520 lines
10 KiB
C
520 lines
10 KiB
C
/*
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* apprentice - make one pass through /etc/magic, learning its secrets.
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*
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* Copyright (c) Ian F. Darwin, 1987.
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* Written by Ian F. Darwin.
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*
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* This software is not subject to any license of the American Telephone
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* and Telegraph Company or of the Regents of the University of California.
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*
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* Permission is granted to anyone to use this software for any purpose on
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* any computer system, and to alter it and redistribute it freely, subject
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* to the following restrictions:
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*
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* 1. The author is not responsible for the consequences of use of this
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* software, no matter how awful, even if they arise from flaws in it.
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*
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* 2. The origin of this software must not be misrepresented, either by
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* explicit claim or by omission. Since few users ever read sources,
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* credits must appear in the documentation.
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*
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* 3. Altered versions must be plainly marked as such, and must not be
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* misrepresented as being the original software. Since few users
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* ever read sources, credits must appear in the documentation.
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*
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* 4. This notice may not be removed or altered.
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*/
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#ifndef lint
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static char rcsid[] = "$Id: apprentice.c,v 1.3 1993/08/01 18:16:26 mycroft Exp $";
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#endif /* not lint */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include "file.h"
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#define EATAB {while (isascii((unsigned char) *l) && \
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isspace((unsigned char) *l)) ++l;}
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static int getvalue __P((struct magic *, char **));
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static int hextoint __P((int));
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static char *getstr __P((char *, char *, int, int *));
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static int parse __P((char *, int *, int));
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static int maxmagic = 0;
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int
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apprentice(fn, check)
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char *fn; /* name of magic file */
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int check; /* non-zero? checking-only run. */
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{
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FILE *f;
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char line[BUFSIZ+1];
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int errs = 0;
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f = fopen(fn, "r");
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if (f==NULL) {
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(void) fprintf(stderr, "%s: can't read magic file %s\n",
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progname, fn);
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if (check)
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return -1;
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else
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exit(1);
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}
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maxmagic = MAXMAGIS;
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if ((magic = (struct magic *) malloc(sizeof(struct magic) * maxmagic))
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== NULL) {
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(void) fprintf(stderr, "%s: Out of memory.\n", progname);
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if (check)
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return -1;
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else
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exit(1);
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}
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/* parse it */
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if (check) /* print silly verbose header for USG compat. */
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(void) printf("cont\toffset\ttype\topcode\tmask\tvalue\tdesc\n");
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for (lineno = 1;fgets(line, BUFSIZ, f) != NULL; lineno++) {
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if (line[0]=='#') /* comment, do not parse */
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continue;
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if (strlen(line) <= (unsigned)1) /* null line, garbage, etc */
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continue;
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line[strlen(line)-1] = '\0'; /* delete newline */
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if (parse(line, &nmagic, check) != 0)
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++errs;
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}
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(void) fclose(f);
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return errs ? -1 : 0;
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}
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/*
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* parse one line from magic file, put into magic[index++] if valid
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*/
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static int
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parse(l, ndx, check)
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char *l;
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int *ndx, check;
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{
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int i = 0, nd = *ndx;
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struct magic *m;
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char *t, *s;
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if (nd+1 >= maxmagic){
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maxmagic += 20;
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if ((magic = (struct magic *) realloc(magic,
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sizeof(struct magic) *
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maxmagic)) == NULL) {
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(void) fprintf(stderr, "%s: Out of memory.\n", progname);
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if (check)
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return -1;
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else
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exit(1);
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}
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}
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m = &magic[*ndx];
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m->flag = 0;
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m->cont_level = 0;
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while (*l == '>') {
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++l; /* step over */
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m->cont_level++;
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}
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if (m->cont_level != 0 && *l == '(') {
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++l; /* step over */
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m->flag |= INDIR;
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}
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/* get offset, then skip over it */
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m->offset = (int) strtol(l,&t,0);
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if (l == t)
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magwarn("offset %s invalid", l);
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l = t;
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if (m->flag & INDIR) {
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m->in.type = LONG;
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m->in.offset = 0;
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/*
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* read [.lbs][+-]nnnnn)
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*/
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if (*l == '.') {
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switch (*++l) {
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case 'l':
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m->in.type = LONG;
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break;
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case 's':
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m->in.type = SHORT;
