1 /* $OpenBSD: wbuf.c,v 1.13 2015/08/31 02:53:57 guenther Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stdio.h> 35 #include <errno.h> 36 #include "local.h" 37 38 /* 39 * Write the given character into the (probably full) buffer for 40 * the given file. Flush the buffer out if it is or becomes full, 41 * or if c=='\n' and the file is line buffered. 42 */ 43 int __swbuf(int c,FILE * fp)44 __swbuf(int c, FILE *fp) 45 { 46 int n; 47 48 _SET_ORIENTATION(fp, -1); 49 /* 50 * In case we cannot write, or longjmp takes us out early, 51 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size 52 * (if line buffered) so that we will get called again. 53 * If we did not do this, a sufficient number of putc() 54 * calls might wrap _w from negative to positive. 55 */ 56 fp->_w = fp->_lbfsize; 57 if (cantwrite(fp)) { 58 errno = EBADF; 59 return (EOF); 60 } 61 c = (unsigned char)c; 62 63 /* 64 * If it is completely full, flush it out. Then, in any case, 65 * stuff c into the buffer. If this causes the buffer to fill 66 * completely, or if c is '\n' and the file is line buffered, 67 * flush it (perhaps a second time). The second flush will always 68 * happen on unbuffered streams, where _bf._size==1; __sflush() 69 * guarantees that putc() will always call wbuf() by setting _w 70 * to 0, so we need not do anything else. 71 */ 72 n = fp->_p - fp->_bf._base; 73 if (n >= fp->_bf._size) { 74 if (__sflush(fp)) 75 return (EOF); 76 n = 0; 77 } 78 fp->_w--; 79 *fp->_p++ = c; 80 if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n')) 81 if (__sflush(fp)) 82 return (EOF); 83 return (c); 84 } 85 DEF_STRONG(__swbuf); 86