fix(utimes): Support filenames with backspaces, etc.

[rasa]

• Support filenames with backslashes
• Support if git is defined as a function, such as function git() { yadm "$@"; }
• Add Bash's unofficial "strict" mode: set -euo pipefail
• Move awk script to variable (to simplify escaping)
• Add helpful comments
• Shellcheck clean
• Shfmt clean

Here's a test run on Ubuntu 23.10 with git 2.40.1:

$ gh repo clone rasa/git-os-test

$ cd git-os-test

$ find -printf '%T+\n' | sort -r | head -n 1
2023-12-11+10:25:22.4594244760

$ git utimes
+ touch -h -d@1699829680 "`whoami`"
+ touch -h -d@1699829626 "$USER"
+ touch -h -d@1699829626 $USER
+ touch -h -d@1699829337 "'quotes-and-single-quotes'"
+ touch -h -d@1699829337 '"single-quotes-and-quotes"'
+ touch -h -d@1699829337 a-quote-and-single-quote"'
+ touch -h -d@1699829337 a-single-quote-and-quote'"
+ touch -h -d@1699828363 `whoami`
+ touch -h -d@1699828215 file-in-root-dir.symlink
+ touch -h -d@1699828203 root-dir.symlink
+ touch -h -d@1699828037 file-in-dir.symlink
+ touch -h -d@1699827933  a-space-at-the-beginning
+ touch -h -d@1699720671 "2-quotes"
+ touch -h -d@1699720671 '2-single-quotes'
+ touch -h -d@1699720671 2-quotes-together""
+ touch -h -d@1699720671 2-single-quotes-together''
+ touch -h -d@1699720671 a-single-quote'
+ touch -h -d@1675048836 a-backslash\
+ touch -h -d@1675048802 a-colon:
+ touch -h -d@1627399934 CON.txt
+ touch -h -d@1627399912 CON
+ touch -h -d@1626789305 a-space
+ touch -h -d@1626789277 a-dot.
+ touch -h -d@1626789249 a-less-than<
+ touch -h -d@1626789223 a-greater-than>
+ touch -h -d@1626789196 a-pipe|
+ touch -h -d@1626789165 a-question-mark?
+ touch -h -d@1626789137 a-asterisk*
+ touch -h -d@1626789107 a-quote"
+ touch -h -d@1619369190 executable.sh
+ touch -h -d@1608172298 executable.cmd
+ touch -h -d@1607657114 CASESENSITIVE.TXT
+ touch -h -d@1607656480 CaseSensitive.txt
+ touch -h -d@1607656480 casesensitive.txt
+ touch -h -d@1607651028 file☠☡☢☣.txt
+ touch -h -d@1607650377 dir.symlink
+ touch -h -d@1607650377 dir/file
+ touch -h -d@1607650181 file
+ touch -h -d@1607650181 file.symlink
+ touch -h -d@1607649124 .gitignore
+ touch -h -d@1607649124 LICENSE
+ touch -h -d@1607649124 README.md

$ ls -ltr
total 92
lrwxrwxrwx 1 ross ross    3 Dec 10  2020  dir.symlink -> dir
lrwxrwxrwx 1 ross ross    6 Nov 12 14:30  root-dir.symlink -> dir/..
drwxr-xr-x 2 ross ross 4096 Dec 11 10:25  dir
-rw-r--r-- 1 ross ross   54 Dec 10  2020  README.md
-rw-r--r-- 1 ross ross 1070 Dec 10  2020  LICENSE
lrwxrwxrwx 1 ross ross    4 Dec 10  2020  file.symlink -> file
-rw-r--r-- 1 ross ross    5 Dec 10  2020  file
-rw-r--r-- 1 ross ross   21 Dec 10  2020  file☠☡☢☣.txt
-rw-r--r-- 1 ross ross   18 Dec 10  2020  CaseSensitive.txt
-rw-r--r-- 1 ross ross   18 Dec 10  2020  casesensitive.txt
-rw-r--r-- 1 ross ross   19 Dec 10  2020  CASESENSITIVE.TXT
-rwxr-xr-x 1 ross ross   20 Dec 16  2020  executable.cmd
-rwxr-xr-x 1 ross ross   42 Apr 25  2021  executable.sh
-rw-r--r-- 1 ross ross    9 Jul 20  2021 'a-quote"'
-rw-r--r-- 1 ross ross   12 Jul 20  2021 'a-asterisk*'
-rw-r--r-- 1 ross ross   17 Jul 20  2021 'a-question-mark?'
-rw-r--r-- 1 ross ross    8 Jul 20  2021 'a-pipe|'
-rw-r--r-- 1 ross ross   16 Jul 20  2021 'a-greater-than>'
-rw-r--r-- 1 ross ross   13 Jul 20  2021 'a-less-than<'
-rw-r--r-- 1 ross ross    1 Jul 20  2021  a-dot.
-rw-r--r-- 1 ross ross    9 Jul 20  2021  a-space
-rw-r--r-- 1 ross ross    4 Jul 27  2021  CON
-rw-r--r-- 1 ross ross    8 Jul 27  2021  CON.txt
-rw-r--r-- 1 ross ross    9 Jan 29  2023  a-colon:
-rw-r--r-- 1 ross ross   13 Jan 29  2023 'a-backslash\'
-rw-r--r-- 1 ross ross    0 Nov 11 08:37 "a-single-quote'"
-rw-r--r-- 1 ross ross    0 Nov 11 08:37 "2-single-quotes-together''"
-rw-r--r-- 1 ross ross    0 Nov 11 08:37 "'2-single-quotes'"
-rw-r--r-- 1 ross ross    0 Nov 11 08:37 '2-quotes-together""'
-rw-r--r-- 1 ross ross    0 Nov 11 08:37 '"2-quotes"'
-rw-r--r-- 1 ross ross    0 Nov 12 14:25 ' a-space-at-the-beginning'
lrwxrwxrwx 1 ross ross    8 Nov 12 14:27  file-in-dir.symlink -> dir/file
lrwxrwxrwx 1 ross ross   11 Nov 12 14:30  file-in-root-dir.symlink -> dir/../file
-rw-r--r-- 1 ross ross    9 Nov 12 14:32 '`whoami`'
-rw-r--r-- 1 ross ross    0 Nov 12 14:48 ''\''"single-quotes-and-quotes"'\'''
-rw-r--r-- 1 ross ross    0 Nov 12 14:48 '"'\''quotes-and-single-quotes'\''"'
-rw-r--r-- 1 ross ross    0 Nov 12 14:48 'a-single-quote-and-quote'\''"'
-rw-r--r-- 1 ross ross    0 Nov 12 14:48 'a-quote-and-single-quote"'\'''
-rw-r--r-- 1 ross ross    0 Nov 12 14:53 '$USER'
-rw-r--r-- 1 ross ross    0 Nov 12 14:53 '"$USER"'
-rw-r--r-- 1 ross ross    0 Nov 12 14:54 '"`whoami`"'

[hyperupcall]

lgtm, thanks for the cleanup

[spacewander]

@rasa
Merged. Thanks!

[rasa]

@spacewander @hyperupcall I don't plan on making any more changes to this code, unless bugs are found. It's production ready, imho.

[spacewander]

@spacewander @hyperupcall I don't plan on making any more changes to this code, unless bugs are found. It's production ready, imho.

Copy that.