149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
/*
|
|
* Copyright (c) Ian F. Darwin 1986-1995.
|
|
* Software written by Ian F. Darwin and others;
|
|
* maintained 1995-present by Christos Zoulas and others.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice immediately at the beginning of the file, without modification,
|
|
* this list of conditions, and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
|
|
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
/*
|
|
* is_tar() -- figure out whether file is a tar archive.
|
|
*
|
|
* Stolen (by the author!) from the public domain tar program:
|
|
* Public Domain version written 26 Aug 1985 John Gilmore (ihnp4!hoptoad!gnu).
|
|
*
|
|
* @(#)list.c 1.18 9/23/86 Public Domain - gnu
|
|
*
|
|
* Comments changed and some code/comments reformatted
|
|
* for file command by Ian Darwin.
|
|
*/
|
|
|
|
#include "file.h"
|
|
#include "magic.h"
|
|
#include <string.h>
|
|
#include <ctype.h>
|
|
#include <sys/types.h>
|
|
#include "tar.h"
|
|
|
|
#ifndef lint
|
|
FILE_RCSID("@(#)$Id: is_tar.c,v 1.25 2004/09/11 19:15:57 christos Exp $")
|
|
#endif
|
|
|
|
#define isodigit(c) ( ((c) >= '0') && ((c) <= '7') )
|
|
|
|
private int is_tar(const unsigned char *, size_t);
|
|
private int from_oct(int, const char *); /* Decode octal number */
|
|
|
|
protected int
|
|
file_is_tar(struct magic_set *ms, const unsigned char *buf, size_t nbytes)
|
|
{
|
|
/*
|
|
* Do the tar test first, because if the first file in the tar
|
|
* archive starts with a dot, we can confuse it with an nroff file.
|
|
*/
|
|
switch (is_tar(buf, nbytes)) {
|
|
case 1:
|
|
if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
|
|
"application/x-tar" : "tar archive") == -1)
|
|
return -1;
|
|
return 1;
|
|
case 2:
|
|
if (file_printf(ms, (ms->flags & MAGIC_MIME) ?
|
|
"application/x-tar, POSIX" : "POSIX tar archive") == -1)
|
|
return -1;
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return
|
|
* 0 if the checksum is bad (i.e., probably not a tar archive),
|
|
* 1 for old UNIX tar file,
|
|
* 2 for Unix Std (POSIX) tar file.
|
|
*/
|
|
private int
|
|
is_tar(const unsigned char *buf, size_t nbytes)
|
|
{
|
|
const union record *header = (const union record *)(const void *)buf;
|
|
int i;
|
|
int sum, recsum;
|
|
const char *p;
|
|
|
|
if (nbytes < sizeof(union record))
|
|
return 0;
|
|
|
|
recsum = from_oct(8, header->header.chksum);
|
|
|
|
sum = 0;
|
|
p = header->charptr;
|
|
for (i = sizeof(union record); --i >= 0;) {
|
|
/*
|
|
* We cannot use unsigned char here because of old compilers,
|
|
* e.g. V7.
|
|
*/
|
|
sum += 0xFF & *p++;
|
|
}
|
|
|
|
/* Adjust checksum to count the "chksum" field as blanks. */
|
|
for (i = sizeof(header->header.chksum); --i >= 0;)
|
|
sum -= 0xFF & header->header.chksum[i];
|
|
sum += ' '* sizeof header->header.chksum;
|
|
|
|
if (sum != recsum)
|
|
return 0; /* Not a tar archive */
|
|
|
|
if (0==strcmp(header->header.magic, TMAGIC))
|
|
return 2; /* Unix Standard tar archive */
|
|
|
|
return 1; /* Old fashioned tar archive */
|
|
}
|
|
|
|
|
|
/*
|
|
* Quick and dirty octal conversion.
|
|
*
|
|
* Result is -1 if the field is invalid (all blank, or nonoctal).
|
|
*/
|
|
private int
|
|
from_oct(int digs, const char *where)
|
|
{
|
|
int value;
|
|
|
|
while (isspace((unsigned char)*where)) { /* Skip spaces */
|
|
where++;
|
|
if (--digs <= 0)
|
|
return -1; /* All blank field */
|
|
}
|
|
value = 0;
|
|
while (digs > 0 && isodigit(*where)) { /* Scan til nonoctal */
|
|
value = (value << 3) | (*where++ - '0');
|
|
--digs;
|
|
}
|
|
|
|
if (digs > 0 && *where && !isspace((unsigned char)*where))
|
|
return -1; /* Ended on non-space/nul */
|
|
|
|
return value;
|
|
}
|