/* $OpenBSD: tty-term.c,v 1.104 2025/11/07 12:43:47 jsg Exp $ */

/*
 * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * 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 <curses.h>
#include <fnmatch.h>
#include <stdlib.h>
#include <string.h>
#include <term.h>
#include <vis.h>

#include "tmux.h"

static char     *tty_term_strip(const char *);

struct tty_terms tty_terms = LIST_HEAD_INITIALIZER(tty_terms);

enum tty_code_type {
        TTYCODE_NONE = 0,
        TTYCODE_STRING,
        TTYCODE_NUMBER,
        TTYCODE_FLAG,
};

struct tty_code {
        enum tty_code_type      type;
        union {
                char           *string;
                int             number;
                int             flag;
        } value;
};

struct tty_term_code_entry {
        enum tty_code_type      type;
        const char             *name;
};

static const struct tty_term_code_entry tty_term_codes[] = {
        [TTYC_ACSC] = { TTYCODE_STRING, "acsc" },
        [TTYC_AM] = { TTYCODE_FLAG, "am" },
        [TTYC_AX] = { TTYCODE_FLAG, "AX" },
        [TTYC_BCE] = { TTYCODE_FLAG, "bce" },
        [TTYC_BEL] = { TTYCODE_STRING, "bel" },
        [TTYC_BIDI] = { TTYCODE_STRING, "Bidi" },
        [TTYC_BLINK] = { TTYCODE_STRING, "blink" },
        [TTYC_BOLD] = { TTYCODE_STRING, "bold" },
        [TTYC_CIVIS] = { TTYCODE_STRING, "civis" },
        [TTYC_CLEAR] = { TTYCODE_STRING, "clear" },
        [TTYC_CLMG] = { TTYCODE_STRING, "Clmg" },
        [TTYC_CMG] = { TTYCODE_STRING, "Cmg" },
        [TTYC_CNORM] = { TTYCODE_STRING, "cnorm" },
        [TTYC_COLORS] = { TTYCODE_NUMBER, "colors" },
        [TTYC_CR] = { TTYCODE_STRING, "Cr" },
        [TTYC_CSR] = { TTYCODE_STRING, "csr" },
        [TTYC_CS] = { TTYCODE_STRING, "Cs" },
        [TTYC_CUB1] = { TTYCODE_STRING, "cub1" },
        [TTYC_CUB] = { TTYCODE_STRING, "cub" },
        [TTYC_CUD1] = { TTYCODE_STRING, "cud1" },
        [TTYC_CUD] = { TTYCODE_STRING, "cud" },
        [TTYC_CUF1] = { TTYCODE_STRING, "cuf1" },
        [TTYC_CUF] = { TTYCODE_STRING, "cuf" },
        [TTYC_CUP] = { TTYCODE_STRING, "cup" },
        [TTYC_CUU1] = { TTYCODE_STRING, "cuu1" },
        [TTYC_CUU] = { TTYCODE_STRING, "cuu" },
        [TTYC_CVVIS] = { TTYCODE_STRING, "cvvis" },
        [TTYC_DCH1] = { TTYCODE_STRING, "dch1" },
        [TTYC_DCH] = { TTYCODE_STRING, "dch" },
        [TTYC_DIM] = { TTYCODE_STRING, "dim" },
        [TTYC_DL1] = { TTYCODE_STRING, "dl1" },
        [TTYC_DL] = { TTYCODE_STRING, "dl" },
        [TTYC_DSEKS] = { TTYCODE_STRING, "Dseks" },
        [TTYC_DSFCS] = { TTYCODE_STRING, "Dsfcs" },
        [TTYC_DSBP] = { TTYCODE_STRING, "Dsbp" },
        [TTYC_DSMG] = { TTYCODE_STRING, "Dsmg" },
        [TTYC_E3] = { TTYCODE_STRING, "E3" },
        [TTYC_ECH] = { TTYCODE_STRING, "ech" },
        [TTYC_ED] = { TTYCODE_STRING, "ed" },
        [TTYC_EL1] = { TTYCODE_STRING, "el1" },
        [TTYC_EL] = { TTYCODE_STRING, "el" },
        [TTYC_ENACS] = { TTYCODE_STRING, "enacs" },
        [TTYC_ENBP] = { TTYCODE_STRING, "Enbp" },
        [TTYC_ENEKS] = { TTYCODE_STRING, "Eneks" },
        [TTYC_ENFCS] = { TTYCODE_STRING, "Enfcs" },
