Support more path types in vcs_relative_path

[jamesottaway]

Fixes #303

I see now that the old local p=$( printf "%s" "$( pwd -P )/${1}" | sed 's#//*#/#g' ) line was trying to generate an absolute path, but it didn't support ../ and also assumed it was being given a relative path and hence failed when passed an absolute one.

I got the implementation of abs from StackOverflow and ran ShellCheck over it to fix a few small things, which avoids both caveats of the old line.

By moving this out of vcs_relative_path any improvements/fixes needed can be scoped to the new abs function, and vcs_relative_path is now much easier to follow.

[jamesottaway]

Proof it works on macOS:

❯ uname -a
Darwin JamesBookAir.local 19.4.0 Darwin Kernel Version 19.4.0: Wed Mar  4 22:28:40 PST 2020; root:xnu-6153.101.6~15/RELEASE_X86_64 x86_64

❯ echo $PWD
/Users/james/src/github.com/jamesottaway/blackbox

❯ git rev-parse --show-toplevel
/Users/james/src/github.com/jamesottaway/blackbox

❯ git checkout resolve-dot-dot
Switched to branch 'resolve-dot-dot'

❯ source bin/_blackbox_common.sh

❯ vcs_relative_path Makefile
Makefile%

❯ vcs_relative_path bin/../Makefile
Makefile%

❯ vcs_relative_path $PWD/bin/../Makefile
Makefile%

and on Ubuntu:

❯ uname -a
Linux JamesPrecision3431 5.3.0-46-generic #38-Ubuntu SMP Fri Mar 27 17:37:05 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

❯ echo $PWD
/home/james/src/github.com/jamesottaway/blackbox

❯ git rev-parse --show-toplevel
/home/james/src/github.com/jamesottaway/blackbox

❯ git checkout resolve-dot-dot
Switched to branch 'resolve-dot-dot'
Your branch is up to date with 'origin/resolve-dot-dot'.

❯ source bin/_blackbox_common.sh

❯ vcs_relative_path Makefile
Makefile%                                                                                                                                              

❯ vcs_relative_path bin/../Makefile
Makefile%                                                                                                                                              

❯ vcs_relative_path $PWD/bin/../Makefile
Makefile%

[TomOnTime]

Looks great! Could you please add a comment that cites the StackOverflow page? Other than that, its ready to merge.

[jamesottaway]

All done. While I'm here, and on a similar topic to #302, is this likely to make it into a new version?

[tlimoncelli]

Thanks!

[tlimoncelli]

Hi @jamesottaway !

Sadly I had to revert 87b7cd0. "make test" fails. Can you take a look. A file at the base of the repo adds "/" to .gitignore instead of "/filename".

========== CREATED: secret.txt.gpg
========== UPDATING REPO:
NOTE: "already tracked!" messages are safe to ignore.
[master 67cf029] registered in blackbox: secret.txt
 3 files changed, 2 insertions(+)
 create mode 100644 secret.txt.gpg
========== UPDATING VCS: DONE
Local repo updated.  Please push when ready.
    git push
ASSERT FAILED: line '/secret.txt' should exist in file .gitignore
==== file contents: START .gitignore
/
/var/folders/qw/qp8v2j353wz7q57_jymyxj0h0000gn/T/SO.p8wByYEg
==== file contents: END .gitignore