1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 23 /* All Rights Reserved */ 24 25 26 #ident "%Z%%M% %I% %E% SMI" /* SVr4.0 1.10 */ 27 /* LINTLIBRARY */ 28 29 # include <unistd.h> 30 # include <errno.h> 31 # include <string.h> 32 33 # include "lp.h" 34 # include "msgs.h" 35 36 /* 37 ** Choose at least one byte that won't appear in the body or header 38 ** of a message. 39 */ 40 unsigned char Resync[HEAD_RESYNC_LEN] = { 0x01, 0xFE }; 41 unsigned char Endsync[HEAD_RESYNC_LEN] = { 0x02, 0xFD }; 42 43 44 /* 45 ** write_fifo() - WRITE A BUFFER WITH HEADER AND CHECKSUM 46 */ 47 48 #if defined(__STDC__) 49 int write_fifo ( int fifo, char * buf, unsigned int size ) 50 #else 51 int write_fifo (fifo, buf, size) 52 int fifo; 53 char *buf; 54 unsigned int size; 55 #endif 56 { 57 unsigned short chksum = 0; 58 int wbytes = 0; 59 60 (void)memcpy (buf + HEAD_RESYNC, Resync, HEAD_RESYNC_LEN); 61 (void)memcpy (buf + TAIL_ENDSYNC(size), Endsync, TAIL_ENDSYNC_LEN); 62 63 CALC_CHKSUM (buf, size, chksum); 64 (void)htos (buf + TAIL_CHKSUM(size), chksum); 65 66 67 /* 68 ** A message must be written in one call, to avoid interleaving 69 ** messages from several processes. 70 ** 71 ** The caller is responsible for trapping SIGPIPE, so 72 ** we just return what the "write()" system call does. 73 ** 74 ** Well, almost. If the pipe was almost full, we may have 75 ** written a partial message. If this is the case, we lie 76 ** and say the pipe was full, so the caller can try again. 77 ** 78 ** read_fifo can deal with a truncated message, so we let it 79 ** do the grunt work associated with partial messages. 80 ** 81 ** NOTE: Writing the remainder of the message is not feasible 82 ** as someone else may have written something to the fifo 83 ** while we were setting up to retry. 84 */ 85 86 if ((wbytes = write(fifo, buf, size)) > 0) 87 if (wbytes != size) 88 return(0); 89 90 return(wbytes); 91 } 92