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sendn.c

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/************************************************************************
* File: sendn.c
* Purpose: Provides a C file for the sendn function from
* the book Advanced Programming in the UNIX Environment by Richard Stevens.
* The sendn function calls the send function repeatedly until n bytes
* have been written to the file descriptor.
*************************************************************************/

/* This is neccessary to avoid muliple definitions of fd_set, etc when both
* RPC via PCNFS and Windows Sockets are to be available. */
#ifdef USE_PCNFS
#undef USE_PCNFS
#endif
#include "rcs_defs.hh"          /* _Windows */

#include <string.h>             /* strerror */
#include <stdlib.h>             /* memset() */

#ifndef UNDER_CE
#include <errno.h>              /* errno  */
#endif
#include <math.h>               /* fabs() */

#include "sendn.h"              /* sendn() */
#include "rcs_prnt.hh"          /* rcs_print_error() */
#include "_timer.h"             /* etime(), esleep() */
#include "sokintrf.h"           /* dl_send(), dl_select(), dl_WSAGetLastError() */
                                /* struct timeval, fd_set */

/* Write "n" bytes to a descriptor. */
int RCS_EXPORT
sendn (int fd, const void *vptr, int n, int _flags, double _timeout)
{
  int nleft;
  long nwritten;
  int select_ret;
  double start_time, current_time;
  char *ptr;
  struct timeval timeout_tv;
  fd_set send_fd_set;

  timeout_tv.tv_sec = (long) _timeout;
  timeout_tv.tv_usec = (long) (_timeout * 1000000.0);
  if (timeout_tv.tv_usec >= 1000000)
    {
      timeout_tv.tv_usec = timeout_tv.tv_usec % 1000000;
    }
  FD_ZERO (&send_fd_set);
  RCS_FD_SET (fd, &send_fd_set);

  ptr = (char *) vptr;          /* can't do pointer arithmetic on void* */
  nleft = n;
  start_time = etime ();
  while (nleft > 0)
    {
      if (fabs (_timeout) > 1E-6)
        {
          if (_timeout > 0)
            {
              select_ret =
                dl_select (fd + 1, (fd_set *) NULL, &send_fd_set,
                           (fd_set *) NULL, &timeout_tv);
            }
          else
            {
              select_ret =
                dl_select (fd + 1, (fd_set *) NULL, &send_fd_set,
                           (fd_set *) NULL, NULL);
            }
          switch (select_ret)
            {
            case -1:
#if !defined(_Windows) || defined(gnuwin32)
              rcs_print_error ("Error in select: %d -> %s\n", errno,
                               strerror (errno));
#else
              rcs_print_error ("Error in select: %d\n",
                               dl_WSAGetLastError ());
#endif
              rcs_print_error
                ("sendn(fd=%d, vptr=%p, int n=%d, int _flags=%d, double _timeout=%f) failed.\n",
                 fd, vptr, n, _flags, _timeout);
              return -1;

            case 0:
              rcs_print_error ("Write timed out.\n");
              return -1;

            default:
              break;
            }
        }
      if ((nwritten = dl_send (fd, ptr, nleft, _flags)) == -1)
        {
#if!defined(_WINDOWS) || defined(gnuwin32)
          rcs_print_error ("Send error: %d = %s\n", errno, strerror (errno));
#else
          rcs_print_error ("Send error: %d\n", dl_WSAGetLastError ());
#endif
          return (-1);          /* error */
        }
      nleft -= nwritten;
      ptr += nwritten;
      if (nleft > 0 && _timeout > 0.0)
        {
          current_time = etime ();
          if (current_time - start_time > _timeout)
            {
              rcs_print_error ("sendn: timed out after %f seconds.\n",
                               current_time - start_time);
              return (-1);
            }
          esleep (0.001);
        }
    }
  rcs_print_debug (PRINT_SOCKET_WRITE_SIZE, "wrote %d bytes to %d\n", n, fd);
  return (n);
}

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