Why don’t you look at the source code, it’s only 150 lines?
The nesting is limited by using an int as the depth counter. The C standard guarantees that MAX_INT is at least 32767, so that’s a limit on portable nesting depth. Nowadays int is typically 32 or 64 bits, so a much higher limit in typical C implementations.
If I see correctly, the library doesn’t check for overflow, however. This might conceivably be an exploitable vulnerability (and such an overflow would constitute UB).
The nesting is limited by using an int as the depth counter. The C standard guarantees that MAX_INT is at least 32767, so that’s a limit on portable nesting depth. Nowadays int is typically 32 or 64 bits, so a much higher limit in typical C implementations.
If I see correctly, the library doesn’t check for overflow, however. This might conceivably be an exploitable vulnerability (and such an overflow would constitute UB).