        [TTYC_ENMG] = { TTYCODE_STRING, "Enmg" },
        [TTYC_FSL] = { TTYCODE_STRING, "fsl" },
        [TTYC_HLS] = { TTYCODE_STRING, "Hls" },
        [TTYC_HOME] = { TTYCODE_STRING, "home" },
        [TTYC_HPA] = { TTYCODE_STRING, "hpa" },
        [TTYC_ICH1] = { TTYCODE_STRING, "ich1" },
        [TTYC_ICH] = { TTYCODE_STRING, "ich" },
        [TTYC_IL1] = { TTYCODE_STRING, "il1" },
        [TTYC_IL] = { TTYCODE_STRING, "il" },
        [TTYC_INDN] = { TTYCODE_STRING, "indn" },
        [TTYC_INVIS] = { TTYCODE_STRING, "invis" },
        [TTYC_KCBT] = { TTYCODE_STRING, "kcbt" },
        [TTYC_KCUB1] = { TTYCODE_STRING, "kcub1" },
        [TTYC_KCUD1] = { TTYCODE_STRING, "kcud1" },
        [TTYC_KCUF1] = { TTYCODE_STRING, "kcuf1" },
        [TTYC_KCUU1] = { TTYCODE_STRING, "kcuu1" },
        [TTYC_KDC2] = { TTYCODE_STRING, "kDC" },
        [TTYC_KDC3] = { TTYCODE_STRING, "kDC3" },
        [TTYC_KDC4] = { TTYCODE_STRING, "kDC4" },
        [TTYC_KDC5] = { TTYCODE_STRING, "kDC5" },
        [TTYC_KDC6] = { TTYCODE_STRING, "kDC6" },
        [TTYC_KDC7] = { TTYCODE_STRING, "kDC7" },
        [TTYC_KDCH1] = { TTYCODE_STRING, "kdch1" },
        [TTYC_KDN2] = { TTYCODE_STRING, "kDN" }, /* not kDN2 */
        [TTYC_KDN3] = { TTYCODE_STRING, "kDN3" },
        [TTYC_KDN4] = { TTYCODE_STRING, "kDN4" },
        [TTYC_KDN5] = { TTYCODE_STRING, "kDN5" },
        [TTYC_KDN6] = { TTYCODE_STRING, "kDN6" },
        [TTYC_KDN7] = { TTYCODE_STRING, "kDN7" },
        [TTYC_KEND2] = { TTYCODE_STRING, "kEND" },
        [TTYC_KEND3] = { TTYCODE_STRING, "kEND3" },
        [TTYC_KEND4] = { TTYCODE_STRING, "kEND4" },
        [TTYC_KEND5] = { TTYCODE_STRING, "kEND5" },
        [TTYC_KEND6] = { TTYCODE_STRING, "kEND6" },
        [TTYC_KEND7] = { TTYCODE_STRING, "kEND7" },
        [TTYC_KEND] = { TTYCODE_STRING, "kend" },
        [TTYC_KF10] = { TTYCODE_STRING, "kf10" },
        [TTYC_KF11] = { TTYCODE_STRING, "kf11" },
        [TTYC_KF12] = { TTYCODE_STRING, "kf12" },
        [TTYC_KF13] = { TTYCODE_STRING, "kf13" },
        [TTYC_KF14] = { TTYCODE_STRING, "kf14" },
        [TTYC_KF15] = { TTYCODE_STRING, "kf15" },
        [TTYC_KF16] = { TTYCODE_STRING, "kf16" },
        [TTYC_KF17] = { TTYCODE_STRING, "kf17" },
        [TTYC_KF18] = { TTYCODE_STRING, "kf18" },
        [TTYC_KF19] = { TTYCODE_STRING, "kf19" },
        [TTYC_KF1] = { TTYCODE_STRING, "kf1" },
        [TTYC_KF20] = { TTYCODE_STRING, "kf20" },
        [TTYC_KF21] = { TTYCODE_STRING, "kf21" },
        [TTYC_KF22] = { TTYCODE_STRING, "kf22" },
        [TTYC_KF23] = { TTYCODE_STRING, "kf23" },
        [TTYC_KF24] = { TTYCODE_STRING, "kf24" },
        [TTYC_KF25] = { TTYCODE_STRING, "kf25" },
        [TTYC_KF26] = { TTYCODE_STRING, "kf26" },
        [TTYC_KF27] = { TTYCODE_STRING, "kf27" },
        [TTYC_KF28] = { TTYCODE_STRING, "kf28" },
        [TTYC_KF29] = { TTYCODE_STRING, "kf29" },
        [TTYC_KF2] = { TTYCODE_STRING, "kf2" },
        [TTYC_KF30] = { TTYCODE_STRING, "kf30" },
        [TTYC_KF31] = { TTYCODE_STRING, "kf31" },
        [TTYC_KF32] = { TTYCODE_STRING, "kf32" },
        [TTYC_KF33] = { TTYCODE_STRING, "kf33" },