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break;
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case 'b':
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m->in.type = BYTE;
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break;
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default:
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magwarn("indirect offset type %c invalid", *l);
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break;
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}
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l++;
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}
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s = l;
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if (*l == '+' || *l == '-') l++;
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if (isdigit((unsigned char)*l)) {
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m->in.offset = strtol(l, &t, 0);
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if (*s == '-') m->in.offset = - m->in.offset;
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}
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if (*t++ != ')')
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magwarn("missing ')' in indirect offset");
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l = t;
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}
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while (isascii((unsigned char)*l) && isdigit((unsigned char)*l))
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++l;
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EATAB;
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#define NBYTE 4
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#define NSHORT 5
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#define NLONG 4
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#define NSTRING 6
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#define NDATE 4
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#define NBESHORT 7
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#define NBELONG 6
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#define NBEDATE 6
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#define NLESHORT 7
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#define NLELONG 6
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#define NLEDATE 6
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/* get type, skip it */
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if (strncmp(l, "byte", NBYTE)==0) {
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m->type = BYTE;
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l += NBYTE;
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} else if (strncmp(l, "short", NSHORT)==0) {
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m->type = SHORT;
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l += NSHORT;
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} else if (strncmp(l, "long", NLONG)==0) {
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m->type = LONG;
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l += NLONG;
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} else if (strncmp(l, "string", NSTRING)==0) {
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m->type = STRING;
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l += NSTRING;
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} else if (strncmp(l, "date", NDATE)==0) {
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m->type = DATE;
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l += NDATE;
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} else if (strncmp(l, "beshort", NBESHORT)==0) {
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m->type = BESHORT;
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l += NBESHORT;
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} else if (strncmp(l, "belong", NBELONG)==0) {
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m->type = BELONG;
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l += NBELONG;
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} else if (strncmp(l, "bedate", NBEDATE)==0) {
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m->type = BEDATE;
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l += NBEDATE;
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} else if (strncmp(l, "leshort", NLESHORT)==0) {
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m->type = LESHORT;
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l += NLESHORT;
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} else if (strncmp(l, "lelong", NLELONG)==0) {
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m->type = LELONG;
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l += NLELONG;
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} else if (strncmp(l, "ledate", NLEDATE)==0) {
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m->type = LEDATE;
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l += NLEDATE;
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} else {
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magwarn("type %s invalid", l);
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return -1;
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}
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/* New-style anding: "0 byte&0x80 =0x80 dynamically linked" */
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if (*l == '&') {
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++l;
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m->mask = strtol(l, &l, 0);
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} else
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m->mask = 0L;
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EATAB;
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switch (*l) {
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case '>':
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case '<':
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/* Old-style anding: "0 byte &0x80 dynamically linked" */
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case '&':
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case '^':
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case '=':
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m->reln = *l;
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++l;
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break;
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case '!':
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if (m->type != STRING) {
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m->reln = *l;
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++l;
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break;
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}
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/* FALL THROUGH */
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default:
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if (*l == 'x' && isascii((unsigned char)l[1]) &&
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isspace((unsigned char)l[1])) {
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m->reln = *l;
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++l;
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goto GetDesc; /* Bill The Cat */
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}
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m->reln = '=';
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break;
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}
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EATAB;
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if (getvalue(m, &l))
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return -1;
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/*
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* TODO finish this macro and start using it!
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* #define offsetcheck {if (offset > HOWMANY-1)
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* magwarn("offset too big"); }
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*/
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/*
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* now get last part - the description
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*/
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GetDesc:
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EATAB;
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if (l[0] == '\b') {
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++l;
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m->nospflag = 1;
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} else if ((l[0] == '\\') && (l[1] == 'b')) {
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++l;
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++l;
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m->nospflag = 1;
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} else
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m->nospflag = 0;
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while ((m->desc[i++] = *l++) != '\0' && i<MAXDESC)
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/* NULLBODY */;
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if (check) {
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mdump(m);
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}
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++(*ndx); /* make room for next */
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return 0;
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}
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/*
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* Read a numeric value from a pointer, into the value union of a magic
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* pointer, according to the magic type. Update the string pointer to point
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* just after the number read. Return 0 for success, non-zero for failure.
