1/*	$NetBSD: fparseln.c,v 1.9 2009/01/11 02:46:29 christos Exp $	*/
2
3/*
4 * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28#if defined(LIBC_SCCS) && !defined(lint)
29__RCSID("$NetBSD: fparseln.c,v 1.9 2009/01/11 02:46:29 christos Exp $");
30#endif /* LIBC_SCCS and not lint */
31
32#include "namespace.h"
33
34#include <assert.h>
35#include <errno.h>
36#include <stdio.h>
37#include <string.h>
38#include <stdlib.h>
39
40#ifdef __weak_alias
41__weak_alias(fparseln,_fparseln)
42#endif
43
44#if ! HAVE_FPARSELN || BROKEN_FPARSELN
45
46#ifndef HAVE_NBTOOL_CONFIG_H
47#include "reentrant.h"
48#include "local.h"
49#else
50#define FLOCKFILE(fp)
51#define FUNLOCKFILE(fp)
52#endif
53
54#if defined(_REENTRANT) && !HAVE_NBTOOL_CONFIG_H
55#define __fgetln(f, l) __fgetstr(f, l, '\n')
56#else
57#define __fgetln(f, l) fgetln(f, l)
58#endif
59
60static int isescaped(const char *, const char *, int);
61
62/* isescaped():
63 *	Return true if the character in *p that belongs to a string
64 *	that starts in *sp, is escaped by the escape character esc.
65 */
66static int
67isescaped(const char *sp, const char *p, int esc)
68{
69	const char     *cp;
70	size_t		ne;
71
72	_DIAGASSERT(sp != NULL);
73	_DIAGASSERT(p != NULL);
74
75	/* No escape character */
76	if (esc == '\0')
77		return 0;
78
79	/* Count the number of escape characters that precede ours */
80	for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
81		continue;
82
83	/* Return true if odd number of escape characters */
84	return (ne & 1) != 0;
85}
86
87
88/* fparseln():
89 *	Read a line from a file parsing continuations ending in \
90 *	and eliminating trailing newlines, or comments starting with
91 *	the comment char.
92 */
93char *
94fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
95{
96	static const char dstr[3] = { '\\', '\\', '#' };
97
98	size_t	s, len;
99	char   *buf;
100	char   *ptr, *cp;
101	int	cnt;
102	char	esc, con, nl, com;
103
104	_DIAGASSERT(fp != NULL);
105
106	len = 0;
107	buf = NULL;
108	cnt = 1;
109
110	if (str == NULL)
111		str = dstr;
112
113	esc = str[0];
114	con = str[1];
115	com = str[2];
116	/*
117	 * XXX: it would be cool to be able to specify the newline character,
118	 * but unfortunately, fgetln does not let us
119	 */
120	nl  = '\n';
121
122	FLOCKFILE(fp);
123
124	while (cnt) {
125		cnt = 0;
126
127		if (lineno)
128			(*lineno)++;
129
130		if ((ptr = __fgetln(fp, &s)) == NULL)
131			break;
132
133		if (s && com) {		/* Check and eliminate comments */
134			for (cp = ptr; cp < ptr + s; cp++)
135				if (*cp == com && !isescaped(ptr, cp, esc)) {
136					s = cp - ptr;
137					cnt = s == 0 && buf == NULL;
138					break;
139				}
140		}
141
142		if (s && nl) { 		/* Check and eliminate newlines */
143			cp = &ptr[s - 1];
144
145			if (*cp == nl)
146				s--;	/* forget newline */
147		}
148
149		if (s && con) {		/* Check and eliminate continuations */
150			cp = &ptr[s - 1];
151
152			if (*cp == con && !isescaped(ptr, cp, esc)) {
153				s--;	/* forget continuation char */
154				cnt = 1;
155			}
156		}
157
158		if (s == 0) {
159			/*
160			 * nothing to add, skip realloc except in case
161			 * we need a minimal buf to return an empty line
162			 */
163			if (cnt || buf != NULL)
164				continue;
165		}
166
167		if ((cp = realloc(buf, len + s + 1)) == NULL) {
168			FUNLOCKFILE(fp);
169			free(buf);
170			return NULL;
171		}
172		buf = cp;
173
174		(void) memcpy(buf + len, ptr, s);
175		len += s;
176		buf[len] = '\0';
177	}
178
179	FUNLOCKFILE(fp);
180
181	if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
182	    strchr(buf, esc) != NULL) {
183		ptr = cp = buf;
184		while (cp[0] != '\0') {
185			int skipesc;
186
187			while (cp[0] != '\0' && cp[0] != esc)
188				*ptr++ = *cp++;
189			if (cp[0] == '\0' || cp[1] == '\0')
190				break;
191
192			skipesc = 0;
193			if (cp[1] == com)
194				skipesc += (flags & FPARSELN_UNESCCOMM);
195			if (cp[1] == con)
196				skipesc += (flags & FPARSELN_UNESCCONT);
197			if (cp[1] == esc)
198				skipesc += (flags & FPARSELN_UNESCESC);
199			if (cp[1] != com && cp[1] != con && cp[1] != esc)
200				skipesc = (flags & FPARSELN_UNESCREST);
201
202			if (skipesc)
203				cp++;
204			else
205				*ptr++ = *cp++;
206			*ptr++ = *cp++;
207		}
208		*ptr = '\0';
209		len = strlen(buf);
210	}
211
212	if (size)
213		*size = len;
214	return buf;
215}
216
217#ifdef TEST
218
219int main(int, char **);
220
221int
222main(int argc, char **argv)
223{
224	char   *ptr;
225	size_t	size, line;
226
227	line = 0;
228	while ((ptr = fparseln(stdin, &size, &line, NULL,
229	    FPARSELN_UNESCALL)) != NULL)
230		printf("line %d (%d) |%s|\n", line, size, ptr);
231	return 0;
232}
233
234/*
235
236# This is a test
237line 1
238line 2 \
239line 3 # Comment
240line 4 \# Not comment \\\\
241
242# And a comment \
243line 5 \\\
244line 6
245
246*/
247
248#endif /* TEST */
249#endif	/* ! HAVE_FPARSELN || BROKEN_FPARSELN */
250