        [TTYC_KF34] = { TTYCODE_STRING, "kf34" },
        [TTYC_KF35] = { TTYCODE_STRING, "kf35" },
        [TTYC_KF36] = { TTYCODE_STRING, "kf36" },
        [TTYC_KF37] = { TTYCODE_STRING, "kf37" },
        [TTYC_KF38] = { TTYCODE_STRING, "kf38" },
        [TTYC_KF39] = { TTYCODE_STRING, "kf39" },
        [TTYC_KF3] = { TTYCODE_STRING, "kf3" },
        [TTYC_KF40] = { TTYCODE_STRING, "kf40" },
        [TTYC_KF41] = { TTYCODE_STRING, "kf41" },
        [TTYC_KF42] = { TTYCODE_STRING, "kf42" },
        [TTYC_KF43] = { TTYCODE_STRING, "kf43" },
        [TTYC_KF44] = { TTYCODE_STRING, "kf44" },
        [TTYC_KF45] = { TTYCODE_STRING, "kf45" },
        [TTYC_KF46] = { TTYCODE_STRING, "kf46" },
        [TTYC_KF47] = { TTYCODE_STRING, "kf47" },
        [TTYC_KF48] = { TTYCODE_STRING, "kf48" },
        [TTYC_KF49] = { TTYCODE_STRING, "kf49" },
        [TTYC_KF4] = { TTYCODE_STRING, "kf4" },
        [TTYC_KF50] = { TTYCODE_STRING, "kf50" },
        [TTYC_KF51] = { TTYCODE_STRING, "kf51" },
        [TTYC_KF52] = { TTYCODE_STRING, "kf52" },
        [TTYC_KF53] = { TTYCODE_STRING, "kf53" },
        [TTYC_KF54] = { TTYCODE_STRING, "kf54" },
        [TTYC_KF55] = { TTYCODE_STRING, "kf55" },
        [TTYC_KF56] = { TTYCODE_STRING, "kf56" },
        [TTYC_KF57] = { TTYCODE_STRING, "kf57" },
        [TTYC_KF58] = { TTYCODE_STRING, "kf58" },
        [TTYC_KF59] = { TTYCODE_STRING, "kf59" },
        [TTYC_KF5] = { TTYCODE_STRING, "kf5" },
        [TTYC_KF60] = { TTYCODE_STRING, "kf60" },
        [TTYC_KF61] = { TTYCODE_STRING, "kf61" },
        [TTYC_KF62] = { TTYCODE_STRING, "kf62" },
        [TTYC_KF63] = { TTYCODE_STRING, "kf63" },
        [TTYC_KF6] = { TTYCODE_STRING, "kf6" },
        [TTYC_KF7] = { TTYCODE_STRING, "kf7" },
        [TTYC_KF8] = { TTYCODE_STRING, "kf8" },
        [TTYC_KF9] = { TTYCODE_STRING, "kf9" },
        [TTYC_KHOM2] = { TTYCODE_STRING, "kHOM" },
        [TTYC_KHOM3] = { TTYCODE_STRING, "kHOM3" },
        [TTYC_KHOM4] = { TTYCODE_STRING, "kHOM4" },
        [TTYC_KHOM5] = { TTYCODE_STRING, "kHOM5" },
        [TTYC_KHOM6] = { TTYCODE_STRING, "kHOM6" },
        [TTYC_KHOM7] = { TTYCODE_STRING, "kHOM7" },
        [TTYC_KHOME] = { TTYCODE_STRING, "khome" },
        [TTYC_KIC2] = { TTYCODE_STRING, "kIC" },
        [TTYC_KIC3] = { TTYCODE_STRING, "kIC3" },
        [TTYC_KIC4] = { TTYCODE_STRING, "kIC4" },
        [TTYC_KIC5] = { TTYCODE_STRING, "kIC5" },
        [TTYC_KIC6] = { TTYCODE_STRING, "kIC6" },
        [TTYC_KIC7] = { TTYCODE_STRING, "kIC7" },
        [TTYC_KICH1] = { TTYCODE_STRING, "kich1" },
        [TTYC_KIND] = { TTYCODE_STRING, "kind" },
        [TTYC_KLFT2] = { TTYCODE_STRING, "kLFT" },
        [TTYC_KLFT3] = { TTYCODE_STRING, "kLFT3" },
        [TTYC_KLFT4] = { TTYCODE_STRING, "kLFT4" },
        [TTYC_KLFT5] = { TTYCODE_STRING, "kLFT5" },
        [TTYC_KLFT6] = { TTYCODE_STRING, "kLFT6" },
        [TTYC_KLFT7] = { TTYCODE_STRING, "kLFT7" },
        [TTYC_KMOUS] = { TTYCODE_STRING, "kmous" },
        [TTYC_KNP] = { TTYCODE_STRING, "knp" },
        [TTYC_KNXT2] = { TTYCODE_STRING, "kNXT" },
        [TTYC_KNXT3] = { TTYCODE_STRING, "kNXT3" },
        [TTYC_KNXT4] = { TTYCODE_STRING, "kNXT4" },
