On 2020-Sep-03, Tom Lane wrote: > Alvaro Herrera <alvhe...@2ndquadrant.com> writes: > > A pretty minor issue: when reporting that WAL appears invalid because > > contrecord length doesn't match, we may as well print to the server log > > the value that we're expecting. Patch attached. > > ITYW > > + (long long) (total_len - gotlen), > > just to be sure about what's getting casted to what.
Well, the intention there is to cast the first operand (which is uint32) so that it turns into signed 64-bits; the subtraction then occurs in 64 bit arithmetic normally. If I let the subtraction occur in 32-bit width unsigned, the result might overflow 32 bits. I'm thinking in 1 - UINT32_MAX or some such. Maybe to make that more explicit, it should be + ((long long) total_len) - gotlen, (If I understand the precedence correctly, it's the same thing I wrote). -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
