/* $OpenBSD: tmux.c,v 1.216 2025/10/28 10:51:30 nicm Exp $ */

/*
 * Copyright (c) 2007 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 <sys/stat.h>
#include <sys/utsname.h>

#include <err.h>
#include <errno.h>
#include <event.h>
#include <fcntl.h>
#include <langinfo.h>
#include <locale.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <util.h>

#include "tmux.h"

struct options  *global_options;        /* server options */
struct options  *global_s_options;      /* session options */
struct options  *global_w_options;      /* window options */
struct environ  *global_environ;

struct timeval   start_time;
const char      *socket_path;
int              ptm_fd = -1;
const char      *shell_command;

static __dead void       usage(int);
static char             *make_label(const char *, char **);

static int               areshell(const char *);
static const char       *getshell(void);

static __dead void
usage(int status)
{
        fprintf(status ? stderr : stdout,
            "usage: %s [-2CDhlNuVv] [-c shell-command] [-f file] [-L socket-name]\n"
            "            [-S socket-path] [-T features] [command [flags]]\n",
            getprogname());
        exit(status);
}

static const char *
getshell(void)
{
        struct passwd   *pw;
        const char      *shell;

        shell = getenv("SHELL");
        if (checkshell(shell))
                return (shell);

        pw = getpwuid(getuid());
        if (pw != NULL && checkshell(pw->pw_shell))
                return (pw->pw_shell);

        return (_PATH_BSHELL);
}

int
checkshell(const char *shell)
{
        if (shell == NULL || *shell != '/')
                return (0);
        if (areshell(shell))
                return (0);
        if (access(shell, X_OK) != 0)
                return (0);
        return (1);
}

static int
areshell(const char *shell)
{
        const char      *progname, *ptr;

        if ((ptr = strrchr(shell, '/')) != NULL)
                ptr++;
        else
                ptr = shell;
        progname = getprogname();
        if (*progname == '-')
                progname++;
        if (strcmp(ptr, progname) == 0)
                return (1);
        return (0);
}

static char *
expand_path(const char *path, const char *home)
{
        char                    *expanded, *name;
        const char              *end;
        struct environ_entry    *value;

        if (strncmp(path, "~/", 2) == 0) {
                if (home == NULL)
                        return (NULL);
                xasprintf(&expanded, "%s%s", home, path + 1);
                return (expanded);
        }

        if (*path == '$') {
                end = strchr(path, '/');
                if (end == NULL)
                        name = xstrdup(path + 1);
                else
                        name = xstrndup(path + 1, end - path - 1);
                value = environ_find(global_environ, name);
                free(name);
                if (value == NULL)
                        return (NULL);
                if (end == NULL)
                        end = "";
                xasprintf(&expanded, "%s%s", value->value, end);
                return (expanded);
        }

        return (xstrdup(path));
}

static void
expand_paths(const char *s, char ***paths, u_int *n, int no_realpath)
{
        const char      *home = find_home();
        char            *copy, *next, *tmp, resolved[PATH_MAX], *expanded;
        char            *path;
        u_int            i;

        *paths = NULL;
        *n = 0;

        copy = tmp = xstrdup(s);
        while ((next = strsep(&tmp, ":")) != NULL) {
                expanded = expand_path(next, home);
                if (expanded == NULL) {
                        log_debug("%s: invalid path: %s", __func__, next);
                        continue;
                }
                if (no_realpath)
                        path = expanded;
                else {
                        if (realpath(expanded, resolved) == NULL) {
                                log_debug("%s: realpath(\"%s\") failed: %s", __func__,
                          expanded, strerror(errno));
                                free(expanded);
                                continue;
                        }
                        path = xstrdup(resolved);
                        free(expanded);
                }
                for (i = 0; i < *n; i++) {
                        if (strcmp(path, (*paths)[i]) == 0)
                                break;
                }
                if (i != *n) {
                        log_debug("%s: duplicate path: %s", __func__, path);
                        free(path);
                        continue;
                }
                *paths = xreallocarray(*paths, (*n) + 1, sizeof *paths);
                (*paths)[(*n)++] = path;
        }
        free(copy);
}

static char *
make_label(const char *label, char **cause)
{
        char            **paths, *path, *base;
        u_int             i, n;
        struct stat       sb;
        uid_t             uid;