        [TTYC_KNXT5] = { TTYCODE_STRING, "kNXT5" },
        [TTYC_KNXT6] = { TTYCODE_STRING, "kNXT6" },
        [TTYC_KNXT7] = { TTYCODE_STRING, "kNXT7" },
        [TTYC_KPP] = { TTYCODE_STRING, "kpp" },
        [TTYC_KPRV2] = { TTYCODE_STRING, "kPRV" },
        [TTYC_KPRV3] = { TTYCODE_STRING, "kPRV3" },
        [TTYC_KPRV4] = { TTYCODE_STRING, "kPRV4" },
        [TTYC_KPRV5] = { TTYCODE_STRING, "kPRV5" },
        [TTYC_KPRV6] = { TTYCODE_STRING, "kPRV6" },
        [TTYC_KPRV7] = { TTYCODE_STRING, "kPRV7" },
        [TTYC_KRIT2] = { TTYCODE_STRING, "kRIT" },
        [TTYC_KRIT3] = { TTYCODE_STRING, "kRIT3" },
        [TTYC_KRIT4] = { TTYCODE_STRING, "kRIT4" },
        [TTYC_KRIT5] = { TTYCODE_STRING, "kRIT5" },
        [TTYC_KRIT6] = { TTYCODE_STRING, "kRIT6" },
        [TTYC_KRIT7] = { TTYCODE_STRING, "kRIT7" },
        [TTYC_KRI] = { TTYCODE_STRING, "kri" },
        [TTYC_KUP2] = { TTYCODE_STRING, "kUP" }, /* not kUP2 */
        [TTYC_KUP3] = { TTYCODE_STRING, "kUP3" },
        [TTYC_KUP4] = { TTYCODE_STRING, "kUP4" },
        [TTYC_KUP5] = { TTYCODE_STRING, "kUP5" },
        [TTYC_KUP6] = { TTYCODE_STRING, "kUP6" },
        [TTYC_KUP7] = { TTYCODE_STRING, "kUP7" },
        [TTYC_MS] = { TTYCODE_STRING, "Ms" },
        [TTYC_NOBR] = { TTYCODE_STRING, "Nobr" },
        [TTYC_OL] = { TTYCODE_STRING, "ol" },
        [TTYC_OP] = { TTYCODE_STRING, "op" },
        [TTYC_RECT] = { TTYCODE_STRING, "Rect" },
        [TTYC_REV] = { TTYCODE_STRING, "rev" },
        [TTYC_RGB] = { TTYCODE_FLAG, "RGB" },
        [TTYC_RIN] = { TTYCODE_STRING, "rin" },
        [TTYC_RI] = { TTYCODE_STRING, "ri" },
        [TTYC_RMACS] = { TTYCODE_STRING, "rmacs" },
        [TTYC_RMCUP] = { TTYCODE_STRING, "rmcup" },
        [TTYC_RMKX] = { TTYCODE_STRING, "rmkx" },
        [TTYC_SETAB] = { TTYCODE_STRING, "setab" },
        [TTYC_SETAF] = { TTYCODE_STRING, "setaf" },
        [TTYC_SETAL] = { TTYCODE_STRING, "setal" },
        [TTYC_SETRGBB] = { TTYCODE_STRING, "setrgbb" },
        [TTYC_SETRGBF] = { TTYCODE_STRING, "setrgbf" },
        [TTYC_SETULC] = { TTYCODE_STRING, "Setulc" },
        [TTYC_SETULC1] = { TTYCODE_STRING, "Setulc1" },
        [TTYC_SE] = { TTYCODE_STRING, "Se" },
        [TTYC_SXL] =  { TTYCODE_FLAG, "Sxl" },
        [TTYC_SGR0] = { TTYCODE_STRING, "sgr0" },
        [TTYC_SITM] = { TTYCODE_STRING, "sitm" },
        [TTYC_SMACS] = { TTYCODE_STRING, "smacs" },
        [TTYC_SMCUP] = { TTYCODE_STRING, "smcup" },
        [TTYC_SMKX] = { TTYCODE_STRING, "smkx" },
        [TTYC_SMOL] = { TTYCODE_STRING, "Smol" },
        [TTYC_SMSO] = { TTYCODE_STRING, "smso" },
        [TTYC_SMULX] = { TTYCODE_STRING, "Smulx" },
        [TTYC_SMUL] = { TTYCODE_STRING, "smul" },
        [TTYC_SMXX] =  { TTYCODE_STRING, "smxx" },
        [TTYC_SS] = { TTYCODE_STRING, "Ss" },
        [TTYC_SWD] = { TTYCODE_STRING, "Swd" },
        [TTYC_SYNC] = { TTYCODE_STRING, "Sync" },
        [TTYC_TC] = { TTYCODE_FLAG, "Tc" },
        [TTYC_TSL] = { TTYCODE_STRING, "tsl" },
        [TTYC_U8] = { TTYCODE_NUMBER, "U8" },
        [TTYC_VPA] = { TTYCODE_STRING, "vpa" },
        [TTYC_XT] = { TTYCODE_FLAG, "XT" }
};

