1/*	$NetBSD: fparseln.c,v 1.9 1999/09/20 04:48:06 lukem 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 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed by Christos Zoulas.
17 * 4. The name of the author may not be used to endorse or promote products
18 *    derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: src/lib/libutil/fparseln.c,v 1.5 2002/03/21 23:52:49 obrien Exp $");
34
35#include <sys/types.h>
36#include <assert.h>
37#include <errno.h>
38#include <stdio.h>
39#include <string.h>
40#include <stdlib.h>
41#include <util.h>
42
43static int isescaped(const char *, const char *, int);
44
45/* isescaped():
46 *	Return true if the character in *p that belongs to a string
47 *	that starts in *sp, is escaped by the escape character esc.
48 */
49static int
50isescaped(sp, p, esc)
51	const char *sp, *p;
52	int esc;
53{
54	const char     *cp;
55	size_t		ne;
56
57#if 0
58	_DIAGASSERT(sp != NULL);
59	_DIAGASSERT(p != NULL);
60#endif
61
62	/* No escape character */
63	if (esc == '\0')
64		return 1;
65
66	/* Count the number of escape characters that precede ours */
67	for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
68		continue;
69
70	/* Return true if odd number of escape characters */
71	return (ne & 1) != 0;
72}
73
74
75/* fparseln():
76 *	Read a line from a file parsing continuations ending in \
77 *	and eliminating trailing newlines, or comments starting with
78 *	the comment char.
79 */
80char *
81fparseln(fp, size, lineno, str, flags)
82	FILE		*fp;
83	size_t		*size;
84	size_t		*lineno;
85	const char	 str[3];
86	int		 flags;
87{
88	static const char dstr[3] = { '\\', '\\', '#' };
89
90	size_t	s, len;
91	char   *buf;
92	char   *ptr, *cp;
93	int	cnt;
94	char	esc, con, nl, com;
95
96#if 0
97	_DIAGASSERT(fp != NULL);
98#endif
99
100	len = 0;
101	buf = NULL;
102	cnt = 1;
103
104	if (str == NULL)
105		str = dstr;
106
107	esc = str[0];
108	con = str[1];
109	com = str[2];
110	/*
111	 * XXX: it would be cool to be able to specify the newline character,
112	 * but unfortunately, fgetln does not let us
113	 */
114	nl  = '\n';
115
116	while (cnt) {
117		cnt = 0;
118
119		if (lineno)
120			(*lineno)++;
121
122		if ((ptr = fgetln(fp, &s)) == NULL)
123			break;
124
125		if (s && com) {		/* Check and eliminate comments */
126			for (cp = ptr; cp < ptr + s; cp++)
127				if (*cp == com && !isescaped(ptr, cp, esc)) {
128					s = cp - ptr;
129					cnt = s == 0 && buf == NULL;
130					break;
131				}
132		}
133
134		if (s && nl) { 		/* Check and eliminate newlines */
135			cp = &ptr[s - 1];
136
137			if (*cp == nl)
138				s--;	/* forget newline */
139		}
140
141		if (s && con) {		/* Check and eliminate continuations */
142			cp = &ptr[s - 1];
143
144			if (*cp == con && !isescaped(ptr, cp, esc)) {
145				s--;	/* forget escape */
146				cnt = 1;
147			}
148		}
149
150		if (s == 0 && buf != NULL)
151			continue;
152
153		if ((cp = realloc(buf, len + s + 1)) == NULL) {
154			free(buf);
155			return NULL;
156		}
157		buf = cp;
158
159		(void) memcpy(buf + len, ptr, s);
160		len += s;
161		buf[len] = '\0';
162	}
163
164	if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
165	    strchr(buf, esc) != NULL) {
166		ptr = cp = buf;
167		while (cp[0] != '\0') {
168			int skipesc;
169
170			while (cp[0] != '\0' && cp[0] != esc)
171				*ptr++ = *cp++;
172			if (cp[0] == '\0' || cp[1] == '\0')
173				break;
174
175			skipesc = 0;
176			if (cp[1] == com)
177				skipesc += (flags & FPARSELN_UNESCCOMM);
178			if (cp[1] == con)
179				skipesc += (flags & FPARSELN_UNESCCONT);
180			if (cp[1] == esc)
181				skipesc += (flags & FPARSELN_UNESCESC);
182			if (cp[1] != com && cp[1] != con && cp[1] != esc)
183				skipesc = (flags & FPARSELN_UNESCREST);
184
185			if (skipesc)
186				cp++;
187			else
188				*ptr++ = *cp++;
189			*ptr++ = *cp++;
190		}
191		*ptr = '\0';
192		len = strlen(buf);
193	}
194
195	if (size)
196		*size = len;
197	return buf;
198}
199
200#ifdef TEST
201
202int main(int, char **);
203
204int
205main(argc, argv)
206	int argc;
207	char **argv;
208{
209	char   *ptr;
210	size_t	size, line;
211
212	line = 0;
213	while ((ptr = fparseln(stdin, &size, &line, NULL,
214	    FPARSELN_UNESCALL)) != NULL)
215		printf("line %d (%d) |%s|\n", line, size, ptr);
216	return 0;
217}
218
219/*
220
221# This is a test
222line 1
223line 2 \
224line 3 # Comment
225line 4 \# Not comment \\\\
226
227# And a comment \
228line 5 \\\
229line 6
230
231*/
232
233#endif /* TEST */
234