fix off by 1 error

[rrdtool.git] / src / rrd_daemon.c

/**
 * RRDTool - src/rrd_daemon.c
 * Copyright (C) 2008-2010 Florian octo Forster
 * Copyright (C) 2008,2009 Kevin Brintnall
 *
 * 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; only version 2 of the License is applicable.
 *
 * 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 *
 * Authors:
 *   Florian octo Forster <octo at verplant.org>
 *   kevin brintnall <kbrint@rufus.net>
 **/

#if 0
/*
 * First tell the compiler to stick to the C99 and POSIX standards as close as
 * possible.
 */
#ifndef __STRICT_ANSI__ /* {{{ */
# define __STRICT_ANSI__
#endif

#ifndef _ISOC99_SOURCE
# define _ISOC99_SOURCE
#endif

#ifdef _POSIX_C_SOURCE
# undef _POSIX_C_SOURCE
#endif
#define _POSIX_C_SOURCE 200112L

/* Single UNIX needed for strdup. */
#ifdef _XOPEN_SOURCE
# undef _XOPEN_SOURCE
#endif
#define _XOPEN_SOURCE 500

#ifndef _REENTRANT
# define _REENTRANT
#endif

#ifndef _THREAD_SAFE
# define _THREAD_SAFE
#endif

#ifdef _GNU_SOURCE
# undef _GNU_SOURCE
#endif
/* }}} */
#endif /* 0 */

/*
 * Now for some includes..
 */
/* {{{ */

#include "rrd_tool.h"
#include "rrd_client.h"
#include "unused.h"

#include <stdlib.h>

#ifndef WIN32
#ifdef HAVE_STDINT_H
#  include <stdint.h>
#endif
#include <unistd.h>
#include <strings.h>
#include <inttypes.h>
#include <sys/socket.h>

#else

#endif
#include <stdio.h>
#include <string.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/un.h>
#include <netdb.h>
#include <poll.h>
#include <syslog.h>
#include <pthread.h>
#include <errno.h>
#include <assert.h>
#include <sys/time.h>
#include <time.h>
#include <libgen.h>
#include <grp.h>

#ifdef HAVE_LIBWRAP
#include <tcpd.h>
#endif /* HAVE_LIBWRAP */

#include <glib-2.0/glib.h>
/* }}} */

#define RRDD_LOG(severity, ...) \
  do { \
    if (stay_foreground) { \
      fprintf(stderr, __VA_ARGS__); \
      fprintf(stderr, "\n"); } \
    syslog ((severity), __VA_ARGS__); \
  } while (0)

/*
 * Types
 */
typedef enum { RESP_ERR = -1, RESP_OK = 0 } response_code;

struct listen_socket_s
{
  int fd;
  char addr[PATH_MAX + 1];
  int family;

  /* state for BATCH processing */
  time_t batch_start;
  int batch_cmd;

  /* buffered IO */
  char *rbuf;
  off_t next_cmd;
  off_t next_read;

  char *wbuf;
  ssize_t wbuf_len;

  uint32_t permissions;

  gid_t  socket_group;
  mode_t socket_permissions;
};
typedef struct listen_socket_s listen_socket_t;

struct command_s;
typedef struct command_s command_t;
/* note: guard against "unused" warnings in the handlers */
#define DISPATCH_PROTO  listen_socket_t UNUSED(*sock),\
                        time_t UNUSED(now),\
                        char  UNUSED(*buffer),\
                        size_t UNUSED(buffer_size)

#define HANDLER_PROTO   command_t UNUSED(*cmd),\
                        DISPATCH_PROTO

struct command_s {
  char   *cmd;
  int (*handler)(HANDLER_PROTO);

  char  context;                /* where we expect to see it */
#define CMD_CONTEXT_CLIENT      (1<<0)
#define CMD_CONTEXT_BATCH       (1<<1)
#define CMD_CONTEXT_JOURNAL     (1<<2)
#define CMD_CONTEXT_ANY         (0x7f)

  char *syntax;
  char *help;
};

struct cache_item_s;
typedef struct cache_item_s cache_item_t;
struct cache_item_s
{
  char *file;
  char **values;
  size_t values_num;            /* number of valid pointers */
  size_t values_alloc;          /* number of allocated pointers */
  time_t last_flush_time;
  double last_update_stamp;
#define CI_FLAGS_IN_TREE  (1<<0)
#define CI_FLAGS_IN_QUEUE (1<<1)
  int flags;
  pthread_cond_t  flushed;
  cache_item_t *prev;
  cache_item_t *next;
};

struct callback_flush_data_s
{
  time_t now;
  time_t abs_timeout;
  char **keys;
  size_t keys_num;
};
typedef struct callback_flush_data_s callback_flush_data_t;

enum queue_side_e
{
  HEAD,
  TAIL
};
typedef enum queue_side_e queue_side_t;

/* describe a set of journal files */
typedef struct {
  char **files;
  size_t files_num;
} journal_set;

#define RBUF_SIZE (RRD_CMD_MAX*2)

/*
 * Variables
 */
static int stay_foreground = 0;
static uid_t daemon_uid;

static listen_socket_t *listen_fds = NULL;
static size_t listen_fds_num = 0;

static listen_socket_t default_socket;

enum {
  RUNNING,              /* normal operation */
  FLUSHING,             /* flushing remaining values */
  SHUTDOWN              /* shutting down */
} state = RUNNING;

static pthread_t *queue_threads;
static pthread_cond_t queue_cond = PTHREAD_COND_INITIALIZER;
static int config_queue_threads = 4;

static pthread_t flush_thread;
static pthread_cond_t flush_cond = PTHREAD_COND_INITIALIZER;

static pthread_mutex_t connection_threads_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  connection_threads_done = PTHREAD_COND_INITIALIZER;
static int connection_threads_num = 0;

/* Cache stuff */
static GTree          *cache_tree = NULL;
static cache_item_t   *cache_queue_head = NULL;
static cache_item_t   *cache_queue_tail = NULL;
static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;

static int config_write_interval = 300;
static int config_write_jitter   = 0;
static int config_flush_interval = 3600;
static int config_flush_at_shutdown = 0;
static char *config_pid_file = NULL;
static char *config_base_dir = NULL;
static size_t _config_base_dir_len = 0;
static int config_write_base_only = 0;
static size_t config_alloc_chunk = 1;

static listen_socket_t **config_listen_address_list = NULL;
static size_t config_listen_address_list_len = 0;

static uint64_t stats_queue_length = 0;
static uint64_t stats_updates_received = 0;
static uint64_t stats_flush_received = 0;
static uint64_t stats_updates_written = 0;
static uint64_t stats_data_sets_written = 0;
static uint64_t stats_journal_bytes = 0;
static uint64_t stats_journal_rotate = 0;
static pthread_mutex_t stats_lock = PTHREAD_MUTEX_INITIALIZER;

static int opt_no_overwrite = 0; /* default for the daemon */

/* Journaled updates */
#define JOURNAL_REPLAY(s) ((s) == NULL)
#define JOURNAL_BASE "rrd.journal"
static journal_set *journal_cur = NULL;
static journal_set *journal_old = NULL;
static char *journal_dir = NULL;
static FILE *journal_fh = NULL;         /* current journal file handle */
static long  journal_size = 0;          /* current journal size */
#define JOURNAL_MAX (1 * 1024 * 1024 * 1024)
static pthread_mutex_t journal_lock = PTHREAD_MUTEX_INITIALIZER;
static int journal_write(char *cmd, char *args);
static void journal_done(void);
static void journal_rotate(void);

/* prototypes for forward refernces */
static int handle_request_help (HANDLER_PROTO);

/* 
 * Functions
 */
static void sig_common (const char *sig) /* {{{ */
{
  RRDD_LOG(LOG_NOTICE, "caught SIG%s", sig);
  if (state == RUNNING) {
      state = FLUSHING;
  }
  pthread_cond_broadcast(&flush_cond);
  pthread_cond_broadcast(&queue_cond);
} /* }}} void sig_common */

static void sig_int_handler (int UNUSED(s)) /* {{{ */
{
  sig_common("INT");
} /* }}} void sig_int_handler */

static void sig_term_handler (int UNUSED(s)) /* {{{ */
{
  sig_common("TERM");
} /* }}} void sig_term_handler */

static void sig_usr1_handler (int UNUSED(s)) /* {{{ */
{
  config_flush_at_shutdown = 1;
  sig_common("USR1");
} /* }}} void sig_usr1_handler */

static void sig_usr2_handler (int UNUSED(s)) /* {{{ */
{
  config_flush_at_shutdown = 0;
  sig_common("USR2");
} /* }}} void sig_usr2_handler */

static void install_signal_handlers(void) /* {{{ */
{
  /* These structures are static, because `sigaction' behaves weird if the are
   * overwritten.. */
  static struct sigaction sa_int;
  static struct sigaction sa_term;
  static struct sigaction sa_pipe;
  static struct sigaction sa_usr1;
  static struct sigaction sa_usr2;

  /* Install signal handlers */
  memset (&sa_int, 0, sizeof (sa_int));
  sa_int.sa_handler = sig_int_handler;
  sigaction (SIGINT, &sa_int, NULL);

  memset (&sa_term, 0, sizeof (sa_term));
  sa_term.sa_handler = sig_term_handler;
  sigaction (SIGTERM, &sa_term, NULL);

  memset (&sa_pipe, 0, sizeof (sa_pipe));
  sa_pipe.sa_handler = SIG_IGN;
  sigaction (SIGPIPE, &sa_pipe, NULL);

  memset (&sa_pipe, 0, sizeof (sa_usr1));
  sa_usr1.sa_handler = sig_usr1_handler;
  sigaction (SIGUSR1, &sa_usr1, NULL);

  memset (&sa_usr2, 0, sizeof (sa_usr2));
  sa_usr2.sa_handler = sig_usr2_handler;
  sigaction (SIGUSR2, &sa_usr2, NULL);

} /* }}} void install_signal_handlers */

static int open_pidfile(char *action, int oflag) /* {{{ */
{
  int fd;
  const char *file;
  char *file_copy, *dir;

  file = (config_pid_file != NULL)
    ? config_pid_file
    : LOCALSTATEDIR "/run/rrdcached.pid";

  /* dirname may modify its argument */
  file_copy = strdup(file);
  if (file_copy == NULL)
  {
    fprintf(stderr, "rrdcached: strdup(): %s\n",
        rrd_strerror(errno));
    return -1;
  }

  dir = dirname(file_copy);
  if (rrd_mkdir_p(dir, 0777) != 0)
  {
    fprintf(stderr, "Failed to create pidfile directory '%s': %s\n",
        dir, rrd_strerror(errno));
    return -1;
  }

  free(file_copy);

  fd = open(file, oflag, S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
  if (fd < 0)
    fprintf(stderr, "rrdcached: can't %s pid file '%s' (%s)\n",
            action, file, rrd_strerror(errno));

  return(fd);
} /* }}} static int open_pidfile */

/* check existing pid file to see whether a daemon is running */
static int check_pidfile(void)
{
  int pid_fd;
  pid_t pid;
  char pid_str[16];

  pid_fd = open_pidfile("open", O_RDWR);
  if (pid_fd < 0)
    return pid_fd;

  if (read(pid_fd, pid_str, sizeof(pid_str)) <= 0)
    return -1;

  pid = atoi(pid_str);
  if (pid <= 0)
    return -1;

  /* another running process that we can signal COULD be
   * a competing rrdcached */
  if (pid != getpid() && kill(pid, 0) == 0)
  {
    fprintf(stderr,
            "FATAL: Another rrdcached daemon is running?? (pid %d)\n", pid);
    close(pid_fd);
    return -1;
  }

  lseek(pid_fd, 0, SEEK_SET);
  if (ftruncate(pid_fd, 0) == -1)
  {
    fprintf(stderr,
            "FATAL: Faild to truncate stale PID file. (pid %d)\n", pid);
    close(pid_fd);
    return -1;
  }

  fprintf(stderr,
          "rrdcached: removed stale PID file (no rrdcached on pid %d)\n"
          "rrdcached: starting normally.\n", pid);

  return pid_fd;
} /* }}} static int check_pidfile */

static int write_pidfile (int fd) /* {{{ */
{
  pid_t pid;
  FILE *fh;

  pid = getpid ();

  fh = fdopen (fd, "w");
  if (fh == NULL)
  {
    RRDD_LOG (LOG_ERR, "write_pidfile: fdopen() failed.");
    close(fd);
    return (-1);
  }

  fprintf (fh, "%i\n", (int) pid);
  fclose (fh);

  return (0);
} /* }}} int write_pidfile */

static int remove_pidfile (void) /* {{{ */
{
  char *file;
  int status;

  file = (config_pid_file != NULL)
    ? config_pid_file
    : LOCALSTATEDIR "/run/rrdcached.pid";

  status = unlink (file);
  if (status == 0)
    return (0);
  return (errno);
} /* }}} int remove_pidfile */

static char *next_cmd (listen_socket_t *sock, ssize_t *len) /* {{{ */
{
  char *eol;

  eol = memchr(sock->rbuf + sock->next_cmd, '\n',
               sock->next_read - sock->next_cmd);

  if (eol == NULL)
  {
    /* no commands left, move remainder back to front of rbuf */
    memmove(sock->rbuf, sock->rbuf + sock->next_cmd,
            sock->next_read - sock->next_cmd);
    sock->next_read -= sock->next_cmd;
    sock->next_cmd = 0;
    *len = 0;
    return NULL;
  }
  else
  {
    char *cmd = sock->rbuf + sock->next_cmd;
    *eol = '\0';

    sock->next_cmd = eol - sock->rbuf + 1;

    if (eol > sock->rbuf && *(eol-1) == '\r')
      *(--eol) = '\0'; /* handle "\r\n" EOL */

