/23 08:45:27 nicm Exp $ */
+/* $OpenBSD: environ.c,v 1.31 2026/06/13 20:07:30 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -152,7 +152,8 @@ environ_clear(struct environ *env, const char *name)
 void
 environ_put(struct environ *env, const char *var, int flags)
 {
-	char	*name, *value;
+	char		*name;
+	const char	*value;
 
 	value = strchr(var, '=');
 	if (value == NULL)

usr.bin/tmux/format.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: format.c,v 1.376 2026/06/13 09:17:29 nicm Exp $ */
+/* $OpenBSD: format.c,v 1.377 2026/06/13 20:07:30 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -3760,7 +3760,7 @@ format_table_compare(const void *key0, const void *entry0)
 }
 
 /* Get a format callback. */
-static struct format_table_entry *
+static const struct format_table_entry *
 format_table_get(const char *key)
 {
 	return (bsearch(key, format_table, nitems(format_table),
@@ -4094,7 +4094,7 @@ static char *
 format_find(struct format_tree *ft, const char *key, int modifiers,
     const char *time_format)
 {
-	struct format_table_entry	*fte;
+	const struct format_table_entry	*fte;
 	void				*value;
 	struct format_entry		*fe, fe_find;
 	struct environ_entry		*envent;

usr.bin/tmux/input-keys.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: input-keys.c,v 1.112 2026/03/31 11:46:43 nicm Exp $ */
+/* $OpenBSD: input-keys.c,v 1.113 2026/06/13 20:07:30 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -484,7 +484,7 @@ input_key_vt10x(struct bufferevent *bev, key_code key)
 {
 	struct utf8_data	 ud;
 	key_code		 onlykey;
-	char			*p;
+	const char		*p;
 	static const char	*standard_map[2] = {
 		"1!9(0)=+;:'\",<.>/-8? 2",
 		"119900=+;;'',,..\x1f\x1f\x7f\x7f\0\0",

usr.bin/tmux/input.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: input.c,v 1.259 2026/06/01 13:28:49 nicm Exp $ */
+/* $OpenBSD: input.c,v 1.260 2026/06/13 20:07:30 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1365,7 +1365,7 @@ input_esc_dispatch(struct input_ctx *ictx)
 {
 	struct screen_write_ctx		*sctx = &ictx->ctx;
 	struct screen			*s = sctx->s;
-	struct input_table_entry	*entry;
+	const struct input_table_entry	*entry;
 
 	if (ictx->flags & INPUT_DISCARD)
 		return (0);
@@ -1439,12 +1439,12 @@ input_esc_dispatch(struct input_ctx *ictx)
 static int
 input_csi_dispatch(struct input_ctx *ictx)
 {
-	struct screen_write_ctx	       *sctx = &ictx->ctx;
-	struct screen		       *s = sctx->s;
-	struct input_table_entry       *entry;
-	struct options		       *oo;
-	int				i, n, m, ek, set, p;
-	u_int				cx, bg = ictx->cell.cell.bg;
+	struct screen_write_ctx		*sctx = &ictx->ctx;
+	struct screen			*s = sctx->s;
+	const struct input_table_entry	*entry;
+	struct options			*oo;
+	int				 i, n, m, ek, set, p;
+	u_int				 cx, bg = ictx->cell.cell.bg;
 
 	if (ictx->flags & INPUT_DISCARD)
 		return (0);
@@ -3188,7 +3188,7 @@ static int
 input_osc_52_parse(struct input_ctx *ictx, const char *p, u_char **out,
     int *outlen, char *clip)
 {
-	char		*end;
+	const char	*end;
 	size_t		 len;
 	const char	*allow = "cpqs01234567";
 	u_int		 i, j = 0;