From 6d8ca934e86e63c3e867ecef355bd373412f6b6a Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Mon, 19 Jul 2010 19:44:45 +0200 Subject: [PATCH] Don't segfault upon too deeply nested subtransactions. Build a list of parent transactions and iterate it in the correct order instead of using recursion to avoid a stack overflow. --- src/backend/access/transam/xact.c | 24 ++++++++++++++++++++++-- 1 files changed, 22 insertions(+), 2 deletions(-) diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 6ba6534..be0b448 100644 *** a/src/backend/access/transam/xact.c --- b/src/backend/access/transam/xact.c *************** AssignTransactionId(TransactionState s) *** 409,417 **** /* * Ensure parent(s) have XIDs, so that a child always has an XID later * than its parent. */ ! if (isSubXact && !TransactionIdIsValid(s->parent->transactionId)) ! AssignTransactionId(s->parent); /* * Generate a new Xid and record it in PG_PROC and pg_subtrans. --- 409,437 ---- /* * Ensure parent(s) have XIDs, so that a child always has an XID later * than its parent. + * We don't use recursion here to allow arbitrarily deep nesting. */ ! if(isSubXact && !TransactionIdIsValid(s->parent->transactionId)){ ! TransactionState p = s->parent; ! TransactionState* parents; ! size_t parentOffset = 0; ! ! parents = palloc(sizeof(TransactionState) * s->nestingLevel); ! ! while(p && !TransactionIdIsValid(p->transactionId)){ ! parents[parentOffset++] = p; ! p = p->parent; ! } ! ! while(parentOffset != 0){ ! /* ! * Note that this won't recurse because p will never have a ! * parent with an invalid transactionId at that point. ! */ ! AssignTransactionId(parents[--parentOffset]); ! } ! pfree(parents); ! } /* * Generate a new Xid and record it in PG_PROC and pg_subtrans. -- 1.7.2.rc1.10.gae32f