/*
	 * Copyright 2012 Red Hat, Inc.
	 *
	 * This copyrighted material is made available to anyone wishing to use,
	 * modify, copy, or redistribute it subject to the terms and conditions
	 * of the GNU General Public License v2 or (at your option) any later version.
	 */
	
	#include <inttypes.h>
	#include <unistd.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <stdint.h>
	#include <stddef.h>
	#include <poll.h>
	#include <fcntl.h>
	#include <string.h>
	#include <errno.h>
	#include <limits.h>
	#include <time.h>
	#include <stdarg.h>
	#include <signal.h>
	#include <sys/time.h>
	#include <sys/types.h>
	#include <sys/wait.h>
	#include <sys/prctl.h>
	#include <grp.h>
	
	#include "dlm_daemon.h"
	
	
	static int _log_stderr;
	
	#define log_helper(fmt, args...) \
	do { \
		if (_log_stderr) \
			fprintf(stderr, "%llu " fmt "\n", (unsigned long long)monotime(), ##args); \
	} while (0)
	
	
	/*
	 * Restrict the commands that can be run.
	 */
	
	#define CMD_ID_LVCHANGE_REFRESH 1
	#define CMD_ID_LVS 2
	
	static int _get_cmd_id(char **av, int av_count)
	{
		if ((av_count >= 3) &&
		    !strcmp(av[0], "lvm") &&
		    !strcmp(av[1], "lvchange") &&
		    !strcmp(av[2], "--refresh")) {
			return CMD_ID_LVCHANGE_REFRESH;
		}
	
		if ((av_count >= 2) &&
		    !strcmp(av[0], "lvm") &&
		    !strcmp(av[1], "lvs")) {
			return CMD_ID_LVS;
		}
	
		return 0;
	}
	
	/*
	 * Keep track of running pids mainly because when the process
	 * exits we get the pid, and need to look up the uuid from the
	 * pid to return the uuid/pid/result back to the main daemon.
	 */
	
	#define MAX_RUNNING 32
	
	struct running {
		char uuid[RUN_UUID_LEN];
		int pid;
		int cmd_id;
	};
	
	static struct running running_cmds[MAX_RUNNING];
	static int running_count;
	
	static int _save_running_cmd(char *uuid, int pid, int cmd_id)
	{
		int i;
	
		for (i = 0; i < MAX_RUNNING; i++) {
			if (!running_cmds[i].pid) {
				running_cmds[i].pid = pid;
				running_cmds[i].cmd_id = cmd_id;
				memcpy(running_cmds[i].uuid, uuid, RUN_UUID_LEN);
				running_count++;
				return 0;
			}
		}
		log_helper("too many running commands");
		return -1;
	}
	
	static struct running *_get_running_cmd(int pid)
	{
		int i;
	
		for (i = 0; i < MAX_RUNNING; i++) {
			if (running_cmds[i].pid == pid)
				return &running_cmds[i];
		}
		return NULL;
	}
	
	static struct running *_get_running_uuid(char *uuid)
	{
		int i;
	
		for (i = 0; i < MAX_RUNNING; i++) {
			if (!strcmp(running_cmds[i].uuid, uuid))
				return &running_cmds[i];
		}
		return NULL;
	}
	
	static void _clear_running_cmd(struct running *running)
	{
		running_count--;
		running->pid = 0;
		running->cmd_id = 0;
		memset(running->uuid, 0, RUN_UUID_LEN);
	}
	
	/* runs in child process that was forked by helper */
	
	static void exec_command(char *cmd_str, int out_fd)
	{
		char cmd_buf[16];
		char arg[ONE_ARG_LEN];
		char *av[MAX_AV_COUNT + 1]; /* +1 for NULL */
		int av_count = 0;
		int i, rv, arg_len, cmd_len, cmd_id;
	
		for (i = 0; i < MAX_AV_COUNT + 1; i++)
			av[i] = NULL;
	
		if (!cmd_str[0])
			return;
	
