1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)wbuf.c 8.1 (Berkeley) 6/4/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 #include <errno.h> 40 #include <stdio.h> 41 #include "local.h" 42 43 /* 44 * Write the given character into the (probably full) buffer for 45 * the given file. Flush the buffer out if it is or becomes full, 46 * or if c=='\n' and the file is line buffered. 47 * 48 * Non-MT-safe 49 */ 50 int 51 __swbuf(int c, FILE *fp) 52 { 53 unsigned char *old_p; 54 int n; 55 56 /* 57 * In case we cannot write, or longjmp takes us out early, 58 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size 59 * (if line buffered) so that we will get called again. 60 * If we did not do this, a sufficient number of putc() 61 * calls might wrap _w from negative to positive. 62 */ 63 fp->_w = fp->_lbfsize; 64 if (prepwrite(fp) != 0) { 65 errno = EBADF; 66 return (EOF); 67 } 68 c = (unsigned char)c; 69 70 ORIENT(fp, -1); 71 72 /* 73 * If it is completely full, flush it out. Then, in any case, 74 * stuff c into the buffer. If this causes the buffer to fill 75 * completely, or if c is '\n' and the file is line buffered, 76 * flush it (perhaps a second time). The second flush will always 77 * happen on unbuffered streams, where _bf._size==1; fflush() 78 * guarantees that putc() will always call wbuf() by setting _w 79 * to 0, so we need not do anything else. 80 */ 81 n = fp->_p - fp->_bf._base; 82 if (n >= fp->_bf._size) { 83 if (__fflush(fp) != 0) 84 return (EOF); 85 n = 0; 86 } 87 fp->_w--; 88 *fp->_p++ = c; 89 old_p = fp->_p; 90 if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n')) { 91 if (__fflush(fp) != 0) { 92 if (fp->_p == old_p && errno == EINTR) { 93 fp->_p--; 94 fp->_w++; 95 } 96 return (EOF); 97 } 98 } 99 return (c); 100 } 101