Fix the preupdate hook so that it works when the "old.*" row has a column with a non-NULL default value that was added by ALTER TABLE ADD COLUMN after the current record was created.

FossilOrigin-Name: 00a398cf900179aa5a8aab09fe4a671d99e7a31583282848ef39390f2ef246eb

2 files changed, 33 insertions, 7 deletions

diff --git a/ext/session/sessionfault3.test b/ext/session/sessionfault3.test
index af5a4cdb4..5af9c9ed7 100644
--- a/ext/session/sessionfault3.test
+++ b/ext/session/sessionfault3.test
@@ -56,4 +56,28 @@ do_faultsim_test 1 -faults oom* -prep {
   faultsim_test_result {0 {}} {1 SQLITE_NOMEM}
 }
 
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+  INSERT INTO t1 VALUES(1, 'one');
+  INSERT INTO t1 VALUES(2, 'two');
+  ALTER TABLE t1 ADD COLUMN c DEFAULT 'abcdefghijklmnopqrstuvwxyz';
+}
+faultsim_save_and_close
+
+do_faultsim_test 2 -faults oom-t* -prep {
+  faultsim_restore_and_reopen
+  db eval {SELECT * FROM sqlite_schema}
+} -body {
+  sqlite3session S db main
+  S attach *
+  execsql {
+    DELETE FROM t1 WHERE a = 1;
+  }
+} -test {
+  faultsim_test_result {0 {}} {1 SQLITE_NOMEM}
+  catch { S delete }
+}
+
 finish_test
diff --git a/ext/session/sqlite3session.c b/ext/session/sqlite3session.c
index 7a8132bfa..72f424923 100644
--- a/ext/session/sqlite3session.c
+++ b/ext/session/sqlite3session.c
@@ -48,8 +48,7 @@ struct sqlite3_session {
   int bEnable;                    /* True if currently recording */
   int bIndirect;                  /* True if all changes are indirect */
   int bAutoAttach;                /* True to auto-attach tables */
-  int bImplicitPK;                /* True to handle tables with implicit PK */
-  int rc;                         /* Non-zero if an error has occurred */
+  int bImplicitPK;                /* True to handle tables with implicit PK */ int rc;                         /* Non-zero if an error has occurred */
   void *pFilterCtx;               /* First argument to pass to xTableFilter */
   int (*xTableFilter)(void *pCtx, const char *zTab);
   i64 nMalloc;                    /* Number of bytes of data allocated */
@@ -1757,16 +1756,19 @@ static void sessionPreupdateOneChange(
       for(i=0; i<(pTab->nCol-pTab->bRowid); i++){
         sqlite3_value *p = 0;
         if( op!=SQLITE_INSERT ){
-          TESTONLY(int trc = ) pSession->hook.xOld(pSession->hook.pCtx, i, &p);
-          assert( trc==SQLITE_OK );
+          /* This may fail if the column has a non-NULL default and was added 
+          ** using ALTER TABLE ADD COLUMN after this record was created. */
+          rc = pSession->hook.xOld(pSession->hook.pCtx, i, &p);
         }else if( pTab->abPK[i] ){
           TESTONLY(int trc = ) pSession->hook.xNew(pSession->hook.pCtx, i, &p);
           assert( trc==SQLITE_OK );
         }
 
-        /* This may fail if SQLite value p contains a utf-16 string that must
-        ** be converted to utf-8 and an OOM error occurs while doing so. */
-        rc = sessionSerializeValue(0, p, &nByte);
+        if( rc==SQLITE_OK ){
+          /* This may fail if SQLite value p contains a utf-16 string that must
+          ** be converted to utf-8 and an OOM error occurs while doing so. */
+          rc = sessionSerializeValue(0, p, &nByte);
+        }
         if( rc!=SQLITE_OK ) goto error_out;
       }
       if( pTab->bRowid ){