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-rw-r--r--src/spawn-agent.c120
1 files changed, 120 insertions, 0 deletions
diff --git a/src/spawn-agent.c b/src/spawn-agent.c
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+++ b/src/spawn-agent.c
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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;
+}