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)
34static char sccsid[] = "@(#)fgetln.c	8.2 (Berkeley) 1/2/94";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include "namespace.h"
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43#include "un-namespace.h"
44#include "libc_private.h"
45#include "local.h"
46
47/*
48 * Expand the line buffer.  Return -1 on error.
49#ifdef notdef
50 * The `new size' does not account for a terminating '\0',
51 * so we add 1 here.
52#endif
53 */
54int
55__slbexpand(FILE *fp, size_t newsize)
56{
57	void *p;
58
59#ifdef notdef
60	++newsize;
61#endif
62	if (fp->_lb._size >= newsize)
63		return (0);
64	if ((p = realloc(fp->_lb._base, newsize)) == NULL)
65		return (-1);
66	fp->_lb._base = p;
67	fp->_lb._size = newsize;
68	return (0);
69}
70
71/*
72 * Get an input line.  The returned pointer often (but not always)
73 * points into a stdio buffer.  Fgetln does not alter the text of
74 * the returned line (which is thus not a C string because it will
75 * not necessarily end with '\0'), but does allow callers to modify
76 * it if they wish.  Thus, we set __SMOD in case the caller does.
77 */
78char *
79fgetln(FILE *fp, size_t *lenp)
80{
81	unsigned char *p;
82	size_t len;
83	size_t off;
84
85	FLOCKFILE(fp);
86	ORIENT(fp, -1);
87	/* make sure there is input */
88	if (fp->_r <= 0 && __srefill(fp)) {
89		*lenp = 0;
90		FUNLOCKFILE(fp);
91		return (NULL);
92	}
93
94	/* look for a newline in the input */
95	if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
96		char *ret;
97
98		/*
99		 * Found one.  Flag buffer as modified to keep fseek from
100		 * `optimising' a backward seek, in case the user stomps on
101		 * the text.
102		 */
103		p++;		/* advance over it */
104		ret = (char *)fp->_p;
105		*lenp = len = p - fp->_p;
106		fp->_flags |= __SMOD;
107		fp->_r -= len;
108		fp->_p = p;
109		FUNLOCKFILE(fp);
110		return (ret);
111	}
112
113	/*
114	 * We have to copy the current buffered data to the line buffer.
115	 * As a bonus, though, we can leave off the __SMOD.
116	 *
117	 * OPTIMISTIC is length that we (optimistically) expect will
118	 * accommodate the `rest' of the string, on each trip through the
119	 * loop below.
120	 */
121#define OPTIMISTIC 80
122
123	for (len = fp->_r, off = 0;; len += fp->_r) {
124		size_t diff;
125
126		/*
127		 * Make sure there is room for more bytes.  Copy data from
128		 * file buffer to line buffer, refill file and look for
129		 * newline.  The loop stops only when we find a newline.
130		 */
131		if (__slbexpand(fp, len + OPTIMISTIC))
132			goto error;
133		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
134		    len - off);
135		off = len;
136		if (__srefill(fp))
137			break;	/* EOF or error: return partial line */
138		if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
139			continue;
140
141		/* got it: finish up the line (like code above) */
142		p++;
143		diff = p - fp->_p;
144		len += diff;
145		if (__slbexpand(fp, len))
146			goto error;
147		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
148		    diff);
149		fp->_r -= diff;
150		fp->_p = p;
151		break;
152	}
153	*lenp = len;
154#ifdef notdef
155	fp->_lb._base[len] = 0;
156#endif
157	FUNLOCKFILE(fp);
158	return ((char *)fp->_lb._base);
159
160error:
161	*lenp = 0;		/* ??? */
162	FUNLOCKFILE(fp);
163	return (NULL);		/* ??? */
164}
165