u_int
tty_term_ncodes(void)
{
        return (nitems(tty_term_codes));
}

static char *
tty_term_strip(const char *s)
{
        const char     *ptr;
        static char     buf[8192];
        size_t          len;

        /* Ignore strings with no padding. */
        if (strchr(s, '$') == NULL)
                return (xstrdup(s));

        len = 0;
        for (ptr = s; *ptr != '\0'; ptr++) {
                if (*ptr == '$' && *(ptr + 1) == '<') {
                        while (*ptr != '\0' && *ptr != '>')
                                ptr++;
                        if (*ptr == '>')
                                ptr++;
                        if (*ptr == '\0')
                                break;
                }

                buf[len++] = *ptr;
                if (len == (sizeof buf) - 1)
                        break;
        }
        buf[len] = '\0';

        return (xstrdup(buf));
}

static char *
tty_term_override_next(const char *s, size_t *offset)
{
        static char     value[8192];
        size_t          n = 0, at = *offset;

        if (s[at] == '\0')
                return (NULL);

        while (s[at] != '\0') {
                if (s[at] == ':') {
                        if (s[at + 1] == ':') {
                                value[n++] = ':';
                                at += 2;
                        } else
                                break;
                } else {
                        value[n++] = s[at];
                        at++;
                }
                if (n == (sizeof value) - 1)
                        return (NULL);
        }
        if (s[at] != '\0')
                *offset = at + 1;
        else
                *offset = at;
        value[n] = '\0';
        return (value);
}

void
tty_term_apply(struct tty_term *term, const char *capabilities, int quiet)
{
        const struct tty_term_code_entry        *ent;
        struct tty_code                         *code;
        size_t                                   offset = 0;
        char                                    *cp, *value, *s;
        const char                              *errstr, *name = term->name;
        u_int                                    i;
        int                                      n, remove;

        while ((s = tty_term_override_next(capabilities, &offset)) != NULL) {
                if (*s == '\0')
                        continue;
                value = NULL;

                remove = 0;
                if ((cp = strchr(s, '=')) != NULL) {
                        *cp++ = '\0';
                        value = xstrdup(cp);
                        if (strunvis(value, cp) == -1) {
                                free(value);
                                value = xstrdup(cp);
                        }
                } else if (s[strlen(s) - 1] == '@') {
                        s[strlen(s) - 1] = '\0';
                        remove = 1;
                } else
                        value = xstrdup("");

                if (!quiet) {
                        if (remove)
                                log_debug("%s override: %s@", name, s);
                        else if (*value == '\0')
                                log_debug("%s override: %s", name, s);
                        else
                                log_debug("%s override: %s=%s", name, s, value);
                }

                for (i = 0; i < tty_term_ncodes(); i++) {
                        ent = &tty_term_codes[i];
                        if (strcmp(s, ent->name) != 0)
                                continue;
                        code = &term->codes[i];

                        if (remove) {
                                code->type = TTYCODE_NONE;
                                continue;
                        }
                        switch (ent->type) {
                        case TTYCODE_NONE:
                                break;
                        case TTYCODE_STRING:
                                if (code->type == TTYCODE_STRING)
                                        free(code->value.string);
                                code->value.string = xstrdup(value);
                                code->type = ent->type;
                                break;
                        case TTYCODE_NUMBER:
                                n = strtonum(value, 0, INT_MAX, &errstr);
                                if (errstr != NULL)
                                        break;
                                code->value.number = n;
                                code->type = ent->type;
                                break;
                        case TTYCODE_FLAG:
                                code->value.flag = 1;
                                code->type = ent->type;
                                break;
                        }
                }

                free(value);
        }
}

void
tty_term_apply_overrides(struct tty_term *term)
{
        struct options_entry            *o;
        struct options_array_item       *a;
        union options_value             *ov;
        const char                      *s, *acs;
        size_t                           offset;
        char                            *first;

