src/tests/kits/net/sock/write.c

   1 /* -*- c-basic-offset: 8; -*-
   2  *
   3  * Copyright (c) 1993 W. Richard Stevens.  All rights reserved.
   4  * Permission to use or modify this software and its documentation only for
   5  * educational purposes and without fee is hereby granted, provided that
   6  * the above copyright notice appear in all copies.  The author makes no
   7  * representations about the suitability of this software for any purpose.
   8  * It is provided "as is" without express or implied warranty.
   9  */
  10
  11 #include "sock.h"
  12
  13 #ifndef UIO_MAXIOV
  14 #define UIO_MAXIOV      16      /* we assume this; may not be true? */
  15 #endif
  16
  17 ssize_t
  18 dowrite(int fd, const void *vptr, size_t nbytes)
  19 {
  20         struct iovec    iov[UIO_MAXIOV];
  21         const char     *ptr;
  22         int             chunksize, i, n, nleft, nwritten, ntotal;
  23
  24         if (chunkwrite == 0 && usewritev == 0)
  25                 return(write(fd, vptr, nbytes));                /* common case */
  26
  27         /*
  28          * Figure out what sized chunks to write.
  29          * Try to use UIO_MAXIOV chunks.
  30          */
  31
  32         chunksize = nbytes / UIO_MAXIOV;
  33         if (chunksize <= 0)
  34                 chunksize = 1;
  35         else if ((nbytes % UIO_MAXIOV) != 0)
  36                 chunksize++;
  37
  38         ptr = vptr;
  39         nleft = nbytes;
  40         for (i = 0; i < UIO_MAXIOV; i++)
  41           {
  42             iov[i].iov_base = (void *) ptr;
  43             n = (nleft >= chunksize) ? chunksize : nleft;
  44             iov[i].iov_len = n;
  45             if (verbose)
  46               fprintf(stderr, "iov[%2d].iov_base = %x, iov[%2d].iov_len = %d\n",
  47                       i, (u_int32_t) iov[i].iov_base, i, (int) iov[i].iov_len);
  48                 ptr += n;
  49                 if ((nleft -= n) == 0)
  50                         break;
  51         }
  52         if (i == UIO_MAXIOV)
  53                 err_quit("i == UIO_MAXIOV");
  54
  55         if (usewritev)
  56                 return(writev(fd, iov, i+1));
  57         else {
  58                 ntotal = 0;
  59                 for (n = 0; n <= i; n++) {
  60                         nwritten = write(fd, iov[n].iov_base, iov[n].iov_len);
  61                         if (nwritten != (int) iov[n].iov_len)
  62                                 return(-1);
  63                         ntotal += nwritten;
  64                 }
  65                 return(ntotal);
  66         }
  67 }