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 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