/*
 * -*- mode: Fundamental; tab-width: 4; -*-
 * ex:ts=4
 *
 * Daemon control program, with Java Startup options.
 *
 *	Original by Ernst de Haan <znerd@freebsd.org>
 *	www/jakarta-tomcat4/files/daemonctl.c
 *
 * $FreeBSD: /tmp/pcvs/ports/java/jboss3/files/Attic/daemonctl.c,v 1.1 2004-06-21 16:42:59 vanilla Exp $
 */

#include <assert.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/uio.h>

/* The maximum size of the PID file, in bytes */
#define MAX_FILE_SIZE			32

/* The interval in seconds between the checks to make sure the process
   died after a kill */
#define STOP_TIME_INTERVAL		1

#define ERR_ILLEGAL_ARGUMENT				1
#define ERR_PID_FILE_NOT_FOUND				2
#define ERR_PID_FILE_TOO_LARGE				3
#define ERR_PID_FILE_CONTAINS_ILLEGAL_CHAR	4
#define ERR_KILL_FAILED						5
#define ERR_ALREADY_RUNNING					6
#define ERR_NOT_RUNNING						7
#define ERR_CHDIR_TO_APP_HOME				8
#define ERR_ACCESS_JAR_FILE					17
#define ERR_STDOUT_LOGFILE_OPEN				9
#define ERR_STDERR_LOGFILE_OPEN				10
#define ERR_FORK_FAILED						11
#define ERR_STAT_JAVA_HOME					12
#define ERR_JAVA_HOME_NOT_DIR				13
#define ERR_STAT_JAVA_CMD					14
#define ERR_JAVA_CMD_NOT_FILE				15
#define ERR_JAVA_CMD_NOT_EXECUTABLE			16

/*
	Function declarations.
 */
static void printUsage (void);
static int openPIDFile (void);
static int readPID (int);
static void writePID (int file, int pid);
static void start (int optcount, char * opts []);
static void stop (void);
static void restart (int optcount, char * opts []);

/**
 * Main function. This function is called when this program is executed.
 *
 * @param argc
 *    the number of arguments plus one, so always greater than 0.
 *
 * @param argv
 *    the arguments in an array of character pointers, where the last argument
 *    element is followed by a NULL element.
 */
int
main (
 int argc,
 char *argv [])
{

	/* Declare variables, like all other good ANSI C programs do :) */
	int i, jopt;
	char *argument, **jargs;

	/* Parse the arguments */
	if (argc < 2)
	{
		printUsage ();
		return 0;
	}

	/* XXX: Fix for setting up the environment for the java wrapper script */
	setuid (geteuid ());
	setgid (getegid ());

	/*
		Build up java-option block.
	 */
	jopt = 0;
	for (i = 1; i < argc; i++)
	{
		if (*argv [i] == '-')
			jopt++;
	}
	if (jopt == 0)
		jargs = NULL;
	else
	{
		int j = 0;
		jargs = malloc (sizeof (char *) * jopt);
		for (i = 0; i < argc; i++)
		{
			if (*argv [i] == '-')
				jargs [j++] = argv [i];
		}
	}

	/*
		Decide on just what to call.
	 */
	argument = argv [argc - 1];
	if (strcmp ("start", argument) == 0)
	{
		start (jopt, jargs);

	} else if (strcmp ("stop", argument) == 0)
	{
		stop ();
	} else if (strcmp ("restart", argument) == 0)
	{
		restart (jopt, jargs);

	} else {
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Illegal argument \"%s\".\n", argument);
		printUsage ();
		exit (ERR_ILLEGAL_ARGUMENT);
	}

	return 0;
}


/**
 * Prints usage information to stdout.
 */
static void
printUsage (void)
{
	printf ("Usage: %%CONTROL_SCRIPT_NAME%% [java-options] {start|stop|restart}\n");
}

/**
 * Attempts to open the PID file. If that file is successfully opened, then
 * the file handle (an int) will be returned.
 *
 * @return
 *    the file handle.
 */
static int
openPIDFile (void)
{

 	int file;

	/* Attempt to open the PID file */
	file = open ("%%PID_FILE%%", O_RDWR);
	if (file < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to open %%PID_FILE%% for reading and writing: ");
		perror (NULL);
		exit (ERR_PID_FILE_NOT_FOUND);
	}

	return file;
}


/**
 * Reads a PID from the specified file. The file is identified by a file
 * handle.
 *
 * @param file
 *    the file handle.
 *
 * @return
 *    the PID, or -1 if the file was empty.
 */
static int
readPID (
 int file)
{

	char *buffer;
	int hadNewline = 0;
	unsigned int count;
	unsigned int i;
	int pid;

