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 <errno.h>
41#include <limits.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include "un-namespace.h"
46#include "libc_private.h"
47#include "local.h"
48
49/*
50 * Expand the line buffer.  Return -1 on error.
51#ifdef notdef
52 * The `new size' does not account for a terminating '\0',
53 * so we add 1 here.
54#endif
55 */
56int
57__slbexpand(FILE *fp, size_t newsize)
58{
59	void *p;
60
61#ifdef notdef
62	++newsize;
63#endif
64	if (fp->_lb._size >= newsize)
65		return (0);
66	if (newsize > INT_MAX) {
67		errno = ENOMEM;
68		return (-1);
69	}
70	if ((p = realloc(fp->_lb._base, newsize)) == NULL)
71		return (-1);
72	fp->_lb._base = p;
73	fp->_lb._size = newsize;
74	return (0);
75}
76
77/*
78 * Get an input line.  The returned pointer often (but not always)
79 * points into a stdio buffer.  Fgetln does not alter the text of
80 * the returned line (which is thus not a C string because it will
81 * not necessarily end with '\0'), but does allow callers to modify
82 * it if they wish.  Thus, we set __SMOD in case the caller does.
83 */
84char *
85fgetln(FILE *fp, size_t *lenp)
86{
87	unsigned char *p;
88	size_t len;
89	size_t off;
90
91	FLOCKFILE(fp);
92	ORIENT(fp, -1);
93	/* make sure there is input */
94	if (fp->_r <= 0 && __srefill(fp)) {
95		*lenp = 0;
96		FUNLOCKFILE(fp);
97		return (NULL);
98	}
99
100	/* look for a newline in the input */
101	if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
102		char *ret;
103
104		/*
105		 * Found one.  Flag buffer as modified to keep fseek from
106		 * `optimising' a backward seek, in case the user stomps on
107		 * the text.
108		 */
109		p++;		/* advance over it */
110		ret = (char *)fp->_p;
111		*lenp = len = p - fp->_p;
112		fp->_flags |= __SMOD;
113		fp->_r -= len;
114		fp->_p = p;
115		FUNLOCKFILE(fp);
116		return (ret);
117	}
118
119	/*
120	 * We have to copy the current buffered data to the line buffer.
121	 * As a bonus, though, we can leave off the __SMOD.
122	 *
123	 * OPTIMISTIC is length that we (optimistically) expect will
124	 * accommodate the `rest' of the string, on each trip through the
125	 * loop below.
126	 */
127#define OPTIMISTIC 80
128
129	for (len = fp->_r, off = 0;; len += fp->_r) {
130		size_t diff;
131
132		/*
133		 * Make sure there is room for more bytes.  Copy data from
134		 * file buffer to line buffer, refill file and look for
135		 * newline.  The loop stops only when we find a newline.
136		 */
137		if (__slbexpand(fp, len + OPTIMISTIC))
138			goto error;
139		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
140		    len - off);
141		off = len;
142		if (__srefill(fp)) {
143			if (__sfeof(fp))
144				break;
145			goto error;
146		}
147		if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
148			continue;
149
150		/* got it: finish up the line (like code above) */
151		p++;
152		diff = p - fp->_p;
153		len += diff;
154		if (__slbexpand(fp, len))
155			goto error;
156		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
157		    diff);
158		fp->_r -= diff;
159		fp->_p = p;
160		break;
161	}
162	*lenp = len;
163#ifdef notdef
164	fp->_lb._base[len] = '\0';
165#endif
166	FUNLOCKFILE(fp);
167	return ((char *)fp->_lb._base);
168
169error:
170	*lenp = 0;		/* ??? */
171	fp->_flags |= __SERR;
172	FUNLOCKFILE(fp);
173	return (NULL);		/* ??? */
174}
175