softmagic.c

sleuthit-2.09 一个磁盘的工具集

				case FILE_OPADD:
					offset = (int32_t)((p->hl[3]<<24)|
							 (p->hl[2]<<16)|
							 (p->hl[1]<<8)|
							 (p->hl[0])) +
						 off;
					break;
				case FILE_OPMINUS:
					offset = (int32_t)((p->hl[3]<<24)|
							 (p->hl[2]<<16)|
							 (p->hl[1]<<8)|
							 (p->hl[0])) -
						 off;
					break;
				case FILE_OPMULTIPLY:
					offset = (int32_t)((p->hl[3]<<24)|
							 (p->hl[2]<<16)|
							 (p->hl[1]<<8)|
							 (p->hl[0])) *
						 off;
					break;
				case FILE_OPDIVIDE:
					offset = (int32_t)((p->hl[3]<<24)|
							 (p->hl[2]<<16)|
							 (p->hl[1]<<8)|
							 (p->hl[0])) /
						 off;
					break;
				case FILE_OPMODULO:
					offset = (int32_t)((p->hl[3]<<24)|
							 (p->hl[2]<<16)|
							 (p->hl[1]<<8)|
							 (p->hl[0])) %
						 off;
					break;
				}
			} else
				offset = (int32_t)((p->hl[3]<<24)|
						 (p->hl[2]<<16)|
						 (p->hl[1]<<8)|
						 (p->hl[0]));
			if (m->in_op & FILE_OPINVERSE)
				offset = ~offset;
			break;
		case FILE_MELONG:
			if (nbytes < (offset + 4))
				return 0;
			if (off) {
				switch (m->in_op & FILE_OPS_MASK) {
				case FILE_OPAND:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) &
						 off;
					break;
				case FILE_OPOR:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) |
						 off;
					break;
				case FILE_OPXOR:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) ^
						 off;
					break;
				case FILE_OPADD:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) +
						 off;
					break;
				case FILE_OPMINUS:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) -
						 off;
					break;
				case FILE_OPMULTIPLY:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) *
						 off;
					break;
				case FILE_OPDIVIDE:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) /
						 off;
					break;
				case FILE_OPMODULO:
					offset = (int32_t)((p->hl[1]<<24)|
							 (p->hl[0]<<16)|
							 (p->hl[3]<<8)|
							 (p->hl[2])) %
						 off;
					break;
				}
			} else
				offset = (int32_t)((p->hl[1]<<24)|
						 (p->hl[0]<<16)|
						 (p->hl[3]<<8)|
						 (p->hl[2]));
			if (m->in_op & FILE_OPINVERSE)
				offset = ~offset;
			break;
		case FILE_LONG:
			if (nbytes < (offset + 4))
				return 0;
			if (off) {
				switch (m->in_op & FILE_OPS_MASK) {
				case FILE_OPAND:
					offset = p->l & off;
					break;
				case FILE_OPOR:
					offset = p->l | off;
					break;
				case FILE_OPXOR:
					offset = p->l ^ off;
					break;
				case FILE_OPADD:
					offset = p->l + off;
					break;
				case FILE_OPMINUS:
					offset = p->l - off;
					break;
				case FILE_OPMULTIPLY:
					offset = p->l * off;
					break;
				case FILE_OPDIVIDE:
					offset = p->l / off;
					break;
				case FILE_OPMODULO:
					offset = p->l % off;
					break;
			/*	case TOOMANYSWITCHBLOCKS:
			 *		ugh = p->eye % m->strain;
			 *		rub;
			 *	case BEER:
			 *		off = p->tab & m->in_gest;
			 *		sleep;
			 */
				}
			} else
				offset = p->l;
			if (m->in_op & FILE_OPINVERSE)
				offset = ~offset;
			break;
		}

		if (m->flag & INDIROFFADD)
			offset += ms->c.li[cont_level-1].off;
		if (mcopy(ms, p, m->type, 0, s, offset, nbytes, count) == -1)
			return -1;
		ms->offset = offset;

		if ((ms->flags & MAGIC_DEBUG) != 0) {
			mdebug(offset, (char *)(void *)p,
			    sizeof(union VALUETYPE));
			file_mdump(m);
		}
	}

	/* Verify we have enough data to match magic type */
	switch (m->type) {
	case FILE_BYTE:
		if (nbytes < (offset + 1)) /* should alway be true */
			return 0;
		break;
		
	case FILE_SHORT:
	case FILE_BESHORT:
	case FILE_LESHORT:
		if (nbytes < (offset + 2))
			return 0;
		break;
		
	case FILE_LONG:
	case FILE_BELONG:
	case FILE_LELONG:
	case FILE_MELONG:
	case FILE_DATE:
	case FILE_BEDATE:
	case FILE_LEDATE:
	case FILE_MEDATE:
	case FILE_LDATE:
	case FILE_BELDATE:
	case FILE_LELDATE:
	case FILE_MELDATE:
		if (nbytes < (offset + 4))
			return 0;
		break;
		
