Module: StillActive::Diff

Extended by:
Diff
Included in:
Diff
Defined in:
lib/still_active/diff.rb

Overview

Compares two still_active JSON snapshots and produces a structured Diff. Designed for PR review: surfaces regressions (CI-failable deltas) on top of the full added/removed/bumped breakdown.

Schema versions accepted: see SUPPORTED_SCHEMA_VERSIONS. A snapshot with a higher schema_version is rejected loudly rather than silently parsed.

Defined Under Namespace

Classes: Added, Bumped, Regression, Removed, Result, SignalChange, UnsupportedSchemaError

Constant Summary collapse

SUPPORTED_SCHEMA_VERSIONS = 
[1].freeze
SCORECARD_DROP_THRESHOLD =

absolute drop to flag

1.0
SCORECARD_GOOD_THRESHOLD =

categorical threshold (good -> below-good)

7.0
NEW_GEM_LIBYEAR_THRESHOLD =

added gems already this far behind regress

0.5
LIBYEAR_DELTA_THRESHOLD =

floating-point fuzz

0.01
NUMERIC_GEM_FIELDS =

The diff dereferences gem fields with type-sensitive operations: a non-Hash value crashes the intersection branch, an arithmetic field that isn’t numeric crashes (libyear/scorecard) or silently fabricates a count (vulnerability_count via .to_i), and a non-array vulnerabilities silently drops advisory ids. The baseline is untrusted user input, so validate the shape the diff requires here and let the rest of the code assume it.

["vulnerability_count", "scorecard_score", "libyear"].freeze

Instance Method Summary collapse

Instance Method Details

#advisory_ids(data) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 276

def advisory_ids(data)
  Array(data["vulnerabilities"]).flat_map { |v| [v["id"], *Array(v["aliases"])].compact }.uniq
end

#call(baseline:, current:) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 29

def call(baseline:, current:)
  validate_schema!(baseline, "baseline")
  validate_schema!(current, "current")

  b_gems = baseline.fetch("gems", {})
  c_gems = current.fetch("gems", {})

  added = (c_gems.keys - b_gems.keys).sort.map { |n| Added.new(name: n, data: c_gems[n]) }
  removed = (b_gems.keys - c_gems.keys).sort.map { |n| Removed.new(name: n, data: b_gems[n]) }

  bumped = []
  signal_changes = []
  (b_gems.keys & c_gems.keys).sort.each do |name|
    before = b_gems[name]
    after = c_gems[name]
    if before["version_used"] != after["version_used"]
      bumped << Bumped.new(
        name: name,
        before_version: before["version_used"],
        after_version: after["version_used"],
        kind: classify_bump(before, after),
        before: before,
        after: after,
      )
    end
    changes = collect_signal_changes(before, after)
    signal_changes << SignalChange.new(name: name, changes: changes, before: before, after: after) if changes.any?
  end

  ruby = ruby_delta(baseline["ruby"], current["ruby"])
  regressions = collect_regressions(
    added: added,
    bumped: bumped,
    signal_changes: signal_changes,
    ruby_delta: ruby,
  )

  Result.new(
    added: added,
    removed: removed,
    bumped: bumped,
    signal_changes: signal_changes,
    regressions: regressions,
    ruby: ruby,
  )
end

#classify_bump(before, after) ⇒ Object

Categorises a version bump:

  • :introduced_vulns - new advisories appeared on the resolved version

  • :closed_vulns - all advisories cleared

  • :older_relative - libyear-to-latest grew (rare; usually unchanged)

  • :fresher - libyear-to-latest shrank

  • :neutral - no obvious signal change



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# File 'lib/still_active/diff.rb', line 146

def classify_bump(before, after)
  opened = vuln_count(after) - vuln_count(before)
  return :introduced_vulns if opened.positive?
  return :closed_vulns if opened.negative?