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*/
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static int
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getvalue(m, p)
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struct magic *m;
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char **p;
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{
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int slen;
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if (m->type == STRING) {
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*p = getstr(*p, m->value.s, sizeof(m->value.s), &slen);
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m->vallen = slen;
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} else {
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if (m->reln != 'x') {
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switch(m->type) {
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/*
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* Do not remove the casts below. They are vital.
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* When later compared with the data, the sign
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* extension must have happened.
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*/
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case BYTE:
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m->value.l = (char) strtol(*p,p,0);
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break;
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case SHORT:
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case BESHORT:
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case LESHORT:
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m->value.l = (short) strtol(*p,p,0);
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break;
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case DATE:
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case BEDATE:
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case LEDATE:
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case LONG:
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case BELONG:
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case LELONG:
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m->value.l = (long) strtol(*p,p,0);
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break;
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default:
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magwarn("can't happen: m->type=%d\n", m->type);
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return -1;
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}
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}
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}
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return 0;
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}
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/*
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* Convert a string containing C character escapes. Stop at an unescaped
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* space or tab.
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* Copy the converted version to "p", returning its length in *slen.
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* Return updated scan pointer as function result.
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*/
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static char *
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getstr(s, p, plen, slen)
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register char *s;
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register char *p;
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int plen, *slen;
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{
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char *origs = s, *origp = p;
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char *pmax = p + plen - 1;
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register int c;
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register int val;
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while ((c = *s++) != '\0') {
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if (isspace((unsigned char) c))
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break;
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if (p >= pmax) {
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fprintf(stderr, "String too long: %s\n", origs);
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break;
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}
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if(c == '\\') {
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switch(c = *s++) {
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case '\0':
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goto out;
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default:
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*p++ = (char) c;
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break;
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case 'n':
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*p++ = '\n';
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break;
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case 'r':
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*p++ = '\r';
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break;
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case 'b':
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*p++ = '\b';
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break;
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case 't':
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*p++ = '\t';
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break;
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case 'f':
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*p++ = '\f';
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break;
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case 'v':
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*p++ = '\v';
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break;
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/* \ and up to 3 octal digits */
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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val = c - '0';
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c = *s++; /* try for 2 */
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if(c >= '0' && c <= '7') {
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val = (val<<3) | (c - '0');
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c = *s++; /* try for 3 */
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if(c >= '0' && c <= '7')
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val = (val<<3) | (c-'0');
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else
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--s;
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}
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else
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--s;
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*p++ = (char)val;
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break;
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/* \x and up to 3 hex digits */
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case 'x':
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val = 'x'; /* Default if no digits */
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c = hextoint(*s++); /* Get next char */
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if (c >= 0) {
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val = c;
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c = hextoint(*s++);
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if (c >= 0) {
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val = (val << 4) + c;
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c = hextoint(*s++);
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if (c >= 0) {
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val = (val << 4) + c;
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} else
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--s;
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} else
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--s;
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} else
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--s;
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*p++ = (char)val;
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break;
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}
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} else
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*p++ = (char)c;
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}
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out:
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*p = '\0';
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*slen = p - origp;
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return s;
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}
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/* Single hex char to int; -1 if not a hex char. */
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static int
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hextoint(c)
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int c;
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{
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if (!isascii((unsigned char) c)) return -1;
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if (isdigit((unsigned char) c)) return c - '0';
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if ((c>='a')&&(c<='f')) return c + 10 - 'a';
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if ((c>='A')&&(c<='F')) return c + 10 - 'A';
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return -1;
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}
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/*
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* Print a string containing C character escapes.
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*/
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void
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showstr(s)
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const char *s;
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{
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register char c;
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while((c = *s++) != '\0') {
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if(c >= 040 && c <= 0176) /* TODO isprint && !iscntrl */
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putchar(c);
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else {
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putchar('\\');
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switch (c) {
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case '\n':
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putchar('n');
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break;
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case '\r':
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putchar('r');
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break;
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case '\b':
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putchar('b');
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break;
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case '\t':
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putchar('t');
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break;
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case '\f':
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putchar('f');
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break;
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case '\v':
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putchar('v');
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break;
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default:
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printf("%.3o", c & 0377);
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break;
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}
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}
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}
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putchar('\t');
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}
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