		/* this should already be done, but make sure */
		cmd_str[RUN_COMMAND_LEN - 1] = '\0';
	
		memset(&arg, 0, sizeof(arg));
		arg_len = 0;
		cmd_len = strlen(cmd_str);
	
		for (i = 0; i < cmd_len; i++) {
			if (!cmd_str[i])
				break;
	
			if (av_count == MAX_AV_COUNT)
				break;
	
			if (cmd_str[i] == '\\') {
				if (i == (cmd_len - 1))
					break;
				i++;
	
				if (cmd_str[i] == '\\') {
					arg[arg_len++] = cmd_str[i];
					continue;
				}
				if (isspace(cmd_str[i])) {
					arg[arg_len++] = cmd_str[i];
					continue;
				} else {
					break;
				}
			}
	
			if (isalnum(cmd_str[i]) || ispunct(cmd_str[i])) {
				arg[arg_len++] = cmd_str[i];
			} else if (isspace(cmd_str[i])) {
				if (arg_len)
					av[av_count++] = strdup(arg);
	
				memset(arg, 0, sizeof(arg));
				arg_len = 0;
			} else {
				break;
			}
		}
	
		if ((av_count < MAX_AV_COUNT) && arg_len) {
			av[av_count++] = strdup(arg);
		}
	
		/*
		for (i = 0; i < MAX_AV_COUNT + 1; i++) {
			if (!av[i])
				break;
	
			log_helper("command av[%d] \"%s\"", i, av[i]);
		}
		*/
	
		cmd_id = _get_cmd_id(av, av_count);
	
		/* tell the parent the command we have identified to run */
		memset(cmd_buf, 0, sizeof(cmd_buf));
		snprintf(cmd_buf, sizeof(cmd_buf), "cmd_id %d", cmd_id);
		rv = write(out_fd, cmd_buf, sizeof(cmd_buf));
		if (rv < 0)
			log_helper("write cmd_buf from child error %d", rv);
		close(out_fd);
	
		/* if we return before exec, the child does exit(1) (failure) */
		if (!cmd_id)
			return;
	
		execvp(av[0], av);
	}
	
	static int read_request(int fd, struct run_request *req)
	{
		int rv;
	 retry:

		rv = read(fd, req, sizeof(struct run_request));

		if (rv == -1 && errno == EINTR)

			goto retry;
	

		if (rv != sizeof(struct run_request))

			return -1;
		return 0;
	}
	
	static int send_status(int fd)
	{
		struct run_reply rep;
		int rv;
	
		memset(&rep, 0, sizeof(rep));
	
		rv = write(fd, &rep, sizeof(rep));
	
		if (rv == sizeof(rep))
			return 0;
		return -1;
	}
	
	static int send_result(struct running *running, int fd, int pid, int result)
	{
		struct run_reply rep;
		int rv;
	
		memset(&rep, 0, sizeof(rep));
	
		rep.header.type = DLM_MSG_RUN_REPLY;
	
		memcpy(rep.uuid, running->uuid, RUN_UUID_LEN);
		rep.info.local_pid = pid;
		rep.info.local_result = result;
	
		rv = write(fd, &rep, sizeof(rep));
	
		if (rv == sizeof(rep))
			return 0;
		return -1;
	}
	
	#define HELPER_STATUS_INTERVAL 30
	#define STANDARD_TIMEOUT_MS (HELPER_STATUS_INTERVAL*1000)
	#define RECOVERY_TIMEOUT_MS 1000
	
	/* run by the child helper process forked by dlm_controld in setup_helper */
	
	int run_helper(int in_fd, int out_fd, int log_stderr)
	{
		struct pollfd pollfd;
		struct run_request req;
		struct running *running;
		struct dlm_header *hd = (struct dlm_header *)&req;
		char cmd_buf[16];
		siginfo_t info;
		unsigned int fork_count = 0;
		unsigned int done_count = 0;
		time_t now, last_send, last_good = 0;
		int timeout = STANDARD_TIMEOUT_MS;
		int rv, pid, cmd_id;
	