	case FILE_STRING:
	case FILE_PSTRING:
	case FILE_SEARCH:
		if (nbytes < (offset + m->vallen))
			return 0;
		break;

	case FILE_REGEX:
		if (nbytes < offset)
			return 0;
		break;

	case FILE_DEFAULT:	/* nothing to check */
	default:
		break;
	}
	if (!mconvert(ms, m))
		return 0;
	return 1;
}

private uint64_t
file_strncmp(const char *s1, const char *s2, size_t len, uint32_t flags)
{
	/*
	 * Convert the source args to unsigned here so that (1) the
	 * compare will be unsigned as it is in strncmp() and (2) so
	 * the ctype functions will work correctly without extra
	 * casting.
	 */
	const unsigned char *a = (const unsigned char *)s1;
	const unsigned char *b = (const unsigned char *)s2;
	uint64_t v;

	/*
	 * What we want here is:
	 * v = strncmp(m->value.s, p->s, m->vallen);
	 * but ignoring any nulls.  bcmp doesn't give -/+/0
	 * and isn't universally available anyway.
	 */
	v = 0;
	if (0L == flags) { /* normal string: do it fast */
		while (len-- > 0)
			if ((v = *b++ - *a++) != '\0')
				break; 
	}
	else { /* combine the others */
		while (len-- > 0) {
			if ((flags & STRING_IGNORE_LOWERCASE) &&
			    islower(*a)) {
				if ((v = tolower(*b++) - *a++) != '\0')
					break;
			}
			else if ((flags & STRING_IGNORE_UPPERCASE) &&
			    isupper(*a)) {
				if ((v = toupper(*b++) - *a++) != '\0')
					break;
			}
			else if ((flags & STRING_COMPACT_BLANK) && 
			    isspace(*a)) { 
				a++;
				if (isspace(*b++)) {
					while (isspace(*b))
						b++;
				}
				else {
					v = 1;
					break;
				}
			}
			else if ((flags & STRING_COMPACT_OPTIONAL_BLANK) &&
			    isspace(*a)) {
				a++;
				while (isspace(*b))
					b++;
			}
			else {
				if ((v = *b++ - *a++) != '\0')
					break;
			}
		}
	}
	return v;
}

private uint64_t
file_strncmp16(const char *a, const char *b, size_t len, uint32_t flags)
{
	/*
	 * XXX - The 16-bit string compare probably needs to be done
	 * differently, especially if the flags are to be supported.
	 * At the moment, I am unsure.
	 */
	flags = 0;
	return file_strncmp(a, b, len, flags);
}

private int
magiccheck(struct magic_set *ms, struct magic *m)
{
	uint64_t l = m->value.q;
	uint64_t v;
	int matched;
	union VALUETYPE *p = &ms->ms_value;

	switch (m->type) {
	case FILE_BYTE:
		v = p->b;
		break;

	case FILE_SHORT:
	case FILE_BESHORT:
	case FILE_LESHORT:
		v = p->h;
		break;

	case FILE_LONG:
	case FILE_BELONG:
	case FILE_LELONG:
	case FILE_MELONG:
	case FILE_DATE:
	case FILE_BEDATE:
	case FILE_LEDATE:
	case FILE_MEDATE:
	case FILE_LDATE:
	case FILE_BELDATE:
	case FILE_LELDATE:
	case FILE_MELDATE:
		v = p->l;
		break;

	case FILE_QUAD:
	case FILE_LEQUAD:
	case FILE_BEQUAD:
	case FILE_QDATE:
	case FILE_BEQDATE:
	case FILE_LEQDATE:
	case FILE_QLDATE:
	case FILE_BEQLDATE:
	case FILE_LEQLDATE:
		v = p->q;
		break;

	case FILE_DEFAULT:
		l = 0;
		v = 0;
		break;

	case FILE_STRING:
	case FILE_PSTRING:
		l = 0;
		v = file_strncmp(m->value.s, p->s, (size_t)m->vallen, m->str_flags);
		break;

	case FILE_BESTRING16:
	case FILE_LESTRING16:
		l = 0;
		v = file_strncmp16(m->value.s, p->s, (size_t)m->vallen, m->str_flags);
		break;

	case FILE_SEARCH: { /* search ms->search.s for the string m->value.s */
		size_t slen;
		size_t idx;

		if (ms->search.s == NULL)
			return 0;

		slen = MIN(m->vallen, sizeof(m->value.s));
		l = 0;
		v = 0;
		ms->search.offset = m->offset;

		for (idx = 0; m->str_count == 0 || idx < m->str_count; idx++) {
			if (slen + idx > ms->search.s_len)
				break;

			v = file_strncmp(m->value.s, ms->search.s + idx, slen, m->str_flags);
			if (v == 0) {	/* found match */
				ms->search.offset = m->offset + idx;
				break;
			}
		}
		break;
	}
	case FILE_REGEX: {
		int rc;
		regex_t rx;
		char errmsg[512];

