rules:
  - id: io-readfull-n
    patterns:
        - pattern-either:
              - pattern: |
                      $N, $ERR = io.ReadFull($R, $SLICE)
                      if $ERR != nil || $N != len($SLICE) {
                              ...
                      }
              - pattern: |
                      $N, $ERR = io.ReadFull($R, $SLICE)
                      if $N != len($SLICE) || $ERR != nil {
                              ...
                      }
    message: "io.ReadFull() returns err == nil iff n == len(slice)"
    languages: [go]
    severity: ERROR