NetBSD/usr.bin/file/apprentice.c

370 lines
7.0 KiB
C

/*
* apprentice - make one pass through /etc/magic, learning its secrets.
*
* Copyright (c) Ian F. Darwin, 1987.
* Written by Ian F. Darwin.
*
* This software is not subject to any license of the American Telephone
* and Telegraph Company or of the Regents of the University of California.
*
* Permission is granted to anyone to use this software for any purpose on
* any computer system, and to alter it and redistribute it freely, subject
* to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of this
* software, no matter how awful, even if they arise from flaws in it.
*
* 2. The origin of this software must not be misrepresented, either by
* explicit claim or by omission. Since few users ever read sources,
* credits must appear in the documentation.
*
* 3. Altered versions must be plainly marked as such, and must not be
* misrepresented as being the original software. Since few users
* ever read sources, credits must appear in the documentation.
*
* 4. This notice may not be removed or altered.
*/
#include <stdio.h>
#include <ctype.h>
#include "file.h"
#ifndef lint
static char *moduleid =
"@(#)$Header: /cvsroot/src/usr.bin/file/Attic/apprentice.c,v 1.1.1.1 1993/03/21 09:45:37 cgd Exp $";
#endif /* lint */
#define MAXSTR 500
#define EATAB {while (isascii(*l) && isspace(*l)) ++l;}
extern char *progname;
extern char *magicfile;
extern int debug; /* option */
extern int nmagic; /* number of valid magic[]s */
extern long strtol();
struct magic magic[MAXMAGIS];
char *getstr();
apprentice(fn, check)
char *fn; /* name of magic file */
int check; /* non-zero: checking-only run. */
{
FILE *f;
char line[MAXSTR+1];
int errs = 0;
f = fopen(fn, "r");
if (f==NULL) {
(void) fprintf(stderr, "%s: can't read magic file %s\n",
progname, fn);
if (check)
return -1;
else
exit(1);
}
/* parse it */
if (check) /* print silly verbose header for USG compat. */
(void) printf("cont\toffset\ttype\topcode\tvalue\tdesc\n");
while (fgets(line, MAXSTR, f) != NULL) {
if (line[0]=='#') /* comment, do not parse */
continue;
if (strlen(line) <= 1) /* null line, garbage, etc */
continue;
line[strlen(line)-1] = '\0'; /* delete newline */
if (parse(line, &nmagic, check) != 0)
++errs;
}
(void) fclose(f);
return errs ? -1 : 0;
}
/*
* parse one line from magic file, put into magic[index++] if valid
*/
int
parse(l, ndx, check)
char *l;
int *ndx, check;
{
int i = 0, nd = *ndx;
int slen;
static int warned = 0;
struct magic *m;
extern int errno;
/*
* TODO malloc the magic structures (linked list?) so this can't happen
*/
if (nd+1 >= MAXMAGIS){
if (warned++ == 0)
warning(
"magic table overflow - increase MAXMAGIS beyond %d in file/apprentice.c\n",
MAXMAGIS);
return -1;
}
m = &magic[*ndx];
if (*l == '>') {
++l; /* step over */
m->contflag = 1;
} else
m->contflag = 0;
/* get offset, then skip over it */
m->offset = atoi(l);
while (isascii(*l) && isdigit(*l))
++l;
EATAB;
#define NBYTE 4
#define NSHORT 5
#define NLONG 4
#define NSTRING 6
/* get type, skip it */
if (strncmp(l, "byte", NBYTE)==0) {
m->type = BYTE;
l += NBYTE;
} else if (strncmp(l, "short", NSHORT)==0) {
m->type = SHORT;
l += NSHORT;
} else if (strncmp(l, "long", NLONG)==0) {
m->type = LONG;
l += NLONG;
} else if (strncmp(l, "string", NSTRING)==0) {
m->type = STRING;
l += NSTRING;
} else {
errno = 0;
warning("type %s invalid", l);
return -1;
}
EATAB;
if (*l == '>' || *l == '<' || *l == '&' || *l == '=') {
m->reln = *l;
++l;
} else
m->reln = '=';
EATAB;
/*
* TODO finish this macro and start using it!
