1 /* $NetBSD: wbuf.c,v 1.7 1997/07/13 20:15:39 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)wbuf.c 8.1 (Berkeley) 6/4/93"; 43 #else 44 __RCSID("$NetBSD: wbuf.c,v 1.7 1997/07/13 20:15:39 christos Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <errno.h> 49 #include <stdio.h> 50 #include "local.h" 51 52 /* 53 * Write the given character into the (probably full) buffer for 54 * the given file. Flush the buffer out if it is or becomes full, 55 * or if c=='\n' and the file is line buffered. 56 */ 57 int 58 __swbuf(c, fp) 59 register int c; 60 register FILE *fp; 61 { 62 register int n; 63 64 /* 65 * In case we cannot write, or longjmp takes us out early, 66 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size 67 * (if line buffered) so that we will get called again. 68 * If we did not do this, a sufficient number of putc() 69 * calls might wrap _w from negative to positive. 70 */ 71 fp->_w = fp->_lbfsize; 72 if (cantwrite(fp)) { 73 errno = EBADF; 74 return (EOF); 75 } 76 c = (unsigned char)c; 77 78 /* 79 * If it is completely full, flush it out. Then, in any case, 80 * stuff c into the buffer. If this causes the buffer to fill 81 * completely, or if c is '\n' and the file is line buffered, 82 * flush it (perhaps a second time). The second flush will always 83 * happen on unbuffered streams, where _bf._size==1; fflush() 84 * guarantees that putc() will always call wbuf() by setting _w 85 * to 0, so we need not do anything else. 86 */ 87 n = fp->_p - fp->_bf._base; 88 if (n >= fp->_bf._size) { 89 if (fflush(fp)) 90 return (EOF); 91 n = 0; 92 } 93 fp->_w--; 94 *fp->_p++ = c; 95 if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n')) 96 if (fflush(fp)) 97 return (EOF); 98 return (c); 99 } 100