	/* Read the PID file contents */
	buffer = (char *) malloc ((MAX_FILE_SIZE + 1) * sizeof (char));
	count = read (file, buffer, MAX_FILE_SIZE + 1);
	if (count > MAX_FILE_SIZE) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: The file %%PID_FILE%% contains more than %d bytes.\n", MAX_FILE_SIZE);
		exit (ERR_PID_FILE_TOO_LARGE);
	}

	/* Convert the bytes to a number */
	pid = 0;
	for (i=0; i<count; i++) {
		char c = buffer[i];
		if (c >= '0' && c <= '9') {
			char digit = c - '0';
			pid *= 10;
			pid += digit;
		} else if (i == (count - 1) && c == '\n') {
			/* XXX: Ignore a newline at the end of the file */
			hadNewline = 1;
		} else {
			printf (" [ FAILED ]\n");
			fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: The file %%PID_FILE%% contains an illegal character (%d) at position %d.\n", c, i);
			exit (ERR_PID_FILE_CONTAINS_ILLEGAL_CHAR);
		}
	}
	printf (" [ DONE ]\n");

	if (count == 0 || (count == 1 && hadNewline == 1)) {
		return -1;
	}

	return pid;
}


/**
 * Writes a process ID to the specified file. The file is identified by a file
 * handle.
 *
 * @param file
 *    the file handle, always greater than 0.
 *
 * @param pid
 *    the PID to store, always greater than 0.
 */
static void
writePID (
 int file,
 int pid)
{

	char *buffer;
	int nbytes;

	/* Check preconditions */
	assert (file > 0);
	assert (pid > 0);

	printf (">> Writing PID file...");

	lseek (file, (off_t) 0, SEEK_SET);
	ftruncate (file, (off_t) 0);
	nbytes = asprintf (&buffer, "%d\n", pid);
	write (file, buffer, nbytes);
	printf (" [ DONE ]\n");
}


/**
 * Checks if the specified process is running.
 *
 * @param pid
 *    the process id, greater than 0.
 *
 * @return
 *    0 if the specified process is not running, a different value otherwise.
 */
static int
existsProcess (
 int pid)
{

	int result;

	/* Check preconditions */
	assert (pid > 0);

	/* See if the process exists */
   	result = kill (pid, 0);

	/* If the result is 0, then the process exists */
	if (result == 0) {
		return 1;
	} else {
		return 0;
	}
}


/**
 * Kills the process identified by the specified ID.
 *
 * @param pid
 *    the process id, greater than 0.
 */
static void
killProcess (
 int pid)
{

	int result;
	unsigned int waited;
	unsigned int forced;
	unsigned int interval = STOP_TIME_INTERVAL;
	unsigned int timeout  = %%STOP_TIMEOUT%%;

	/* Check preconditions */
	assert (pid > 0);

	printf (">> Terminating process %d...", pid);
	result = kill (pid, SIGTERM);
	if (result < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to kill process %d: ", pid);
		perror (NULL);
		exit (ERR_KILL_FAILED);
	}

	/* Wait until the process is actually killed */
    result = existsProcess (pid);
	for (waited=0; result == 1 && waited < timeout; waited += interval)
	{
		printf (".");
		fflush (NULL);
		sleep (interval);
    	result = existsProcess (pid);
	}

	/* If the process still exists, then have no mercy and kill it */
	forced = 0;
	if (result == 1) {

		/* Force the process to die */
		result = kill (pid, SIGKILL);
		if (result == 0) {
			forced = 1;
			printf (" [ DONE ]\n");
			fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Process %d did not terminate within %%STOP_TIMEOUT%% sec. Killed.\n", pid);
		} else if (result != ESRCH) {
			printf (" [ FAILED ]\n");
			fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to kill process %d: ", pid);
			perror (NULL);
			exit (ERR_KILL_FAILED);
		}
	}

	if (forced == 0) {
		printf (" [ DONE ]\n");
	}
}

/**
 * Starts the daemon.
 */
static void
start (
 int optcount,
 char * opts [])
{
	int file;
	int pid;
	int result;
	int stdoutLogFile;
	int stderrLogFile;
	struct stat sb;

	/* Open and read the PID file */
	printf (">> Reading PID file (%%PID_FILE%%)...");
	file = openPIDFile ();
	pid = readPID (file);

	printf (">> Starting %%APP_TITLE%% %%PORTVERSION%%...");
	if (pid != -1) {

		/* Check if the process actually exists */
		result = existsProcess (pid);
		if (result == 1) {
			printf (" [ FAILED ]\n");
			fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: %%APP_TITLE%% %%PORTVERSION%% is already running, PID is %d.\n", pid);
			exit (ERR_ALREADY_RUNNING);
		}
	}

	/* Check if the JDK home directory is actually a directory */
	result = stat ("%%JAVA_HOME%%", &sb);
	if (result != 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to stat %%JAVA_HOME%%: ");
		perror (NULL);
		exit (ERR_STAT_JAVA_HOME);
	}
	if (!S_ISDIR (sb.st_mode)) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Java home directory %%JAVA_HOME%% is not a directory.\n");
		exit (ERR_JAVA_HOME_NOT_DIR);
	}

