2022-11-18 11:08:42 -0600, Clinton Bunch:
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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)
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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.