is_tar.c File Reference

#include <rz_userconf.h>
#include "file.h"
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include "tar.h"

Go to the source code of this file.

Macros
#define	isodigit(c)   (((c) >= '0') && ((c) <= '7'))

Functions
static int	from_oct (int digs, const char *where)
static int	is_tar (const ut8 *buf, size_t nbytes)
int	file_is_tar (RzMagic *ms, const ut8 *buf, size_t nbytes)

Variables
static const char	tartype [][32]

Macro Definition Documentation

isodigit

#define isodigit

(

c

)

(((c) >= '0') && ((c) <= '7'))

Definition at line 61 of file is_tar.c.

Function Documentation

file_is_tar()

int file_is_tar	(	RzMagic *	ms,
		const ut8 *	buf,
		size_t	nbytes
	)

Definition at line 125 of file is_tar.c.

                                                            {
    /*
     * 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.
     */
    int tar = is_tar(buf, nbytes);
    int mime = ms->flags & RZ_MAGIC_MIME;
 
    if (tar < 1 || tar > 3) {
        return 0;
    }
    if (mime == RZ_MAGIC_MIME_ENCODING) {
        return 0;
    }
    if (file_printf(ms, mime ? "application/x-tar" : tartype[tar - 1]) == -1) {
        return -1;
    }
    return 1;
}

References file_printf(), is_tar(), mime, nbytes, tar(), and tartype.

from_oct()

static int from_oct ( int  digs, const char *  where  )

static

Definition at line 62 of file is_tar.c.

                                                 {
    int value = 0;
    while (isspace((ut8)*where)) { /* Skip spaces */
        where++;
        if (--digs <= 0) {
            return -1; /* All blank field */
        }
    }
    while (digs > 0 && isodigit(*where)) { /* Scan til nonoctal */
        value = (value << 3) | (*where++ - '0');
        --digs;
    }
    if (digs > 0 && *where && !isspace((ut8)*where)) {
        return -1; /* Ended on non-space/nul */
    }
    return value;
}

References isodigit, isspace, and value.

Referenced by is_tar().

is_tar()

static int is_tar ( const ut8 *  buf, size_t  nbytes  )

static

Definition at line 87 of file is_tar.c.

                                                 {
    const union record *header = (const union record *)(const void *)buf;
    int i, 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 ut8 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 (strcmp(header->header.magic, GNUTMAGIC) == 0) {
        return 3; /* GNU Unix Standard tar archive */
    }
    if (strcmp(header->header.magic, TMAGIC) == 0) {
        return 2; /* Unix Standard tar archive */
    }
    return 1; /* Old fashioned tar archive */
}

References from_oct(), GNUTMAGIC, header, i, nbytes, p, and TMAGIC.

Referenced by file_is_tar().

Variable Documentation

tartype

const char tartype[][32]

static

Initial value:

= {
    "tar archive",
    "POSIX tar archive",
    "POSIX tar archive (GNU)",
}

Definition at line 50 of file is_tar.c.

Referenced by file_is_tar().