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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/prctl.h>
#include <signal.h>
#include <fcntl.h>
#include "log.h"
#include "util.h"
#include "spawn-agent.h"
static pid_t agent_pid = 0;
void agent_open(void) {
pid_t parent_pid;
if (agent_pid > 0)
return;
/* We check STDIN here, not STDOUT, since this is about input,
* not output */
if (!isatty(STDIN_FILENO))
return;
parent_pid = getpid();
/* Spawns a temporary TTY agent, making sure it goes away when
* we go away */
agent_pid = fork();
if (agent_pid < 0) {
log_error("Failed to fork agent: %m");
return;
}
if (agent_pid == 0) {
/* In the child */
int fd;
bool stdout_is_tty, stderr_is_tty;
/* Make sure the agent goes away when the parent dies */
if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
_exit(EXIT_FAILURE);
/* Check whether our parent died before we were able
* to set the death signal */
if (getppid() != parent_pid)
_exit(EXIT_SUCCESS);
/* Don't leak fds to the agent */
close_all_fds(NULL, 0);
stdout_is_tty = isatty(STDOUT_FILENO);
stderr_is_tty = isatty(STDERR_FILENO);
if (!stdout_is_tty || !stderr_is_tty) {
/* Detach from stdout/stderr. and reopen
* /dev/tty for them. This is important to
* ensure that when systemctl is started via
* popen() or a similar call that expects to
* read EOF we actually do generate EOF and
* not delay this indefinitely by because we
* keep an unused copy of stdin around. */
fd = open("/dev/tty", O_WRONLY);
if (fd < 0) {
log_error("Failed to open /dev/tty: %m");
_exit(EXIT_FAILURE);
}
if (!stdout_is_tty)
dup2(fd, STDOUT_FILENO);
if (!stderr_is_tty)
dup2(fd, STDERR_FILENO);
if (fd > 2)
close(fd);
}
execl(SYSTEMD_TTY_ASK_PASSWORD_AGENT_BINARY_PATH, SYSTEMD_TTY_ASK_PASSWORD_AGENT_BINARY_PATH, "--watch", NULL);
log_error("Unable to execute agent: %m");
_exit(EXIT_FAILURE);
}
}
void agent_close(void) {
if (agent_pid <= 0)
return;
/* Inform agent that we are done */
kill(agent_pid, SIGTERM);
kill(agent_pid, SIGCONT);
wait_for_terminate(agent_pid, NULL);
agent_pid = 0;
}
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