Avoid integer overflow in query parameter encoding#720
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Many large bytea parameters wrapped the typecast buffer size, then the bytea encoder wrote past the allocation. Fixes #719
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Jun 5, 2026
| sql = big_count.times.map{|n| "$#{n+1}" }.join(",") | ||
| @conn.exec_params('select '+sql, params, 0, tm) | ||
| rescue PG::UnableToSend | ||
| # ignore "PQsendQueryParams cannot allocate memory for output buffer" |
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This happens when the host running the test doesn't have enough free memory?
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libpq allocates 2 GB at the maximum, due to using signed int for the buffer size: https://github.com/postgres/postgres/blob/b45137f315bb49fa4f50ae9cc16fda0a49196610/src/interfaces/libpq/fe-misc.c#L301
So this test will always raise PG::UnableToSend with the current libpq implementation. The important thing here is that it doesn't crash due to memory access error.
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Many large bytea parameters wrapped the typecast buffer size, then the bytea encoder wrote past the allocation.
Fixes #719