Branch patterns with POSIX character classes like [[:digit:]] silently match the wrong branches

[matt-edmondson]

What's wrong

BranchPattern says it honours the same constructs as git's wildmatch for git branch --list (GitBranchStateCache/Refs/BranchPattern.cs:22-25). The #43 fix added ranges, sets, negation and escapes, but not POSIX character classes: [:alpha:], [:digit:], [:alnum:], [:upper:], [:lower:], [:space:], [:xdigit:], [:punct:] and the rest. git supports all of these.

In TryMatchBracket (BranchPattern.cs:190-214), the first ] after [[:digit: closes the bracket. The expression becomes the set { '[', ':', 'd', 'i', 'g', 't' } and the second ] is matched as a literal character.

Failure scenario

• Pattern: origin/release-[[:digit:]]*
• Branch: origin/release-1.0
• Here: no match, because 1 is not in the set.
• git: git branch --list 'release-[[:digit:]]*' lists the branch.

TryParse accepts the pattern, so /state and /branches return 200 with those branches missing. The client never hears about assets changed on them. The same pattern also wrongly matches a branch such as origin/release-d]x.

Suggested fix / acceptance criteria

• In TryMatchBracket, recognise [:name:] as a bracket member and test the character with the matching ASCII predicate (char.IsAsciiDigit, char.IsAsciiLetter, and so on). Keep the linear walk with no regular expressions.
• Reject an unknown class name such as [[:bogus:]] in TryParse with a 400, rather than letting it mismatch silently. git's wildmatch aborts the match in that case.
• Add tests for [[:digit:]], [[:digit:]], [[:alpha:]_-], a mix like [a[:digit:]], and the malformed [[:bogus:]].
• Update the remarks at BranchPattern.cs:22-25 to list the classes.

[matt-edmondson]

Triage

• Category: Bug
• Priority: Medium. A valid-looking pattern is accepted but silently leaves out branches, so clients miss changes on them. Workaround: use [0-9] ranges.
• Area / suggested assignment: GitBranchStateCache/Refs/BranchPattern (TryMatchBracket, TryParse, remarks).
• Duplicates: none. It follows on from Branch patterns with [...] character classes match no branches, though git's branch --list honours them #43, which added ranges, sets, negation and escapes.
• In progress: no. The open PRs here, Delegate git process invocation to ktsu.RunCommand [patch] #51, Bump Testably.Abstractions.FileSystem.Interface from 10.3.0 to 10.4.0 #54 and Bump Testably.Abstractions.Testing from 7.0.2 to 7.1.0 #55, are the RunCommand delegation and dependency bumps.

Suggested next step: add POSIX class parsing inside brackets, reject unknown classes with a 400, and add the listed tests. One nit: the test list names [[:digit:]] twice. The second one was probably meant to be another class, such as [[:alnum:]].

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