While well-defined unsigned integer underflow might signal a logic
mistake or processing of unchecked user input. Please Clang's undefined
behavior sanitizer:
restore.c:91:37: runtime error: unsigned integer overflow: 1 - 2 cannot be represented in type 'unsigned long'
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>