Re: [Zutils-bug] zstd support?

[Antonio Diaz Diaz]

Daniel Baumann wrote:
> On 10/05/2018 06:55 PM, Antonio Diaz Diaz wrote:
> > Has zstd improved since the last time I tried it[1][2]?
>
> In the context of zutils, I don't think it matters if zstd is good or
> not. zstd is available and people are using it, thereore zutils imho
> should cover it.
>
> (otherwise, with that logic zutils should not support xz either, right?)

Xz was not supported by the first version of zutils. Support was added 
later because other GNU projects were (misled to) using it. Even so, 
support for xz is partially optional. Both ztest and zupdate ignore xz 
files if no xz decompressor is installed. I even have the hope that I'll 
be able to remove xz support from zutils someday.

In addition to having a format that makes xz look good in comparison, 
zstd seems an order of magnitude more difficult to support than any of 
the four formats already supported. It does not provide an unique magic 
string, and supporting dictionary decompression may be difficult. Zstd 
is all about performance at any price for the needs of Facebook. Just 
like brotli is tuned to the needs of Google.

I would prefer to not mislead the users of zutils by supporting a format 
like zstd that considers the checksum an informative field that can be 
ignored. "We [software developers] have a moral duty to choose wisely 
the formats we use because everybody else will blindly use whatever 
formats we choose"[1].

[1] http://www.nongnu.org/lzip/xz_inadequate.html#why

In any case, I'm now so delayed with all my other projects that I can't 
add support for any format to zutils in the next several months.


Best regards,
Antonio.