statefile.c

/***********************************************************************/ /**
 * @file statefile.c:
 *
 * Routines to save and recover DataLink state information to/from a file.
 *
 * This file is part of the DataLink Library.
 *
 * Copyright (c) 2023 Chad Trabant, EarthScope Data Services
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***************************************************************************/

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

#include "libdali.h"
#include "portable.h"

/***********************************************************************/ /**
 * @brief Save a DataLink connection state to a file
 *
 * Save the all the current the sequence numbers and time stamps into the
 * given state file.
 *
 * @param dlconn DataLink Connection Parameters
 * @param statefile File to save state to
 *
 * @retval -1 Error
 * @retval 0 Completed successfully
 ***************************************************************************/
int
dl_savestate (DLCP *dlconn, const char *statefile)
{
  char line[200];
  int linelen;
  int statefd;

  if (!dlconn || !statefile)
    return -1;

  /* Open the state file */
  if ((statefd = dlp_openfile (statefile, 'w')) < 0)
  {
    dl_log_r (dlconn, 2, 0, "cannot open state file for writing\n");
    return -1;
  }

  dl_log_r (dlconn, 1, 2, "saving connection state to state file\n");

  /* Write state information: <server address> <packet ID> <packet time> */
  linelen = snprintf (line, sizeof (line), "%s %lld %lld\n",
                      dlconn->addr, (long long int)dlconn->pktid,
                      (long long int)dlconn->pkttime);

  if (write (statefd, line, linelen) != linelen)
  {
    dl_log_r (dlconn, 2, 0, "cannot write to state file, %s\n", strerror (errno));
    return -1;
  }

  if (close (statefd))
  {
    dl_log_r (dlconn, 2, 0, "cannot close state file, %s\n", strerror (errno));
    return -1;
  }

  return 0;
} /* End of dl_savestate() */

/***********************************************************************/ /**
 * @brief Recover DataLink connection state from a file
 *
 * Recover connection state from a state file and set the state
 * parameters in a given DataLink Connection Paramters.
 *
 * @param dlconn DataLink Connection Parameters
 * @param statefile File to recover state from
 *
 * @retval -1 Error
 * @retval 0 Completed successfully
 * @retval 1 File could not be opened (probably not found)
 ***************************************************************************/
int
dl_recoverstate (DLCP *dlconn, const char *statefile)
{
  int statefd;
  char line[200];
  char addrstr[100];
  int fields;
  int found = 0;
  int count = 1;

  if (!dlconn || !statefile)
    return -1;

  /* Open the state file */
  if ((statefd = dlp_openfile (statefile, 'r')) < 0)
  {
    if (errno == ENOENT)
    {
      dl_log_r (dlconn, 1, 0, "could not find state file: %s\n", statefile);
      return 1;
    }
    else
    {
      dl_log_r (dlconn, 2, 0, "could not open state file, %s\n", strerror (errno));
      return -1;
    }
  }

  dl_log_r (dlconn, 1, 1, "recovering connection state from state file\n");

  /* Loop through lines in the file and find the matching server address */
  while ((dl_readline (statefd, line, sizeof (line))) >= 0)
  {
    long long int spktid;
    long long int spkttime;

    addrstr[0] = '\0';

    fields = sscanf (line, "%s %lld %lld\n", addrstr, &spktid, &spkttime);

    if (fields < 0)
      continue;

    if (fields < 3)
    {
      dl_log_r (dlconn, 2, 0, "could not parse line %d of state file\n", count);
    }

    /* Check for a matching server address and set connection values if found */
    if (!strncmp (dlconn->addr, addrstr, sizeof (addrstr)))
    {
      dlconn->pktid   = spktid;
      dlconn->pkttime = spkttime;

      found = 1;
      break;
    }

    count++;
  }

  if (!found)
  {
    dl_log_r (dlconn, 1, 0, "Server address not found in state file: %s\n", dlconn->addr);
  }

  if (close (statefd))
  {
    dl_log_r (dlconn, 2, 0, "could not close state file, %s\n", strerror (errno));
    return -1;
  }

  return 0;
} /* End of dl_recoverstate() */