[cvl]: Escape Lua metacharacters in delete-dependency and must/when filters

[gupta-08]

Description of PR

Summary:

CVL interpolates Redis keys and YANG values into generated Lua and into
libyang3 list-key path predicates. Values that contain ', \, or %
can break those strings, so delete-dependency lookup, must/when evaluation,
and list-node creation fail or match the wrong entries.

This change:

• Escapes \ and ' before interpolating keys into delete-dependency Lua
  filters in GetDepDataForDelete().
• Uses plain string.find (plain=true) so % is not treated as a Lua
  pattern character in leaf-list matching.
• Escapes the same characters when building must/when Lua predicates in the
  xpath engine patch.
• Quotes libyang3 list-key predicates the way libyang does: single quotes
  unless the value itself contains ', then double quotes
  (formatLyPredicateValue() used by AddListNode()).

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• New Test case
• Test case improvement

Back port request

• 202311
• 202405
• 202411
• 202505
• 202511
• 202512
• 202605

Tested branch

• master
• 202311
• 202405
• 202411
• 202505
• 202511
• 202512
• 202605
• N/A

Test result

Added / updated CVL unit tests:

• TestGetDepDataForDeleteSpecialKeyChars — keys containing ', \, %
• TestGetDepDataForDeleteLeafListPatternChars — leaf-list values with Lua
  pattern characters
• TestValidateEditConfig_Must_Predicate_Escape_SingleQuote
• TestValidateEditConfig_Must_Predicate_Escape_Backslash
• TestValidateEditConfig_When_Predicate_Escape_SingleQuote
• TestValidateEditConfig_When_Predicate_Escape_Backslash

Approach

What is the motivation for this PR?

GetDepDataForDelete() embeds Redis key values into a Lua script using
fmt.Sprintf and string.find. Unescaped quotes break the Lua string, and
unescaped % is treated as a pattern. must/when predicates had the same
issue when config values were written into Lua predicate strings.

AddListNode() always wrapped list-key values in single quotes
([key='value']). Libyang3 uses double quotes when the value contains ',
so keys with a single quote fail path parsing.

That can cause:

• failed or incomplete dependent-delete discovery
• incorrect must/when validation for values that contain ', \, or %
• failed list-node create when a key value contains '

How did you do it?

In cvl/cvl_api.go (GetDepDataForDelete()):

• Escape \ and ' in the key before building the Lua filter script.
• Call string.find(..., 1, true) so the search is a plain string match.

In patches/xpath.patch:

• Escape \ and ' when assigning SFilter.Predicate from config values
  (currentQuery, constantQuery, and childQuery evaluation).

In cvl/internal/yparser/ly_path.go and cvl/internal/yparser/yparser.go:

• Add formatLyPredicateValue() and use it in AddListNode() so list-key
  predicates match libyang quoting ('value' or "value").

No change to Redis data; only generated Lua and libyang path strings are
sanitized.

How did you verify/test it?

CVL Go unit tests covering:

• delete-dependency filters with special characters in keys and leaf-lists
• must/when predicates whose values contain ' or \

Existing TestGetDepDataForDelete coverage is unchanged.

Any platform specific information?

No. Generic CVL / Lua / libyang3 path behavior.

Supported testbed topology if it's a new test case?

N/A

Documentation

N/A

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: gupta-08 / name: Aditi Gupta (a78cb8a)

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