	/* Check if the Java command is actually an executable regular file */
	result = stat ("%%JAVA_HOME%%/%%JAVA_CMD%%", &sb);
	if (result != 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to stat %%JAVA_HOME%%/%%JAVA_CMD%%: ");
		perror (NULL);
		exit (ERR_STAT_JAVA_CMD);
	}
	if (!S_ISREG (sb.st_mode)) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Java command %%JAVA_HOME%%/%%JAVA_CMD%% is not a regular file.\n");
		exit (ERR_JAVA_CMD_NOT_FILE);
	}
	result = access ("%%JAVA_HOME%%/%%JAVA_CMD%%", X_OK);
	if (result != 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Java command %%JAVA_HOME%%/%%JAVA_CMD%% is not executable: ");
		perror (NULL);
		exit (ERR_JAVA_CMD_NOT_EXECUTABLE);
	}

	/* Change directory */
	result = chdir ("%%APP_HOME%%");
	if (result < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to access directory %%APP_HOME%%: ");
		perror (NULL);
		exit (ERR_CHDIR_TO_APP_HOME);
	}

	/* See if the JAR file exists */
	result = access ("%%APP_HOME%%/%%JAR_FILE%%", R_OK);
	if (result < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to access JAR file %%APP_HOME%%/%%JAR_FILE%%: ");
		perror (NULL);
		exit (ERR_ACCESS_JAR_FILE);
	}

	/* Open the stdout log file */
	stdoutLogFile = open ("%%STDOUT_LOG%%", O_WRONLY);
	if (stdoutLogFile < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to open %%STDOUT_LOG%% for writing: ");
		perror (NULL);
		exit (ERR_STDOUT_LOGFILE_OPEN);
	}
	lseek (stdoutLogFile, (off_t) 0, SEEK_END);

	/* Open the stderr log file */
	stderrLogFile = open ("%%STDERR_LOG%%", O_WRONLY);
	if (stderrLogFile < 0) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to open %%STDERR_LOG%% for writing: ");
		perror (NULL);
		exit (ERR_STDERR_LOGFILE_OPEN);
	}
	lseek (stderrLogFile, (off_t) 0, SEEK_END);

	/* Split this process in two */
	pid = fork ();
	if (pid == -1) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: Unable to fork: ");
		perror (NULL);
		exit (ERR_FORK_FAILED);
	}

	if (pid == 0)
	{
		int i, argc;
		char **argv;

		/* Redirect stdout to log file */
		dup2 (stdoutLogFile, STDOUT_FILENO);

		/* Redirect stderr to log file */
		dup2 (stderrLogFile, STDERR_FILENO);

		/* TODO: Support redirection of both stdout and stderr to the same
		         file using pipe (2) */

		/*
			Build the argument vector, with the java-options if any.
		 */
		argv = malloc (sizeof (char *) * (optcount + 5));
		argc = 0;
		argv [argc++] = "%%JAVA_HOME%%/%%JAVA_CMD%%";
		for (i = 0; i < optcount; i++)
			argv [argc++] = opts [i];
		argv [argc++] = "-cp";
		argv [argc++] = "%%JAVA_CP%%";
		argv [argc++] = "%%JAVA_MAIN%%";
		argv [argc++] = NULL;

		/* Execute the command */
		execv (argv [0], argv);

		perror (NULL);
	} else
	{
		printf (" [ DONE ]\n");
		writePID (file, pid);
	}
}

/**
 * Stops the daemon.
 */
static void
stop (void)
{

	int file;
	int pid;

	/* Open and read the PID file */
	printf (">> Reading PID file (%%PID_FILE%%)...");
	file = openPIDFile ();
	pid = readPID (file);

	printf (">> Checking if %%APP_TITLE%% %%PORTVERSION%% is running...");

	/* If there is a PID, see if the process still exists */
	if (pid != -1) {
		int result = kill (pid, 0);
		if (result != 0 && errno == ESRCH) {
			ftruncate (file, (off_t) 0);
			pid = -1;
		}
	}

	/* If there is no running process, produce an error */
	if (pid == -1) {
		printf (" [ FAILED ]\n");
		fprintf (stderr, "%%CONTROL_SCRIPT_NAME%%: %%APP_TITLE%% %%PORTVERSION%% is currently not running.\n");
		exit (ERR_NOT_RUNNING);
	}
	printf (" [ DONE ]\n");

	/* Terminate the process */
	killProcess (pid);

	/* Clear the PID file */
	ftruncate (file, (off_t) 0);
}


/**
 * Restarts the process. If it not currently running, then it will fail.
 */
static void
restart (
 int optcount,
 char * opts [])
{
	stop ();
	start (optcount, opts);
}