ls implementation

[JRF63]

This passes all of coreutils ls' tests excluding non-POSIX ones.

Two tests have quirks though:

• test_ls_file_type skips block/character devices if not run with sudo -E cargo .... Those need elevated permission to create.
• test_ls_time will stall a bit because it needs to wait for the ctime of the file to change. This is already an improvement over the 4 second wait time of the original.

There's also the -k option which coreutils always has enabled. Specification says to use 512-byte blocks if -k isn't specified but they always have it as 1024-byte blocks with or without -k.

[jgarzik]

One comment, in re args parsing and long options:

For the common case where an ls argument exists in both POSIX specification and GNU/Linux implementation, it is nice to mirror the long options strings in posixutils, to ensure compatibility in long options where possible.

Mandatory arguments to long options are mandatory for short options too.
  -a, --all                  do not ignore entries starting with .
  -A, --almost-all           do not list implied . and ..
      --author               with -l, print the author of each file
  -b, --escape               print C-style escapes for nongraphic characters
      --block-size=SIZE      with -l, scale sizes by SIZE when printing them;
                               e.g., '--block-size=M'; see SIZE format below
  -B, --ignore-backups       do not list implied entries ending with ~
  -c                         with -lt: sort by, and show, ctime (time of last
                               modification of file status information);
                               with -l: show ctime and sort by name;
                               otherwise: sort by ctime, newest first
  -C                         list entries by columns
      --color[=WHEN]         colorize the output; WHEN can be 'always' (default
                               if omitted), 'auto', or 'never'; more info below
  -d, --directory            list directories themselves, not their contents
  -D, --dired                generate output designed for Emacs' dired mode
  -f                         do not sort, enable -aU, disable -ls --color
  -F, --classify             append indicator (one of */=>@|) to entries
      --file-type            likewise, except do not append '*'
      --format=WORD          across -x, commas -m, horizontal -x, long -l,
                               single-column -1, verbose -l, vertical -C
      --full-time            like -l --time-style=full-iso
  -g                         like -l, but do not list owner
      --group-directories-first
                             group directories before files;
                               can be augmented with a --sort option, but any
                               use of --sort=none (-U) disables grouping
  -G, --no-group             in a long listing, don't print group names
  -h, --human-readable       with -l and -s, print sizes like 1K 234M 2G etc.
      --si                   likewise, but use powers of 1000 not 1024
  -H, --dereference-command-line
                             follow symbolic links listed on the command line
      --dereference-command-line-symlink-to-dir
                             follow each command line symbolic link
                               that points to a directory
      --hide=PATTERN         do not list implied entries matching shell PATTERN
                               (overridden by -a or -A)
      --hyperlink[=WHEN]     hyperlink file names; WHEN can be 'always'
                               (default if omitted), 'auto', or 'never'
      --indicator-style=WORD  append indicator with style WORD to entry names:
                               none (default), slash (-p),
                               file-type (--file-type), classify (-F)
  -i, --inode                print the index number of each file
  -I, --ignore=PATTERN       do not list implied entries matching shell PATTERN
  -k, --kibibytes            default to 1024-byte blocks for disk usage;
                               used only with -s and per directory totals
  -l                         use a long listing format
  -L, --dereference          when showing file information for a symbolic
                               link, show information for the file the link
                               references rather than for the link itself
  -m                         fill width with a comma separated list of entries
  -n, --numeric-uid-gid      like -l, but list numeric user and group IDs
  -N, --literal              print entry names without quoting
  -o                         like -l, but do not list group information
  -p, --indicator-style=slash
                             append / indicator to directories
  -q, --hide-control-chars   print ? instead of nongraphic characters
      --show-control-chars   show nongraphic characters as-is (the default,
                               unless program is 'ls' and output is a terminal)
  -Q, --quote-name           enclose entry names in double quotes
      --quoting-style=WORD   use quoting style WORD for entry names:
                               literal, locale, shell, shell-always,
                               shell-escape, shell-escape-always, c, escape
                               (overrides QUOTING_STYLE environment variable)
  -r, --reverse              reverse order while sorting
  -R, --recursive            list subdirectories recursively
  -s, --size                 print the allocated size of each file, in blocks
  -S                         sort by file size, largest first
      --sort=WORD            sort by WORD instead of name: none (-U), size (-S),
                               time (-t), version (-v), extension (-X)
      --time=WORD            change the default of using modification times;
                               access time (-u): atime, access, use;
                               change time (-c): ctime, status;
                               birth time: birth, creation;
                             with -l, WORD determines which time to show;
                             with --sort=time, sort by WORD (newest first)
      --time-style=TIME_STYLE  time/date format with -l; see TIME_STYLE below
  -t                         sort by time, newest first; see --time
  -T, --tabsize=COLS         assume tab stops at each COLS instead of 8
  -u                         with -lt: sort by, and show, access time;
                               with -l: show access time and sort by name;
                               otherwise: sort by access time, newest first
  -U                         do not sort; list entries in directory order
  -v                         natural sort of (version) numbers within text
  -w, --width=COLS           set output width to COLS.  0 means no limit
  -x                         list entries by lines instead of by columns
  -X                         sort alphabetically by entry extension
  -Z, --context              print any security context of each file
  -1                         list one file per line.  Avoid '\n' with -q or -b
      --help     display this help and exit
      --version  output version information and exit

[JRF63]

I'm pretty sure it's already doing that with the exception of --indicator-style. The long option for that one doesn't make sense over -p if it doesn't accept a directory indicator.

[jgarzik]

Does not build on MacOS,

error[E0308]: mismatched types
   --> tree/src/ls_util/entry.rs:129:35
    |
129 | ...f mode & (libc::S_IXUSR | libc::S_IXGRP | libc::S_IXOTH) != 0 {
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `u16`

error[E0277]: no implementation for `u32 & u16`
   --> tree/src/ls_util/entry.rs:129:33
    |
129 | ...   if mode & (libc::S_IXUSR | libc::S_IXGRP | libc::S_IXOTH) != 0 {
    |               ^ no implementation for `u32 & u16`
    |
    = help: the trait `BitAnd<u16>` is not implemented for `u32`
    = help: the following other types implement trait `BitAnd<Rhs>`:
              <u32 as BitAnd>
              <u32 as BitAnd<&u32>>
              <&'a u32 as BitAnd<u32>>
              <&u32 as BitAnd<&u32>>

error[E0308]: mismatched types
   --> tree/src/ls_util/entry.rs:664:30
    |
664 |     file_mode.push(if mode & libc::S_IRUSR != 0 { 'r' } else { '-' });
    |                              ^^^^^^^^^^^^^ expected `u32`, found `u16`

error[E0277]: no implementation for `u32 & u16`

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