    *len = eol - cmd;

    return cmd;
  }

  /* NOTREACHED */
  assert(1==0);
} /* }}} char *next_cmd */

/* add the characters directly to the write buffer */
static int add_to_wbuf(listen_socket_t *sock, char *str, size_t len) /* {{{ */
{
  char *new_buf;

  assert(sock != NULL);

  new_buf = rrd_realloc(sock->wbuf, sock->wbuf_len + len + 1);
  if (new_buf == NULL)
  {
    RRDD_LOG(LOG_ERR, "add_to_wbuf: realloc failed");
    return -1;
  }

  strncpy(new_buf + sock->wbuf_len, str, len + 1);

  sock->wbuf = new_buf;
  sock->wbuf_len += len;

  return 0;
} /* }}} static int add_to_wbuf */

/* add the text to the "extra" info that's sent after the status line */
static int add_response_info(listen_socket_t *sock, char *fmt, ...) /* {{{ */
{
  va_list argp;
  char buffer[RRD_CMD_MAX];
  int len;

  if (JOURNAL_REPLAY(sock)) return 0;
  if (sock->batch_start) return 0; /* no extra info returned when in BATCH */

  va_start(argp, fmt);
#ifdef HAVE_VSNPRINTF
  len = vsnprintf(buffer, sizeof(buffer), fmt, argp);
#else
  len = vsprintf(buffer, fmt, argp);
#endif
  va_end(argp);
  if (len < 0)
  {
    RRDD_LOG(LOG_ERR, "add_response_info: vnsprintf failed");
    return -1;
  }

  return add_to_wbuf(sock, buffer, len);
} /* }}} static int add_response_info */

static int count_lines(char *str) /* {{{ */
{
  int lines = 0;

  if (str != NULL)
  {
    while ((str = strchr(str, '\n')) != NULL)
    {
      ++lines;
      ++str;
    }
  }

  return lines;
} /* }}} static int count_lines */

/* send the response back to the user.
 * returns 0 on success, -1 on error
 * write buffer is always zeroed after this call */
static int send_response (listen_socket_t *sock, response_code rc,
                          char *fmt, ...) /* {{{ */
{
  va_list argp;
  char buffer[RRD_CMD_MAX];
  int lines;
  ssize_t wrote;
  int rclen, len;

  if (JOURNAL_REPLAY(sock)) return rc;

  if (sock->batch_start)
  {
    if (rc == RESP_OK)
      return rc; /* no response on success during BATCH */
    lines = sock->batch_cmd;
  }
  else if (rc == RESP_OK)
    lines = count_lines(sock->wbuf);
  else
    lines = -1;

  rclen = snprintf(buffer, sizeof buffer, "%d ", lines);
  va_start(argp, fmt);
#ifdef HAVE_VSNPRINTF
  len = vsnprintf(buffer+rclen, sizeof(buffer)-rclen, fmt, argp);
#else
  len = vsprintf(buffer+rclen, fmt, argp);
#endif
  va_end(argp);
  if (len < 0)
    return -1;

  len += rclen;

  /* append the result to the wbuf, don't write to the user */
  if (sock->batch_start)
    return add_to_wbuf(sock, buffer, len);

  /* first write must be complete */
  if (len != write(sock->fd, buffer, len))
  {
    RRDD_LOG(LOG_INFO, "send_response: could not write status message");
    return -1;
  }

  if (sock->wbuf != NULL && rc == RESP_OK)
  {
    wrote = 0;
    while (wrote < sock->wbuf_len)
    {
      ssize_t wb = write(sock->fd, sock->wbuf + wrote, sock->wbuf_len - wrote);
      if (wb <= 0)
      {
        RRDD_LOG(LOG_INFO, "send_response: could not write results");
        return -1;
      }
      wrote += wb;
    }
  }

  free(sock->wbuf); sock->wbuf = NULL;
  sock->wbuf_len = 0;

  return 0;
} /* }}} */

static void wipe_ci_values(cache_item_t *ci, time_t when)
{
  ci->values = NULL;
  ci->values_num = 0;
  ci->values_alloc = 0;

  ci->last_flush_time = when;
  if (config_write_jitter > 0)
    ci->last_flush_time += (rrd_random() % config_write_jitter);
}

/* remove_from_queue
 * remove a "cache_item_t" item from the queue.
 * must hold 'cache_lock' when calling this
 */
static void remove_from_queue(cache_item_t *ci) /* {{{ */
{
  if (ci == NULL) return;
  if ((ci->flags & CI_FLAGS_IN_QUEUE) == 0) return; /* not queued */

  if (ci->prev == NULL)
    cache_queue_head = ci->next; /* reset head */
  else
    ci->prev->next = ci->next;

  if (ci->next == NULL)
    cache_queue_tail = ci->prev; /* reset the tail */
  else
    ci->next->prev = ci->prev;

  ci->next = ci->prev = NULL;
  ci->flags &= ~CI_FLAGS_IN_QUEUE;

  pthread_mutex_lock (&stats_lock);
  assert (stats_queue_length > 0);
  stats_queue_length--;
  pthread_mutex_unlock (&stats_lock);

} /* }}} static void remove_from_queue */

/* free the resources associated with the cache_item_t
 * must hold cache_lock when calling this function
 */
static void *free_cache_item(cache_item_t *ci) /* {{{ */
{
  if (ci == NULL) return NULL;

  remove_from_queue(ci);

  for (size_t i=0; i < ci->values_num; i++)
    free(ci->values[i]);

  free (ci->values);
  free (ci->file);

  /* in case anyone is waiting */
  pthread_cond_broadcast(&ci->flushed);
  pthread_cond_destroy(&ci->flushed);

  free (ci);

  return NULL;
} /* }}} static void *free_cache_item */

/*
 * enqueue_cache_item:
 * `cache_lock' must be acquired before calling this function!
 */
static int enqueue_cache_item (cache_item_t *ci, /* {{{ */
    queue_side_t side)
{
  if (ci == NULL)
    return (-1);

  if (ci->values_num == 0)
    return (0);

  if (side == HEAD)
  {
    if (cache_queue_head == ci)
      return 0;

    /* remove if further down in queue */
    remove_from_queue(ci);

    ci->prev = NULL;
    ci->next = cache_queue_head;
    if (ci->next != NULL)
      ci->next->prev = ci;
    cache_queue_head = ci;

    if (cache_queue_tail == NULL)
      cache_queue_tail = cache_queue_head;
  }
  else /* (side == TAIL) */
  {
    /* We don't move values back in the list.. */
    if (ci->flags & CI_FLAGS_IN_QUEUE)
      return (0);

    assert (ci->next == NULL);
    assert (ci->prev == NULL);

    ci->prev = cache_queue_tail;

    if (cache_queue_tail == NULL)
      cache_queue_head = ci;
    else
      cache_queue_tail->next = ci;

    cache_queue_tail = ci;
  }

  ci->flags |= CI_FLAGS_IN_QUEUE;

  pthread_cond_signal(&queue_cond);
  pthread_mutex_lock (&stats_lock);
  stats_queue_length++;
  pthread_mutex_unlock (&stats_lock);

  return (0);
} /* }}} int enqueue_cache_item */

/*
 * tree_callback_flush:
 * Called via `g_tree_foreach' in `flush_thread_main'. `cache_lock' is held
 * while this is in progress.
 */
static gboolean tree_callback_flush (gpointer key, gpointer value, /* {{{ */
    gpointer data)
{
  cache_item_t *ci;
  callback_flush_data_t *cfd;

  ci = (cache_item_t *) value;
  cfd = (callback_flush_data_t *) data;

  if (ci->flags & CI_FLAGS_IN_QUEUE)
    return FALSE;

  if (ci->values_num > 0
      && (ci->last_flush_time <= cfd->abs_timeout || state != RUNNING))
  {
    enqueue_cache_item (ci, TAIL);
  }
  else if (((cfd->now - ci->last_flush_time) >= config_flush_interval)
      && (ci->values_num <= 0))
  {
    assert ((char *) key == ci->file);
    if (!rrd_add_ptr((void ***)&cfd->keys, &cfd->keys_num, (void *)key))
    {
      RRDD_LOG (LOG_ERR, "tree_callback_flush: rrd_add_ptrs failed.");
      return (FALSE);
    }
  }

  return (FALSE);
} /* }}} gboolean tree_callback_flush */

static int flush_old_values (int max_age)
{
  callback_flush_data_t cfd;
  size_t k;

  memset (&cfd, 0, sizeof (cfd));
  /* Pass the current time as user data so that we don't need to call
   * `time' for each node. */
  cfd.now = time (NULL);
  cfd.keys = NULL;
  cfd.keys_num = 0;

  if (max_age > 0)
    cfd.abs_timeout = cfd.now - max_age;
  else
    cfd.abs_timeout = cfd.now + 2*config_write_jitter + 1;

  /* `tree_callback_flush' will return the keys of all values that haven't
   * been touched in the last `config_flush_interval' seconds in `cfd'.
   * The char*'s in this array point to the same memory as ci->file, so we
   * don't need to free them separately. */
  g_tree_foreach (cache_tree, tree_callback_flush, (gpointer) &cfd);

  for (k = 0; k < cfd.keys_num; k++)
  {
    gboolean status = g_tree_remove(cache_tree, cfd.keys[k]);
    /* should never fail, since we have held the cache_lock
     * the entire time */
    assert(status == TRUE);
  }

  if (cfd.keys != NULL)
  {
    free (cfd.keys);
    cfd.keys = NULL;
  }

  return (0);
} /* int flush_old_values */

static void *flush_thread_main (void UNUSED(*args)) /* {{{ */
{
  struct timeval now;
  struct timespec next_flush;
  int status;

  gettimeofday (&now, NULL);
  next_flush.tv_sec = now.tv_sec + config_flush_interval;
  next_flush.tv_nsec = 1000 * now.tv_usec;

  pthread_mutex_lock(&cache_lock);

  while (state == RUNNING)
  {
    gettimeofday (&now, NULL);
    if ((now.tv_sec > next_flush.tv_sec)
        || ((now.tv_sec == next_flush.tv_sec)
          && ((1000 * now.tv_usec) > next_flush.tv_nsec)))
    {
      RRDD_LOG(LOG_DEBUG, "flushing old values");

      /* Determine the time of the next cache flush. */
      next_flush.tv_sec = now.tv_sec + config_flush_interval;

      /* Flush all values that haven't been written in the last
       * `config_write_interval' seconds. */
      flush_old_values (config_write_interval);

      /* unlock the cache while we rotate so we don't block incoming
       * updates if the fsync() blocks on disk I/O */
      pthread_mutex_unlock(&cache_lock);
      journal_rotate();
      pthread_mutex_lock(&cache_lock);
    }

    status = pthread_cond_timedwait(&flush_cond, &cache_lock, &next_flush);
    if (status != 0 && status != ETIMEDOUT)
    {
      RRDD_LOG (LOG_ERR, "flush_thread_main: "
                "pthread_cond_timedwait returned %i.", status);
    }
  }

  if (config_flush_at_shutdown)
    flush_old_values (-1); /* flush everything */

  state = SHUTDOWN;

  pthread_mutex_unlock(&cache_lock);

  return NULL;
} /* void *flush_thread_main */

static void *queue_thread_main (void UNUSED(*args)) /* {{{ */
{
  pthread_mutex_lock (&cache_lock);

  while (state != SHUTDOWN
         || (cache_queue_head != NULL && config_flush_at_shutdown))
  {
    cache_item_t *ci;
    char *file;
    char **values;
    size_t values_num;
    int status;

    /* Now, check if there's something to store away. If not, wait until
     * something comes in. */
    if (cache_queue_head == NULL)
    {
      status = pthread_cond_wait (&queue_cond, &cache_lock);
      if ((status != 0) && (status != ETIMEDOUT))
      {
        RRDD_LOG (LOG_ERR, "queue_thread_main: "
            "pthread_cond_wait returned %i.", status);
      }
    }

    /* Check if a value has arrived. This may be NULL if we timed out or there
     * was an interrupt such as a signal. */
    if (cache_queue_head == NULL)
      continue;

    ci = cache_queue_head;

    /* copy the relevant parts */
    file = strdup (ci->file);
    if (file == NULL)
    {
      RRDD_LOG (LOG_ERR, "queue_thread_main: strdup failed.");
      continue;
    }

    assert(ci->values != NULL);
    assert(ci->values_num > 0);

    values = ci->values;
    values_num = ci->values_num;

    wipe_ci_values(ci, time(NULL));
    remove_from_queue(ci);

    pthread_mutex_unlock (&cache_lock);

    rrd_clear_error ();
    status = rrd_update_r (file, NULL, (int) values_num, (void *) values);
    if (status != 0)
    {
      RRDD_LOG (LOG_NOTICE, "queue_thread_main: "
          "rrd_update_r (%s) failed with status %i. (%s)",
          file, status, rrd_get_error());
    }

    journal_write("wrote", file);