		_log_stderr = log_stderr;
	
		rv = setgroups(0, NULL);

		if (rv < 0)

			log_helper("error clearing helper groups errno %i", errno);
	
		memset(&pollfd, 0, sizeof(pollfd));
		pollfd.fd = in_fd;
		pollfd.events = POLLIN;
	
		now = monotime();
		last_send = now;
		rv = send_status(out_fd);

		if (!rv)
			last_good = now;
	
		openlog("dlm_controld", LOG_CONS | LOG_PID, LOG_LOCAL4);
	
		while (1) {
			rv = poll(&pollfd, 1, timeout);

			if (rv == -1 && errno == EINTR)

				continue;
	

			if (rv < 0)

				exit(0);
	
			now = monotime();
	

			if (now - last_good >= HELPER_STATUS_INTERVAL &&
			    now - last_send >= 2) {
				last_send = now;
				rv = send_status(out_fd);

				if (!rv)
					last_good = now;
			}
	
			memset(&req, 0, sizeof(req));
	

			if (pollfd.revents & POLLIN) {

				rv = read_request(in_fd, &req);

				if (rv)

					continue;
	

				if (hd->type == DLM_MSG_RUN_REQUEST) {
					int cmd_pipe[2];
	

					if (running_count >= MAX_RUNNING) {
						log_helper("too many running commands");
						exit(1);

					}
	
					/*
					 * Child writes cmd_buf to cmd_pipe, parent reads
					 * cmd_buf from cmd_pipe.  cmd_buf contains the
					 * string "cmd_id <num>" where <num> is CMD_ID_NUM
					 * identifying the command being run by the child.
					 */
	

					if (pipe(cmd_pipe))

						exit(1);
	
					pid = fork();

					if (!pid) {
						close(cmd_pipe[0]);
						exec_command(req.command, cmd_pipe[1]);
						exit(1);

					}
	
					close(cmd_pipe[1]);
	
					memset(cmd_buf, 0, sizeof(cmd_buf));
					cmd_id = 0;
	
					rv = read(cmd_pipe[0], cmd_buf, sizeof(cmd_buf));

					if (rv < 0)

						log_helper("helper read child cmd_id error %d", rv);
	
					close(cmd_pipe[0]);
	
					sscanf(cmd_buf, "cmd_id %d", &cmd_id);
	
					_save_running_cmd(req.uuid, pid, cmd_id);
	
					fork_count++;
	

					log_helper("helper run %s pid %d cmd_id %d running %d fork_count %d done_count %d %s",
						   req.uuid, pid, cmd_id, running_count, fork_count, done_count, req.command);
	
				} else if (hd->type == DLM_MSG_RUN_CANCEL) {
	
					/* TODO: should we also send kill to the pid? */
	
					if (!(running = _get_running_uuid(req.uuid)))
						log_helper("no running cmd for cancel uuid");
					else {
						log_helper("cancel running cmd uuid %s pid %d", running->uuid, running->pid);
						_clear_running_cmd(running);
					}
				}
			}
	
			if (pollfd.revents & (POLLERR | POLLHUP | POLLNVAL))
				exit(0);
	
			/* collect child exits until no more children exist (ECHILD)
			   or none are ready (WNOHANG) */
	
			while (1) {
				memset(&info, 0, sizeof(info));
	
				rv = waitid(P_ALL, 0, &info, WEXITED | WNOHANG);
	
				if ((rv < 0) && (errno == ECHILD)) {
					/*
					log_helper("helper no children exist fork_count %d done_count %d", fork_count, done_count);
					*/
					timeout = STANDARD_TIMEOUT_MS;
				}
	
				else if (!rv && !info.si_pid) {
					log_helper("helper no children ready fork_count %d done_count %d", fork_count, done_count);
					timeout = RECOVERY_TIMEOUT_MS;
				}
	
				else if (!rv && info.si_pid) {
					done_count++;
	
					if (!(running = _get_running_cmd(info.si_pid))) {
						log_helper("running cmd for pid %d result %d not found",
							   info.si_pid, info.si_status);
						continue;
					} else {
						log_helper("running cmd for pid %d result %d done",
							   info.si_pid, info.si_status);
					}
	
					if (info.si_status) {
						syslog(LOG_ERR, "%llu run error %s id %d pid %d status %d code %d",
						       (unsigned long long)monotime(),
						       running->uuid, running->cmd_id, running->pid,
						       info.si_status, info.si_code);
					}
	
					send_result(running, out_fd, info.si_pid, info.si_status);
	
					_clear_running_cmd(running);
					continue;
				}
	
				else {
					log_helper("helper waitid rv %d errno %d fork_count %d done_count %d",
						  rv, errno, fork_count, done_count);
				}
	
				break;
			}

		}
	
		closelog();
		return 0;
	}