/**************************************************************************/
/*                                                                        */
/*                                 OCaml                                  */
/*                                                                        */
/*             Xavier Leroy, projet Cristal, INRIA Rocquencourt           */
/*                                                                        */
/*   Copyright 1996 Institut National de Recherche en Informatique et     */
/*     en Automatique.                                                    */
/*                                                                        */
/*   All rights reserved.  This file is distributed under the terms of    */
/*   the GNU Lesser General Public License version 2.1, with the          */
/*   special exception on linking described in the file LICENSE.          */
/*                                                                        */
/**************************************************************************/

#include <string.h>
#include <caml/mlvalues.h>
#include <caml/memory.h>
#include <caml/signals.h>
#include "unixsupport.h"

CAMLprim value unix_read(value fd, value buf, value ofs, value len)
{
  long numbytes;
  int ret;
  char iobuf[UNIX_BUFFER_SIZE];

  Begin_root (buf);
    numbytes = Long_val(len);
    if (numbytes > UNIX_BUFFER_SIZE) numbytes = UNIX_BUFFER_SIZE;
    caml_enter_blocking_section();
    ret = read(Int_val(fd), iobuf, (int) numbytes);
    caml_leave_blocking_section();
    if (ret == -1) uerror("read", Nothing);
    memmove (&Byte(buf, Long_val(ofs)), iobuf, ret);
  End_roots();
  return Val_int(ret);
}