    /* Search again in the tree.  It's possible someone issued a "FORGET"
     * while we were writing the update values. */
    pthread_mutex_lock(&cache_lock);
    ci = (cache_item_t *) g_tree_lookup(cache_tree, file);
    if (ci)
      pthread_cond_broadcast(&ci->flushed);
    pthread_mutex_unlock(&cache_lock);

    if (status == 0)
    {
      pthread_mutex_lock (&stats_lock);
      stats_updates_written++;
      stats_data_sets_written += values_num;
      pthread_mutex_unlock (&stats_lock);
    }

    rrd_free_ptrs((void ***) &values, &values_num);
    free(file);

    pthread_mutex_lock (&cache_lock);
  }
  pthread_mutex_unlock (&cache_lock);

  return (NULL);
} /* }}} void *queue_thread_main */

static int buffer_get_field (char **buffer_ret, /* {{{ */
    size_t *buffer_size_ret, char **field_ret)
{
  char *buffer;
  size_t buffer_pos;
  size_t buffer_size;
  char *field;
  size_t field_size;
  int status;

  buffer = *buffer_ret;
  buffer_pos = 0;
  buffer_size = *buffer_size_ret;
  field = *buffer_ret;
  field_size = 0;

  if (buffer_size <= 0)
    return (-1);

  /* This is ensured by `handle_request'. */
  assert (buffer[buffer_size - 1] == '\0');

  status = -1;
  while (buffer_pos < buffer_size)
  {
    /* Check for end-of-field or end-of-buffer */
    if (buffer[buffer_pos] == ' ' || buffer[buffer_pos] == '\0')
    {
      field[field_size] = 0;
      field_size++;
      buffer_pos++;
      status = 0;
      break;
    }
    /* Handle escaped characters. */
    else if (buffer[buffer_pos] == '\\')
    {
      if (buffer_pos >= (buffer_size - 1))
        break;
      buffer_pos++;
      field[field_size] = buffer[buffer_pos];
      field_size++;
      buffer_pos++;
    }
    /* Normal operation */ 
    else
    {
      field[field_size] = buffer[buffer_pos];
      field_size++;
      buffer_pos++;
    }
  } /* while (buffer_pos < buffer_size) */

  if (status != 0)
    return (status);

  *buffer_ret = buffer + buffer_pos;
  *buffer_size_ret = buffer_size - buffer_pos;
  *field_ret = field;

  return (0);
} /* }}} int buffer_get_field */

/* if we're restricting writes to the base directory,
 * check whether the file falls within the dir
 * returns 1 if OK, otherwise 0
 */
static int check_file_access (const char *file, listen_socket_t *sock) /* {{{ */
{
  assert(file != NULL);

  if (!config_write_base_only
      || JOURNAL_REPLAY(sock)
      || config_base_dir == NULL)
    return 1;

  if (strstr(file, "../") != NULL) goto err;

  /* relative paths without "../" are ok */
  if (*file != '/') return 1;

  /* file must be of the format base + "/" + <1+ char filename> */
  if (strlen(file) < _config_base_dir_len + 2) goto err;
  if (strncmp(file, config_base_dir, _config_base_dir_len) != 0) goto err;
  if (*(file + _config_base_dir_len) != '/') goto err;

  return 1;

err:
  if (sock != NULL && sock->fd >= 0)
    send_response(sock, RESP_ERR, "%s\n", rrd_strerror(EACCES));

  return 0;
} /* }}} static int check_file_access */

/* when using a base dir, convert relative paths to absolute paths.
 * if necessary, modifies the "filename" pointer to point
 * to the new path created in "tmp".  "tmp" is provided
 * by the caller and sizeof(tmp) must be >= PATH_MAX.
 *
 * this allows us to optimize for the expected case (absolute path)
 * with a no-op.
 */
static void get_abs_path(char **filename, char *tmp)
{
  assert(tmp != NULL);
  assert(filename != NULL && *filename != NULL);

  if (config_base_dir == NULL || **filename == '/')
    return;

  snprintf(tmp, PATH_MAX, "%s/%s", config_base_dir, *filename);
  *filename = tmp;
} /* }}} static int get_abs_path */

static int flush_file (const char *filename) /* {{{ */
{
  cache_item_t *ci;

  pthread_mutex_lock (&cache_lock);

  ci = (cache_item_t *) g_tree_lookup (cache_tree, filename);
  if (ci == NULL)
  {
    pthread_mutex_unlock (&cache_lock);
    return (ENOENT);
  }

  if (ci->values_num > 0)
  {
    /* Enqueue at head */
    enqueue_cache_item (ci, HEAD);
    pthread_cond_wait(&ci->flushed, &cache_lock);
  }

  /* DO NOT DO ANYTHING WITH ci HERE!!  The entry
   * may have been purged during our cond_wait() */

  pthread_mutex_unlock(&cache_lock);

  return (0);
} /* }}} int flush_file */

static int syntax_error(listen_socket_t *sock, command_t *cmd) /* {{{ */
{
  char *err = "Syntax error.\n";

  if (cmd && cmd->syntax)
    err = cmd->syntax;

  return send_response(sock, RESP_ERR, "Usage: %s", err);
} /* }}} static int syntax_error() */

static int handle_request_stats (HANDLER_PROTO) /* {{{ */
{
  uint64_t copy_queue_length;
  uint64_t copy_updates_received;
  uint64_t copy_flush_received;
  uint64_t copy_updates_written;
  uint64_t copy_data_sets_written;
  uint64_t copy_journal_bytes;
  uint64_t copy_journal_rotate;

  uint64_t tree_nodes_number;
  uint64_t tree_depth;

  pthread_mutex_lock (&stats_lock);
  copy_queue_length       = stats_queue_length;
  copy_updates_received   = stats_updates_received;
  copy_flush_received     = stats_flush_received;
  copy_updates_written    = stats_updates_written;
  copy_data_sets_written  = stats_data_sets_written;
  copy_journal_bytes      = stats_journal_bytes;
  copy_journal_rotate     = stats_journal_rotate;
  pthread_mutex_unlock (&stats_lock);

  pthread_mutex_lock (&cache_lock);
  tree_nodes_number = (uint64_t) g_tree_nnodes (cache_tree);
  tree_depth        = (uint64_t) g_tree_height (cache_tree);
  pthread_mutex_unlock (&cache_lock);

  add_response_info(sock,
                    "QueueLength: %"PRIu64"\n", copy_queue_length);
  add_response_info(sock,
                    "UpdatesReceived: %"PRIu64"\n", copy_updates_received);
  add_response_info(sock,
                    "FlushesReceived: %"PRIu64"\n", copy_flush_received);
  add_response_info(sock,
                    "UpdatesWritten: %"PRIu64"\n", copy_updates_written);
  add_response_info(sock,
                    "DataSetsWritten: %"PRIu64"\n", copy_data_sets_written);
  add_response_info(sock, "TreeNodesNumber: %"PRIu64"\n", tree_nodes_number);
  add_response_info(sock, "TreeDepth: %"PRIu64"\n", tree_depth);
  add_response_info(sock, "JournalBytes: %"PRIu64"\n", copy_journal_bytes);
  add_response_info(sock, "JournalRotate: %"PRIu64"\n", copy_journal_rotate);

  send_response(sock, RESP_OK, "Statistics follow\n");

  return (0);
} /* }}} int handle_request_stats */

static int handle_request_flush (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  int status;

  status = buffer_get_field (&buffer, &buffer_size, &file);
  if (status != 0)
  {
    return syntax_error(sock,cmd);
  }
  else
  {
    pthread_mutex_lock(&stats_lock);
    stats_flush_received++;
    pthread_mutex_unlock(&stats_lock);

    get_abs_path(&file, file_tmp);
    if (!check_file_access(file, sock)) return 0;

    status = flush_file (file);
    if (status == 0)
      return send_response(sock, RESP_OK, "Successfully flushed %s.\n", file);
    else if (status == ENOENT)
    {
      /* no file in our tree; see whether it exists at all */
      struct stat statbuf;

      memset(&statbuf, 0, sizeof(statbuf));
      if (stat(file, &statbuf) == 0 && S_ISREG(statbuf.st_mode))
        return send_response(sock, RESP_OK, "Nothing to flush: %s.\n", file);
      else
        return send_response(sock, RESP_ERR, "No such file: %s.\n", file);
    }
    else if (status < 0)
      return send_response(sock, RESP_ERR, "Internal error.\n");
    else
      return send_response(sock, RESP_ERR, "Failed with status %i.\n", status);
  }

  /* NOTREACHED */
  assert(1==0);
} /* }}} int handle_request_flush */

static int handle_request_flushall(HANDLER_PROTO) /* {{{ */
{
  RRDD_LOG(LOG_DEBUG, "Received FLUSHALL");

  pthread_mutex_lock(&cache_lock);
  flush_old_values(-1);
  pthread_mutex_unlock(&cache_lock);

  return send_response(sock, RESP_OK, "Started flush.\n");
} /* }}} static int handle_request_flushall */

static int handle_request_pending(HANDLER_PROTO) /* {{{ */
{
  int status;
  char *file, file_tmp[PATH_MAX];
  cache_item_t *ci;

  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);

  get_abs_path(&file, file_tmp);

  pthread_mutex_lock(&cache_lock);
  ci = g_tree_lookup(cache_tree, file);
  if (ci == NULL)
  {
    pthread_mutex_unlock(&cache_lock);
    return send_response(sock, RESP_ERR, "%s\n", rrd_strerror(ENOENT));
  }

  for (size_t i=0; i < ci->values_num; i++)
    add_response_info(sock, "%s\n", ci->values[i]);

  pthread_mutex_unlock(&cache_lock);
  return send_response(sock, RESP_OK, "updates pending\n");
} /* }}} static int handle_request_pending */

static int handle_request_forget(HANDLER_PROTO) /* {{{ */
{
  int status;
  gboolean found;
  char *file, file_tmp[PATH_MAX];

  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);

  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) return 0;

  pthread_mutex_lock(&cache_lock);
  found = g_tree_remove(cache_tree, file);
  pthread_mutex_unlock(&cache_lock);

  if (found == TRUE)
  {
    if (!JOURNAL_REPLAY(sock))
      journal_write("forget", file);

    return send_response(sock, RESP_OK, "Gone!\n");
  }
  else
    return send_response(sock, RESP_ERR, "%s\n", rrd_strerror(ENOENT));

  /* NOTREACHED */
  assert(1==0);
} /* }}} static int handle_request_forget */

static int handle_request_queue (HANDLER_PROTO) /* {{{ */
{
  cache_item_t *ci;

  pthread_mutex_lock(&cache_lock);

  ci = cache_queue_head;
  while (ci != NULL)
  {
    add_response_info(sock, "%d %s\n", ci->values_num, ci->file);
    ci = ci->next;
  }

  pthread_mutex_unlock(&cache_lock);

  return send_response(sock, RESP_OK, "in queue.\n");
} /* }}} int handle_request_queue */

static int handle_request_update (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  int values_num = 0;
  int status;
  char orig_buf[RRD_CMD_MAX];

  cache_item_t *ci;

  /* save it for the journal later */
  if (!JOURNAL_REPLAY(sock))
    strncpy(orig_buf, buffer, min(RRD_CMD_MAX,buffer_size));

  status = buffer_get_field (&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);

  pthread_mutex_lock(&stats_lock);
  stats_updates_received++;
  pthread_mutex_unlock(&stats_lock);

  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) return 0;

  pthread_mutex_lock (&cache_lock);
  ci = g_tree_lookup (cache_tree, file);

  if (ci == NULL) /* {{{ */
  {
    struct stat statbuf;
    cache_item_t *tmp;

    /* don't hold the lock while we setup; stat(2) might block */
    pthread_mutex_unlock(&cache_lock);

    memset (&statbuf, 0, sizeof (statbuf));
    status = stat (file, &statbuf);
    if (status != 0)
    {
      RRDD_LOG (LOG_NOTICE, "handle_request_update: stat (%s) failed.", file);

      status = errno;
      if (status == ENOENT)
        return send_response(sock, RESP_ERR, "No such file: %s\n", file);
      else
        return send_response(sock, RESP_ERR,
                             "stat failed with error %i.\n", status);
    }
    if (!S_ISREG (statbuf.st_mode))
      return send_response(sock, RESP_ERR, "Not a regular file: %s\n", file);

    if (access(file, R_OK|W_OK) != 0)
      return send_response(sock, RESP_ERR, "Cannot read/write %s: %s\n",
                           file, rrd_strerror(errno));

    ci = (cache_item_t *) malloc (sizeof (cache_item_t));
    if (ci == NULL)
    {
      RRDD_LOG (LOG_ERR, "handle_request_update: malloc failed.");

      return send_response(sock, RESP_ERR, "malloc failed.\n");
    }
    memset (ci, 0, sizeof (cache_item_t));

    ci->file = strdup (file);
    if (ci->file == NULL)
    {
      free (ci);
      RRDD_LOG (LOG_ERR, "handle_request_update: strdup failed.");

      return send_response(sock, RESP_ERR, "strdup failed.\n");
    }

    wipe_ci_values(ci, now);
    ci->flags = CI_FLAGS_IN_TREE;
    pthread_cond_init(&ci->flushed, NULL);

    pthread_mutex_lock(&cache_lock);

    /* another UPDATE might have added this entry in the meantime */
    tmp = g_tree_lookup (cache_tree, file);
    if (tmp == NULL)
      g_tree_replace (cache_tree, (void *) ci->file, (void *) ci);
    else
    {
      free_cache_item (ci);
      ci = tmp;
    }

    /* state may have changed while we were unlocked */
    if (state == SHUTDOWN)
      return -1;
  } /* }}} */
  assert (ci != NULL);

