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freebsd-dev/usr.bin/file/apprentice.c

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C
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/*
* 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 <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include "file.h"
#ifndef lint
static char *moduleid =
"@(#)$Id: apprentice.c,v 1.2 1995/05/30 06:29:58 rgrimes Exp $";
#endif /* lint */
#define EATAB {while (isascii((unsigned char) *l) && \
isspace((unsigned char) *l)) ++l;}
#define LOWCASE(l) (isupper((unsigned char) (l)) ? \
tolower((unsigned char) (l)) : (l))
static int getvalue __P((struct magic *, char **));
static int hextoint __P((int));
static char *getstr __P((char *, char *, int, int *));
static int parse __P((char *, int *, int));
static void eatsize __P((char **));
static int maxmagic = 0;
static int apprentice_1 __P((char *, int));
int
apprentice(fn, check)
char *fn; /* list of magic files */
int check; /* non-zero? checking-only run. */
{
char *p, *mfn;
int file_err, errs = -1;
maxmagic = MAXMAGIS;
magic = (struct magic *) calloc(sizeof(struct magic), maxmagic);
mfn = malloc(strlen(fn)+1);
if (magic == NULL || mfn == NULL) {
(void) fprintf(stderr, "%s: Out of memory.\n", progname);
if (check)
return -1;
else
exit(1);
}
fn = strcpy(mfn, fn);
while (fn) {
p = strchr(fn, ':');
if (p)
*p++ = '\0';
file_err = apprentice_1(fn, check);
if (file_err > errs)
errs = file_err;
fn = p;
}
if (errs == -1)
(void) fprintf(stderr, "%s: couldn't find any magic files!\n",
progname);
if (!check && errs)
exit(1);
free(mfn);
return errs;
}
static int
apprentice_1(fn, check)
char *fn; /* name of magic file */
int check; /* non-zero? checking-only run. */
{
static const char hdr[] =
"cont\toffset\ttype\topcode\tmask\tvalue\tdesc";
FILE *f;
char line[BUFSIZ+1];
int errs = 0;
f = fopen(fn, "r");
if (f==NULL) {
if (errno != ENOENT)
(void) fprintf(stderr,
"%s: can't read magic file %s (%s)\n",
progname, fn, strerror(errno));
return -1;
}
/* parse it */
if (check) /* print silly verbose header for USG compat. */
(void) printf("%s\n", hdr);
for (lineno = 1;fgets(line, BUFSIZ, f) != NULL; lineno++) {
if (line[0]=='#') /* comment, do not parse */
continue;
if (strlen(line) <= (unsigned)1) /* null line, garbage, etc */
continue;
line[strlen(line)-1] = '\0'; /* delete newline */
if (parse(line, &nmagic, check) != 0)
errs = 1;
}
(void) fclose(f);
return errs;
}
/*
* extend the sign bit if the comparison is to be signed
*/
unsigned long
signextend(m, v)
struct magic *m;
unsigned long v;
{
if (!(m->flag & UNSIGNED))
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:
v = (char) v;
break;
case SHORT:
case BESHORT:
case LESHORT:
v = (short) v;
break;
case DATE:
case BEDATE:
case LEDATE:
case LONG:
case BELONG:
case LELONG:
v = (long) v;
break;
case STRING:
break;
default:
magwarn("can't happen: m->type=%d\n",
m->type);
return -1;
}
return v;
}
/*
* parse one line from magic file, put into magic[index++] if valid
*/
static int
parse(l, ndx, check)
char *l;
int *ndx, check;
{
int i = 0, nd = *ndx;
struct magic *m;
char *t, *s;
#define ALLOC_INCR 20
if (nd+1 >= maxmagic){
maxmagic += ALLOC_INCR;
if ((magic = (struct magic *) realloc(magic,
sizeof(struct magic) *
maxmagic)) == NULL) {
(void) fprintf(stderr, "%s: Out of memory.\n", progname);
if (check)
return -1;
else
exit(1);
}
memset(&magic[*ndx], 0, sizeof(struct magic) * ALLOC_INCR);
}
m = &magic[*ndx];
m->flag = 0;
m->cont_level = 0;
while (*l == '>') {
++l; /* step over */
m->cont_level++;
}
if (m->cont_level != 0 && *l == '(') {
++l; /* step over */
m->flag |= INDIR;
}
/* get offset, then skip over it */
m->offset = (int) strtoul(l,&t,0);
if (l == t)
magwarn("offset %s invalid", l);
l = t;
if (m->flag & INDIR) {
m->in.type = LONG;
m->in.offset = 0;
/*
* read [.lbs][+-]nnnnn)
*/
if (*l == '.') {
l++;
switch (LOWCASE(*l)) {
case 'l':
m->in.type = LONG;
break;
case 'h':
case 's':
m->in.type = SHORT;
break;
case 'c':
case 'b':
m->in.type = BYTE;
break;
default:
magwarn("indirect offset type %c invalid", *l);
break;
}
l++;
}
s = l;
if (*l == '+' || *l == '-') l++;
if (isdigit((unsigned char)*l)) {
m->in.offset = strtoul(l, &t, 0);
if (*s == '-') m->in.offset = - m->in.offset;
