On Thu, Jun 26, 2025 at 08:48:32AM +0530, Dilip Kumar wrote: > On Thu, Jun 26, 2025 at 6:22 AM Michael Paquier <mich...@paquier.xyz> wrote: >> So you are suggesting the addition of an extra ReadPageInternal() that >> forces a read of only the read, perform the checks on the header, then >> read the rest. After reading SizeOfXLogShortPHD worth of data, >> shouldn't the checks on xlp_rem_len be done a bit earlier than what >> you are proposing in this patch? > > I did not get the point, IMHO it has to be validated after the record > on the next page has been read.
As proposed in the patch, the first ReadPageInternal() reads SizeOfXLogShortPHD worth of data (right?), so we should have access to XLogPageHeaderData.xlp_rem_len before attempting the second ReadPageInternal() worth Min(total_len - gotlen + SizeOfXLogShortPHD, XLOG_BLCKSZ) of data. The check that fails with a "invalid contrecord length %u" relies on xlp_rem_len, total_len, RecPtr and gotlen. We know all this information before the second ReadPageInternal(). -- Michael
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