/* $OpenBSD: fgets.c,v 1.16 2016/09/21 04:38:56 guenther Exp $ */ /*- * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Chris Torek. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include "local.h" /* * Read at most n-1 characters from the given file. * Stop when a newline has been read, or the count runs out. * Return first argument, or NULL if no characters were read. * Do not return NULL if n == 1. */ char * fgets(char *buf, int n, FILE *fp) { size_t len; char *s; unsigned char *p, *t; if (n <= 0) { /* sanity check */ errno = EINVAL; return (NULL); } FLOCKFILE(fp); _SET_ORIENTATION(fp, -1); s = buf; n--; /* leave space for NUL */ while (n != 0) { /* * If the buffer is empty, refill it. */ if (fp->_r <= 0) { if (__srefill(fp)) { /* EOF/error: stop with partial or no line */ if (s == buf) { FUNLOCKFILE(fp); return (NULL); } break; } } len = fp->_r; p = fp->_p; /* * Scan through at most n bytes of the current buffer, * looking for '\n'. If found, copy up to and including * newline, and stop. Otherwise, copy entire chunk * and loop. */ if (len > n) len = n; t = memchr(p, '\n', len); if (t != NULL) { len = ++t - p; fp->_r -= len; fp->_p = t; (void)memcpy(s, p, len); s[len] = '\0'; FUNLOCKFILE(fp); return (buf); } fp->_r -= len; fp->_p += len; (void)memcpy(s, p, len); s += len; n -= len; } *s = '\0'; FUNLOCKFILE(fp); return (buf); } DEF_STRONG(fgets);