can we use different function in place of atoi in vacuumdb.c file

Hi all,
While reviewing one patch, I found that if we give any non-integer string to atoi (say aa), then it is returning zero(0) as output so we are not giving any error(assuming 0 as valid argument) and continuing our operations.

Ex:
Let say, we gave "-P aa" (patch is in review[1]), then it will disable parallel vacuum because atoi is returning zero as parallel degree but ideally it should give error or at least it should not disable parallel vacuum.

I think, in-place of atoi, we should use different function ( defGetInt32, strtoint) or we can write own function.

Thoughts?

[1]: https://www.postgresql.org/message-id/CA%2Bfd4k6DgwtQSr4%3DUeY%2BWbGuF7-oD%3Dm-ypHPy%2BsYHiXZc%2BhTUQ%40mail.gmail.com
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Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com