tar bugfix patch n.347 (recoded, version 4)

[Vladimir N. Oleynik]

Roberto,

>> My reall busybox router have script:
>>
>> $ tar cf - /etc /bin/ /usr /home | ( cd /mnt/copy_here; tar xf - )
>>
>> for save configuration.
>>
>> Its make
>> - double shell to memory
>> - double tar to memory
>>
>> We can`t change fork() to vfork() trivially, this applets use BSS
>> variables (prezeroed) and for vfork() is not separetelly.
>>
> 
>  vfork is used only for execve family, using it for others thing COULD 
> serially left the sistem in unpredictable state, AFAIK:

Oops. I think about fork() to vfork emulation of sigjmp().

>  Even in the case
> 
>  find . -type file | xargs <something>
> 
>  which <something> belong to busybox, fork and fails with many zombies?
>  Fast creation of big zombies should consume memory so fast that 
> watchdog sw could miss to kill parent in time before system hang.

Its can`t fast make zombies. Only if this script have "&" --
make as background ;-) Else, the interpeteter wait own child, and
after exited both pipe process the zombies dies automatically.


--w
vodz