  delta = (after["libyear"] || 0.0) - (before["libyear"] || 0.0)
  return :older_relative if delta > LIBYEAR_DELTA_THRESHOLD
  return :fresher if delta < -LIBYEAR_DELTA_THRESHOLD

  :neutral
end

#collect_regressions(added:, bumped:, signal_changes:, ruby_delta:) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 203

def collect_regressions(added:, bumped:, signal_changes:, ruby_delta:)
  regs = []

  added.each do |a|
    data = a.data
    if vuln_count(data).positive?
      regs << Regression.new(kind: :new_gem_with_vulns, gem: a.name, detail: "#{vuln_count(data)} vulns at introduction")
    elsif data["archived"]
      regs << Regression.new(kind: :new_gem_archived, gem: a.name, detail: "added gem points at archived repo")
    elsif data["libyear"] && data["libyear"] > NEW_GEM_LIBYEAR_THRESHOLD
      regs << Regression.new(kind: :new_gem_stale, gem: a.name, detail: "added gem already #{data["libyear"]} libyears behind latest")
    end
  end

  bumped.each do |b|
    if b.kind == :introduced_vulns
      regs << Regression.new(
        kind: :bump_introduced_vulns,
        gem: b.name,
        detail: "#{b.before_version} -> #{b.after_version}",
      )
    end
  end

  signal_changes.each do |sc|
    sc.changes.each do |ch|
      case ch[:kind]
      when :archived
        regs << Regression.new(kind: :archived, gem: sc.name, detail: "repo archived since baseline")
      when :new_vulnerability
        ids = Array(ch[:ids]).join(", ")
        regs << Regression.new(kind: :new_vulnerability, gem: sc.name, detail: "#{ch[:from]} -> #{ch[:to]}#{" (#{ids})" unless ids.empty?}")
      when :scorecard_dropped
        note = ch[:crossed_good] ? " crossed #{SCORECARD_GOOD_THRESHOLD}" : ""
        regs << Regression.new(kind: :scorecard_dropped, gem: sc.name, detail: "#{ch[:from]} -> #{ch[:to]}#{note}")
      when :version_yanked
        regs << Regression.new(kind: :version_yanked, gem: sc.name, detail: "pinned version yanked from rubygems")
      when :libyear_worsened
        regs << Regression.new(
          kind: :libyear_worsened,
          gem: sc.name,
          detail: "libyear #{ch[:from]} -> #{ch[:to]} (+#{ch[:delta]}y; same pinned version)",
        )
      end
    end
  end

  if ruby_delta && ruby_delta[:newly_eol]
    regs << Regression.new(kind: :ruby_eol_introduced, gem: "(ruby)", detail: "Ruby #{ruby_delta[:to]} is now EOL")
  end

  regs
end

#collect_signal_changes(before, after) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 158

def collect_signal_changes(before, after)
  changes = []

  if !before["archived"] && after["archived"]
    changes << { kind: :archived, from: false, to: true }
  end

  opened = vuln_count(after) - vuln_count(before)
  if opened.positive? && before["version_used"] == after["version_used"]
    # Set difference is enough for the common case. Edge case: an advisory
    # backfilled with a CVE alias alongside an existing GHSA can show up as
    # "new" in this list even though it's a re-keying of the same issue.
    # The vulnerability_count gate above keeps that to detail-string noise.
    new_ids = advisory_ids(after) - advisory_ids(before)
    changes << { kind: :new_vulnerability, from: vuln_count(before), to: vuln_count(after), ids: new_ids.first(3) }
  end

  if before["scorecard_score"] && after["scorecard_score"]
    drop = before["scorecard_score"] - after["scorecard_score"]
    # OSSF treats >= 7.0 as "good". A score landing at 7.0 stays good (a 7.5
    # -> 7.0 dip is noise within the safe zone). Only drops below 7.0 cross.
    crossed = before["scorecard_score"] >= SCORECARD_GOOD_THRESHOLD && after["scorecard_score"] < SCORECARD_GOOD_THRESHOLD
    if drop >= SCORECARD_DROP_THRESHOLD || crossed
      changes << { kind: :scorecard_dropped, from: before["scorecard_score"], to: after["scorecard_score"], crossed_good: crossed }
    end
  end

