Fix how `vcs_relative_path` first resolves an absolute path

[jamesottaway]

Second attempt to fix #303.

The problem in #304 was that vcs_relative_path needs its argument to exist when called, and blackbox_register_new_file was calling shred_file before vcs_ignore.

I ran the tests after changing that order and applying the same change to vcs_relative_path as before, but now my new test for blackbox_cat started failing:

********************
********************
********* She enrolls secrets.txt.
********************
********************
========== PLAINFILE secret.txt
========== ENCRYPTED secret.txt.gpg
========== Importing keychain: START
gpg: key C6CB856A3A3DFB80: public key "Bob Example (my password is the lowercase letter b) <[email protected]>" imported
gpg: Total number processed: 2
gpg:               imported: 1
gpg:              unchanged: 1
========== Importing keychain: DONE
========== Encrypting: secret.txt
========== Encrypting: DONE
========== Adding file to list.
========== CREATED: secret.txt.gpg
========== UPDATING REPO:
NOTE: "already tracked!" messages are safe to ignore.
[master ab86c55] 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
********************
********************
********* She cats secrets.txt.gpg.
********************
********************
========== PLAINFILE "secret.txt"
ERROR: secret.txt not found in /run/user/1000/tmp.TVLFg8a5XV/keyrings/live/blackbox-files.txt
PWD=/run/user/1000/tmp.TVLFg8a5XV
Exiting...
gpg-agent[5671]: homedir has been removed - shutting down
gpg-agent[5671]: gpg-agent (GnuPG) 2.2.12 stopped
gpg-agent[5674]: homedir has been removed - shutting down
gpg-agent[5674]: gpg-agent (GnuPG) 2.2.12 stopped

When I checked /run/user/1000/tmp.TVLFg8a5XV/keyrings/live/blackbox-files.txt it definitely contained a line for secret.txt, as proven by the additional assert_line_exists I added to the previous phase in the WIP commit, plus my own validation:

❯ cat /run/user/1000/tmp.TVLFg8a5XV/keyrings/live/blackbox-files.txt
secret.txt

I see some Circle CI config in the repo, so is there a way to run the tests somewhere other than my machine as a sanity check?

[tlimoncelli]

The CircleCI stuff was set up by someone else and I never learned what it did.... which I regret since now it doesn't work and I don't know how to fix it. :-(

Does "make test" work for you on the current master branch? (just checking)

How about a different algorithm that doesn't require the file to exist?

[tlimoncelli]

Sadly this still fails for me. Are you testing on macos? Its a little different than linux.

********* She enrolls secrets.txt.
********************
********************
========== PLAINFILE secret.txt
========== ENCRYPTED secret.txt.gpg
========== Importing keychain: START
gpg: key 2831D06A94A006FD: public key "Bob Example (my password is the lowercase letter b) <[email protected]>" imported
gpg: Total number processed: 2
gpg:               imported: 1
gpg:              unchanged: 1
========== Importing keychain: DONE
========== Encrypting: secret.txt
========== Encrypting: DONE
========== Adding file to list.
========== CREATED: secret.txt.gpg
========== UPDATING REPO:
NOTE: "already tracked!" messages are safe to ignore.
[master 0468fb5] 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.50tX48h4/secret.txt
==== file contents: END .gitignore

[tlimoncelli]

wsdwr

I'm sorry but I don't recognize this acronym.

This PR is listed as draft. @jamesottaway is it ready to be reviewed?

[jamesottaway]

I don't remember what was keeping this from being reviewed, but I recall abandoning it after losing myself under an avalanche of Bash. The ability to run Blackbox from arbitrary subdirectories still makes sense, but I'm no longer in the role where I was using Blackbox. Would love to see someone carry this forward, if someone else is willing to take it on.