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For open/openat, if the flags parameter does not contain O_CREAT, the
3rd (variadic) mode_t parameter is irrelevant.  Many developers in the past
have passed mode_t (0, 044, 0644, or such), which might lead future people
to copy this broken idiom, and perhaps even believe this parameter has some
meaning or implication or application. Delete them all.
This comes out of a conversation where tb@ noticed that a strange (but
intentional) pledge behaviour is to always knock-out high-bits from
mode_t on a number of system calls as a safety factor, and his bewilderment
that this appeared to be happening against valid modes (at least visually),
but no sorry, they are all irrelevant junk.  They could all be 0xdeafbeef.
ok millert

/* $OpenBSD: job.c,v 1.66 2021/10/24 21:24:17 deraadt Exp $ */

/*
 * Copyright (c) 2009 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/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>

#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "tmux.h"

/*
 * Job scheduling. Run queued commands in the background and record their
 * output.
 */

static void	job_read_callback(struct bufferevent *, void *);
static void	job_write_callback(struct bufferevent *, void *);
static void	job_error_callback(struct bufferevent *, short, void *);

/* A single job. */
struct job {
	enum {
		JOB_RUNNING,
		JOB_DEAD,
		JOB_CLOSED
	} state;

	int			 flags;

	char			*cmd;
	pid_t			 pid;
	char		         tty[TTY_NAME_MAX];
	int			 status;

	int			 fd;
	struct bufferevent	*event;

	job_update_cb		 updatecb;
	job_complete_cb		 completecb;
	job_free_cb		 freecb;
	void			*data;

	LIST_ENTRY(job)		 entry;
};

/* All jobs list. */
static LIST_HEAD(joblist, job) all_jobs = LIST_HEAD_INITIALIZER(all_jobs);

/* Start a job running. */
struct job *
job_run(const char *cmd, int argc, char **argv, struct environ *e, struct session *s,
    const char *cwd, job_update_cb updatecb, job_complete_cb completecb,
    job_free_cb freecb, void *data, int flags, int sx, int sy)
{
	struct job	 *job;
	struct environ	 *env;
	pid_t		  pid;
	int		  nullfd, out[2], master;
	const char	 *home;
	sigset_t	  set, oldset;
	struct winsize	  ws;
	char		**argvp, tty[TTY_NAME_MAX];

	/*
	 * Do not set TERM during .tmux.conf, it is nice to be able to use
	 * if-shell to decide on default-terminal based on outside TERM.
	 */
	env = environ_for_session(s, !cfg_finished);
	if (e != NULL) {
		environ_copy(e, env);
	}

	sigfillset(&set);
	sigprocmask(SIG_BLOCK, &set, &oldset);

	if (flags & JOB_PTY) {
		memset(&ws, 0, sizeof ws);
		ws.ws_col = sx;
		ws.ws_row = sy;
		pid = fdforkpty(ptm_fd, &master, tty, NULL, &ws);
	} else {
		if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, out) != 0)
			goto fail;
		pid = fork();
	}
	if (cmd == NULL) {
		cmd_log_argv(argc, argv, "%s:", __func__);
		log_debug("%s: cwd=%s", __func__, cwd == NULL ? "" : cwd);
	} else {
		log_debug("%s: cmd=%s, cwd=%s", __func__, cmd,
		    cwd == NULL ? "" : cwd);
	}

	switch (pid) {
	case -1:
		if (~flags & JOB_PTY) {
			close(out[0]);
			close(out[1]);
		}
		goto fail;
	case 0:
		proc_clear_signals(server_proc, 1);
		sigprocmask(SIG_SETMASK, &oldset, NULL);

		if ((cwd == NULL || chdir(cwd) != 0) &&
		    ((home = find_home()) == NULL || chdir(home) != 0) &&
		    chdir("/") != 0)
			fatal("chdir failed");

		environ_push(env);
		environ_free(env);

		if (~flags & JOB_PTY) {
			if (dup2(out[1], STDIN_FILENO) == -1)
				fatal("dup2 failed");
			if (dup2(out[1], STDOUT_FILENO) == -1)
				fatal("dup2 failed");
			if (out[1] != STDIN_FILENO && out[1] != STDOUT_FILENO)
				close(out[1]);
			close(out[0]);

			nullfd = open(_PATH_DEVNULL, O_RDWR);
			if (nullfd == -1)
				fatal("open failed");
			if (dup2(nullfd, STDERR_FILENO) == -1)
				fatal("dup2 failed");
			if (nullfd != STDERR_FILENO)
				close(nullfd);
		}
		closefrom(STDERR_FILENO + 1);

		if (cmd != NULL) {
			execl(_PATH_BSHELL, "sh", "-c", cmd, (char *) NULL);
			fatal("execl failed");
		} else {
			argvp = cmd_copy_argv(argc, argv);
			execvp(argvp[0], argvp);
			fatal("execvp failed");
		}
	}

	sigprocmask(SIG_SETMASK, &oldset, NULL);
	environ_free(env);

	job = xmalloc(sizeof *job);
	job->state = JOB_RUNNING;
	job->flags = flags;

	if (cmd != NULL)
		job->cmd = xstrdup(cmd);
	else
		job->cmd = cmd_stringify_argv(argc, argv);
	job->pid = pid;
	strlcpy(job->tty, tty, sizeof job->tty);
	job->status = 0;

