Function collectCommands

source code/utils/bash/ast.ts:484–957

* Recursively collect leaf `command` nodes from a structural wrapper node. * Returns an error result on any disallowed node type, or null on success.

(
  node: Node,
  commands: SimpleCommand[],
  varScope: Map<string, string>,
)

 * Returns an error result on any disallowed node type, or null on success.
 */
function collectCommands(
  node: Node,
  commands: SimpleCommand[],
  varScope: Map<string, string>,
): ParseForSecurityResult | null {
  if (node.type === 'command') {
    // Pass `commands` as the innerCommands accumulator — any $() extracted
    // during walkCommand gets appended alongside the outer command.
    const result = walkCommand(node, [], commands, varScope)
    if (result.kind !== 'simple') return result
    commands.push(...result.commands)
    return null
  }

  if (node.type === 'redirected_statement') {
    return walkRedirectedStatement(node, commands, varScope)
  }

  if (node.type === 'comment') {
    return null
  }

  if (STRUCTURAL_TYPES.has(node.type)) {
    // SECURITY: `||`, `|`, `|&`, `&` must NOT carry varScope linearly. In bash:
    //   `||` RHS runs conditionally → vars set there MAY not be set
    //   `|`/`|&` stages run in subshells → vars set there are NEVER visible after
    //   `&` LHS runs in a background subshell → same as above
    // Flag-omission attack: `true || FLAG=--dry-run && cmd $FLAG` — bash skips
    // the `||` RHS (FLAG unset → $FLAG empty), runs `cmd` WITHOUT --dry-run.
    // With linear scope, our argv has ['cmd','--dry-run'] → looks SAFE → bypass.
    //
    // Fix: snapshot incoming scope at entry. After these separators, reset to
    // the snapshot — vars set in clauses between separators don't leak. `scope`
    // for clauses BETWEEN `&&`/`;` chains shares state (common `VAR=x && cmd
    // $VAR`). `scope` crosses `||`/`|`/`&` as the pre-structure snapshot only.
    //
    // `&&` and `;` DO carry scope: `VAR=x && cmd $VAR` is sequential, VAR is set.
    //
    // NOTE: `scope` and `varScope` diverge after the first `||`/`|`/`&`. The
    // caller's varScope is only mutated for the `&&`/`;` prefix — this is
    // conservative (vars set in `A && B | C && D` leak A+B into caller, not
    // C+D) but safe.
    //
    // Efficiency: snapshot is only needed if we hit `||`/`|`/`|&`/`&`. For
    // the dominant case (`ls`, `git status` — no such separators), skip the
    // Map alloc via a cheap pre-scan. For `pipeline`, node.type already tells
    // us stages are subshells — copy once at entry, no snapshot needed (each
    // reset uses the entry copy pattern via varScope, which is untouched).
    const isPipeline = node.type === 'pipeline'
    let needsSnapshot = false
    if (!isPipeline) {
      for (const c of node.children) {
        if (c && (c.type === '||' || c.type === '&')) {
          needsSnapshot = true
          break
        }
      }
    }