ctdb-daemon: Add helper process to execute event scripts

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>

1 files changed, 136 insertions, 0 deletions

diff --git a/ctdb/server/ctdb_event_helper.c b/ctdb/server/ctdb_event_helper.c
new file mode 100644
index 00000000000..4c62e41af63
--- /dev/null
+++ b/ctdb/server/ctdb_event_helper.c
@@ -0,0 +1,136 @@
+/*
+   ctdb event script helper
+
+   Copyright (C) Amitay Isaacs  2013
+
+   This program 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 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "system/filesys.h"
+
+static char *progname = NULL;
+
+
+/* CTDB sends SIGTERM, when process must die */
+static void sigterm(int sig)
+{
+	pid_t pid;
+
+	/* all the child processes are running in the same process group */
+	pid = getpgrp();
+	if (pid == -1) {
+		kill(-getpid(), SIGKILL);
+	} else {
+		kill(-pid, SIGKILL);
+	}
+	_exit(0);
+}
+
+static void set_close_on_exec(int fd)
+{
+	int v;
+
+	v = fcntl(fd, F_GETFD, 0);
+	if (v == -1) {
+		return;
+	}
+	fcntl(fd, F_SETFD, v | FD_CLOEXEC);
+}
+
+static int check_executable(const char *path)
+{
+	struct stat st;
+
+	if (stat(path, &st) != 0) {
+		fprintf(stderr, "Failed to access '%s' - %s\n",
+			path, strerror(errno));
+		return errno;
+	}
+
+	if (!(st.st_mode & S_IXUSR)) {
+		return ENOEXEC;
+	}
+
+	return 0;
+}
+
+static void usage(void)
+{
+	fprintf(stderr, "\n");
+	fprintf(stderr, "Usage: %s <log-fd> <output-fd> <script_path> <event> [<args>]\n",
+		progname);
+}
+
+int main(int argc, char *argv[])
+{
+	int log_fd, write_fd;
+	pid_t pid;
+	int status, output;
+
+	progname = argv[0];
+
+	if (argc < 5) {
+		usage();
+		exit(1);
+	}
+
+	log_fd = atoi(argv[1]);
+	write_fd = atoi(argv[2]);
+
+	set_close_on_exec(write_fd);
+
+	close(STDOUT_FILENO);
+	close(STDERR_FILENO);
+	dup2(log_fd, STDOUT_FILENO);
+	dup2(log_fd, STDERR_FILENO);
+	close(log_fd);
+
+	if (setpgid(0, 0) != 0) {
+		fprintf(stderr, "Failed to create process group for event script - %s\n",
+			strerror(errno));
+		exit(1);
+	}
+
+	signal(SIGTERM, sigterm);
+
+	pid = fork();
+	if (pid < 0) {
+		fprintf(stderr, "Failed to fork - %s\n", strerror(errno));
+		exit(errno);
+	}
+
+	if (pid == 0) {
+		int save_errno;
+
+		execv(argv[3], &argv[3]);
+		if (errno == EACCES) {
+			save_errno = check_executable(argv[3]);
+		} else {
+			save_errno = errno;
+			fprintf(stderr, "Error executing '%s' - %s\n",
+				argv[3], strerror(errno));
+		}
+		_exit(save_errno);
+	}
+
+	waitpid(pid, &status, 0);
+	if (WIFEXITED(status)) {
+		output = -WEXITSTATUS(status);
+		write(write_fd, &output, sizeof(output));
+		exit(output);
+	}
+
+	exit(1);
+}