	LIST_INSERT_HEAD(&all_jobs, job, entry);

	job->updatecb = updatecb;
	job->completecb = completecb;
	job->freecb = freecb;
	job->data = data;

	if (~flags & JOB_PTY) {
		close(out[1]);
		job->fd = out[0];
	} else
		job->fd = master;
	setblocking(job->fd, 0);

	job->event = bufferevent_new(job->fd, job_read_callback,
	    job_write_callback, job_error_callback, job);
	if (job->event == NULL)
		fatalx("out of memory");
	bufferevent_enable(job->event, EV_READ|EV_WRITE);

	log_debug("run job %p: %s, pid %ld", job, job->cmd, (long) job->pid);
	return (job);

fail:
	sigprocmask(SIG_SETMASK, &oldset, NULL);
	environ_free(env);
	return (NULL);
}

/* Take job's file descriptor and free the job. */
int
job_transfer(struct job *job, pid_t *pid, char *tty, size_t ttylen)
{
	int	fd = job->fd;

	log_debug("transfer job %p: %s", job, job->cmd);

	if (pid != NULL)
		*pid = job->pid;
	if (tty != NULL)
		strlcpy(tty, job->tty, ttylen);

	LIST_REMOVE(job, entry);
	free(job->cmd);

	if (job->freecb != NULL && job->data != NULL)
		job->freecb(job->data);

	if (job->event != NULL)
		bufferevent_free(job->event);

	free(job);
	return (fd);
}

/* Kill and free an individual job. */
void
job_free(struct job *job)
{
	log_debug("free job %p: %s", job, job->cmd);

	LIST_REMOVE(job, entry);
	free(job->cmd);

	if (job->freecb != NULL && job->data != NULL)
		job->freecb(job->data);

	if (job->pid != -1)
		kill(job->pid, SIGTERM);
	if (job->event != NULL)
		bufferevent_free(job->event);
	if (job->fd != -1)
		close(job->fd);

	free(job);
}

/* Resize job. */
void
job_resize(struct job *job, u_int sx, u_int sy)
{
	struct winsize	 ws;

	if (job->fd == -1 || (~job->flags & JOB_PTY))
		return;

	log_debug("resize job %p: %ux%u", job, sx, sy);

	memset(&ws, 0, sizeof ws);
	ws.ws_col = sx;
	ws.ws_row = sy;
	if (ioctl(job->fd, TIOCSWINSZ, &ws) == -1)
		fatal("ioctl failed");
}

/* Job buffer read callback. */
static void
job_read_callback(__unused struct bufferevent *bufev, void *data)
{
	struct job	*job = data;

	if (job->updatecb != NULL)
		job->updatecb(job);
}

/*
 * Job buffer write callback. Fired when the buffer falls below watermark
 * (default is empty). If all the data has been written, disable the write
 * event.
 */
static void
job_write_callback(__unused struct bufferevent *bufev, void *data)
{
	struct job	*job = data;
	size_t		 len = EVBUFFER_LENGTH(EVBUFFER_OUTPUT(job->event));

	log_debug("job write %p: %s, pid %ld, output left %zu", job, job->cmd,
	    (long) job->pid, len);

	if (len == 0 && (~job->flags & JOB_KEEPWRITE)) {
		shutdown(job->fd, SHUT_WR);
		bufferevent_disable(job->event, EV_WRITE);
	}
}

/* Job buffer error callback. */
static void
job_error_callback(__unused struct bufferevent *bufev, __unused short events,
    void *data)
{
	struct job	*job = data;

	log_debug("job error %p: %s, pid %ld", job, job->cmd, (long) job->pid);

	if (job->state == JOB_DEAD) {
		if (job->completecb != NULL)
			job->completecb(job);
		job_free(job);
	} else {
		bufferevent_disable(job->event, EV_READ);
		job->state = JOB_CLOSED;
	}
}

/* Job died (waitpid() returned its pid). */
void
job_check_died(pid_t pid, int status)
{
	struct job	*job;

	LIST_FOREACH(job, &all_jobs, entry) {
		if (pid == job->pid)
			break;
	}
	if (job == NULL)
		return;
	if (WIFSTOPPED(status)) {
		if (WSTOPSIG(status) == SIGTTIN || WSTOPSIG(status) == SIGTTOU)
			return;
		killpg(job->pid, SIGCONT);
		return;
	}
	log_debug("job died %p: %s, pid %ld", job, job->cmd, (long) job->pid);

	job->status = status;

	if (job->state == JOB_CLOSED) {
		if (job->completecb != NULL)
			job->completecb(job);
		job_free(job);
	} else {
		job->pid = -1;
		job->state = JOB_DEAD;
	}
}

/* Get job status. */
int
job_get_status(struct job *job)
{
	return (job->status);
}

/* Get job data. */
void *
job_get_data(struct job *job)
{
	return (job->data);
}

/* Get job event. */
struct bufferevent *
job_get_event(struct job *job)
{
	return (job->event);
}

/* Kill all jobs. */
void
job_kill_all(void)
{
	struct job	*job;

	LIST_FOREACH(job, &all_jobs, entry) {
		if (job->pid != -1)
			kill(job->pid, SIGTERM);
	}
}

/* Are any jobs still running? */
int
job_still_running(void)
{
	struct job	*job;

	LIST_FOREACH(job, &all_jobs, entry) {
		if ((~job->flags & JOB_NOWAIT) && job->state == JOB_RUNNING)
			return (1);
	}
	return (0);
}

/* Print job summary. */
void
job_print_summary(struct cmdq_item *item, int blank)
{
	struct job	*job;
	u_int		 n = 0;

	LIST_FOREACH(job, &all_jobs, entry) {
		if (blank) {
			cmdq_print(item, "%s", "");
			blank = 0;
		}
		cmdq_print(item, "Job %u: %s [fd=%d, pid=%ld, status=%d]",
		    n, job->cmd, job->fd, (long)job->pid, job->status);
		n++;
	}
}