/*
 * Name:         insertfile (client)
 * Author:       Manuel Mausz, 0728348
 * Description:  Server writes data read from client via IPC message queue to
 *               file. If filesize is reached server quits automatically. Client
 *               sends data read from file via IPC message queue to server
 *               Offset specifies file offset to start writing for server.
 * Created:      12.03.2009
 * Exercise:     1h B
 */
 
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include "global.h"
 
/*
 * NAME: sighandler
 * PURPOSE:
 * signal handler sets global error flag to 1
 *
 * PARAMETERS:
 * int signum ... signal number
 *
 * RETURN VALUE:
 * void
 *
 * GLOBAL VARS:
 * error
 */
static void sighandler(int signum)
{
#ifdef DEBUG
  (void) printf("signal %d received\n", signum);
#endif
  error = 1;
}
 
/*
 * NAME: usage
 * PURPOSE:
 * prints program usage to stderr and terminates with EXIT_FAILURE
 *
 * PARAMETERS:
 * void
 *
 * RETURN VALUE:
 * void
 *
 * GLOBAL VARS:
 * me
 */
static void usage(void)
{
  (void) fprintf(stderr, "Usage: %s -o offset [file]\n", me);
  (void) exit(EXIT_FAILURE);
}
 
/*
 * NAME: read_send
 * PURPOSE:
 * sends data read from stream pointed to by fp via IPC msg queue to server.
 * offset specifies absolute file offset to start writing for the server.
 * functions returns after all data has been sent or on error.
 *
 * PARAMETERS:
 * FILE *fp    ... pointer to stream to read from
 * int msgqid  ... msg queue id
 * long offset ... offset
 *
 * RETURN VALUE:
 * void
 *
 * GLOBAL VARS:
 * error
 */
static void read_send(FILE *fp, int msgqid, long offset)
{
  int len;
  msg_t msg;
 
  /* read + send */
  if (!error)
  {
    msg.mtype = offset + 1;
    while(!error && !feof(fp))
    {
      /* read from file */
      len = fread(&msg.data, sizeof(msg.data[0]), sizeof(msg.data), fp);
      if (ferror(fp))
      {
        (void) printferr("Error while reading from file");
        break;
      }
      msg.len = len;
 
#ifdef DEBUG
      (void) printf("sending [%ld]+%d bytes to msg queue\n", msg.mtype - 1, msg.len);
#endif
 
      /* send message */
      if (!error && msgsnd(msgqid, &msg, MSGSIZE, 0) == -1)
        (void) printferr("Couldn't send message");
 
      /* increase offset */
      msg.mtype += len;
    }
    if (!error && ferror(fp))
      (void) printferr("Error while reading from file");
  }
}
 
/*
 * NAME: main
 * PURPOSE:
 * install signal handler, parse commandline options,
 * get msg queue id and call read_send
 *
 * PARAMETERS:
 * standard parameters of main
 *
 * RETURN VALUE:
 * int ... 0 on success, 1 on error
 *
 * GLOBAL VARS:
 * me, error
 */
int main(int argc, char *argv[])
{
  int opt, msgqid = -1;
  long offset = -1;
  char *endptr;
  char *filename = NULL;
  FILE *fp = stdin;
  struct sigaction new_action, old_action;
 
  /* save me */
  me = argv[0];
 
  /* install signal handler */
  new_action.sa_handler = sighandler;
  sigemptyset(&new_action.sa_mask);
  new_action.sa_flags = 0; /* to avoid restart of blocking syscalls */
  INSTALL_SIGNAL(SIGINT,   new_action, old_action)
  INSTALL_SIGNAL(SIGQUIT,  new_action, old_action)
  INSTALL_SIGNAL(SIGTERM,  new_action, old_action)
 
  /* parse cmdline options */
  while ((opt = getopt(argc, argv, "o:")) != -1)
  {
    switch(opt)
    {
      case 'o':
        offset = strtol(optarg, &endptr, 0);
 
        if ((errno == ERANGE && (offset == LONG_MAX || offset == LONG_MIN))
            || (errno != 0 && offset == 0))
          (void) bailout("Invalid offset value");
 
        if (*endptr != '\0' || offset < 0)
          (void) bailout("Invalid offset value. Only positive numbers allowed.");
 
        break;
      default:
        (void) usage();
        break;
    }
  }
  argv += optind;
 
  /* parse next commandline option */
  if (argv)
    filename = *argv;
 
  /* check required option value */
  if (offset < 0)
    (void) usage();
 
#ifdef DEBUG
  (void) printf("offset=%ld filename=%s\n", offset, filename);
#endif
 
  /* open file to read from */
  if (!error && filename != NULL && (fp = fopen(filename, "r")) == NULL)
    (void) bailout("%s", filename);
 
  /* get message queue id */
  if (!error && (msgqid = msgget(IPC_KEY, 0)) == -1)
  {
    if (errno == ENOENT)
    {
      errno = 0;
      (void) printferr("Couldn't get message queue. Server not running?");
    }
    else
      (void) printferr("Couldn't get message queue");
  }
#ifdef DEBUG
  if (msgqid != -1)
    (void) printf("msgqid=%d\n", msgqid);
#endif
 
  /* read and send data */
  if (!error)
    (void) read_send(fp, msgqid, offset);
 
  /* cleanup stuff */
#ifdef DEBUG
  (void) printf("doing cleanup...\n");
#endif
 
  /* close open fds */
  if (filename != NULL && fp != stdin)
    (void) fclose(fp);
 
  return (error) ? 1 : 0;
}
 
/* vim: set et sw=2 ts=2: */