		if (ms->search.s == NULL)
			return 0;

		l = 0;
		rc = regcomp(&rx, m->value.s,
		    REG_EXTENDED|REG_NEWLINE|
		    ((m->str_flags & STRING_IGNORE_CASE) ? REG_ICASE : 0));
		if (rc) {
			(void)regerror(rc, &rx, errmsg, sizeof(errmsg));
			file_magerror(ms, "regex error %d, (%s)",
			    rc, errmsg);
			v = (uint64_t)-1;
		}
		else {
			regmatch_t pmatch[1];
#ifndef REG_STARTEND
#define	REG_STARTEND	0
			size_t l = ms->search.s_len - 1;
			char c = ms->search.s[l];
			((char *)(intptr_t)ms->search.s)[l] = '\0';
#else
			pmatch[0].rm_so = 0;
			pmatch[0].rm_eo = ms->search.s_len;
#endif
			rc = regexec(&rx, (const char *)ms->search.s,
			    1, pmatch, REG_STARTEND);
#if REG_STARTEND == 0
			((char *)(intptr_t)ms->search.s)[l] = c;
#endif
			switch (rc) {
			case 0:
				ms->search.s += (int)pmatch[0].rm_so;
				ms->search.offset += (size_t)pmatch[0].rm_so;
				ms->search.rm_len =
				    (size_t)(pmatch[0].rm_eo - pmatch[0].rm_so);
				v = 0;
				break;

			case REG_NOMATCH:
				v = 1;
				break;

			default:
				(void)regerror(rc, &rx, errmsg, sizeof(errmsg));
				file_magerror(ms, "regexec error %d, (%s)",
				    rc, errmsg);
				v = (uint64_t)-1;
				break;
			}
			regfree(&rx);
		}
		if (v == (uint64_t)-1)
			return -1;
		break;
	}
	default:
		file_magerror(ms, "invalid type %d in magiccheck()", m->type);
		return -1;
	}

	v = file_signextend(ms, m, v);

	switch (m->reln) {
	case 'x':
		if ((ms->flags & MAGIC_DEBUG) != 0)
			(void) fprintf(stderr, "%llu == *any* = 1\n",
			    (unsigned long long)v);
		matched = 1;
		break;

	case '!':
		matched = v != l;
		if ((ms->flags & MAGIC_DEBUG) != 0)
			(void) fprintf(stderr, "%llu != %llu = %d\n",
			    (unsigned long long)v, (unsigned long long)l,
			    matched);
		break;

	case '=':
		matched = v == l;
		if ((ms->flags & MAGIC_DEBUG) != 0)
			(void) fprintf(stderr, "%llu == %llu = %d\n",
			    (unsigned long long)v, (unsigned long long)l,
			    matched);
		break;

	case '>':
		if (m->flag & UNSIGNED) {
			matched = v > l;
			if ((ms->flags & MAGIC_DEBUG) != 0)
				(void) fprintf(stderr, "%llu > %llu = %d\n",
				    (unsigned long long)v,
				    (unsigned long long)l, matched);
		}
		else {
			matched = (int64_t) v > (int64_t) l;
			if ((ms->flags & MAGIC_DEBUG) != 0)
				(void) fprintf(stderr, "%lld > %lld = %d\n",
				    (long long)v, (long long)l, matched);
		}
		break;

	case '<':
		if (m->flag & UNSIGNED) {
			matched = v < l;
			if ((ms->flags & MAGIC_DEBUG) != 0)
				(void) fprintf(stderr, "%llu < %llu = %d\n",
				    (unsigned long long)v,
				    (unsigned long long)l, matched);
		}
		else {
			matched = (int64_t) v < (int64_t) l;
			if ((ms->flags & MAGIC_DEBUG) != 0)
				(void) fprintf(stderr, "%lld < %lld = %d\n",
				       (long long)v, (long long)l, matched);
		}
		break;

	case '&':
		matched = (v & l) == l;
		if ((ms->flags & MAGIC_DEBUG) != 0)
			(void) fprintf(stderr, "((%llx & %llx) == %llx) = %d\n",
			    (unsigned long long)v, (unsigned long long)l,
			    (unsigned long long)l, matched);
		break;

	case '^':
		matched = (v & l) != l;
		if ((ms->flags & MAGIC_DEBUG) != 0)
			(void) fprintf(stderr, "((%llx & %llx) != %llx) = %d\n",
			    (unsigned long long)v, (unsigned long long)l,
			    (unsigned long long)l, matched);
		break;

	default:
		matched = 0;
		file_magerror(ms, "cannot happen: invalid relation `%c'",
		    m->reln);
		return -1;
	}

	return matched;
}

private int
print_sep(struct magic_set *ms, int firstline)
{
	if (firstline)
		return 0;
	/*
	 * we found another match 
	 * put a newline and '-' to do some simple formatting
	 */
	return file_printf(ms, "\n- ");
}