0.4.1

internal/windowsx/powershell_json.go

@@ -0,0 +1,55 @@
+package windowsx
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// decodePowerShellJSON extracts the first JSON value from PowerShell stdout.
+// Windows PowerShell can occasionally surround redirected output with startup,
+// progress, or CLIXML noise. The command runner keeps stderr separate, but this
+// parser is deliberately defensive so a valid JSON payload is not discarded
+// merely because a host emits an unexpected banner before/after it.
+func decodePowerShellJSON(raw string, out any) error {
+	raw = strings.TrimSpace(strings.TrimPrefix(raw, "\ufeff"))
+	if raw == "" {
+		raw = "[]"
+	}
+
+	payload, err := firstJSONValue(raw)
+	if err != nil {
+		return fmt.Errorf("no JSON value in PowerShell output: %w (output=%q)", err, raw)
+	}
+
+	payload = strings.TrimSpace(payload)
+	// Windows PowerShell/ConvertTo-Json may return a single object when only one
+	// item exists. RemoteApp callers always decode into a slice, so normalize it.
+	if strings.HasPrefix(payload, "{") {
+		payload = "[" + payload + "]"
+	}
+	if err := json.Unmarshal([]byte(payload), out); err != nil {
+		return fmt.Errorf("decode PowerShell JSON: %w (json=%q, output=%q)", err, payload, raw)
+	}
+	return nil
+}
+
+func firstJSONValue(raw string) (string, error) {
+	var lastErr error
+	for i := 0; i < len(raw); i++ {
+		if raw[i] != '[' && raw[i] != '{' {
+			continue
+		}
+		dec := json.NewDecoder(strings.NewReader(raw[i:]))
+		var msg json.RawMessage
+		if err := dec.Decode(&msg); err != nil {
+			lastErr = err
+			continue
+		}
+		return string(msg), nil
+	}
+	if lastErr == nil {
+		lastErr = fmt.Errorf("missing JSON object/array delimiter")
+	}
+	return "", lastErr
+}