diff options
| -rw-r--r-- | src/backend/access/transam/xlog.c | 36 |
1 files changed, 20 insertions, 16 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index a1215a0b8cf..cbfa68a4e7b 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -3829,15 +3829,32 @@ retry: } /* + * Read the record length. + * * NB: Even though we use an XLogRecord pointer here, the whole record - * header might not fit on this page. xl_tot_len is the first field in - * struct, so it must be on this page, but we cannot safely access any - * other fields yet. + * header might not fit on this page. xl_tot_len is the first field of + * the struct, so it must be on this page (the records are MAXALIGNed), + * but we cannot access any other fields until we've verified that we + * got the whole header. */ record = (XLogRecord *) (readBuf + (*RecPtr) % XLOG_BLCKSZ); total_len = record->xl_tot_len; /* + * If the whole record header is on this page, validate it immediately. + * Otherwise validate it after reading the rest of the header from next + * page. + */ + if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord) + { + if (!ValidXLogRecordHeader(RecPtr, record, emode, randAccess)) + goto next_record_is_invalid; + gotheader = true; + } + else + gotheader = false; + + /* * Allocate or enlarge readRecordBuf as needed. To avoid useless small * increases, round its size to a multiple of XLOG_BLCKSZ, and make sure * it's at least 4*Max(BLCKSZ, XLOG_BLCKSZ) to start with. (That is @@ -3865,19 +3882,6 @@ retry: readRecordBufSize = newSize; } - /* - * If we got the whole header already, validate it immediately. Otherwise - * we validate it after reading the rest of the header from the next page. - */ - if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord) - { - if (!ValidXLogRecordHeader(RecPtr, record, emode, randAccess)) - goto next_record_is_invalid; - gotheader = true; - } - else - gotheader = false; - len = XLOG_BLCKSZ - (*RecPtr) % XLOG_BLCKSZ; if (total_len > len) { |