To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: djtart/x timestamps problem
Date: Sat, 16 Jul 94 11:55:41 CEST
From: Bruno Fassino <MC4507 AT mclink DOT it>


About my problem with timestamps and djtart/x: I looked at the 
djtart.c code, and I probably found the cause of the problem.
In djtart.c the following structure is defined:

>typedef struct {
>  char name[100];
>  char operm[8];
>  char ouid[8];
>  char ogid[8];
>  char osize[11];    <<<---****
>  char otime[12];
>  char ocsum[8];
>  char flags[2];
>  char filler[355];
>} TARREC;


Unix man pages say the following (I checked three different Unix 
systems and I got the same results):

>  The header block looks like:
>
>       #define TBLOCK  512
>       #define NAMSIZ  100
>       union hblock {
>               char dummy[TBLOCK];
>               struct header {
>                       char name[NAMSIZ];
>                       char mode[8];
>                       char uid[8];
>                       char gid[8];
>                       char size[12];    <<<---****
>                       char mtime[12];
>                       char chksum[8];
>                       char linkflag;
>                       char linkname[NAMSIZ];
>               } dbuf;
>       };


It seems to me that the problem is caused by the `osize' field 
which should have a length of 12 instead of 11.  Normally this 
doesn't cause any problem because the `osize' and `otime' fields 
should be blank separated, so the 
> sscanf(header.otime, "%lo", &ftime);
(line 71 of djtart.c) skips an initial blank, and correctly reads 
ftime.  Unfortunately I found several tar archives where the 
`osize' and `otime' fields are NULL separated: in this cases the 
sscanf doesn't read anything, so the resulting timestamp is 
random.


I changed the size of `osize' to 12, reduced the size of `filler' 
to 354, and now djtart seems to work correctly on all tar 
archives.

                Bruno