* #define offsetcheck {if (offset > HOWMANY-1) warning("offset too big"); }
*/
switch(m->type) {
/*
* Do not remove the casts below. They are vital.
* When later compared with the data, the sign extension must
* have happened.
*/
case BYTE:
m->value.l = (char) strtol(l,&l,0);
break;
case SHORT:
m->value.l = (short) strtol(l,&l,0);
break;
case LONG:
m->value.l = (long) strtol(l,&l,0);
break;
case STRING:
l = getstr(l, m->value.s, sizeof(m->value.s), &slen);
m->vallen = slen;
break;
default:
warning("can't happen: m->type=%d\n", m->type);
return -1;
}
/*
* now get last part - the description
*/
EATAB;
while ((m->desc[i++] = *l++) != '\0' && i<MAXDESC)
/* NULLBODY */;
if (check) {
mdump(m);
}
++(*ndx); /* make room for next */
return 0;
}
/*
* Convert a string containing C character escapes. Stop at an unescaped
* space or tab.
* Copy the converted version to "p", returning its length in *slen.
* Return updated scan pointer as function result.
*/
char *
getstr(s, p, plen, slen)
register char *s;
register char *p;
int plen, *slen;
{
char *origs = s, *origp = p;
char *pmax = p + plen - 1;
register int c;
register int val;
while((c = *s++) != '\0') {
if (isspace(c)) break;
if (p >= pmax) {
fprintf(stderr, "String too long: %s\n", origs);
break;
}
if(c == '\\') {
switch(c = *s++) {
case '\0':
goto out;
default:
*p++ = c;
break;
case 'n':
*p++ = '\n';
break;
case 'r':
*p++ = '\r';
break;
case 'b':
*p++ = '\b';
break;
case 't':
*p++ = '\t';
break;
case 'f':
*p++ = '\f';
break;
case 'v':
*p++ = '\v';
break;
/* \ and up to 3 octal digits */
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
val = c - '0';
c = *s++; /* try for 2 */
if(c >= '0' && c <= '7') {
val = (val<<3) | (c - '0');
c = *s++; /* try for 3 */
if(c >= '0' && c <= '7')
val = (val<<3) | (c-'0');
else
--s;
}
else
--s;
*p++ = val;
break;
/* \x and up to 3 hex digits */
case 'x':
val = 'x'; /* Default if no digits */
c = hextoint(*s++); /* Get next char */
if (c >= 0) {
val = c;
c = hextoint(*s++);
if (c >= 0) {
val = (val << 4) + c;
c = hextoint(*s++);
if (c >= 0) {
val = (val << 4) + c;
} else
--s;
} else
--s;
} else
--s;
*p++ = val;
break;
}
} else
*p++ = c;
}
out:
*p = '\0';
*slen = p - origp;
return(s);
}
/* Single hex char to int; -1 if not a hex char. */
int
hextoint(c)
char c;
{
if (!isascii(c)) return -1;
if (isdigit(c)) return c - '0';
if ((c>='a')&(c<='f')) return c + 10 - 'a';
if ((c>='A')&(c<='F')) return c + 10 - 'A';
return -1;
}
/*
* Print a string containing C character escapes.
*/
void
showstr(s)
register char *s;
{
register char c;
while((c = *s++) != '\0') {
if(c >= 040 && c <= 0176)
putchar(c);
else {
putchar('\\');
switch (c) {
case '\n':
putchar('n');
break;
case '\r':
putchar('r');
break;
case '\b':
putchar('b');
break;
case '\t':
putchar('t');
break;
case '\f':
putchar('f');
break;
case '\v':
putchar('v');
break;
default:
printf("%.3o", c & 0377);
break;
}
}
}
putchar('\t');
}