This closes#2181.
`who --lookup` is failing with a runtime panic (double free).
Since `crate::dns-lookup` already includes a safe wrapper for `getaddrinfo`
I used this crate instead of further debugging the existing code in
utmpx::canon_host().
* It was neccessary to remove the version constraint for libc in uucore.
Refactor code from the `backwards_thru_file()` function into a new
`ReverseChunks` iterator, and use that iterator to simplify the
implementation of the `backwards_thru_file()` function. The
`ReverseChunks` iterator yields `Vec<u8>` objects, each of which
references bytes of a given file.
- add `==` as undocumented alias of `=`
- handle negated comparison of `=` as literal
- negation generally applies to only the first expression of a Boolean chain,
except when combining evaluation of two literal strings
Refactor common code out of two branches of the `unbounded_tail()`
function into a new `unbounded_tail_collect()` helper function, that
collects from an iterator into a `VecDeque` and keeps either the last
`n` elements or all but the first `n` elements.
This commit also adds a new struct, `RingBuffer`, in a new module,
`ringbuffer.rs`, to be responsible for keeping the last `n` elements
of an iterator.
When merging files we need to prioritize files that occur earlier in the
command line arguments with -m.
This also makes the extsort merge step (and thus extsort itself) stable again.
Refactor the counting code from the inner loop of the `wc` program
into the `WordCount::from_line()` associated function. This commit
also splits that function up into other helper functions that
encapsulate decoding characters and finding word boundaries from raw
bytes.
This commit also implements the `Sum` trait for the `WordCount`
struct, so that we can simply call `sum()` on an iterator that yields
`WordCount` instances.
This is a refactor to reduce duplicate code, it affects chmod/ls/stat.
* merge `stat/src/fsext::pretty_access` into `uucore/src/lib/feature/fs::display_permissions_unix`
* move tests for `fs::display_permissions` from `test_stat::test_access` to `uucore/src/lib/features/fs::test_display_permissions`
* adjust `uu_chmod`, `uu_ls` and `uu_stat` to use `uucore::fs::display_permissions`
FileMerger is much more efficient than the previous algorithm,
which looped over all elements every time to determine the next element.
FileMerger uses a BinaryHeap, which should bring the complexity for
the merge step down from O(n²) to O(n log n).
