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 <stdio.h>
33 #include <string.h>
34 #include <stdlib.h>
35 #include <compat.h>
36
37 static int isescaped(const char *, const char *, int);
38
39 /*
40 * isescaped():
41 * Return true if the character in *p that belongs to a string
42 * that starts in *sp, is escaped by the escape character esc.
43 */
44 static int
45 isescaped(const char *sp, const char *p, int esc)
46 {
47 const char *cp;
48 size_t ne;
49
50 /* No escape character */
51 if (esc == '\0')
52 return (1);
53
54 /* Count the number of escape characters that precede ours */
55 for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
56 continue;
57
58 /* Return true if odd number of escape characters */
59 return ((ne & 1) != 0);
60 }
61
62
63 /*
64 * fparseln():
65 * Read a line from a file parsing continuations ending in \
66 * and eliminating trailing newlines, or comments starting with
67 * the comment char.
68 */
69 char *
70 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
71 {
72 static const char dstr[3] = { '\\', '\\', '#' };
73
74 size_t s, len;
75 char *buf;
76 char *ptr, *cp;
77 int cnt;
78 char esc, con, nl, com;
79
80 len = 0;
81 buf = NULL;
82 cnt = 1;
83
84 if (str == NULL)
85 str = dstr;
86
87 esc = str[0];
88 con = str[1];
89 com = str[2];
90 /*
91 * XXX: it would be cool to be able to specify the newline character,
92 * but unfortunately, fgetln does not let us
93 */
94 nl = '\n';
95
96 while (cnt) {
97 cnt = 0;
98
99 if (lineno)
100 (*lineno)++;
101
102 if ((ptr = fgetln(fp, &s)) == NULL)
103 break;
104
105 if (s && com) { /* Check and eliminate comments */
106 for (cp = ptr; cp < ptr + s; cp++)
107 if (*cp == com && !isescaped(ptr, cp, esc)) {
108 s = cp - ptr;
109 cnt = s == 0 && buf == NULL;
110 break;
111 }
112 }
113
114 if (s && nl) { /* Check and eliminate newlines */
115 cp = &ptr[s - 1];
116
117 if (*cp == nl)
118 s--; /* forget newline */
119 }
120
121 if (s && con) { /* Check and eliminate continuations */
122 cp = &ptr[s - 1];
123
124 if (*cp == con && !isescaped(ptr, cp, esc)) {
125 s--; /* forget escape */
126 cnt = 1;
127 }
128 }
129
130 if (s == 0 && buf != NULL)
131 continue;
132
133 if ((cp = realloc(buf, len + s + 1)) == NULL) {
134 free(buf);
135 return (NULL);
136 }
137 buf = cp;
138
139 (void) memcpy(buf + len, ptr, s);
140 len += s;
141 buf[len] = '\0';
142 }
143
144 if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
145 strchr(buf, esc) != NULL) {
146 ptr = cp = buf;
147 while (cp[0] != '\0') {
148 int skipesc;
149
150 while (cp[0] != '\0' && cp[0] != esc)
151 *ptr++ = *cp++;
152 if (cp[0] == '\0' || cp[1] == '\0')
153 break;
154
155 skipesc = 0;
156 if (cp[1] == com)
157 skipesc += (flags & FPARSELN_UNESCCOMM);
158 if (cp[1] == con)
159 skipesc += (flags & FPARSELN_UNESCCONT);
160 if (cp[1] == esc)
161 skipesc += (flags & FPARSELN_UNESCESC);
162 if (cp[1] != com && cp[1] != con && cp[1] != esc)
163 skipesc = (flags & FPARSELN_UNESCREST);
164
165 if (skipesc)
166 cp++;
167 else
168 *ptr++ = *cp++;
169 *ptr++ = *cp++;
170 }
171 *ptr = '\0';
172 len = strlen(buf);
173 }
174
175 if (size) {
176 *size = len;
177 }
178 return (buf);
179 }
180
181 #ifdef TEST
182
183 int
184 main(int argc, char *argv[])
185 {
186 char *ptr;
187 size_t size, line;
188
189 line = 0;
190 while ((ptr = fparseln(stdin, &size, &line, NULL,
191 FPARSELN_UNESCALL)) != NULL) {
192 printf("line %d (%d) |%s|\n", line, size, ptr);
193 }
194 return (0);
195 }
196
197 /*
198 * # This is a test
199 * line 1
200 * line 2 \
201 * line 3 # Comment
202 * line 4 \# Not comment \\\\
203 *
204 * # And a comment \
205 * line 5 \\\
206 * line 6
207 *
208 */
209
210 #endif /* TEST */