        /* Update capabilities from the option. */
        o = options_get_only(global_options, "terminal-overrides");
        a = options_array_first(o);
        while (a != NULL) {
                ov = options_array_item_value(a);
                s = ov->string;

                offset = 0;
                first = tty_term_override_next(s, &offset);
                if (first != NULL && fnmatch(first, term->name, 0) == 0)
                        tty_term_apply(term, s + offset, 0);
                a = options_array_next(a);
        }

        /* Log the SIXEL flag. */
        log_debug("SIXEL flag is %d", !!(term->flags & TERM_SIXEL));

        /* Update the RGB flag if the terminal has RGB colours. */
        if (tty_term_has(term, TTYC_SETRGBF) &&
            tty_term_has(term, TTYC_SETRGBB))
                term->flags |= TERM_RGBCOLOURS;
        else
                term->flags &= ~TERM_RGBCOLOURS;
        log_debug("RGBCOLOURS flag is %d", !!(term->flags & TERM_RGBCOLOURS));

        /*
         * Set or clear the DECSLRM flag if the terminal has the margin
         * capabilities.
         */
        if (tty_term_has(term, TTYC_CMG) && tty_term_has(term, TTYC_CLMG))
                term->flags |= TERM_DECSLRM;
        else
                term->flags &= ~TERM_DECSLRM;
        log_debug("DECSLRM flag is %d", !!(term->flags & TERM_DECSLRM));

        /*
         * Set or clear the DECFRA flag if the terminal has the rectangle
         * capability.
         */
        if (tty_term_has(term, TTYC_RECT))
                term->flags |= TERM_DECFRA;
        else
                term->flags &= ~TERM_DECFRA;
        log_debug("DECFRA flag is %d", !!(term->flags & TERM_DECFRA));

        /*
         * Terminals without am (auto right margin) wrap at at $COLUMNS - 1
         * rather than $COLUMNS (the cursor can never be beyond $COLUMNS - 1).
         *
         * Terminals without xenl (eat newline glitch) ignore a newline beyond
         * the right edge of the terminal, but tmux doesn't care about this -
         * it always uses absolute only moves the cursor with a newline when
         * also sending a linefeed.
         *
         * This is irritating, most notably because it is painful to write to
         * the very bottom-right of the screen without scrolling.
         *
         * Flag the terminal here and apply some workarounds in other places to
         * do the best possible.
         */
        if (!tty_term_flag(term, TTYC_AM))
                term->flags |= TERM_NOAM;
        else
                term->flags &= ~TERM_NOAM;
        log_debug("NOAM flag is %d", !!(term->flags & TERM_NOAM));

        /* Generate ACS table. If none is present, use nearest ASCII. */
        memset(term->acs, 0, sizeof term->acs);
        if (tty_term_has(term, TTYC_ACSC))
                acs = tty_term_string(term, TTYC_ACSC);
        else
                acs = "a#j+k+l+m+n+o-p-q-r-s-t+u+v+w+x|y<z>~.";
        for (; acs[0] != '\0' && acs[1] != '\0'; acs += 2)
                term->acs[(u_char) acs[0]][0] = acs[1];
}

struct tty_term *
tty_term_create(struct tty *tty, char *name, char **caps, u_int ncaps,
    int *feat, char **cause)
{
        struct tty_term                         *term;
        const struct tty_term_code_entry        *ent;
        struct tty_code                         *code;
        struct options_entry                    *o;
        struct options_array_item               *a;
        union options_value                     *ov;
        u_int                                    i, j;
        const char                              *s, *value, *errstr;
        size_t                                   offset, namelen;
        char                                    *first;
        int                                      n;
        struct environ_entry                    *envent;

        log_debug("adding term %s", name);

        term = xcalloc(1, sizeof *term);
        term->tty = tty;
        term->name = xstrdup(name);
        term->codes = xcalloc(tty_term_ncodes(), sizeof *term->codes);
        LIST_INSERT_HEAD(&tty_terms, term, entry);

        /* Fill in codes. */
        for (i = 0; i < ncaps; i++) {
                namelen = strcspn(caps[i], "=");
                if (namelen == 0)
                        continue;
                value = caps[i] + namelen + 1;

                for (j = 0; j < tty_term_ncodes(); j++) {
                        ent = &tty_term_codes[j];
                        if (strncmp(ent->name, caps[i], namelen) != 0)
                                continue;
                        if (ent->name[namelen] != '\0')
                                continue;

                        code = &term->codes[j];
                        code->type = TTYCODE_NONE;
                        switch (ent->type) {
                        case TTYCODE_NONE:
                                break;
                        case TTYCODE_STRING:
                                code->type = TTYCODE_STRING;
                                code->value.string = tty_term_strip(value);
                                break;
                        case TTYCODE_NUMBER:
                                n = strtonum(value, 0, INT_MAX, &errstr);
                                if (errstr != NULL)
                                        log_debug("%s: %s", ent->name, errstr);
                                else {
                                        code->type = TTYCODE_NUMBER;
                                        code->value.number = n;
                                }
                                break;
                        case TTYCODE_FLAG:
                                code->type = TTYCODE_FLAG;
                                code->value.flag = (*value == '1');
                                break;
                        }
                }
        }

