mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-15 10:17:20 +00:00
c7510038dc
The following files were moved to different names: - file.man -> file.1 - magic.man -> magic.5 The following file was removed: - Magdir/Makefile
101 lines
2.2 KiB
C
101 lines
2.2 KiB
C
/*
|
|
* is_tar() -- figure out whether file is a tar archive.
|
|
*
|
|
* Stolen (by the author!) from the public domain tar program:
|
|
* Pubic Domain version written 26 Aug 1985 John Gilmore (ihnp4!hoptoad!gnu).
|
|
*
|
|
* @(#)list.c 1.18 9/23/86 Public Domain - gnu
|
|
* $Id: is_tar.c,v 1.8 1993/09/16 21:09:35 christos Exp $
|
|
*
|
|
* Comments changed and some code/comments reformatted
|
|
* for file command by Ian Darwin.
|
|
*/
|
|
|
|
#include <string.h>
|
|
#include <ctype.h>
|
|
#include <sys/types.h>
|
|
#include "tar.h"
|
|
|
|
#define isodigit(c) ( ((c) >= '0') && ((c) <= '7') )
|
|
|
|
#if defined(__STDC__) || defined(__cplusplus)
|
|
static long from_oct(int, char*); /* Decode octal number */
|
|
#else
|
|
static long from_oct();
|
|
#endif
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
int
|
|
is_tar(buf, nbytes)
|
|
unsigned char *buf;
|
|
int nbytes;
|
|
{
|
|
register union record *header = (union record *)buf;
|
|
register int i;
|
|
register long sum, recsum;
|
|
register 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 can't 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).
|
|
*/
|
|
static long
|
|
from_oct(digs, where)
|
|
register int digs;
|
|
register char *where;
|
|
{
|
|
register long value;
|
|
|
|
while (isspace(*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(*where))
|
|
return -1; /* Ended on non-space/nul */
|
|
|
|
return value;
|
|
}
|