1 /*- 2 * Copyright (c) 1994 Søren Schmidt 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer, 10 * in this position and unchanged. 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. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #ifndef lint 30 static const char rcsid[] = 31 "$FreeBSD$"; 32 #endif /* not lint */ 33 34 #include <stdio.h> 35 #include <string.h> 36 #include "decode.h" 37 38 int decode(FILE *fd, char *buffer, int len) 39 { 40 int n, pos = 0, tpos; 41 char *bp, *p; 42 char tbuffer[3]; 43 char temp[128]; 44 45 #define DEC(c) (((c) - ' ') & 0x3f) 46 47 do { 48 if (!fgets(temp, sizeof(temp), fd)) 49 return(0); 50 } while (strncmp(temp, "begin ", 6)); 51 sscanf(temp, "begin %o %s", (unsigned *)&n, temp); 52 bp = buffer; 53 for (;;) { 54 if (!fgets(p = temp, sizeof(temp), fd)) 55 return(0); 56 if ((n = DEC(*p)) <= 0) 57 break; 58 for (++p; n > 0; p += 4, n -= 3) { 59 tpos = 0; 60 if (n >= 3) { 61 tbuffer[tpos++] = DEC(p[0])<<2 | DEC(p[1])>>4; 62 tbuffer[tpos++] = DEC(p[1])<<4 | DEC(p[2])>>2; 63 tbuffer[tpos++] = DEC(p[2])<<6 | DEC(p[3]); 64 } 65 else { 66 if (n >= 1) { 67 tbuffer[tpos++] = 68 DEC(p[0])<<2 | DEC(p[1])>>4; 69 } 70 if (n >= 2) { 71 tbuffer[tpos++] = 72 DEC(p[1])<<4 | DEC(p[2])>>2; 73 } 74 if (n >= 3) { 75 tbuffer[tpos++] = 76 DEC(p[2])<<6 | DEC(p[3]); 77 } 78 } 79 if (tpos == 0) 80 continue; 81 if (tpos + pos > len) { 82 tpos = len - pos; 83 /* 84 * Arrange return value > len to indicate 85 * overflow. 86 */ 87 pos++; 88 } 89 bcopy(tbuffer, bp, tpos); 90 pos += tpos; 91 bp += tpos; 92 if (pos > len) 93 return(pos); 94 } 95 } 96 if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n")) 97 return(0); 98 return(pos); 99 } 100