  /* don't re-write updates in replay mode */
  if (!JOURNAL_REPLAY(sock))
    journal_write("update", orig_buf);

  while (buffer_size > 0)
  {
    char *value;
    double stamp;
    char *eostamp;

    status = buffer_get_field (&buffer, &buffer_size, &value);
    if (status != 0)
    {
      RRDD_LOG (LOG_INFO, "handle_request_update: Error reading field.");
      break;
    }

    /* make sure update time is always moving forward. We use double here since
       update does support subsecond precision for timestamps ... */
    stamp = strtod(value, &eostamp);
    if (eostamp == value || eostamp == NULL || *eostamp != ':')
    {
      pthread_mutex_unlock(&cache_lock);
      return send_response(sock, RESP_ERR,
                           "Cannot find timestamp in '%s'!\n", value);
    }
    else if (stamp <= ci->last_update_stamp)
    {
      pthread_mutex_unlock(&cache_lock);
      return send_response(sock, RESP_ERR,
                           "illegal attempt to update using time %lf when last"
                           " update time is %lf (minimum one second step)\n",
                           stamp, ci->last_update_stamp);
    }
    else
      ci->last_update_stamp = stamp;

    if (!rrd_add_strdup_chunk(&ci->values, &ci->values_num, value,
                              &ci->values_alloc, config_alloc_chunk))
    {
      RRDD_LOG (LOG_ERR, "handle_request_update: rrd_add_strdup failed.");
      continue;
    }

    values_num++;
  }

  if (((now - ci->last_flush_time) >= config_write_interval)
      && ((ci->flags & CI_FLAGS_IN_QUEUE) == 0)
      && (ci->values_num > 0))
  {
    enqueue_cache_item (ci, TAIL);
  }

  pthread_mutex_unlock (&cache_lock);

  if (values_num < 1)
    return send_response(sock, RESP_ERR, "No values updated.\n");
  else
    return send_response(sock, RESP_OK,
                         "errors, enqueued %i value(s).\n", values_num);

  /* NOTREACHED */
  assert(1==0);

} /* }}} int handle_request_update */

static int handle_request_fetch (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  char *cf;

  char *start_str;
  char *end_str;
  time_t start_tm;
  time_t end_tm;

  unsigned long step;
  unsigned long ds_cnt;
  char **ds_namv;
  rrd_value_t *data;

  int status;
  unsigned long i;
  time_t t;
  rrd_value_t *data_ptr;

  file = NULL;
  cf = NULL;
  start_str = NULL;
  end_str = NULL;

  /* Read the arguments */
  do /* while (0) */
  {
    status = buffer_get_field (&buffer, &buffer_size, &file);
    if (status != 0)
      break;

    status = buffer_get_field (&buffer, &buffer_size, &cf);
    if (status != 0)
      break;

    status = buffer_get_field (&buffer, &buffer_size, &start_str);
    if (status != 0)
    {
      start_str = NULL;
      status = 0;
      break;
    }

    status = buffer_get_field (&buffer, &buffer_size, &end_str);
    if (status != 0)
    {
      end_str = NULL;
      status = 0;
      break;
    }
  } while (0);

  if (status != 0)
    return (syntax_error(sock,cmd));

  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) return 0;

  status = flush_file (file);
  if ((status != 0) && (status != ENOENT))
    return (send_response (sock, RESP_ERR,
          "flush_file (%s) failed with status %i.\n", file, status));

  t = time (NULL); /* "now" */

  /* Parse start time */
  if (start_str != NULL)
  {
    char *endptr;
    long value;

    endptr = NULL;
    errno = 0;
    value = strtol (start_str, &endptr, /* base = */ 0);
    if ((endptr == start_str) || (errno != 0))
      return (send_response(sock, RESP_ERR,
            "Cannot parse start time `%s': Only simple integers are allowed.\n",
            start_str));

    if (value > 0)
      start_tm = (time_t) value;
    else
      start_tm = (time_t) (t + value);
  }
  else
  {
    start_tm = t - 86400;
  }

  /* Parse end time */
  if (end_str != NULL)
  {
    char *endptr;
    long value;

    endptr = NULL;
    errno = 0;
    value = strtol (end_str, &endptr, /* base = */ 0);
    if ((endptr == end_str) || (errno != 0))
      return (send_response(sock, RESP_ERR,
            "Cannot parse end time `%s': Only simple integers are allowed.\n",
            end_str));

    if (value > 0)
      end_tm = (time_t) value;
    else
      end_tm = (time_t) (t + value);
  }
  else
  {
    end_tm = t;
  }

  step = -1;
  ds_cnt = 0;
  ds_namv = NULL;
  data = NULL;

  status = rrd_fetch_r (file, cf, &start_tm, &end_tm, &step,
      &ds_cnt, &ds_namv, &data);
  if (status != 0)
    return (send_response(sock, RESP_ERR,
          "rrd_fetch_r failed: %s\n", rrd_get_error ()));

  add_response_info (sock, "FlushVersion: %lu\n", 1);
  add_response_info (sock, "Start: %lu\n", (unsigned long) start_tm);
  add_response_info (sock, "End: %lu\n", (unsigned long) end_tm);
  add_response_info (sock, "Step: %lu\n", step);
  add_response_info (sock, "DSCount: %lu\n", ds_cnt);

#define SSTRCAT(buffer,str,buffer_fill) do { \
    size_t str_len = strlen (str); \
    if ((buffer_fill + str_len) > sizeof (buffer)) \
      str_len = sizeof (buffer) - buffer_fill; \
    if (str_len > 0) { \
      strncpy (buffer + buffer_fill, str, str_len); \
      buffer_fill += str_len; \
      assert (buffer_fill <= sizeof (buffer)); \
      if (buffer_fill == sizeof (buffer)) \
        buffer[buffer_fill - 1] = 0; \
      else \
        buffer[buffer_fill] = 0; \
    } \
  } while (0)

  { /* Add list of DS names */
    char linebuf[1024];
    size_t linebuf_fill;

    memset (linebuf, 0, sizeof (linebuf));
    linebuf_fill = 0;
    for (i = 0; i < ds_cnt; i++)
    {
      if (i > 0)
        SSTRCAT (linebuf, " ", linebuf_fill);
      SSTRCAT (linebuf, ds_namv[i], linebuf_fill);
      rrd_freemem(ds_namv[i]);
    }
    rrd_freemem(ds_namv);
    add_response_info (sock, "DSName: %s\n", linebuf);
  }

  /* Add the actual data */
  assert (step > 0);
  data_ptr = data;
  for (t = start_tm + step; t <= end_tm; t += step)
  {
    char linebuf[1024];
    size_t linebuf_fill;
    char tmp[128];

    memset (linebuf, 0, sizeof (linebuf));
    linebuf_fill = 0;
    for (i = 0; i < ds_cnt; i++)
    {
      snprintf (tmp, sizeof (tmp), " %0.10e", *data_ptr);
      tmp[sizeof (tmp) - 1] = 0;
      SSTRCAT (linebuf, tmp, linebuf_fill);

      data_ptr++;
    }

    add_response_info (sock, "%10lu:%s\n", (unsigned long) t, linebuf);
  } /* for (t) */
  rrd_freemem(data);

  return (send_response (sock, RESP_OK, "Success\n"));
#undef SSTRCAT
} /* }}} int handle_request_fetch */

/* we came across a "WROTE" entry during journal replay.
 * throw away any values that we have accumulated for this file
 */
static int handle_request_wrote (HANDLER_PROTO) /* {{{ */
{
  cache_item_t *ci;
  const char *file = buffer;

  pthread_mutex_lock(&cache_lock);

  ci = g_tree_lookup(cache_tree, file);
  if (ci == NULL)
  {
    pthread_mutex_unlock(&cache_lock);
    return (0);
  }

  if (ci->values)
    rrd_free_ptrs((void ***) &ci->values, &ci->values_num);

  wipe_ci_values(ci, now);
  remove_from_queue(ci);

  pthread_mutex_unlock(&cache_lock);
  return (0);
} /* }}} int handle_request_wrote */

static int handle_request_info (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  int status;
  rrd_info_t *info;

  /* obtain filename */
  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);
  /* get full pathname */
  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) {
    return send_response(sock, RESP_ERR, "Cannot read: %s\n", file);
  }
  /* get data */
  rrd_clear_error ();
  info = rrd_info_r(file);
  if(!info) {
    return send_response(sock, RESP_ERR, "RRD Error: %s\n", rrd_get_error());
  }
  for (rrd_info_t *data = info; data != NULL; data = data->next) {
      switch (data->type) {
      case RD_I_VAL:
          if (isnan(data->value.u_val))
              add_response_info(sock,"%s %d NaN\n",data->key, data->type);
          else
              add_response_info(sock,"%s %d %0.10e\n", data->key, data->type, data->value.u_val);
          break;
      case RD_I_CNT:
          add_response_info(sock,"%s %d %lu\n", data->key, data->type, data->value.u_cnt);
          break;
      case RD_I_INT:
          add_response_info(sock,"%s %d %d\n", data->key, data->type, data->value.u_int);
          break;
      case RD_I_STR:
          add_response_info(sock,"%s %d %s\n", data->key, data->type, data->value.u_str);
          break;
      case RD_I_BLO:
          add_response_info(sock,"%s %d %lu\n", data->key, data->type, data->value.u_blo.size);
          break;
      }
  }

  rrd_info_free(info);

  return send_response(sock, RESP_OK, "Info for %s follows\n",file);
} /* }}} static int handle_request_info  */

static int handle_request_first (HANDLER_PROTO) /* {{{ */
{
  char *i, *file, file_tmp[PATH_MAX];
  int status;
  int idx;
  time_t t;

  /* obtain filename */
  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);
  /* get full pathname */
  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) {
    return send_response(sock, RESP_ERR, "Cannot read: %s\n", file);
  }

  status = buffer_get_field(&buffer, &buffer_size, &i);
  if (status != 0)
    return syntax_error(sock,cmd);
  idx = atoi(i);
  if(idx<0) { 
    return send_response(sock, RESP_ERR, "Invalid index specified (%d)\n", idx);
  }

  /* get data */
  rrd_clear_error ();
  t = rrd_first_r(file,idx);
  if(t<1) {
    return send_response(sock, RESP_ERR, "RRD Error: %s\n", rrd_get_error());
  }
  return send_response(sock, RESP_OK, "%lu\n",(unsigned)t);
} /* }}} static int handle_request_first  */


static int handle_request_last (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  int status;
  time_t t, from_file, step;
  rrd_file_t * rrd_file;
  cache_item_t * ci;
  rrd_t rrd; 

  /* obtain filename */
  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);
  /* get full pathname */
  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) {
    return send_response(sock, RESP_ERR, "Cannot read: %s\n", file);
  }
  rrd_clear_error();
  rrd_init(&rrd);
  rrd_file = rrd_open(file,&rrd,RRD_READONLY);
  if(!rrd_file) {
    return send_response(sock, RESP_ERR, "RRD Error: %s\n", rrd_get_error());
  }
  from_file = rrd.live_head->last_up;
  step = rrd.stat_head->pdp_step;
  rrd_close(rrd_file);
  pthread_mutex_lock(&cache_lock);
  ci = g_tree_lookup(cache_tree, file);
  if (ci)
    t = ci->last_update_stamp;
  else
    t = from_file;
  pthread_mutex_unlock(&cache_lock);
  t -= t % step;
  rrd_free(&rrd);
  if(t<1) {
    return send_response(sock, RESP_ERR, "Error: rrdcached: Invalid timestamp returned\n");
  }
  return send_response(sock, RESP_OK, "%lu\n",(unsigned)t);
} /* }}} static int handle_request_last  */

static int handle_request_create (HANDLER_PROTO) /* {{{ */
{
  char *file, file_tmp[PATH_MAX];
  char *tok;
  int ac = 0;
  char *av[128];
  int status;
  unsigned long step = 300;
  time_t last_up = time(NULL)-10;
  int no_overwrite = opt_no_overwrite;


  /* obtain filename */
  status = buffer_get_field(&buffer, &buffer_size, &file);
  if (status != 0)
    return syntax_error(sock,cmd);
  /* get full pathname */
  get_abs_path(&file, file_tmp);
  if (!check_file_access(file, sock)) {
    return send_response(sock, RESP_ERR, "Cannot read: %s\n", file);
  }
  RRDD_LOG(LOG_INFO, "rrdcreate request for %s",file);

  while ((status = buffer_get_field(&buffer, &buffer_size, &tok)) == 0 && tok) {
    if( ! strncmp(tok,"-b",2) ) {
      status = buffer_get_field(&buffer, &buffer_size, &tok );
      if (status != 0) return syntax_error(sock,cmd);
      last_up = (time_t) atol(tok);
      continue;
    }
    if( ! strncmp(tok,"-s",2) ) {
      status = buffer_get_field(&buffer, &buffer_size, &tok );
      if (status != 0) return syntax_error(sock,cmd);
      step = atol(tok);
      continue;
    }
    if( ! strncmp(tok,"-O",2) ) {
      no_overwrite = 1;
      continue;
    }
    if( ! strncmp(tok,"DS:",3) ) { av[ac++]=tok; continue; }
    if( ! strncmp(tok,"RRA:",4) ) { av[ac++]=tok; continue; }
    return syntax_error(sock,cmd);
  }
  if(step<1) {
    return send_response(sock, RESP_ERR, "The step size cannot be less than 1 second.\n");
  }
  if (last_up < 3600 * 24 * 365 * 10) {
    return send_response(sock, RESP_ERR, "The first entry must be after 1980.\n");
  }

  rrd_clear_error ();
  status = rrd_create_r2(file,step,last_up,no_overwrite,ac,(const char **)av);

  if(!status) {
    return send_response(sock, RESP_OK, "RRD created OK\n");
  }
  return send_response(sock, RESP_ERR, "RRD Error: %s\n", rrd_get_error());
} /* }}} static int handle_request_create  */

