Re: The read builtin erroneously consumes null bytes

[Alexis <flexibeast@gmail.com>]

"Kerin Millar" <kfm@plushkava.net> writes:

> Consider the following test case. It demonstrates NUL being 
> consumed by the read builtin, rather than by cat(1) as it should 
> have been.
>
> $ printf 'a\n\0bc' | dash -c 'read x; cat' | od -An -t x1 -c
>   62  63
>    b   c

POSIX doesn't require a `read` _builtin_, but for the `read` 
_utility_, it says:

> STDIN
>
> If the -d delim option is not specified, or if it is specified 
> and
> delim is not the null string, the standard input shall contain 
> zero or
> more bytes (which need not form valid characters) and shall not
> contain any null bytes.
>
> If the -d delim option is specified and delim is the null 
> string, the
> standard input shall contain zero or more bytes (which need not 
> form
> valid characters).
-- 
   https://pubs.opengroup.org/onlinepubs/9799919799/utilities/read.html#tag_20_100

dash's `read` builtin doesn't have an `-d delim` option, and it 
seems to me that in such a context, it's reasonable to regard `-d 
delim` as "not specified", such that stdin isn't allowed to 
contain any null bytes.


Alexis.