        *cause = NULL;
        if (label == NULL)
                label = "default";
        uid = getuid();

        expand_paths(TMUX_SOCK, &paths, &n, 0);
        if (n == 0) {
                xasprintf(cause, "no suitable socket path");
                return (NULL);
        }
        path = paths[0]; /* can only have one socket! */
        for (i = 1; i < n; i++)
                free(paths[i]);
        free(paths);

        xasprintf(&base, "%s/tmux-%ld", path, (long)uid);
        free(path);
        if (mkdir(base, S_IRWXU) != 0 && errno != EEXIST) {
                xasprintf(cause, "couldn't create directory %s (%s)", base,
                    strerror(errno));
                goto fail;
        }
        if (lstat(base, &sb) != 0) {
                xasprintf(cause, "couldn't read directory %s (%s)", base,
                    strerror(errno));
                goto fail;
        }
        if (!S_ISDIR(sb.st_mode)) {
                xasprintf(cause, "%s is not a directory", base);
                goto fail;
        }
        if (sb.st_uid != uid || (sb.st_mode & TMUX_SOCK_PERM) != 0) {
                xasprintf(cause, "directory %s has unsafe permissions", base);
                goto fail;
        }
        xasprintf(&path, "%s/%s", base, label);
        free(base);
        return (path);

fail:
        free(base);
        return (NULL);
}

char *
shell_argv0(const char *shell, int is_login)
{
        const char      *slash, *name;
        char            *argv0;

        slash = strrchr(shell, '/');
        if (slash != NULL && slash[1] != '\0')
                name = slash + 1;
        else
                name = shell;
        if (is_login)
                xasprintf(&argv0, "-%s", name);
        else
                xasprintf(&argv0, "%s", name);
        return (argv0);
}

void
setblocking(int fd, int state)
{
        int mode;

        if ((mode = fcntl(fd, F_GETFL)) != -1) {
                if (!state)
                        mode |= O_NONBLOCK;
                else
                        mode &= ~O_NONBLOCK;
                fcntl(fd, F_SETFL, mode);
        }
}

uint64_t
get_timer(void)
{
        struct timespec ts;

        /*
         * We want a timestamp in milliseconds suitable for time measurement,
         * so prefer the monotonic clock.
         */
        if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
                clock_gettime(CLOCK_REALTIME, &ts);
        return ((ts.tv_sec * 1000ULL) + (ts.tv_nsec / 1000000ULL));
}

const char *
sig2name(int signo)
{
     static char        s[11];

     if (signo > 0 && signo < NSIG)
             return (sys_signame[signo]);
     xsnprintf(s, sizeof s, "%d", signo);
     return (s);
}

const char *
find_cwd(void)
{
        char             resolved1[PATH_MAX], resolved2[PATH_MAX];
        static char      cwd[PATH_MAX];
        const char      *pwd;

        if (getcwd(cwd, sizeof cwd) == NULL)
                return (NULL);
        if ((pwd = getenv("PWD")) == NULL || *pwd == '\0')
                return (cwd);

        /*
         * We want to use PWD so that symbolic links are maintained,
         * but only if it matches the actual working directory.
         */
        if (realpath(pwd, resolved1) == NULL)
                return (cwd);
        if (realpath(cwd, resolved2) == NULL)
                return (cwd);
        if (strcmp(resolved1, resolved2) != 0)
                return (cwd);
        return (pwd);
}

const char *
find_home(void)
{
        struct passwd           *pw;
        static const char       *home;

        if (home != NULL)
                return (home);

        home = getenv("HOME");
        if (home == NULL || *home == '\0') {
                pw = getpwuid(getuid());
                if (pw != NULL)
                        home = pw->pw_dir;
                else
                        home = NULL;
        }

        return (home);
}

const char *
getversion(void)
{
        static char     *version;
        struct utsname   u;

        if (version == NULL) {
                if (uname(&u) < 0)
                        fatalx("uname failed");
                xasprintf(&version, "openbsd-%s", u.release);
        }
        return (version);
}

int
main(int argc, char **argv)
{
        char                                    *path = NULL, *label = NULL;
        char                                    *cause, **var;
        const char                              *s, *cwd;
        int                                      opt, keys, feat = 0, fflag = 0;
        uint64_t                                 flags = 0;
        const struct options_table_entry        *oe;
        u_int                                    i;

        if (setlocale(LC_CTYPE, "en_US.UTF-8") == NULL &&
            setlocale(LC_CTYPE, "C.UTF-8") == NULL) {
                if (setlocale(LC_CTYPE, "") == NULL)
                        errx(1, "invalid LC_ALL, LC_CTYPE or LANG");
                s = nl_langinfo(CODESET);
                if (strcasecmp(s, "UTF-8") != 0 && strcasecmp(s, "UTF8") != 0)
                        errx(1, "need UTF-8 locale (LC_CTYPE) but have %s", s);
        }

        setlocale(LC_TIME, "");
        tzset();

        if (**argv == '-')
                flags = CLIENT_LOGIN;

        global_environ = environ_create();
        for (var = environ; *var != NULL; var++)
                environ_put(global_environ, *var, 0);
        if ((cwd = find_cwd()) != NULL)
                environ_set(global_environ, "PWD", 0, "%s", cwd);
        expand_paths(TMUX_CONF, &cfg_files, &cfg_nfiles, 1);