/* start "BATCH" processing */
static int batch_start (HANDLER_PROTO) /* {{{ */
{
  int status;
  if (sock->batch_start)
    return send_response(sock, RESP_ERR, "Already in BATCH\n");

  status = send_response(sock, RESP_OK,
                         "Go ahead.  End with dot '.' on its own line.\n");
  sock->batch_start = time(NULL);
  sock->batch_cmd = 0;

  return status;
} /* }}} static int batch_start */

/* finish "BATCH" processing and return results to the client */
static int batch_done (HANDLER_PROTO) /* {{{ */
{
  assert(sock->batch_start);
  sock->batch_start = 0;
  sock->batch_cmd  = 0;
  return send_response(sock, RESP_OK, "errors\n");
} /* }}} static int batch_done */

static int handle_request_quit (HANDLER_PROTO) /* {{{ */
{
  return -1;
} /* }}} static int handle_request_quit */

static command_t list_of_commands[] = { /* {{{ */
  {
    "UPDATE",
    handle_request_update,
    CMD_CONTEXT_ANY,
    "UPDATE <filename> <values> [<values> ...]\n"
    ,
    "Adds the given file to the internal cache if it is not yet known and\n"
    "appends the given value(s) to the entry. See the rrdcached(1) manpage\n"
    "for details.\n"
    "\n"
    "Each <values> has the following form:\n"
    "  <values> = <time>:<value>[:<value>[...]]\n"
    "See the rrdupdate(1) manpage for details.\n"
  },
  {
    "WROTE",
    handle_request_wrote,
    CMD_CONTEXT_JOURNAL,
    NULL,
    NULL
  },
  {
    "FLUSH",
    handle_request_flush,
    CMD_CONTEXT_CLIENT | CMD_CONTEXT_BATCH,
    "FLUSH <filename>\n"
    ,
    "Adds the given filename to the head of the update queue and returns\n"
    "after it has been dequeued.\n"
  },
  {
    "FLUSHALL",
    handle_request_flushall,
    CMD_CONTEXT_CLIENT,
    "FLUSHALL\n"
    ,
    "Triggers writing of all pending updates.  Returns immediately.\n"
  },
  {
    "PENDING",
    handle_request_pending,
    CMD_CONTEXT_CLIENT,
    "PENDING <filename>\n"
    ,
    "Shows any 'pending' updates for a file, in order.\n"
    "The updates shown have not yet been written to the underlying RRD file.\n"
  },
  {
    "FORGET",
    handle_request_forget,
    CMD_CONTEXT_ANY,
    "FORGET <filename>\n"
    ,
    "Removes the file completely from the cache.\n"
    "Any pending updates for the file will be lost.\n"
  },
  {
    "QUEUE",
    handle_request_queue,
    CMD_CONTEXT_CLIENT,
    "QUEUE\n"
    ,
        "Shows all files in the output queue.\n"
    "The output is zero or more lines in the following format:\n"
    "(where <num_vals> is the number of values to be written)\n"
    "\n"
    "<num_vals> <filename>\n"
  },
  {
    "STATS",
    handle_request_stats,
    CMD_CONTEXT_CLIENT,
    "STATS\n"
    ,
    "Returns some performance counters, see the rrdcached(1) manpage for\n"
    "a description of the values.\n"
  },
  {
    "HELP",
    handle_request_help,
    CMD_CONTEXT_CLIENT,
    "HELP [<command>]\n",
    NULL, /* special! */
  },
  {
    "BATCH",
    batch_start,
    CMD_CONTEXT_CLIENT,
    "BATCH\n"
    ,
    "The 'BATCH' command permits the client to initiate a bulk load\n"
    "   of commands to rrdcached.\n"
    "\n"
    "Usage:\n"
    "\n"
    "    client: BATCH\n"
    "    server: 0 Go ahead.  End with dot '.' on its own line.\n"
    "    client: command #1\n"
    "    client: command #2\n"
    "    client: ... and so on\n"
    "    client: .\n"
    "    server: 2 errors\n"
    "    server: 7 message for command #7\n"
    "    server: 9 message for command #9\n"
    "\n"
    "For more information, consult the rrdcached(1) documentation.\n"
  },
  {
    ".",   /* BATCH terminator */
    batch_done,
    CMD_CONTEXT_BATCH,
    NULL,
    NULL
  },
  {
    "FETCH",
    handle_request_fetch,
    CMD_CONTEXT_CLIENT,
    "FETCH <file> <CF> [<start> [<end>]]\n"
    ,
    "The 'FETCH' can be used by the client to retrieve values from an RRD file.\n"
  },
  {
    "INFO",
    handle_request_info,
    CMD_CONTEXT_CLIENT,
    "INFO <filename>\n",
    "The INFO command retrieves information about a specified RRD file.\n"
    "This is returned in standard rrdinfo format, a sequence of lines\n"
    "with the format <keyname> = <value>\n"
    "Note that this is the data as of the last update of the RRD file itself,\n"
    "not the last time data was received via rrdcached, so there may be pending\n"
    "updates in the queue.  If this bothers you, then first run a FLUSH.\n"
  },
  {
    "FIRST",
    handle_request_first,
    CMD_CONTEXT_CLIENT,
    "FIRST <filename> <rra index>\n",
    "The FIRST command retrieves the first data time for a specified RRA in\n"
    "an RRD file.\n"
  },
  {
    "LAST",
    handle_request_last,
    CMD_CONTEXT_CLIENT,
    "LAST <filename>\n",
    "The LAST command retrieves the last update time for a specified RRD file.\n"
    "Note that this is the time of the last update of the RRD file itself, not\n"
    "the last time data was received via rrdcached, so there may be pending\n"
    "updates in the queue.  If this bothers you, then first run a FLUSH.\n"
  },
  {
    "CREATE",
    handle_request_create,
    CMD_CONTEXT_CLIENT | CMD_CONTEXT_BATCH,
    "CREATE <filename> [-b start] [-s step] [-O] <DS definitions> <RRA definitions>\n",
    "The CREATE command will create an RRD file, overwriting any existing file\n"
    "unless the -O option is given or rrdcached was started with the -O option.\n"
    "The start parameter needs to be in seconds since 1/1/70 (AT-style syntax is\n"
    "not acceptable) and the step is in seconds (default is 300).\n"
    "The DS and RRA definitions are as for the 'rrdtool create' command.\n"
  },
  {
    "QUIT",
    handle_request_quit,
    CMD_CONTEXT_CLIENT | CMD_CONTEXT_BATCH,
    "QUIT\n"
    ,
    "Disconnect from rrdcached.\n"
  }
}; /* }}} command_t list_of_commands[] */
static size_t list_of_commands_len = sizeof (list_of_commands)
  / sizeof (list_of_commands[0]);

static command_t *find_command(char *cmd)
{
  size_t i;

  for (i = 0; i < list_of_commands_len; i++)
    if (strcasecmp(cmd, list_of_commands[i].cmd) == 0)
      return (&list_of_commands[i]);
  return NULL;
}

/* We currently use the index in the `list_of_commands' array as a bit position
 * in `listen_socket_t.permissions'. This member schould NEVER be accessed from
 * outside these functions so that switching to a more elegant storage method
 * is easily possible. */
static ssize_t find_command_index (const char *cmd) /* {{{ */
{
  size_t i;

  for (i = 0; i < list_of_commands_len; i++)
    if (strcasecmp(cmd, list_of_commands[i].cmd) == 0)
      return ((ssize_t) i);
  return (-1);
} /* }}} ssize_t find_command_index */

static int socket_permission_check (listen_socket_t *sock, /* {{{ */
    const char *cmd)
{
  ssize_t i;

  if (JOURNAL_REPLAY(sock))
    return (1);

  if (cmd == NULL)
    return (-1);

  if ((strcasecmp ("QUIT", cmd) == 0)
      || (strcasecmp ("HELP", cmd) == 0))
    return (1);
  else if (strcmp (".", cmd) == 0)
    cmd = "BATCH";

  i = find_command_index (cmd);
  if (i < 0)
    return (-1);
  assert (i < 32);

  if ((sock->permissions & (1 << i)) != 0)
    return (1);
  return (0);
} /* }}} int socket_permission_check */

static int socket_permission_add (listen_socket_t *sock, /* {{{ */
    const char *cmd)
{
  ssize_t i;

  i = find_command_index (cmd);
  if (i < 0)
    return (-1);
  assert (i < 32);

  sock->permissions |= (1 << i);
  return (0);
} /* }}} int socket_permission_add */

static void socket_permission_clear (listen_socket_t *sock) /* {{{ */
{
  sock->permissions = 0;
} /* }}} socket_permission_clear */

static void socket_permission_copy (listen_socket_t *dest, /* {{{ */
    listen_socket_t *src)
{
  dest->permissions = src->permissions;
} /* }}} socket_permission_copy */

static void socket_permission_set_all (listen_socket_t *sock) /* {{{ */
{
  size_t i;

  sock->permissions = 0;
  for (i = 0; i < list_of_commands_len; i++)
    sock->permissions |= (1 << i);
} /* }}} void socket_permission_set_all */

/* check whether commands are received in the expected context */
static int command_check_context(listen_socket_t *sock, command_t *cmd)
{
  if (JOURNAL_REPLAY(sock))
    return (cmd->context & CMD_CONTEXT_JOURNAL);
  else if (sock->batch_start)
    return (cmd->context & CMD_CONTEXT_BATCH);
  else
    return (cmd->context & CMD_CONTEXT_CLIENT);

  /* NOTREACHED */
  assert(1==0);
}

static int handle_request_help (HANDLER_PROTO) /* {{{ */
{
  int status;
  char *cmd_str;
  char *resp_txt;
  command_t *help = NULL;

  status = buffer_get_field (&buffer, &buffer_size, &cmd_str);
  if (status == 0)
    help = find_command(cmd_str);

  if (help && (help->syntax || help->help))
  {
    char tmp[RRD_CMD_MAX];

    snprintf(tmp, sizeof(tmp)-1, "Help for %s\n", help->cmd);
    resp_txt = tmp;

    if (help->syntax)
      add_response_info(sock, "Usage: %s\n", help->syntax);

    if (help->help)
      add_response_info(sock, "%s\n", help->help);
  }
  else
  {
    size_t i;

    resp_txt = "Command overview\n";

    for (i = 0; i < list_of_commands_len; i++)
    {
      if (list_of_commands[i].syntax == NULL)
        continue;
      add_response_info (sock, "%s", list_of_commands[i].syntax);
    }
  }

  return send_response(sock, RESP_OK, resp_txt);
} /* }}} int handle_request_help */

static int handle_request (DISPATCH_PROTO) /* {{{ */
{
  char *buffer_ptr = buffer;
  char *cmd_str = NULL;
  command_t *cmd = NULL;
  int status;

  assert (buffer[buffer_size - 1] == '\0');

  status = buffer_get_field (&buffer_ptr, &buffer_size, &cmd_str);
  if (status != 0)
  {
    RRDD_LOG (LOG_INFO, "handle_request: Unable parse command.");
    return (-1);
  }

  if (sock != NULL && sock->batch_start)
    sock->batch_cmd++;

  cmd = find_command(cmd_str);
  if (!cmd)
    return send_response(sock, RESP_ERR, "Unknown command: %s\n", cmd_str);

  if (!socket_permission_check (sock, cmd->cmd))
    return send_response(sock, RESP_ERR, "Permission denied.\n");

  if (!command_check_context(sock, cmd))
    return send_response(sock, RESP_ERR, "Can't use '%s' here.\n", cmd_str);

  return cmd->handler(cmd, sock, now, buffer_ptr, buffer_size);
} /* }}} int handle_request */

static void journal_set_free (journal_set *js) /* {{{ */
{
  if (js == NULL)
    return;

  rrd_free_ptrs((void ***) &js->files, &js->files_num);

  free(js);
} /* }}} journal_set_free */

static void journal_set_remove (journal_set *js) /* {{{ */
{
  if (js == NULL)
    return;

  for (uint i=0; i < js->files_num; i++)
  {
    RRDD_LOG(LOG_DEBUG, "removing old journal %s", js->files[i]);
    unlink(js->files[i]);
  }
} /* }}} journal_set_remove */

/* close current journal file handle.
 * MUST hold journal_lock before calling */
static void journal_close(void) /* {{{ */
{
  if (journal_fh != NULL)
  {
    if (fclose(journal_fh) != 0)
      RRDD_LOG(LOG_ERR, "cannot close journal: %s", rrd_strerror(errno));
  }

  journal_fh = NULL;
  journal_size = 0;
} /* }}} journal_close */

/* MUST hold journal_lock before calling */
static void journal_new_file(void) /* {{{ */
{
  struct timeval now;
  int  new_fd;
  char new_file[PATH_MAX + 1];

  assert(journal_dir != NULL);
  assert(journal_cur != NULL);

  journal_close();

  gettimeofday(&now, NULL);
  /* this format assures that the files sort in strcmp() order */
  snprintf(new_file, PATH_MAX, "%s/%s.%010d.%06d",
           journal_dir, JOURNAL_BASE, (int)now.tv_sec, (int)now.tv_usec);

  new_fd = open(new_file, O_WRONLY|O_CREAT|O_APPEND,
                S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
  if (new_fd < 0)
    goto error;

  journal_fh = fdopen(new_fd, "a");
  if (journal_fh == NULL)
    goto error;

  journal_size = ftell(journal_fh);
  RRDD_LOG(LOG_DEBUG, "started new journal %s", new_file);