        /* Apply terminal features. */
        o = options_get_only(global_options, "terminal-features");
        a = options_array_first(o);
        while (a != NULL) {
                ov = options_array_item_value(a);
                s = ov->string;

                offset = 0;
                first = tty_term_override_next(s, &offset);
                if (first != NULL && fnmatch(first, term->name, 0) == 0)
                        tty_add_features(feat, s + offset, ":");
                a = options_array_next(a);
        }

        /* Check for COLORTERM. */
        envent = environ_find(tty->client->environ, "COLORTERM");
        if (envent != NULL) {
                log_debug("%s COLORTERM=%s", tty->client->name, envent->value);
                if (strcasecmp(envent->value, "truecolor") == 0 ||
                    strcasecmp(envent->value, "24bit") == 0)
                        tty_add_features(feat, "RGB", ",");
                else if (strstr(envent->value, "256") != NULL)
                        tty_add_features(feat, "256", ",");
        }

        /* Apply overrides so any capabilities used for features are changed. */
        tty_term_apply_overrides(term);

        /* These are always required. */
        if (!tty_term_has(term, TTYC_CLEAR)) {
                xasprintf(cause, "terminal does not support clear");
                goto error;
        }
        if (!tty_term_has(term, TTYC_CUP)) {
                xasprintf(cause, "terminal does not support cup");
                goto error;
        }

        /*
         * If TERM has XT or clear starts with CSI then it is safe to assume
         * the terminal is derived from the VT100. This controls whether device
         * attributes requests are sent to get more information.
         *
         * This is a bit of a hack but there aren't that many alternatives.
         * Worst case tmux will just fall back to using whatever terminfo(5)
         * says without trying to correct anything that is missing.
         *
         * Also add few features that VT100-like terminals should either
         * support or safely ignore.
         */
        s = tty_term_string(term, TTYC_CLEAR);
        if (tty_term_flag(term, TTYC_XT) || strncmp(s, "\033[", 2) == 0) {
                term->flags |= TERM_VT100LIKE;
                tty_add_features(feat, "bpaste,focus,title", ",");
        }

        /* Add RGB feature if terminal has RGB colours. */
        if ((tty_term_flag(term, TTYC_TC) || tty_term_has(term, TTYC_RGB)) &&
            (!tty_term_has(term, TTYC_SETRGBF) ||
            !tty_term_has(term, TTYC_SETRGBB)))
                tty_add_features(feat, "RGB", ",");

        /* Apply the features and overrides again. */
        if (tty_apply_features(term, *feat))
                tty_term_apply_overrides(term);

        /* Log the capabilities. */
        for (i = 0; i < tty_term_ncodes(); i++)
                log_debug("%s%s", name, tty_term_describe(term, i));

        return (term);

error:
        tty_term_free(term);
        return (NULL);
}

void
tty_term_free(struct tty_term *term)
{
        u_int   i;

        log_debug("removing term %s", term->name);

        for (i = 0; i < tty_term_ncodes(); i++) {
                if (term->codes[i].type == TTYCODE_STRING)
                        free(term->codes[i].value.string);
        }
        free(term->codes);

        LIST_REMOVE(term, entry);
        free(term->name);
        free(term);
}

int
tty_term_read_list(const char *name, int fd, char ***caps, u_int *ncaps,
    char **cause)
{
        const struct tty_term_code_entry        *ent;
        int                                      error, n;
        u_int                                    i;
        const char                              *s;
        char                                     tmp[11];

        if (setupterm((char *)name, fd, &error) != OK) {
                switch (error) {
                case 1:
                        xasprintf(cause, "can't use hardcopy terminal: %s",
                            name);
                        break;
                case 0:
                        xasprintf(cause, "missing or unsuitable terminal: %s",
                            name);
                        break;
                case -1:
                        xasprintf(cause, "can't find terminfo database");
                        break;
                default:
                        xasprintf(cause, "unknown error");
                        break;
                }
                return (-1);
        }

