/* Implement Input/Output runtime actions for CHILL.
   Copyright (C) 1992,1993 Free Software Foundation, Inc.
   Author: Wilfried Moser, et al

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <setjmp.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>

#include "fileio.h"

#ifdef EOF
#undef EOF
#endif
#define EOF -1

static
Boolean
doRead( Access_Mode* the_access, void* buf, size_t nbyte )
{
  size_t nread;

  nread = read( the_access->association->handle, buf, nbyte );
  if( nread == nbyte )
  {
    CLR_FLAG( the_access, IO_OUTOFFILE );
    return True;
  }
  if( nread == 0 )
  {
    SET_FLAG( the_access, IO_OUTOFFILE );
    return False;
  }
  the_access->association->syserrno = errno;
  RWEXCEPTION( READFAIL, OS_IO_ERROR );
  /* no return */
}

static
int bgetc( int handle, readbuf_t* rbptr )
{
  if( rbptr->cur >= rbptr->len )
    {
      rbptr->len = read( handle, rbptr->buf, READBUFLEN );
      if( rbptr->len == 0 )
	return EOF;
      rbptr->cur = 0;
    }
  return rbptr->buf[rbptr->cur++];
}

static
void bungetc( readbuf_t* rbptr, int c )
{
  rbptr->buf[--rbptr->cur] = c;
}

void*
__readrecord( Access_Mode*  the_access,
              signed long   the_index,
              char*         the_buf_addr,
              char*         file,
              int           line )
{
  unsigned long  info;
  char*          actaddr;
  unsigned short actlen;
  off_t          filepos;
  unsigned short reclen;
  unsigned long  readlen;

  if( !the_access )
    CHILLEXCEPTION( file, line, EMPTY, NULL_ACCESS );

  if( !the_access->association )
    CHILLEXCEPTION( file, line, NOTCONNECTED, IS_NOT_CONNECTED );

  /* Usage must not be WriteOnly */
  if( the_access->association->usage == WriteOnly )
    CHILLEXCEPTION( file, line, READFAIL, BAD_USAGE );

  /* OUTOFFILE must not be True when connected for sequential read */
  if( !TEST_FLAG( the_access, IO_INDEXED )
      && TEST_FLAG( the_access, IO_OUTOFFILE ) )
    CHILLEXCEPTION( file, line, READFAIL, OUT_OF_FILE );

  /*
   *  Positioning
   */
  if( TEST_FLAG( the_access, IO_INDEXED ) )
  {
    /* index expression must be within bounds of index mode */
    if( the_index < the_access->lowindex
        || the_access->highindex < the_index ) 
      CHILLEXCEPTION( file, line, RANGEFAIL, BAD_INDEX );

    filepos = the_access->base + 
              (the_index - the_access->lowindex) * the_access->reclength;

    if( lseek( the_access->association->handle, filepos, SEEK_SET ) == -1L )
      CHILLEXCEPTION( file, line, READFAIL, LSEEK_FAILS );
  }

  /* establish store loc */
  if( !(actaddr = the_buf_addr ))
  {
    /* if not yet allocated, do it now */
    if (!the_access->store_loc)
      if( !(the_access->store_loc = (char*)malloc( the_access->reclength ) ) )
	CHILLEXCEPTION( file, line, SPACEFAIL, STORE_LOC_ALLOC );
    actaddr = the_access->store_loc;
  }
  actlen  = the_access->reclength;

  if( (info = setjmp( __rw_exception )) )
    CHILLEXCEPTION( file, line, info>>16, info & 0xffff );

  if( TEST_FLAG( the_access, IO_TEXTIO ) )
  {
    readlen = actlen - 2;
    if( TEST_FLAG( the_access, IO_INDEXED ) )
    {
      if( ! doRead( the_access, &reclen, sizeof(reclen) ) )
        return NULL;
      if( reclen > readlen )
        CHILLEXCEPTION( file, line, RANGEFAIL, RECORD_TOO_LONG );
      if( ! doRead( the_access, actaddr + 2, reclen ) )
        CHILLEXCEPTION( file, line, READFAIL, RECORD_TOO_SHORT );
    }
    else
    { 
      Association_Mode *assoc = the_access->association;
      int              handle = assoc->handle;
      readbuf_t*       rbuf   = assoc->bufptr;
      char* cptr = actaddr+2;
      int   curr;

      reclen = 0;
      while( readlen-- )
      {
        curr = bgetc( handle, rbuf );
        if( curr == '\n' )
          goto end_of_line;
        if( curr == EOF )
	{
          if( !reclen )
            SET_FLAG( the_access, IO_OUTOFFILE );
          goto end_of_line;
	}
        *cptr++ = curr;
        reclen++;
      }
      if( (curr = bgetc( handle, rbuf )) != '\n' )
	{
	  bungetc( rbuf, curr );
	  CHILLEXCEPTION( file, line, RANGEFAIL, RECORD_TOO_LONG );
	}
end_of_line: ;
    }
    MOV2(actaddr,&reclen);
  }
  else
  {
    switch( the_access->rectype )
    {
    case Fixed:
      if( ! doRead( the_access, actaddr, actlen ) )
        return NULL;
      break;
    case VaryingChars:
      if( TEST_FLAG( the_access->association, IO_VARIABLE ) )
      {
        if( ! doRead( the_access, &reclen, sizeof(reclen) ) )
          return NULL;
        if( reclen > actlen - 2 )
          CHILLEXCEPTION( file, line, RANGEFAIL, RECORD_TOO_LONG );
        readlen = TEST_FLAG( the_access, IO_INDEXED ) ? actlen - 2 : reclen;
        if( ! doRead( the_access, actaddr + 2, readlen ) )
          CHILLEXCEPTION( file, line, READFAIL, RECORD_TOO_SHORT );
      }
      else
      {
        if( ! doRead( the_access, actaddr + 2, reclen = actlen - 2 ) )
          CHILLEXCEPTION( file, line, READFAIL, RECORD_TOO_SHORT );
      }
      MOV2(actaddr,&reclen);
      break;
    }
  }

  return actaddr;
}