  if before["libyear"] && after["libyear"] && before["version_used"] == after["version_used"]
    # Same pinned version + libyear grew = upstream released and we didn't
    # follow. That IS a regression. If version_used moved forward we deliberately
    # don't flag — moving forward isn't a PR regression even when libyear-to-latest
    # technically grows (because upstream is releasing faster).
    delta = after["libyear"] - before["libyear"]
    if delta > LIBYEAR_DELTA_THRESHOLD
      changes << { kind: :libyear_worsened, from: before["libyear"], to: after["libyear"], delta: delta.round(2) }
    end
  end

  if !before["version_yanked"] && after["version_yanked"]
    changes << { kind: :version_yanked }
  end

  changes
end

#ruby_delta(before, after) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 257

def ruby_delta(before, after)
  return if before.nil? && after.nil?

  before ||= {}
  after ||= {}
  {
    version_changed: before["version"] != after["version"],
    from: before["version"],
    to: after["version"],
    newly_eol: !before["eol"] && !!after["eol"],
    libyear_before: before["libyear"],
    libyear_after: after["libyear"],
  }
end

#validate_gem!(role, name, data) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 112

def validate_gem!(role, name, data)
  unless data.is_a?(Hash)
    raise UnsupportedSchemaError, "#{role} gem #{name.inspect} is malformed (expected an object, got #{data.class})"
  end

  NUMERIC_GEM_FIELDS.each do |field|
    value = data[field]
    next if value.nil? || value.is_a?(Numeric)

    raise UnsupportedSchemaError, "#{role} gem #{name.inspect} has a non-numeric #{field} (got #{value.class})"
  end

  vulns = data["vulnerabilities"]
  return if vulns.nil?

  unless vulns.is_a?(Array)
    raise UnsupportedSchemaError, "#{role} gem #{name.inspect} has a malformed vulnerabilities list (expected an array, got #{vulns.class})"
  end

  # advisory_ids dereferences each entry as a hash (entry["id"]); a scalar
  # element would crash there, so reject non-object entries up front.
  vulns.each do |entry|
    next if entry.is_a?(Hash)

    raise UnsupportedSchemaError, "#{role} gem #{name.inspect} has a malformed vulnerability entry (expected an object, got #{entry.class})"
  end
end

#validate_schema!(snapshot, role) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 76

def validate_schema!(snapshot, role)
  # A user can point --baseline at any JSON file. Reject a wrong shape here
  # as an UnsupportedSchemaError (which emit_diff turns into a clean exit 2)
  # rather than letting snapshot["..."] / gems.keys raise a raw stack trace.
  unless snapshot.is_a?(Hash)
    raise UnsupportedSchemaError, "#{role} is not a still_active JSON object (got #{snapshot.class})"
  end

  version = snapshot["schema_version"]
  unless SUPPORTED_SCHEMA_VERSIONS.include?(version)
    raise UnsupportedSchemaError, "#{role} has schema_version=#{version.inspect}; supported: #{SUPPORTED_SCHEMA_VERSIONS.join(", ")}"
  end

  ruby = snapshot["ruby"]
  unless ruby.nil? || ruby.is_a?(Hash)
    raise UnsupportedSchemaError, "#{role} has a malformed ruby section (expected an object, got #{ruby.class})"
  end

  gems = snapshot["gems"]
  return if gems.nil?

  unless gems.is_a?(Hash)
    raise UnsupportedSchemaError, "#{role} has a malformed gems section (expected an object, got #{gems.class})"
  end

  gems.each { |name, data| validate_gem!(role, name, data) }
end

#vuln_count(data) ⇒ Object 



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# File 'lib/still_active/diff.rb', line 272

def vuln_count(data)
  data["vulnerability_count"].to_i
end