how can i create unix-compatible tar (not ustar) from scratch
i don't know how to calculate the checksum

[code]
/* Minix tar.h but it makes ustar tar */

/* The <tar.h> header is used with the tape archiver, tar. */

#ifndef _TAR_H
#define _TAR_H

#define TBLOCK 512
#define NAMSIZ 100
#define PFXSIZ 155

#define TMODLEN 8
#define TUIDLEN 8
#define TGIDLEN 8
#define TSIZLEN 12
#define TMTMLEN 12
#define TCKSLEN 8

#define TMAGIC "ustar"
#define TMAGLEN 6
#define TVERSION "00"
#define TVERSLEN 2
#define TUNMLEN 32
#define TGNMLEN 32
#define TDEVLEN 8

#define REGTYPE '0'
#define AREGTYPE '\0'
#define LNKTYPE '1'
#define SYMTYPE '2'
#define CHRTYPE '3'
#define BLKTYPE '4'
#define DIRTYPE '5'
#define FIFOTYPE '6'
#define CONTTYPE '7'

#define TSUID 04000
#define TSGID 02000
#define TSVTX 01000

#define TUREAD 00400
#define TUWRITE 00200
#define TUEXEC 00100
#define TGREAD 00040
#define TGWRITE 00020
#define TGEXEC 00010
#define TOREAD 00004
#define TOWRITE 00002
#define TOEXEC 00001

union hblock {
char dummy[TBLOCK];
struct header {
char name[NAMSIZ];
char mode[TMODLEN];
char uid[TUIDLEN];
char gid[TGIDLEN];
char size[TSIZLEN];
char mtime[TMTMLEN];
char chksum[TCKSLEN];
char typeflag;
char linkname[NAMSIZ];
char magic[TMAGLEN];
char version[TVERSLEN];
char uname[TUNMLEN];
char gname[TGNMLEN];
char devmajor[TDEVLEN];
char devminor[TDEVLEN];
char prefix[PFXSIZ];
} dbuf;
};

#endif /* _TAR_H */
[\code]


Table 1: tar Header Block (TAR Format)

Field Width Field Name Meaning

------------------------------------------
100 name name of file
8 mode file mode
8 uid owner user ID
8 gid owner group ID
12 size length of file in bytes
12 mtime modify time of file
8 chksum checksum for header
1 link indicator for links
100 linkname name of linked file


can any 1 give me a source in c or asm

or calc the chksum for me and time

[code]
name db "test.txt"
rb 92
mode db "0",0,0,0,0,0,0,0
uid db "0",0,0,0,0,0,0,0
gid db "0",0,0,0,0,0,0,0
size db "2",0,0,0,0,0,0,0,0,0,0,0
mtime db "0",0,0,0,0,0,0,0,0,0,0,0
chksum db "0",0,0,0,0,0,0,0
link db "0"
rb 100
content db "hi"
rb 255
rb 511
db 0
[/code]

Grab the source for GNU tar, and look there.

it's too big and have gnu extension for tape archieves

Hi, tar.asm is in
http://linuxassembly.org/asmutils/asmutils-0.17.tar.gz

it written in nasm.

thnx i will check it