fgets.c - vx32 - Local 9vx git repository for patches.
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       ---
       fgets.c (3363B)
       ---
            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. All advertising materials mentioning features or use of this software
           17  *    must display the following acknowledgement:
           18  *        This product includes software developed by the University of
           19  *        California, Berkeley and its contributors.
           20  * 4. Neither the name of the University nor the names of its contributors
           21  *    may be used to endorse or promote products derived from this software
           22  *    without specific prior written permission.
           23  *
           24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
           25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
           26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
           27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
           28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
           29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
           30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
           31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
           32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
           33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
           34  * SUCH DAMAGE.
           35  */
           36 
           37 #if defined(LIBC_SCCS) && !defined(lint)
           38 static char rcsid[] = "$OpenBSD: fgets.c,v 1.2 1996/08/19 08:32:33 tholo Exp $";
           39 #endif /* LIBC_SCCS and not lint */
           40 
           41 #include <stdio.h>
           42 #include <string.h>
           43 #include "local.h"
           44 
           45 /*
           46  * Read at most n-1 characters from the given file.
           47  * Stop when a newline has been read, or the count runs out.
           48  * Return first argument, or NULL if no characters were read.
           49  */
           50 char *
           51 fgets(buf, n, fp)
           52         char *buf;
           53         register int n;
           54         register FILE *fp;
           55 {
           56         register size_t len;
           57         register char *s;
           58         register unsigned char *p, *t;
           59 
           60         if (n <= 0)                /* sanity check */
           61                 return (NULL);
           62 
           63         s = buf;
           64         n--;                        /* leave space for NUL */
           65         while (n != 0) {
           66                 /*
           67                  * If the buffer is empty, refill it.
           68                  */
           69                 if ((len = fp->_r) <= 0) {
           70                         if (__srefill(fp)) {
           71                                 /* EOF/error: stop with partial or no line */
           72                                 if (s == buf)
           73                                         return (NULL);
           74                                 break;
           75                         }
           76                         len = fp->_r;
           77                 }
           78                 p = fp->_p;
           79 
           80                 /*
           81                  * Scan through at most n bytes of the current buffer,
           82                  * looking for '\n'.  If found, copy up to and including
           83                  * newline, and stop.  Otherwise, copy entire chunk
           84                  * and loop.
           85                  */
           86                 if (len > n)
           87                         len = n;
           88                 t = memchr((void *)p, '\n', len);
           89                 if (t != NULL) {
           90                         len = ++t - p;
           91                         fp->_r -= len;
           92                         fp->_p = t;
           93                         (void)memcpy((void *)s, (void *)p, len);
           94                         s[len] = 0;
           95                         return (buf);
           96                 }
           97                 fp->_r -= len;
           98                 fp->_p += len;
           99                 (void)memcpy((void *)s, (void *)p, len);
          100                 s += len;
          101                 n -= len;
          102         }
          103         *s = 0;
          104         return (buf);
          105 }