1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char rcsid[] = "$OpenBSD: wbuf.c,v 1.7 2004/09/28 18:12:44 otto Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <stdio.h> 38 #include <errno.h> 39 #include "local.h" 40 41 /* 42 * Write the given character into the (probably full) buffer for 43 * the given file. Flush the buffer out if it is or becomes full, 44 * or if c=='\n' and the file is line buffered. 45 */ 46 int 47 __swbuf(int c, FILE *fp) 48 { 49 int n; 50 51 /* 52 * In case we cannot write, or longjmp takes us out early, 53 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size 54 * (if line buffered) so that we will get called again. 55 * If we did not do this, a sufficient number of putc() 56 * calls might wrap _w from negative to positive. 57 */ 58 fp->_w = fp->_lbfsize; 59 if (cantwrite(fp)) { 60 errno = EBADF; 61 return (EOF); 62 } 63 c = (unsigned char)c; 64 65 /* 66 * If it is completely full, flush it out. Then, in any case, 67 * stuff c into the buffer. If this causes the buffer to fill 68 * completely, or if c is '\n' and the file is line buffered, 69 * flush it (perhaps a second time). The second flush will always 70 * happen on unbuffered streams, where _bf._size==1; fflush() 71 * guarantees that putc() will always call wbuf() by setting _w 72 * to 0, so we need not do anything else. 73 */ 74 n = fp->_p - fp->_bf._base; 75 if (n >= fp->_bf._size) { 76 if (fflush(fp)) 77 return (EOF); 78 n = 0; 79 } 80 fp->_w--; 81 *fp->_p++ = c; 82 if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n')) 83 if (fflush(fp)) 84 return (EOF); 85 return (c); 86 } 87