T5996: selectively escape and restore single backslashes in config

[jestabro]

Change Summary

Gory details are summarized in the task, but the short story is that the legacy and modern parser and config output have conflicting practices in handling unescaped backslashes --- the existing filter to allow parsing of legacy output requires a refinement, in order to maintain the occasional use of single backslashes in values.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5996

Related PR(s)

Component(s) name

Proposed changes

How to test

vyos@vyos# set interfaces ethernet eth0 description 'fo\o'
[edit]
vyos@vyos# compare
[interfaces ethernet eth0]
+ description "fo\o"

[edit]
vyos@vyos# commit
[edit]
vyos@vyos# run show configuration commands |match desc
set interfaces ethernet eth0 description 'fo\o'
[edit]
vyos@vyos# set interfaces ethernet eth0 description 'fo\\o'
[edit]
vyos@vyos# compare
[interfaces ethernet eth0]
- description "fo\o"
+ description "fo\\o"

[edit]
vyos@vyos# commit
[edit]
vyos@vyos# run show configuration commands |match desc
set interfaces ethernet eth0 description 'fo\\o'

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[jestabro]

Move to draft temporarily to fix detail in regex.

[jestabro]

Will add a smoketest.

[jestabro]

Converted to draft pending resolution of
https://vyos.dev/T6098#178963
--- restoring unicode support interacts poorly with above.

[jestabro]

The conflict mentioned above will be resolved by T6111:
vyos/vyos1x-config#23
at which point, this can be moved out of draft.

[jestabro]

@Mergifyio backport sagitta

[mergify]

backport sagitta

✅ Backports have been created

• #3334 T5996: selectively escape and restore single backslashes in config (backport #3035) has been created for branch sagitta