  /* record the file in the journal set */
  rrd_add_strdup(&journal_cur->files, &journal_cur->files_num, new_file);

  return;

error:
  RRDD_LOG(LOG_CRIT,
           "JOURNALING DISABLED: Error while trying to create %s : %s",
           new_file, rrd_strerror(errno));
  RRDD_LOG(LOG_CRIT,
           "JOURNALING DISABLED: All values will be flushed at shutdown");

  close(new_fd);
  config_flush_at_shutdown = 1;

} /* }}} journal_new_file */

/* MUST NOT hold journal_lock before calling this */
static void journal_rotate(void) /* {{{ */
{
  journal_set *old_js = NULL;

  if (journal_dir == NULL)
    return;

  RRDD_LOG(LOG_DEBUG, "rotating journals");

  pthread_mutex_lock(&stats_lock);
  ++stats_journal_rotate;
  pthread_mutex_unlock(&stats_lock);

  pthread_mutex_lock(&journal_lock);

  journal_close();

  /* rotate the journal sets */
  old_js = journal_old;
  journal_old = journal_cur;
  journal_cur = calloc(1, sizeof(journal_set));

  if (journal_cur != NULL)
    journal_new_file();
  else
    RRDD_LOG(LOG_CRIT, "journal_rotate: malloc(journal_set) failed\n");

  pthread_mutex_unlock(&journal_lock);

  journal_set_remove(old_js);
  journal_set_free  (old_js);

} /* }}} static void journal_rotate */

/* MUST hold journal_lock when calling */
static void journal_done(void) /* {{{ */
{
  if (journal_cur == NULL)
    return;

  journal_close();

  if (config_flush_at_shutdown)
  {
    RRDD_LOG(LOG_INFO, "removing journals");
    journal_set_remove(journal_old);
    journal_set_remove(journal_cur);
  }
  else
  {
    RRDD_LOG(LOG_INFO, "expedited shutdown; "
             "journals will be used at next startup");
  }

  journal_set_free(journal_cur);
  journal_set_free(journal_old);
  free(journal_dir);

} /* }}} static void journal_done */

static int journal_write(char *cmd, char *args) /* {{{ */
{
  int chars;

  if (journal_fh == NULL)
    return 0;

  pthread_mutex_lock(&journal_lock);
  chars = fprintf(journal_fh, "%s %s\n", cmd, args);
  journal_size += chars;

  if (journal_size > JOURNAL_MAX)
    journal_new_file();

  pthread_mutex_unlock(&journal_lock);

  if (chars > 0)
  {
    pthread_mutex_lock(&stats_lock);
    stats_journal_bytes += chars;
    pthread_mutex_unlock(&stats_lock);
  }

  return chars;
} /* }}} static int journal_write */

static int journal_replay (const char *file) /* {{{ */
{
  FILE *fh;
  int entry_cnt = 0;
  int fail_cnt = 0;
  uint64_t line = 0;
  char entry[RRD_CMD_MAX];
  time_t now;

  if (file == NULL) return 0;

  {
    char *reason = "unknown error";
    int status = 0;
    struct stat statbuf;

    memset(&statbuf, 0, sizeof(statbuf));
    if (stat(file, &statbuf) != 0)
    {
      reason = "stat error";
      status = errno;
    }
    else if (!S_ISREG(statbuf.st_mode))
    {
      reason = "not a regular file";
      status = EPERM;
    }
    if (statbuf.st_uid != daemon_uid)
    {
      reason = "not owned by daemon user";
      status = EACCES;
    }
    if (statbuf.st_mode & (S_IWGRP|S_IWOTH))
    {
      reason = "must not be user/group writable";
      status = EACCES;
    }

    if (status != 0)
    {
      RRDD_LOG(LOG_ERR, "journal_replay: %s : %s (%s)",
               file, rrd_strerror(status), reason);
      return 0;
    }
  }

  fh = fopen(file, "r");
  if (fh == NULL)
  {
    if (errno != ENOENT)
      RRDD_LOG(LOG_ERR, "journal_replay: cannot open journal file: '%s' (%s)",
               file, rrd_strerror(errno));
    return 0;
  }
  else
    RRDD_LOG(LOG_NOTICE, "replaying from journal: %s", file);

  now = time(NULL);

  while(!feof(fh))
  {
    size_t entry_len;

    ++line;
    if (fgets(entry, sizeof(entry), fh) == NULL)
      break;
    entry_len = strlen(entry);

    /* check \n termination in case journal writing crashed mid-line */
    if (entry_len == 0)
      continue;
    else if (entry[entry_len - 1] != '\n')
    {
      RRDD_LOG(LOG_NOTICE, "Malformed journal entry at line %"PRIu64, line);
      ++fail_cnt;
      continue;
    }

    entry[entry_len - 1] = '\0';

    if (handle_request(NULL, now, entry, entry_len) == 0)
      ++entry_cnt;
    else
      ++fail_cnt;
  }

  fclose(fh);

  RRDD_LOG(LOG_INFO, "Replayed %d entries (%d failures)",
           entry_cnt, fail_cnt);

  return entry_cnt > 0 ? 1 : 0;
} /* }}} static int journal_replay */

static int journal_sort(const void *v1, const void *v2)
{
  char **jn1 = (char **) v1;
  char **jn2 = (char **) v2;

  return strcmp(*jn1,*jn2);
}

static void journal_init(void) /* {{{ */
{
  int had_journal = 0;
  DIR *dir;
  struct dirent *dent;
  char path[PATH_MAX+1];

  if (journal_dir == NULL) return;

  pthread_mutex_lock(&journal_lock);

  journal_cur = calloc(1, sizeof(journal_set));
  if (journal_cur == NULL)
  {
    RRDD_LOG(LOG_CRIT, "journal_rotate: malloc(journal_set) failed\n");
    return;
  }

  RRDD_LOG(LOG_INFO, "checking for journal files");

  /* Handle old journal files during transition.  This gives them the
   * correct sort order.  TODO: remove after first release
   */
  {
    char old_path[PATH_MAX+1];
    snprintf(old_path, PATH_MAX, "%s/%s", journal_dir, JOURNAL_BASE ".old" );
    snprintf(path,     PATH_MAX, "%s/%s", journal_dir, JOURNAL_BASE ".0000");
    rename(old_path, path);

    snprintf(old_path, PATH_MAX, "%s/%s", journal_dir, JOURNAL_BASE        );
    snprintf(path,     PATH_MAX, "%s/%s", journal_dir, JOURNAL_BASE ".0001");
    rename(old_path, path);
  }

  dir = opendir(journal_dir);
  if (!dir) {
    RRDD_LOG(LOG_CRIT, "journal_init: opendir(%s) failed\n", journal_dir);
    return;
  }
  while ((dent = readdir(dir)) != NULL)
  {
    /* looks like a journal file? */
    if (strncmp(dent->d_name, JOURNAL_BASE, strlen(JOURNAL_BASE)))
      continue;

    snprintf(path, PATH_MAX, "%s/%s", journal_dir, dent->d_name);

    if (!rrd_add_strdup(&journal_cur->files, &journal_cur->files_num, path))
    {
      RRDD_LOG(LOG_CRIT, "journal_init: cannot add journal file %s!",
               dent->d_name);
      break;
    }
  }
  closedir(dir);

  qsort(journal_cur->files, journal_cur->files_num,
        sizeof(journal_cur->files[0]), journal_sort);

  for (uint i=0; i < journal_cur->files_num; i++)
    had_journal += journal_replay(journal_cur->files[i]);

  journal_new_file();

  /* it must have been a crash.  start a flush */
  if (had_journal && config_flush_at_shutdown)
    flush_old_values(-1);

  pthread_mutex_unlock(&journal_lock);

  RRDD_LOG(LOG_INFO, "journal processing complete");

} /* }}} static void journal_init */

static void free_listen_socket(listen_socket_t *sock) /* {{{ */
{
  assert(sock != NULL);

  free(sock->rbuf);  sock->rbuf = NULL;
  free(sock->wbuf);  sock->wbuf = NULL;
  free(sock);
} /* }}} void free_listen_socket */

static void close_connection(listen_socket_t *sock) /* {{{ */
{
  if (sock->fd >= 0)
  {
    close(sock->fd);
    sock->fd = -1;
  }

  free_listen_socket(sock);

} /* }}} void close_connection */

static void *connection_thread_main (void *args) /* {{{ */
{
  listen_socket_t *sock;
  int fd;

  sock = (listen_socket_t *) args;
  fd = sock->fd;

  /* init read buffers */
  sock->next_read = sock->next_cmd = 0;
  sock->rbuf = malloc(RBUF_SIZE);
  if (sock->rbuf == NULL)
  {
    RRDD_LOG(LOG_ERR, "connection_thread_main: cannot malloc read buffer");
    close_connection(sock);
    return NULL;
  }

  pthread_mutex_lock (&connection_threads_lock);
#ifdef HAVE_LIBWRAP
  /* LIBWRAP does not support multiple threads! By putting this code
     inside pthread_mutex_lock we do not have to worry about request_info
     getting overwritten by another thread.
  */
  struct request_info req;
  request_init(&req, RQ_DAEMON, "rrdcached\0", RQ_FILE, fd, NULL );
  fromhost(&req);
  if(!hosts_access(&req)) {
    RRDD_LOG(LOG_INFO, "refused connection from %s", eval_client(&req));
    pthread_mutex_unlock (&connection_threads_lock);
    close_connection(sock);
    return NULL;
  }
#endif /* HAVE_LIBWRAP */
  connection_threads_num++;
  pthread_mutex_unlock (&connection_threads_lock);

  while (state == RUNNING)
  {
    char *cmd;
    ssize_t cmd_len;
    ssize_t rbytes;
    time_t now;

    struct pollfd pollfd;
    int status;

    pollfd.fd = fd;
    pollfd.events = POLLIN | POLLPRI;
    pollfd.revents = 0;

    status = poll (&pollfd, 1, /* timeout = */ 500);
    if (state != RUNNING)
      break;
    else if (status == 0) /* timeout */
      continue;
    else if (status < 0) /* error */
    {
      status = errno;
      if (status != EINTR)
        RRDD_LOG (LOG_ERR, "connection_thread_main: poll(2) failed.");
      continue;
    }

    if ((pollfd.revents & POLLHUP) != 0) /* normal shutdown */
      break;
    else if ((pollfd.revents & (POLLIN | POLLPRI)) == 0)
    {
      RRDD_LOG (LOG_WARNING, "connection_thread_main: "
          "poll(2) returned something unexpected: %#04hx",
          pollfd.revents);
      break;
    }

    rbytes = read(fd, sock->rbuf + sock->next_read,
                  RBUF_SIZE - sock->next_read);
    if (rbytes < 0)
    {
      RRDD_LOG(LOG_ERR, "connection_thread_main: read() failed.");
      break;
    }
    else if (rbytes == 0)
      break; /* eof */

    sock->next_read += rbytes;

    if (sock->batch_start)
      now = sock->batch_start;
    else
      now = time(NULL);

    while ((cmd = next_cmd(sock, &cmd_len)) != NULL)
    {
      status = handle_request (sock, now, cmd, cmd_len+1);
      if (status != 0)
        goto out_close;
    }
  }

out_close:
  close_connection(sock);

  /* Remove this thread from the connection threads list */
  pthread_mutex_lock (&connection_threads_lock);
  connection_threads_num--;
  if (connection_threads_num <= 0)
    pthread_cond_broadcast(&connection_threads_done);
  pthread_mutex_unlock (&connection_threads_lock);

  return (NULL);
} /* }}} void *connection_thread_main */

static int open_listen_socket_unix (const listen_socket_t *sock) /* {{{ */
{
  int fd;
  struct sockaddr_un sa;
  listen_socket_t *temp;
  int status;
  const char *path;
  char *path_copy, *dir;

  path = sock->addr;
  if (strncmp(path, "unix:", strlen("unix:")) == 0)
    path += strlen("unix:");

  /* dirname may modify its argument */
  path_copy = strdup(path);
  if (path_copy == NULL)
  {
    fprintf(stderr, "rrdcached: strdup(): %s\n",
        rrd_strerror(errno));
    return (-1);
  }

  dir = dirname(path_copy);
  if (rrd_mkdir_p(dir, 0777) != 0)
  {
    fprintf(stderr, "Failed to create socket directory '%s': %s\n",
        dir, rrd_strerror(errno));
    return (-1);
  }

  free(path_copy);

  temp = (listen_socket_t *) rrd_realloc (listen_fds,
      sizeof (listen_fds[0]) * (listen_fds_num + 1));
  if (temp == NULL)
  {
    fprintf (stderr, "rrdcached: open_listen_socket_unix: realloc failed.\n");
    return (-1);
  }
  listen_fds = temp;
  memcpy (listen_fds + listen_fds_num, sock, sizeof (listen_fds[0]));

  fd = socket (PF_UNIX, SOCK_STREAM, /* protocol = */ 0);
  if (fd < 0)
  {
    fprintf (stderr, "rrdcached: unix socket(2) failed: %s\n",
             rrd_strerror(errno));
    return (-1);
  }

  memset (&sa, 0, sizeof (sa));
  sa.sun_family = AF_UNIX;
  strncpy (sa.sun_path, path, sizeof (sa.sun_path) - 1);