}
else
t = l;
if (*t++ != ')')
magwarn("missing ')' in indirect offset");
l = t;
}
while (isascii((unsigned char)*l) && isdigit((unsigned char)*l))
++l;
EATAB;
#define NBYTE 4
#define NSHORT 5
#define NLONG 4
#define NSTRING 6
#define NDATE 4
#define NBESHORT 7
#define NBELONG 6
#define NBEDATE 6
#define NLESHORT 7
#define NLELONG 6
#define NLEDATE 6
if (*l == 'u') {
++l;
m->flag |= UNSIGNED;
}
/* 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 if (strncmp(l, "date", NDATE)==0) {
m->type = DATE;
l += NDATE;
} else if (strncmp(l, "beshort", NBESHORT)==0) {
m->type = BESHORT;
l += NBESHORT;
} else if (strncmp(l, "belong", NBELONG)==0) {
m->type = BELONG;
l += NBELONG;
} else if (strncmp(l, "bedate", NBEDATE)==0) {
m->type = BEDATE;
l += NBEDATE;
} else if (strncmp(l, "leshort", NLESHORT)==0) {
m->type = LESHORT;
l += NLESHORT;
} else if (strncmp(l, "lelong", NLELONG)==0) {
m->type = LELONG;
l += NLELONG;
} else if (strncmp(l, "ledate", NLEDATE)==0) {
m->type = LEDATE;
l += NLEDATE;
} else {
magwarn("type %s invalid", l);
return -1;
}
/* New-style anding: "0 byte&0x80 =0x80 dynamically linked" */
if (*l == '&') {
++l;
m->mask = signextend(m, strtoul(l, &l, 0));
eatsize(&l);
} else
m->mask = ~0L;
EATAB;
switch (*l) {
case '>':
case '<':
/* Old-style anding: "0 byte &0x80 dynamically linked" */
case '&':
case '^':
case '=':
m->reln = *l;
++l;
break;
case '!':
if (m->type != STRING) {
m->reln = *l;
++l;
break;
}
/* FALL THROUGH */
default:
if (*l == 'x' && isascii((unsigned char)l[1]) &&
isspace((unsigned char)l[1])) {
m->reln = *l;
++l;
goto GetDesc; /* Bill The Cat */
}
m->reln = '=';
break;
}
EATAB;
if (getvalue(m, &l))
return -1;
/*
* TODO finish this macro and start using it!
* #define offsetcheck {if (offset > HOWMANY-1)
* magwarn("offset too big"); }
*/
/*
* now get last part - the description
*/
GetDesc:
EATAB;
if (l[0] == '\b') {
++l;
m->nospflag = 1;
} else if ((l[0] == '\\') && (l[1] == 'b')) {
++l;
++l;
m->nospflag = 1;
} else
m->nospflag = 0;
while ((m->desc[i++] = *l++) != '\0' && i<MAXDESC)
/* NULLBODY */;
if (check) {
mdump(m);
}
++(*ndx); /* make room for next */
return 0;
}
/*
* Read a numeric value from a pointer, into the value union of a magic
* pointer, according to the magic type. Update the string pointer to point
* just after the number read. Return 0 for success, non-zero for failure.
*/
static int
getvalue(m, p)
struct magic *m;
char **p;
{
int slen;
if (m->type == STRING) {
*p = getstr(*p, m->value.s, sizeof(m->value.s), &slen);
m->vallen = slen;
} else
if (m->reln != 'x') {
m->value.l = signextend(m, strtoul(*p, p, 0));
eatsize(p);
}
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.
*/
static 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((unsigned char) 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++ = (char) 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++ = (char)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++ = (char)val;
break;
}
} else
*p++ = (char)c;
}
out:
*p = '\0';
*slen = p - origp;
return s;
}
/* Single hex char to int; -1 if not a hex char. */
static int
hextoint(c)
int c;
{
if (!isascii((unsigned char) c)) return -1;
if (isdigit((unsigned char) 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(fp, s, len)
FILE *fp;
const char *s;
int len;
{
register char c;
for (;;) {
c = *s++;
if (len == -1) {
if (c == '\0')
break;
}
else {
if (len-- == 0)
break;
}
if(c >= 040 && c <= 0176) /* TODO isprint && !iscntrl */
(void) fputc(c, fp);
else {
(void) fputc('\\', fp);
switch (c) {
case '\n':
(void) fputc('n', fp);
break;
case '\r':
(void) fputc('r', fp);
break;
case '\b':
(void) fputc('b', fp);
break;
case '\t':
(void) fputc('t', fp);
break;
case '\f':
(void) fputc('f', fp);
break;
case '\v':
(void) fputc('v', fp);
break;
default:
(void) fprintf(fp, "%.3o", c & 0377);
break;
}
}
}
}
/*
* eatsize(): Eat the size spec from a number [eg. 10UL]
*/
static void
eatsize(p)
char **p;
{
char *l = *p;
if (LOWCASE(*l) == 'u')
l++;
switch (LOWCASE(*l)) {
case 'l': /* long */
case 's': /* short */
case 'h': /* short */
case 'b': /* char/byte */
case 'c': /* char/byte */
l++;
/*FALLTHROUGH*/
default:
break;
}
*p = l;
}
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