lib/msgs/mread.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */


#ident  "%Z%%M% %I% %E% SMI"    /* SVr4.0 1.6   */
/* LINTLIBRARY */


#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <stropts.h>

#include "lp.h"
#include "msgs.h"

extern int  Lp_prio_msg;

/*
**  Function:   int mread( MESG *, char *, int)
**  Args:       message descriptor
**          message buffer (var)
**          buffer size
**  Return:     The size of the message in message buffer.
**          or -1 on error.  Possible errnos are:
**      EINVAL  Bad value for md or msgbuf.
**      E2BIG   Not enough space for message.
**      EPIPE   Far end dropped the connection.
**      ENOMSG  No valid message available on fifo.
**
**  mread examines message descriptor and either calls read3_2
**  to read 3.2 HPI messages or getmsg(2) to read 4.0 HPI messages.
**  If a message is read, it is returned in message buffer.
*/

#if defined(__STDC__)
int mread ( MESG * md, char * msgbuf, int size )
#else
int mread ( md, msgbuf, size )
MESG    *md;
char    *msgbuf;
int size;
#endif
{
    int         flag = 0;
    char        buff [MSGMAX];
    struct strbuf   dat;
    struct strbuf   ctl;

    if (md == NULL || msgbuf == NULL)
    {
    errno = EINVAL;
    return(-1);
    }

    switch(md->type)
    {
      case MD_CHILD:
      case MD_STREAM:
      case MD_BOUND:
    if (size <= 0)
    {
        errno = E2BIG;
        return(-1);
    }
    dat.buf = msgbuf;
    dat.maxlen = size;
    dat.len = 0;
    ctl.buf = buff;
    ctl.maxlen = sizeof (buff);
    ctl.len = 0;
    flag = Lp_prio_msg;
    Lp_prio_msg = 0;    /* clean this up so there are no surprises */

    if (Getmsg(md, &ctl, &dat, &flag) < 0)
    {
        if (errno == EBADF)
        errno = EPIPE;
        return(-1);
    }

    if (dat.len == 0)
    {
        (void) Close(md->readfd);
        return(0);
    }
    break;

      case MD_USR_FIFO:
      case MD_SYS_FIFO:
    if (size < CONTROL_LEN)
    {
        errno = E2BIG;
        return(-1);
    }

    if (read3_2(md, msgbuf, size) < 0)
        return(-1);
    break;
    }

    return((int)msize(msgbuf));
}