Re: [PATCH] zsh/random module [UPDATED]

[Stephane Chazelas <stephane@xxxxxxxxxxxx>]

2022-11-18 11:08:42 -0600, Clinton Bunch:
[...]
> > Some comments about the API:
> > 
> > >    -c COUNT
> > >         Sets the number of returned random data.  Defaults to 8,
> > >         unless -i, -L, or -U is specified without -a, in which case
> > >         the default is 1.  COUNT must be between 1 and 64.
> > Why those arbitrary limits? Why not from 0 to inf?
> 
> the getrandom function only guarantees 256 bytes.  64 32-bit integers. 
> Allowing 256 uint8 would be possible, but harder to explain and doesn't work
> well with bounding.  As the difference between the lower and upper limit
> surpasses half the max, the number of bytes thrown away to allow uniformity
> of distribution becomes unwieldy.
> 
> Also zero would not be particularly useful :)

You could call getrandom() as many times as necessary. From a
user point of view (mine at least) that limit doesn't make
sense. Users don't care what API you use underneath.

An array can have from 0 to inf elements, a string 0 to inf
bytes, I should be able to request from 0 to inf numbers/bytes to
store in my array/string.

> > Without -i you get uint8 in hex and with -i uint32 in decimal.
> > Why the different bases?
> 
> It's possible to break a hex string into bytes in a rather straight forward
> way.   A string of decimal numbers not so much, but decimal numbers are
> easier to manipulate.
> 
> If I didn't think it should do *something* when given no arguments, I'd
> eliminate the hex string altogether.

Alternatively, you could add a -f %02x, -f %u -f %c and do
without the -r/-i, with default -c 8 -f %02x -L 0 -U 255.

Or maybe keep the -i but only as an alias for -c 1 -f %u -L 0 -U
$((2**32-1)). (-r would be -f %c)

[...]
> > Trying to use it to get a random word with it, I came up with:
> > 
> > $ set -o extendedglob
> > $ l=({A..Z} {a..z} {0..9} _)
> > $ getrandom -a a -c20 -L1 -U$#l
> > $ echo ${(j[])a//(#m)*/$l[MATCH]}
> > EMhKvFuQlmCVSuet5uh0
> > 
> > Doing it straight by reading /dev/urandom would have been a lot
> > more awkward. Could that be improved/simplified?
> It could be done, but a list of acceptable characters would need to be
> agreed upon and documented.  Are symbols acceptable?  About half of
> passwords require them, but only accept certain ones and that differs from
> website to website.
[...]

I was not suggesting you to add that as an extra feature to
getrandom.

-- 
Stephane