1 /* $NetBSD: fparseln.c,v 1.7 2007/03/08 19:57:53 drochner Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-4-Clause
5 *
6 * Copyright (c) 1997 Christos Zoulas. All rights reserved.
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. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by Christos Zoulas.
19 * 4. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include <sys/types.h>
38 #include <assert.h>
39 #include <errno.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <stdlib.h>
43 #include <libutil.h>
44
45 static int isescaped(const char *, const char *, int);
46
47 /* isescaped():
48 * Return true if the character in *p that belongs to a string
49 * that starts in *sp, is escaped by the escape character esc.
50 */
51 static int
isescaped(const char * sp,const char * p,int esc)52 isescaped(const char *sp, const char *p, 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 0;
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 */
80 char *
fparseln(FILE * fp,size_t * size,size_t * lineno,const char str[3],int flags)81 fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
82 {
83 static const char dstr[3] = { '\\', '\\', '#' };
84
85 size_t s, len;
86 char *buf;
87 char *ptr, *cp;
88 int cnt;
89 char esc, con, nl, com;
90 #ifdef FSTACK
91 #define MAXLINELEN 4096
92 char fbuf[MAXLINELEN];
93 #endif
94
95 #if 0
96 _DIAGASSERT(fp != NULL);
97 #endif
98
99 len = 0;
100 buf = NULL;
101 cnt = 1;
102
103 if (str == NULL)
104 str = dstr;
105
106 esc = str[0];
107 con = str[1];
108 com = str[2];
109 /*
110 * XXX: it would be cool to be able to specify the newline character,
111 * but unfortunately, fgetln does not let us
112 */
113 nl = '\n';
114
115 while (cnt) {
116 cnt = 0;
117
118 if (lineno)
119 (*lineno)++;
120
121 #ifndef FSTACK
122 if ((ptr = fgetln(fp, &s)) == NULL)
123 break;
124 #else
125 if (fgets(fbuf, MAXLINELEN, fp) == NULL)
126 break;
127 fbuf[strcspn(fbuf, "\n")] = '\0';
128 ptr = fbuf;
129 #endif
130
131 if (s && com) { /* Check and eliminate comments */
132 for (cp = ptr; cp < ptr + s; cp++)
133 if (*cp == com && !isescaped(ptr, cp, esc)) {
134 s = cp - ptr;
135 cnt = s == 0 && buf == NULL;
136 break;
137 }
138 }
139
140 if (s && nl) { /* Check and eliminate newlines */
141 cp = &ptr[s - 1];
142
143 if (*cp == nl)
144 s--; /* forget newline */
145 }
146
147 if (s && con) { /* Check and eliminate continuations */
148 cp = &ptr[s - 1];
149
150 if (*cp == con && !isescaped(ptr, cp, esc)) {
151 s--; /* forget continuation char */
152 cnt = 1;
153 }
154 }
155
156 if (s == 0) {
157 /*
158 * nothing to add, skip realloc except in case
159 * we need a minimal buf to return an empty line
160 */
161 if (cnt || buf != NULL)
162 continue;
163 }
164
165 if ((cp = realloc(buf, len + s + 1)) == NULL) {
166 free(buf);
167 return NULL;
168 }
169 buf = cp;
170
171 (void) memcpy(buf + len, ptr, s);
172 len += s;
173 buf[len] = '\0';
174 }
175
176 if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
177 strchr(buf, esc) != NULL) {
178 ptr = cp = buf;
179 while (cp[0] != '\0') {
180 int skipesc;
181
182 while (cp[0] != '\0' && cp[0] != esc)
183 *ptr++ = *cp++;
184 if (cp[0] == '\0' || cp[1] == '\0')
185 break;
186
187 skipesc = 0;
188 if (cp[1] == com)
189 skipesc += (flags & FPARSELN_UNESCCOMM);
190 if (cp[1] == con)
191 skipesc += (flags & FPARSELN_UNESCCONT);
192 if (cp[1] == esc)
193 skipesc += (flags & FPARSELN_UNESCESC);
194 if (cp[1] != com && cp[1] != con && cp[1] != esc)
195 skipesc = (flags & FPARSELN_UNESCREST);
196
197 if (skipesc)
198 cp++;
199 else
200 *ptr++ = *cp++;
201 *ptr++ = *cp++;
202 }
203 *ptr = '\0';
204 len = strlen(buf);
205 }
206
207 if (size)
208 *size = len;
209 return buf;
210 }
211
212 #ifdef TEST
213
214 int
main(int argc,char * argv[])215 main(int argc, char *argv[])
216 {
217 char *ptr;
218 size_t size, line;
219
220 line = 0;
221 while ((ptr = fparseln(stdin, &size, &line, NULL,
222 FPARSELN_UNESCALL)) != NULL)
223 printf("line %d (%d) |%s|\n", line, size, ptr);
224 return 0;
225 }
226
227 /*
228
229 # This is a test
230 line 1
231 line 2 \
232 line 3 # Comment
233 line 4 \# Not comment \\\\
234
235 # And a comment \
236 line 5 \\\
237 line 6
238
239 */
240
241 #endif /* TEST */
242