cdbmake key length and the magic number 429496720

cdbmake has the following code snippet for parsing in
the length of keys formatted as ASCII numbers:

klen =3D 0;
for (;;) {
  get(&ch);
  if (ch =3D=3D ',') break;
  if ((ch < '0') || (ch > '9')) die_readformat();
  if (klen > 429496720) { errno =3D error_nomem; die_write(); }
  klen =3D klen * 10 + (ch - '0');
}

As you can observe, there is an undocumented magic number.
I can=E2=80=99t make sense of that number.

  logBase2(429496720) ~ 28.67

Maybe 4GB limit

  2^30*4 =3D=3D 4294967296
         !=3D 429496720

I am confounded.


  Profpatsch

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