  /* if we've gotten this far, we own the pid file.  any daemon started
   * with the same args must not be alive.  therefore, ensure that we can
   * create the socket...
   */
  unlink(path);

  status = bind (fd, (struct sockaddr *) &sa, sizeof (sa));
  if (status != 0)
  {
    fprintf (stderr, "rrdcached: bind(%s) failed: %s.\n",
             path, rrd_strerror(errno));
    close (fd);
    return (-1);
  }

  /* tweak the sockets group ownership */
  if (sock->socket_group != (gid_t)-1)
  {
    if ( (chown(path, getuid(), sock->socket_group) != 0) ||
         (chmod(path, (S_IRUSR|S_IWUSR|S_IXUSR | S_IRGRP|S_IWGRP)) != 0) )
    {
      fprintf(stderr, "rrdcached: failed to set socket group permissions (%s)\n", strerror(errno));
    }
  }

  if (sock->socket_permissions != (mode_t)-1)
  {
    if (chmod(path, sock->socket_permissions) != 0)
      fprintf(stderr, "rrdcached: failed to set socket file permissions (%o): %s\n",
          (unsigned int)sock->socket_permissions, strerror(errno));
  }

  status = listen (fd, /* backlog = */ 10);
  if (status != 0)
  {
    fprintf (stderr, "rrdcached: listen(%s) failed: %s.\n",
             path, rrd_strerror(errno));
    close (fd);
    unlink (path);
    return (-1);
  }

  listen_fds[listen_fds_num].fd = fd;
  listen_fds[listen_fds_num].family = PF_UNIX;
  strncpy(listen_fds[listen_fds_num].addr, path,
          sizeof (listen_fds[listen_fds_num].addr) - 1);
  listen_fds_num++;

  return (0);
} /* }}} int open_listen_socket_unix */

static int open_listen_socket_network(const listen_socket_t *sock) /* {{{ */
{
  struct addrinfo ai_hints;
  struct addrinfo *ai_res;
  struct addrinfo *ai_ptr;
  char addr_copy[NI_MAXHOST];
  char *addr;
  char *port;
  int status;

  strncpy (addr_copy, sock->addr, sizeof(addr_copy)-1);
  addr_copy[sizeof (addr_copy) - 1] = 0;
  addr = addr_copy;

  memset (&ai_hints, 0, sizeof (ai_hints));
  ai_hints.ai_flags = 0;
#ifdef AI_ADDRCONFIG
  ai_hints.ai_flags |= AI_ADDRCONFIG;
#endif
  ai_hints.ai_family = AF_UNSPEC;
  ai_hints.ai_socktype = SOCK_STREAM;

  port = NULL;
  if (*addr == '[') /* IPv6+port format */
  {
    /* `addr' is something like "[2001:780:104:2:211:24ff:feab:26f8]:12345" */
    addr++;

    port = strchr (addr, ']');
    if (port == NULL)
    {
      fprintf (stderr, "rrdcached: Malformed address: %s\n", sock->addr);
      return (-1);
    }
    *port = 0;
    port++;

    if (*port == ':')
      port++;
    else if (*port == 0)
      port = NULL;
    else
    {
      fprintf (stderr, "rrdcached: Garbage after address: %s\n", port);
      return (-1);
    }
  } /* if (*addr == '[') */
  else
  {
    port = rindex(addr, ':');
    if (port != NULL)
    {
      *port = 0;
      port++;
    }
  }
  ai_res = NULL;
  status = getaddrinfo (addr,
                        port == NULL ? RRDCACHED_DEFAULT_PORT : port,
                        &ai_hints, &ai_res);
  if (status != 0)
  {
    fprintf (stderr, "rrdcached: getaddrinfo(%s) failed: %s\n",
             addr, gai_strerror (status));
    return (-1);
  }

  for (ai_ptr = ai_res; ai_ptr != NULL; ai_ptr = ai_ptr->ai_next)
  {
    int fd;
    listen_socket_t *temp;
    int one = 1;

    temp = (listen_socket_t *) rrd_realloc (listen_fds,
        sizeof (listen_fds[0]) * (listen_fds_num + 1));
    if (temp == NULL)
    {
      fprintf (stderr,
               "rrdcached: open_listen_socket_network: realloc failed.\n");
      continue;
    }
    listen_fds = temp;
    memcpy (listen_fds + listen_fds_num, sock, sizeof (listen_fds[0]));

    fd = socket (ai_ptr->ai_family, ai_ptr->ai_socktype, ai_ptr->ai_protocol);
    if (fd < 0)
    {
      fprintf (stderr, "rrdcached: network socket(2) failed: %s.\n",
               rrd_strerror(errno));
      continue;
    }

    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));

    status = bind (fd, ai_ptr->ai_addr, ai_ptr->ai_addrlen);
    if (status != 0)
    {
      fprintf (stderr, "rrdcached: bind(%s) failed: %s.\n",
               sock->addr, rrd_strerror(errno));
      close (fd);
      continue;
    }

    status = listen (fd, /* backlog = */ 10);
    if (status != 0)
    {
      fprintf (stderr, "rrdcached: listen(%s) failed: %s\n.",
               sock->addr, rrd_strerror(errno));
      close (fd);
      freeaddrinfo(ai_res);
      return (-1);
    }

    listen_fds[listen_fds_num].fd = fd;
    listen_fds[listen_fds_num].family = ai_ptr->ai_family;
    listen_fds_num++;
  } /* for (ai_ptr) */

  freeaddrinfo(ai_res);
  return (0);
} /* }}} static int open_listen_socket_network */

static int open_listen_socket (const listen_socket_t *sock) /* {{{ */
{
  assert(sock != NULL);
  assert(sock->addr != NULL);

  if (strncmp ("unix:", sock->addr, strlen ("unix:")) == 0
      || sock->addr[0] == '/')
    return (open_listen_socket_unix(sock));
  else
    return (open_listen_socket_network(sock));
} /* }}} int open_listen_socket */

#ifndef SD_LISTEN_FDS_START
#  define SD_LISTEN_FDS_START 3
#endif
/*
 * returns number of descriptors passed from systemd
 */
static int open_listen_sockets_systemd(void) /* {{{ */
{
  listen_socket_t *temp;
  struct sockaddr_un sa;
  socklen_t l;
  int sd_fd;
  const char *env;
  unsigned long n;

  /* check if it for us */
  env = getenv("LISTEN_PID");
  if (!env)
    return 0;

  n = strtoul(env, NULL, 10);
  if (!n || n == ULONG_MAX || (pid_t)n != getpid())
    return 0;

  /* get the number of passed descriptors */
  env = getenv("LISTEN_FDS");
  if (!env)
    return 0;

  n = strtoul(env, NULL, 10);
  if (!n || n == ULONG_MAX)
    return 0;

  temp = (listen_socket_t *) rrd_realloc (listen_fds,
     sizeof (listen_fds[0]) * (listen_fds_num + n));
  if (temp == NULL)
  {
    fprintf (stderr, "rrdcached: open_listen_socket_systemd: realloc failed.\n");
    return 0;
  }
  listen_fds = temp;

  for (unsigned int i = 0; i < n; i++)
  {
    sd_fd = SD_LISTEN_FDS_START + i;

    l = sizeof(sa);
    memset(&sa, 0, l);
    if (getsockname(sd_fd, &sa, &l) < 0)
    {
      fprintf(stderr, "open_listen_sockets_systemd: problem getting fd %d: %s\n", sd_fd, rrd_strerror (errno));
      return i;
    }

    listen_fds[listen_fds_num].fd = sd_fd;
    listen_fds[listen_fds_num].family = sa.sun_family;
    listen_fds_num++;
  }
  
  return n;
} /* }}} open_listen_sockets_systemd */

static void open_listen_sockets_traditional(void) /* {{{ */
{
 if (config_listen_address_list_len > 0)
  {
    for (size_t i = 0; i < config_listen_address_list_len; i++)
      open_listen_socket (config_listen_address_list[i]);

    rrd_free_ptrs((void ***) &config_listen_address_list,
                  &config_listen_address_list_len);
  }
  else
  {
    strncpy(default_socket.addr, RRDCACHED_DEFAULT_ADDRESS,
        sizeof(default_socket.addr) - 1);
    default_socket.addr[sizeof(default_socket.addr) - 1] = '\0';

    if (default_socket.permissions == 0)
      socket_permission_set_all (&default_socket);

    open_listen_socket (&default_socket);
  }
} /* }}} open_list_sockets_traditional */

static int close_listen_sockets (void) /* {{{ */
{
  size_t i;

  for (i = 0; i < listen_fds_num; i++)
  {
    close (listen_fds[i].fd);

    if (listen_fds[i].family == PF_UNIX)
      unlink(listen_fds[i].addr);
  }

  free (listen_fds);
  listen_fds = NULL;
  listen_fds_num = 0;

  return (0);
} /* }}} int close_listen_sockets */

static void *listen_thread_main (void UNUSED(*args)) /* {{{ */
{
  struct pollfd *pollfds;
  int pollfds_num;
  int status;
  int i;

  if (listen_fds_num < 1)
  {
    RRDD_LOG(LOG_ERR, "listen_thread_main: no listen_fds !");
    return (NULL);
  }

  pollfds_num = listen_fds_num;
  pollfds = (struct pollfd *) malloc (sizeof (*pollfds) * pollfds_num);
  if (pollfds == NULL)
  {
    RRDD_LOG (LOG_ERR, "listen_thread_main: malloc failed.");
    return (NULL);
  }
  memset (pollfds, 0, sizeof (*pollfds) * pollfds_num);

  RRDD_LOG(LOG_INFO, "listening for connections");

  while (state == RUNNING)
  {
    for (i = 0; i < pollfds_num; i++)
    {
      pollfds[i].fd = listen_fds[i].fd;
      pollfds[i].events = POLLIN | POLLPRI;
      pollfds[i].revents = 0;
    }

    status = poll (pollfds, pollfds_num, /* timeout = */ 1000);
    if (state != RUNNING)
      break;
    else if (status == 0) /* timeout */
      continue;
    else if (status < 0) /* error */
    {
      status = errno;
      if (status != EINTR)
      {
        RRDD_LOG (LOG_ERR, "listen_thread_main: poll(2) failed.");
      }
      continue;
    }

    for (i = 0; i < pollfds_num; i++)
    {
      listen_socket_t *client_sock;
      struct sockaddr_storage client_sa;
      socklen_t client_sa_size;
      pthread_t tid;
      pthread_attr_t attr;

      if (pollfds[i].revents == 0)
        continue;

      if ((pollfds[i].revents & (POLLIN | POLLPRI)) == 0)
      {
        RRDD_LOG (LOG_ERR, "listen_thread_main: "
            "poll(2) returned something unexpected for listen FD #%i.",
            pollfds[i].fd);
        continue;
      }

      client_sock = (listen_socket_t *) malloc (sizeof (listen_socket_t));
      if (client_sock == NULL)
      {
        RRDD_LOG (LOG_ERR, "listen_thread_main: malloc failed.");
        continue;
      }
      memcpy(client_sock, &listen_fds[i], sizeof(listen_fds[0]));

      client_sa_size = sizeof (client_sa);
      client_sock->fd = accept (pollfds[i].fd,
          (struct sockaddr *) &client_sa, &client_sa_size);
      if (client_sock->fd < 0)
      {
        RRDD_LOG (LOG_ERR, "listen_thread_main: accept(2) failed.");
        free(client_sock);
        continue;
      }

      pthread_attr_init (&attr);
      pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);

      status = pthread_create (&tid, &attr, connection_thread_main,
                               client_sock);
      if (status != 0)
      {
        RRDD_LOG (LOG_ERR, "listen_thread_main: pthread_create failed.");
        close_connection(client_sock);
        continue;
      }
    } /* for (pollfds_num) */
  } /* while (state == RUNNING) */

  RRDD_LOG(LOG_INFO, "starting shutdown");

  close_listen_sockets ();

  pthread_mutex_lock (&connection_threads_lock);
  while (connection_threads_num > 0)
    pthread_cond_wait(&connection_threads_done, &connection_threads_lock);
  pthread_mutex_unlock (&connection_threads_lock);

  free(pollfds);

  return (NULL);
} /* }}} void *listen_thread_main */

static int daemonize (void) /* {{{ */
{
  int pid_fd;
  char *base_dir;

  daemon_uid = geteuid();

  pid_fd = open_pidfile("create", O_CREAT|O_EXCL|O_WRONLY);
  if (pid_fd < 0)
    pid_fd = check_pidfile();
  if (pid_fd < 0)
    return pid_fd;

  /* gather sockets passed from systemd; 
   * if none, open all the listen sockets from config or default  */ 

  if (!(open_listen_sockets_systemd() > 0))
    open_listen_sockets_traditional();

  if (listen_fds_num < 1)
  {
    fprintf (stderr, "rrdcached: FATAL: cannot open any listen sockets\n");
    goto error;
  }

  if (!stay_foreground)
  {
    pid_t child;

    child = fork ();
    if (child < 0)
    {
      fprintf (stderr, "daemonize: fork(2) failed.\n");
      goto error;
    }
    else if (child > 0)
      exit(0);

    /* Become session leader */
    setsid ();

    /* Open the first three file descriptors to /dev/null */
    close (2);
    close (1);
    close (0);

    open ("/dev/null", O_RDWR);
    if (dup(0) == -1 || dup(0) == -1){
        RRDD_LOG (LOG_ERR, "faild to run dup.\n");
    }
  } /* if (!stay_foreground) */