        while ((opt = getopt(argc, argv, "2c:CDdf:hlL:NqS:T:uUvV")) != -1) {
                switch (opt) {
                case '2':
                        tty_add_features(&feat, "256", ":,");
                        break;
                case 'c':
                        shell_command = optarg;
                        break;
                case 'D':
                        flags |= CLIENT_NOFORK;
                        break;
                case 'C':
                        if (flags & CLIENT_CONTROL)
                                flags |= CLIENT_CONTROLCONTROL;
                        else
                                flags |= CLIENT_CONTROL;
                        break;
                case 'f':
                        if (!fflag) {
                                fflag = 1;
                                for (i = 0; i < cfg_nfiles; i++)
                                        free(cfg_files[i]);
                                cfg_nfiles = 0;
                        }
                        cfg_files = xreallocarray(cfg_files, cfg_nfiles + 1,
                            sizeof *cfg_files);
                        cfg_files[cfg_nfiles++] = xstrdup(optarg);
                        cfg_quiet = 0;
                        break;
                case 'h':
                        usage(0);
                case 'V':
                        printf("tmux %s\n", getversion());
                        exit(0);
                case 'l':
                        flags |= CLIENT_LOGIN;
                        break;
                case 'L':
                        free(label);
                        label = xstrdup(optarg);
                        break;
                case 'N':
                        flags |= CLIENT_NOSTARTSERVER;
                        break;
                case 'q':
                        break;
                case 'S':
                        free(path);
                        path = xstrdup(optarg);
                        break;
                case 'T':
                        tty_add_features(&feat, optarg, ":,");
                        break;
                case 'u':
                        flags |= CLIENT_UTF8;
                        break;
                case 'v':
                        log_add_level();
                        break;
                default:
                        usage(1);
                }
        }
        argc -= optind;
        argv += optind;

        if (shell_command != NULL && argc != 0)
                usage(1);
        if ((flags & CLIENT_NOFORK) && argc != 0)
                usage(1);

        if ((ptm_fd = getptmfd()) == -1)
                err(1, "getptmfd");
        if (pledge("stdio rpath wpath cpath flock fattr unix getpw sendfd "
            "recvfd proc exec tty ps", NULL) != 0)
                err(1, "pledge");

        /*
         * tmux is a UTF-8 terminal, so if TMUX is set, assume UTF-8.
         * Otherwise, if the user has set LC_ALL, LC_CTYPE or LANG to contain
         * UTF-8, it is a safe assumption that either they are using a UTF-8
         * terminal, or if not they know that output from UTF-8-capable
         * programs may be wrong.
         */
        if (getenv("TMUX") != NULL)
                flags |= CLIENT_UTF8;
        else {
                s = getenv("LC_ALL");
                if (s == NULL || *s == '\0')
                        s = getenv("LC_CTYPE");
                if (s == NULL || *s == '\0')
                        s = getenv("LANG");
                if (s == NULL || *s == '\0')
                        s = "";
                if (strcasestr(s, "UTF-8") != NULL ||
                    strcasestr(s, "UTF8") != NULL)
                        flags |= CLIENT_UTF8;
        }

        global_options = options_create(NULL);
        global_s_options = options_create(NULL);
        global_w_options = options_create(NULL);
        for (oe = options_table; oe->name != NULL; oe++) {
                if (oe->scope & OPTIONS_TABLE_SERVER)
                        options_default(global_options, oe);
                if (oe->scope & OPTIONS_TABLE_SESSION)
                        options_default(global_s_options, oe);
                if (oe->scope & OPTIONS_TABLE_WINDOW)
                        options_default(global_w_options, oe);
        }

        /*
         * The default shell comes from SHELL or from the user's passwd entry
         * if available.
         */
        options_set_string(global_s_options, "default-shell", 0, "%s",
            getshell());

        /* Override keys to vi if VISUAL or EDITOR are set. */
        if ((s = getenv("VISUAL")) != NULL || (s = getenv("EDITOR")) != NULL) {
                options_set_string(global_options, "editor", 0, "%s", s);
                if (strrchr(s, '/') != NULL)
                        s = strrchr(s, '/') + 1;
                if (strstr(s, "vi") != NULL)
                        keys = MODEKEY_VI;
                else
                        keys = MODEKEY_EMACS;
                options_set_number(global_s_options, "status-keys", keys);
                options_set_number(global_w_options, "mode-keys", keys);
        }

        /*
         * If socket is specified on the command-line with -S or -L, it is
         * used. Otherwise, $TMUX is checked and if that fails "default" is
         * used.
         */
        if (path == NULL && label == NULL) {
                s = getenv("TMUX");
                if (s != NULL && *s != '\0' && *s != ',') {
                        path = xstrdup(s);
                        path[strcspn(path, ",")] = '\0';
                }
        }
        if (path == NULL) {
                if ((path = make_label(label, &cause)) == NULL) {
                        if (cause != NULL) {
                                fprintf(stderr, "%s\n", cause);
                                free(cause);
                        }
                        exit(1);
                }
                flags |= CLIENT_DEFAULTSOCKET;
        }
        socket_path = path;
        free(label);

        /* Pass control to the client. */
        exit(client_main(event_init(), argc, argv, flags, feat));
}