[Toybox] dd in toybox?

[Rob Landley]

On 7/9/19 2:55 AM, scsijon wrote:
> 
> 
> On 09/07/19 16:56, Rob Landley wrote:
>> On 7/8/19 10:41 PM, scsijon wrote:
>>> I was wondering if you would consider adding parts of ddfldd
>>> (https://linuxx.info/dcfldd/, https://linux.die.net/man/1/dcfldd and
>>> http://dcfldd.sourceforge.net/) rather than having just the ordinary dd 'bits'
>>> to your dd implementation if possible?
>>
>> What specific feature(s) are you asking for?
>>
>>> I know it's not new, but the extra
>>> operands "pattern, textpattern and errlog" at least seem to be somewhat more
>>> than just clearly usefull, with maybe the pair "hash and hashwindow" also if
>>> possible.
>>
>> Um...
>>
>>> dcfldd is a newer version of dccifd, is functionally the same, but in parallel
>>> able to calculate checksum using hashing algorithms are MD5, SHA-1 and SHA-2,
>>> while it extends partially (by subscription).
>>
>> This differs from piping it through sha1sum how? Never having used this, it's
>> not immediately obvious how or why to...
>>
>>> Or do you have some other way we can deal with these combined
>>> functions easily?
>>
>> Pipelines? This is why Doug McIlroy suggested the pipe operator somewhere around
>> 1973?
>>
>>    yes "hello" | dd
>>
>>> And as usual, i'll state that i'm not a coder nowadays, just a builder with a 3d
>>> perspective outlook, I can't give you a patch, just an idea for someone to work
>>> with. :-)}
>>
>> Could you give me some usage examples?
>>
> 
> ok, this is the usual example given for it,
> 
> dcfldd if=/dev/source hash=md5,sha512 hashwindow=1G md5log=md5.txt
> sha512log=sha512.txt \hashconv=after bs=512 conv=noerror,sync split=1G
> splitformat=aa of=image.dd

tee </dev/source >(sha512sum>sha512.txt) >(md5sum>md5.txt) | split image.dd

> and all done without external pipe, etc. overheads.

Is a pipe a significant overhead? (It naturally takes advantage of SMP, for one
thing...)

> My normal use though, is for fixing and changing formats in .iso  and .img
> files, saves a total rebuild of an iso just to fix a typo, a bane in my life at
> least (if not also for others) when a iso and img.gz are just about ready for a
> release which is why I would like pattern and textpattern added.

Toybox sed should handle binary files?

Rob