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 * 4. 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: src/lib/libc/stdio/fgetln.c,v 1.11 2007/01/09 00:28:06 imp Exp $");
38
39#include "namespace.h"
40#include <errno.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include "un-namespace.h"
45#include "libc_private.h"
46#include "local.h"
47
48/*
49 * Expand the line buffer.  Return -1 on error.
50#ifdef notdef
51 * The `new size' does not account for a terminating '\0',
52 * so we add 1 here.
53#endif
54 */
55int
56__slbexpand(FILE *fp, size_t newsize)
57{
58	void *p;
59
60#ifdef notdef
61	++newsize;
62#endif
63	if (fp->_lb._size >= newsize)
64		return (0);
65	if (newsize > INT_MAX) {
66		errno = ENOMEM;
67		return (-1);
68	}
69	if ((p = realloc(fp->_lb._base, newsize)) == NULL)
70		return (-1);
71	fp->_lb._base = p;
72	fp->_lb._size = newsize;
73	return (0);
74}
75
76/*
77 * Get an input line.  The returned pointer often (but not always)
78 * points into a stdio buffer.  Fgetln does not alter the text of
79 * the returned line (which is thus not a C string because it will
80 * not necessarily end with '\0'), but does allow callers to modify
81 * it if they wish.  Thus, we set __SMOD in case the caller does.
82 */
83char *
84fgetln(FILE *fp, size_t *lenp)
85{
86	unsigned char *p;
87	size_t len;
88	size_t off;
89
90	FLOCKFILE(fp);
91	ORIENT(fp, -1);
92	/* make sure there is input */
93	if (fp->_r <= 0 && __srefill(fp)) {
94		*lenp = 0;
95		FUNLOCKFILE(fp);
96		return (NULL);
97	}
98
99	/* look for a newline in the input */
100	if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
101		char *ret;
102
103		/*
104		 * Found one.  Flag buffer as modified to keep fseek from
105		 * `optimising' a backward seek, in case the user stomps on
106		 * the text.
107		 */
108		p++;		/* advance over it */
109		ret = (char *)fp->_p;
110		*lenp = len = p - fp->_p;
111		fp->_flags |= __SMOD;
112		fp->_r -= len;
113		fp->_p = p;
114		FUNLOCKFILE(fp);
115		return (ret);
116	}
117
118	/*
119	 * We have to copy the current buffered data to the line buffer.
120	 * As a bonus, though, we can leave off the __SMOD.
121	 *
122	 * OPTIMISTIC is length that we (optimistically) expect will
123	 * accomodate the `rest' of the string, on each trip through the
124	 * loop below.
125	 */
126#define OPTIMISTIC 80
127
128	for (len = fp->_r, off = 0;; len += fp->_r) {
129		size_t diff;
130
131		/*
132		 * Make sure there is room for more bytes.  Copy data from
133		 * file buffer to line buffer, refill file and look for
134		 * newline.  The loop stops only when we find a newline.
135		 */
136		if (__slbexpand(fp, len + OPTIMISTIC))
137			goto error;
138		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
139		    len - off);
140		off = len;
141		if (__srefill(fp))
142			break;	/* EOF or error: return partial line */
143		if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
144			continue;
145
146		/* got it: finish up the line (like code above) */
147		p++;
148		diff = p - fp->_p;
149		len += diff;
150		if (__slbexpand(fp, len))
151			goto error;
152		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
153		    diff);
154		fp->_r -= diff;
155		fp->_p = p;
156		break;
157	}
158	*lenp = len;
159#ifdef notdef
160	fp->_lb._base[len] = 0;
161#endif
162	FUNLOCKFILE(fp);
163	return ((char *)fp->_lb._base);
164
165error:
166	*lenp = 0;		/* ??? */
167	fp->_flags |= __SERR;
168	FUNLOCKFILE(fp);
169	return (NULL);		/* ??? */
170}
171