  /* Change into the /tmp directory. */
  base_dir = (config_base_dir != NULL)
    ? config_base_dir
    : "/tmp";

  if (chdir (base_dir) != 0)
  {
    fprintf (stderr, "daemonize: chdir (%s) failed.\n", base_dir);
    goto error;
  }

  install_signal_handlers();

  openlog ("rrdcached", LOG_PID, LOG_DAEMON);
  RRDD_LOG(LOG_INFO, "starting up");

  cache_tree = g_tree_new_full ((GCompareDataFunc) strcmp, NULL, NULL,
                                (GDestroyNotify) free_cache_item);
  if (cache_tree == NULL)
  {
    RRDD_LOG (LOG_ERR, "daemonize: g_tree_new failed.");
    goto error;
  }

  return write_pidfile (pid_fd);

error:
  remove_pidfile();
  return -1;
} /* }}} int daemonize */

static int cleanup (void) /* {{{ */
{
  pthread_cond_broadcast (&flush_cond);
  pthread_join (flush_thread, NULL);

  pthread_cond_broadcast (&queue_cond);
  for (int i = 0; i < config_queue_threads; i++)
    pthread_join (queue_threads[i], NULL);

  if (config_flush_at_shutdown)
  {
    assert(cache_queue_head == NULL);
    RRDD_LOG(LOG_INFO, "clean shutdown; all RRDs flushed");
  }

  free(queue_threads);
  free(config_base_dir);

  pthread_mutex_lock(&cache_lock);
  g_tree_destroy(cache_tree);

  pthread_mutex_lock(&journal_lock);
  journal_done();

  RRDD_LOG(LOG_INFO, "goodbye");
  closelog ();

  remove_pidfile ();
  free(config_pid_file);

  return (0);
} /* }}} int cleanup */

static int read_options (int argc, char **argv) /* {{{ */
{
  int option;
  int status = 0;

  socket_permission_clear (&default_socket);

  default_socket.socket_group = (gid_t)-1;
  default_socket.socket_permissions = (mode_t)-1;

  while ((option = getopt(argc, argv, "Ogl:s:m:P:f:w:z:t:Bb:p:Fj:a:h?")) != -1)
  {
    switch (option)
    {
      case 'O':
        opt_no_overwrite = 1;
        break;

      case 'g':
        stay_foreground=1;
        break;

      case 'l':
      {
        listen_socket_t *new;

        new = malloc(sizeof(listen_socket_t));
        if (new == NULL)
        {
          fprintf(stderr, "read_options: malloc failed.\n");
          return(2);
        }
        memset(new, 0, sizeof(listen_socket_t));

        strncpy(new->addr, optarg, sizeof(new->addr)-1);

        /* Add permissions to the socket {{{ */
        if (default_socket.permissions != 0)
        {
          socket_permission_copy (new, &default_socket);
        }
        else /* if (default_socket.permissions == 0) */
        {
          /* Add permission for ALL commands to the socket. */
          socket_permission_set_all (new);
        }
        /* }}} Done adding permissions. */

        new->socket_group = default_socket.socket_group;
        new->socket_permissions = default_socket.socket_permissions;

        if (!rrd_add_ptr((void ***)&config_listen_address_list,
                         &config_listen_address_list_len, new))
        {
          fprintf(stderr, "read_options: rrd_add_ptr failed.\n");
          return (2);
        }
      }
      break;

      /* set socket group permissions */
      case 's':
      {
        gid_t group_gid;
        struct group *grp;

        group_gid = strtoul(optarg, NULL, 10);
        if (errno != EINVAL && group_gid>0)
        {
          /* we were passed a number */
          grp = getgrgid(group_gid);
        }
        else
        {
          grp = getgrnam(optarg);
        }

        if (grp)
        {
          default_socket.socket_group = grp->gr_gid;
        }
        else
        {
          /* no idea what the user wanted... */
          fprintf (stderr, "read_options: couldn't map \"%s\" to a group, Sorry\n", optarg);
          return (5);
        }
      }
      break;

      /* set socket file permissions */
      case 'm':
      {
        long  tmp;
        char *endptr = NULL;

        tmp = strtol (optarg, &endptr, 8);
        if ((endptr == optarg) || (! endptr) || (*endptr != '\0')
            || (tmp > 07777) || (tmp < 0)) {
          fprintf (stderr, "read_options: Invalid file mode \"%s\".\n",
              optarg);
          return (5);
        }

        default_socket.socket_permissions = (mode_t)tmp;
      }
      break;

      case 'P':
      {
        char *optcopy;
        char *saveptr;
        char *dummy;
        char *ptr;

        socket_permission_clear (&default_socket);

        optcopy = strdup (optarg);
        dummy = optcopy;
        saveptr = NULL;
        while ((ptr = strtok_r (dummy, ", ", &saveptr)) != NULL)
        {
          dummy = NULL;
          status = socket_permission_add (&default_socket, ptr);
          if (status != 0)
          {
            fprintf (stderr, "read_options: Adding permission \"%s\" to "
                "socket failed. Most likely, this permission doesn't "
                "exist. Check your command line.\n", ptr);
            status = 4;
          }
        }

        free (optcopy);
      }
      break;

      case 'f':
      {
        int temp;

        temp = atoi (optarg);
        if (temp > 0)
          config_flush_interval = temp;
        else
        {
          fprintf (stderr, "Invalid flush interval: %s\n", optarg);
          status = 3;
        }
      }
      break;

      case 'w':
      {
        int temp;

        temp = atoi (optarg);
        if (temp > 0)
          config_write_interval = temp;
        else
        {
          fprintf (stderr, "Invalid write interval: %s\n", optarg);
          status = 2;
        }
      }
      break;

      case 'z':
      {
        int temp;

        temp = atoi(optarg);
        if (temp > 0)
          config_write_jitter = temp;
        else
        {
          fprintf (stderr, "Invalid write jitter: -z %s\n", optarg);
          status = 2;
        }

        break;
      }

      case 't':
      {
        int threads;
        threads = atoi(optarg);
        if (threads >= 1)
          config_queue_threads = threads;
        else
        {
          fprintf (stderr, "Invalid thread count: -t %s\n", optarg);
          return 1;
        }
      }
      break;

      case 'B':
        config_write_base_only = 1;
        break;

      case 'b':
      {
        size_t len;
        char base_realpath[PATH_MAX];

        if (config_base_dir != NULL)
          free (config_base_dir);
        config_base_dir = strdup (optarg);
        if (config_base_dir == NULL)
        {
          fprintf (stderr, "read_options: strdup failed.\n");
          return (3);
        }

        if (rrd_mkdir_p (config_base_dir, 0777) != 0)
        {
          fprintf (stderr, "Failed to create base directory '%s': %s\n",
              config_base_dir, rrd_strerror (errno));
          return (3);
        }

        /* make sure that the base directory is not resolved via
         * symbolic links.  this makes some performance-enhancing
         * assumptions possible (we don't have to resolve paths
         * that start with a "/")
         */
        if (realpath(config_base_dir, base_realpath) == NULL)
        {
          fprintf (stderr, "Failed to canonicalize the base directory '%s': "
              "%s\n", config_base_dir, rrd_strerror(errno));
          return 5;
        }

        len = strlen (config_base_dir);
        while ((len > 0) && (config_base_dir[len - 1] == '/'))
        {
          config_base_dir[len - 1] = 0;
          len--;
        }

        if (len < 1)
        {
          fprintf (stderr, "Invalid base directory: %s\n", optarg);
          return (4);
        }

        _config_base_dir_len = len;

        len = strlen (base_realpath);
        while ((len > 0) && (base_realpath[len - 1] == '/'))
        {
          base_realpath[len - 1] = '\0';
          len--;
        }

        if (strncmp(config_base_dir,
                         base_realpath, sizeof(base_realpath)) != 0)
        {
          fprintf(stderr,
                  "Base directory (-b) resolved via file system links!\n"
                  "Please consult rrdcached '-b' documentation!\n"
                  "Consider specifying the real directory (%s)\n",
                  base_realpath);
          return 5;
        }
      }
      break;

      case 'p':
      {
        if (config_pid_file != NULL)
          free (config_pid_file);
        config_pid_file = strdup (optarg);
        if (config_pid_file == NULL)
        {
          fprintf (stderr, "read_options: strdup failed.\n");
          return (3);
        }
      }
      break;

      case 'F':
        config_flush_at_shutdown = 1;
        break;

      case 'j':
      {
        char journal_dir_actual[PATH_MAX];
        journal_dir = realpath((const char *)optarg, journal_dir_actual);
        if (journal_dir)
        {
          // if we were able to properly resolve the path, lets have a copy
          // for use outside this block.
          journal_dir = strdup(journal_dir);           
          status = rrd_mkdir_p(journal_dir, 0777);
          if (status != 0)
          {
            fprintf(stderr, "Failed to create journal directory '%s': %s\n",
                    journal_dir, rrd_strerror(errno));
            return 6;
          }
          if (access(journal_dir, R_OK|W_OK|X_OK) != 0)
          {
            fprintf(stderr, "Must specify a writable directory with -j! (%s)\n",
                    errno ? rrd_strerror(errno) : "");
            return 6;
          }
        } else {
          fprintf(stderr, "Unable to resolve journal path (%s,%s)\n", optarg,
                  errno ? rrd_strerror(errno) : "");
          return 6;
        }
      }
      break;

      case 'a':
      {
        int temp = atoi(optarg);
        if (temp > 0)
          config_alloc_chunk = temp;
        else
        {
          fprintf(stderr, "Invalid allocation size: %s\n", optarg);
          return 10;
        }
      }
      break;

      case 'h':
      case '?':
        printf ("RRDCacheD %s\n"
            "Copyright (C) 2008,2009 Florian octo Forster and Kevin Brintnall\n"
            "\n"
            "Usage: rrdcached [options]\n"
            "\n"
            "Valid options are:\n"
            "  -l <address>  Socket address to listen to.\n"
            "                Default: "RRDCACHED_DEFAULT_ADDRESS"\n"
            "  -P <perms>    Sets the permissions to assign to all following "
                            "sockets\n"
            "  -w <seconds>  Interval in which to write data.\n"
            "  -z <delay>    Delay writes up to <delay> seconds to spread load\n"
            "  -t <threads>  Number of write threads.\n"
            "  -f <seconds>  Interval in which to flush dead data.\n"
            "  -p <file>     Location of the PID-file.\n"
            "  -b <dir>      Base directory to change to.\n"
            "  -B            Restrict file access to paths within -b <dir>\n"
            "  -g            Do not fork and run in the foreground.\n"
            "  -j <dir>      Directory in which to create the journal files.\n"
            "  -F            Always flush all updates at shutdown\n"
            "  -s <id|name>  Group owner of all following UNIX sockets\n"
            "                (the socket will also have read/write permissions "
                            "for that group)\n"
            "  -m <mode>     File permissions (octal) of all following UNIX "
                            "sockets\n"
            "  -a <size>     Memory allocation chunk size. Default is 1.\n"
            "  -O            Do not allow CREATE commands to overwrite existing\n"
            "                files, even if asked to.\n"
            "\n"
            "For more information and a detailed description of all options "
            "please refer\n"
            "to the rrdcached(1) manual page.\n",
            VERSION);
        if (option == 'h')
          status = -1;
        else
          status = 1;
        break;
    } /* switch (option) */
  } /* while (getopt) */

  /* advise the user when values are not sane */
  if (config_flush_interval < 2 * config_write_interval)
    fprintf(stderr, "WARNING: flush interval (-f) should be at least"
            " 2x write interval (-w) !\n");
  if (config_write_jitter > config_write_interval)
    fprintf(stderr, "WARNING: write delay (-z) should NOT be larger than"
            " write interval (-w) !\n");

  if (config_write_base_only && config_base_dir == NULL)
    fprintf(stderr, "WARNING: -B does not make sense without -b!\n"
            "  Consult the rrdcached documentation\n");

  if (journal_dir == NULL)
    config_flush_at_shutdown = 1;

  return (status);
} /* }}} int read_options */

int main (int argc, char **argv)
{
  int status;

  status = read_options (argc, argv);
  if (status != 0)
  {
    if (status < 0)
      status = 0;
    return (status);
  }

  status = daemonize ();
  if (status != 0)
  {
    fprintf (stderr, "rrdcached: daemonize failed, exiting.\n");
    return (1);
  }

  journal_init();

  /* start the queue threads */
  queue_threads = calloc(config_queue_threads, sizeof(*queue_threads));
  if (queue_threads == NULL)
  {
    RRDD_LOG (LOG_ERR, "FATAL: cannot calloc queue threads");
    cleanup();
    return (1);
  }
  for (int i = 0; i < config_queue_threads; i++)
  {
    memset (&queue_threads[i], 0, sizeof (*queue_threads));
    status = pthread_create (&queue_threads[i], NULL, queue_thread_main, NULL);
    if (status != 0)
    {
      RRDD_LOG (LOG_ERR, "FATAL: cannot create queue thread");
      cleanup();
      return (1);
    }
  }

  /* start the flush thread */
  memset(&flush_thread, 0, sizeof(flush_thread));
  status = pthread_create (&flush_thread, NULL, flush_thread_main, NULL);
  if (status != 0)
  {
    RRDD_LOG (LOG_ERR, "FATAL: cannot create flush thread");
    cleanup();
    return (1);
  }

  listen_thread_main (NULL);
  cleanup ();

  return (0);
} /* int main */

/*
 * vim: set sw=2 sts=2 ts=8 et fdm=marker :
 */