100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/*-
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* Copyright (c) 1994 Søren Schmidt
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer,
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef lint
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static const char rcsid[] =
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"$FreeBSD$";
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#endif /* not lint */
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#include <stdio.h>
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#include <string.h>
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#include "decode.h"
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int decode(FILE *fd, char *buffer, int len)
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{
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int n, pos = 0, tpos;
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char *bp, *p;
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char tbuffer[3];
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char temp[128];
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#define DEC(c) (((c) - ' ') & 0x3f)
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do {
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if (!fgets(temp, sizeof(temp), fd))
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return(0);
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} while (strncmp(temp, "begin ", 6));
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sscanf(temp, "begin %o %s", &n, temp);
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bp = buffer;
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for (;;) {
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if (!fgets(p = temp, sizeof(temp), fd))
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return(0);
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if ((n = DEC(*p)) <= 0)
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break;
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for (++p; n > 0; p += 4, n -= 3) {
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tpos = 0;
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if (n >= 3) {
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tbuffer[tpos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
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tbuffer[tpos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
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tbuffer[tpos++] = DEC(p[2])<<6 | DEC(p[3]);
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}
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else {
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if (n >= 1) {
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tbuffer[tpos++] =
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DEC(p[0])<<2 | DEC(p[1])>>4;
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}
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if (n >= 2) {
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tbuffer[tpos++] =
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DEC(p[1])<<4 | DEC(p[2])>>2;
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}
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if (n >= 3) {
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tbuffer[tpos++] =
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DEC(p[2])<<6 | DEC(p[3]);
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}
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}
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if (tpos == 0)
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continue;
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if (tpos + pos > len) {
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tpos = len - pos;
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/*
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* Arrange return value > len to indicate
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* overflow.
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*/
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pos++;
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}
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bcopy(tbuffer, bp, tpos);
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pos += tpos;
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bp += tpos;
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if (pos > len)
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return(pos);
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}
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}
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if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
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return(0);
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return(pos);
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}
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