        *ncaps = 0;
        *caps = NULL;

        for (i = 0; i < tty_term_ncodes(); i++) {
                ent = &tty_term_codes[i];
                switch (ent->type) {
                case TTYCODE_NONE:
                        continue;
                case TTYCODE_STRING:
                        s = tigetstr((char *)ent->name);
                        if (s == NULL || s == (char *)-1)
                                continue;
                        break;
                case TTYCODE_NUMBER:
                        n = tigetnum((char *)ent->name);
                        if (n == -1 || n == -2)
                                continue;
                        xsnprintf(tmp, sizeof tmp, "%d", n);
                        s = tmp;
                        break;
                case TTYCODE_FLAG:
                        n = tigetflag((char *)ent->name);
                        if (n == -1)
                                continue;
                        if (n)
                                s = "1";
                        else
                                s = "0";
                        break;
                default:
                        fatalx("unknown capability type");
                }
                *caps = xreallocarray(*caps, (*ncaps) + 1, sizeof **caps);
                xasprintf(&(*caps)[*ncaps], "%s=%s", ent->name, s);
                (*ncaps)++;
        }

        del_curterm(cur_term);
        return (0);
}

void
tty_term_free_list(char **caps, u_int ncaps)
{
        u_int   i;

        for (i = 0; i < ncaps; i++)
                free(caps[i]);
        free(caps);
}

int
tty_term_has(struct tty_term *term, enum tty_code_code code)
{
        return (term->codes[code].type != TTYCODE_NONE);
}

const char *
tty_term_string(struct tty_term *term, enum tty_code_code code)
{
        if (!tty_term_has(term, code))
                return ("");
        if (term->codes[code].type != TTYCODE_STRING)
                fatalx("not a string: %d", code);
        return (term->codes[code].value.string);
}

const char *
tty_term_string_i(struct tty_term *term, enum tty_code_code code, int a)
{
        const char      *x = tty_term_string(term, code), *s;

        s = tiparm_s(1, 0, x, a);
        if (s == NULL) {
                log_debug("could not expand %s", tty_term_codes[code].name);
                return ("");
        }
        return (s);
}

const char *
tty_term_string_ii(struct tty_term *term, enum tty_code_code code, int a, int b)
{
        const char      *x = tty_term_string(term, code), *s;

        s = tiparm_s(2, 0, x, a, b);
        if (s == NULL) {
                log_debug("could not expand %s", tty_term_codes[code].name);
                return ("");
        }
        return (s);
}

const char *
tty_term_string_iii(struct tty_term *term, enum tty_code_code code, int a,
    int b, int c)
{
        const char      *x = tty_term_string(term, code), *s;

        s = tiparm_s(3, 0, x, a, b, c);
        if (s == NULL) {
                log_debug("could not expand %s", tty_term_codes[code].name);
                return ("");
        }
        return (s);
}

const char *
tty_term_string_s(struct tty_term *term, enum tty_code_code code, const char *a)
{
        const char      *x = tty_term_string(term, code), *s;

        s = tiparm_s(1, 1, x, a);
        if (s == NULL) {
                log_debug("could not expand %s", tty_term_codes[code].name);
                return ("");
        }
        return (s);
}

const char *
tty_term_string_ss(struct tty_term *term, enum tty_code_code code,
    const char *a, const char *b)
{
        const char      *x = tty_term_string(term, code), *s;

        s = tiparm_s(2, 3, x, a, b);
        if (s == NULL) {
                log_debug("could not expand %s", tty_term_codes[code].name);
                return ("");
        }
        return (s);
}

int
tty_term_number(struct tty_term *term, enum tty_code_code code)
{
        if (!tty_term_has(term, code))
                return (0);
        if (term->codes[code].type != TTYCODE_NUMBER)
                fatalx("not a number: %d", code);
        return (term->codes[code].value.number);
}

int
tty_term_flag(struct tty_term *term, enum tty_code_code code)
{
        if (!tty_term_has(term, code))
                return (0);
        if (term->codes[code].type != TTYCODE_FLAG)
                fatalx("not a flag: %d", code);
        return (term->codes[code].value.flag);
}

const char *
tty_term_describe(struct tty_term *term, enum tty_code_code code)
{
        static char      s[256];
        char             out[128];

        switch (term->codes[code].type) {
        case TTYCODE_NONE:
                xsnprintf(s, sizeof s, "%4u: %s: [missing]",
                    code, tty_term_codes[code].name);
                break;
        case TTYCODE_STRING:
                strnvis(out, term->codes[code].value.string, sizeof out,
                    VIS_OCTAL|VIS_CSTYLE|VIS_TAB|VIS_NL);
                xsnprintf(s, sizeof s, "%4u: %s: (string) %s",
                    code, tty_term_codes[code].name,
                    out);
                break;
        case TTYCODE_NUMBER:
                xsnprintf(s, sizeof s, "%4u: %s: (number) %d",
                    code, tty_term_codes[code].name,
                    term->codes[code].value.number);
                break;
        case TTYCODE_FLAG:
                xsnprintf(s, sizeof s, "%4u: %s: (flag) %s",
                    code, tty_term_codes[code].name,
                    term->codes[code].value.flag ? "true" : "false");
                break;
        }
        return (s);
}