1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1994 Søren Schmidt
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer,
12 * in this position and unchanged.
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. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #ifndef lint
32 static const char rcsid[] =
33 "$FreeBSD$";
34 #endif /* not lint */
35
36 #include <stdio.h>
37 #include <string.h>
38 #include "decode.h"
39
decode(FILE * fd,char * buffer,int len)40 int decode(FILE *fd, char *buffer, int len)
41 {
42 int n, pos = 0, tpos;
43 char *bp, *p;
44 char tbuffer[3];
45 char temp[128];
46
47 #define DEC(c) (((c) - ' ') & 0x3f)
48
49 do {
50 if (!fgets(temp, sizeof(temp), fd))
51 return(0);
52 } while (strncmp(temp, "begin ", 6));
53 sscanf(temp, "begin %o %s", (unsigned *)&n, temp);
54 bp = buffer;
55 for (;;) {
56 if (!fgets(p = temp, sizeof(temp), fd))
57 return(0);
58 if ((n = DEC(*p)) <= 0)
59 break;
60 for (++p; n > 0; p += 4, n -= 3) {
61 tpos = 0;
62 if (n >= 3) {
63 tbuffer[tpos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
64 tbuffer[tpos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
65 tbuffer[tpos++] = DEC(p[2])<<6 | DEC(p[3]);
66 }
67 else {
68 if (n >= 1) {
69 tbuffer[tpos++] =
70 DEC(p[0])<<2 | DEC(p[1])>>4;
71 }
72 if (n >= 2) {
73 tbuffer[tpos++] =
74 DEC(p[1])<<4 | DEC(p[2])>>2;
75 }
76 if (n >= 3) {
77 tbuffer[tpos++] =
78 DEC(p[2])<<6 | DEC(p[3]);
79 }
80 }
81 if (tpos == 0)
82 continue;
83 if (tpos + pos > len) {
84 tpos = len - pos;
85 /*
86 * Arrange return value > len to indicate
87 * overflow.
88 */
89 pos++;
90 }
91 bcopy(tbuffer, bp, tpos);
92 pos += tpos;
93 bp += tpos;
94 if (pos > len)
95 return(pos);
96 }
97 }
98 if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
99 return(0);
100 return(pos);
101 }
102