Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -5090,11 +5090,11 @@
 
   /* The dbOrigSize is never set if journal_mode=OFF */
   assert( pPager->journalMode!=PAGER_JOURNALMODE_OFF || pPager->dbOrigSize==0 );
 
   /* If a prior error occurred, report that error again. */
-  if( NEVER(pPager->errCode) ) return pPager->errCode;
+  if( pPager->errCode ) return pPager->errCode;
 
   PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n", 
       pPager->zFilename, zMaster, pPager->dbSize));
 
   if( MEMDB && pPager->dbModified ){

Index: test/malloc_common.tcl
==================================================================
--- test/malloc_common.tcl
+++ test/malloc_common.tcl
@@ -185,11 +185,10 @@
   set ::sqlite_io_error_hit     0
   set ::sqlite_io_error_pending 0
   return $sv
 }
 
-
 # The following procs are used as [do_one_faultsim_test] callbacks when 
 # injecting shared-memory related error faults into test cases.
 #
 proc shmerr_injectinstall {} {
   testvfs shmfault -default true
@@ -205,10 +204,13 @@
 }
 proc shmerr_injectstop {} {
   shmfault ioerr 0 0
 }
 
+# The following procs are used as [do_one_faultsim_test] callbacks when 
+# injecting SQLITE_FULL error faults into test cases.
+#
 proc fullerr_injectinstall {} {
   testvfs shmfault -default true
 }
 proc fullerr_injectuninstall {} {
   catch {db  close}

Index: test/pager1.test
==================================================================
--- test/pager1.test
+++ test/pager1.test
@@ -36,10 +36,12 @@
 #
 # pager1-7.*: Cases specific to "PRAGMA journal_mode=TRUNCATE"
 #
 # pager1-8.*: Cases using temporary and in-memory databases.
 #
+# pager1-9.*: Tests related to the backup API.
+#
 
 set a_string_counter 1
 proc a_string {n} {
   global a_string_counter
   incr a_string_counter
@@ -183,10 +185,13 @@
   do_test pager1-$tn.28 { sql3 { SELECT * FROM t1 } } {21 one 22 two 23 three}
 }
 
 #-------------------------------------------------------------------------
 # Savepoint related test cases.
+#
+# pager1-3.1.2.*: Force a savepoint rollback to cause the database file
+#                 to grow.
 # 
 do_test pager1-3.1.1 {
   faultsim_delete_and_reopen
   execsql {
     CREATE TABLE t1(a PRIMARY KEY, b);
@@ -216,10 +221,43 @@
     INSERT INTO t1 SELECT a+3, randomblob(1500) FROM t1
 } {1 {constraint failed}}
 do_execsql_test pager1-3.4 { SELECT * FROM counter } {3 0}
 do_execsql_test pager1-3.5 { SELECT a FROM t1 } {1 2 3}
 do_execsql_test pager1-3.6 { COMMIT } {}
+
+do_test pager1-3.2.1 {
+  faultsim_delete_and_reopen
+  db func a_string a_string
+  execsql {
+    PRAGMA auto_vacuum = 2;
+    PRAGMA cache_size = 10;
+    CREATE TABLE z(x INTEGER PRIMARY KEY, y);
+    BEGIN;
+      INSERT INTO z VALUES(NULL, a_string(800));
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --   2
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --   4
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --   8
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --  16
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --  32
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     --  64
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     -- 128
+      INSERT INTO z SELECT NULL, a_string(800) FROM z;     -- 256
+    COMMIT;
+  }
+  execsql { PRAGMA auto_vacuum }
+} {2}
+do_execsql_test pager1-3.2.2 {
+  BEGIN;
+    INSERT INTO z VALUES(NULL, a_string(800));
+    INSERT INTO z VALUES(NULL, a_string(800));
+    SAVEPOINT one;
+      DELETE FROM z WHERE x>256;
+      PRAGMA incremental_vacuum;
+      SELECT count(*) FROM z WHERE x < 100;
+    ROLLBACK TO one;
+  COMMIT;
+} {99}
 
 #-------------------------------------------------------------------------
 # Hot journal rollback related test cases.
 #
 # pager1.4.1.*: Test that the pager module deletes very small invalid
@@ -839,8 +877,79 @@
       INSERT INTO x1 VALUES('William');
       INSERT INTO x1 VALUES('Anne');
     ROLLBACK;
   } {}
 }
+
+#-------------------------------------------------------------------------
+# The next block of tests - pager1-9.* - deal with interactions between
+# the pager and the backup API. Test cases:
+#
+#   pager1-9.1.*: Test that a backup completes successfully even if the
+#                 source db is written to during the backup op.
+#
+#   pager1-9.2.*: Test that a backup completes successfully even if the
+#                 source db is written to and then rolled back during a 
+#                 backup operation.
+#
+do_test pager1-9.0.1 {
+  faultsim_delete_and_reopen
+  db func a_string a_string
+  execsql {
+    PRAGMA cache_size = 10;
+    BEGIN;
+      CREATE TABLE ab(a, b, UNIQUE(a, b));
+      INSERT INTO ab VALUES( a_string(200), a_string(300) );
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+      INSERT INTO ab SELECT a_string(200), a_string(300) FROM ab;
+    COMMIT;
+  }
+} {}
+do_test pager1-9.0.2 {
+  sqlite3 db2 test.db2
+  db2 eval { PRAGMA cache_size = 10 }
+  sqlite3_backup B db2 main db main
+  list [B step 10000] [B finish]
+} {SQLITE_DONE SQLITE_OK}
+do_test pager1-9.0.3 {
+ db one {SELECT md5sum(a, b) FROM ab}
+} [db2 one {SELECT md5sum(a, b) FROM ab}]
+
+do_test pager1-9.1.1 {
+  execsql { UPDATE ab SET a = a_string(201) }
+  sqlite3_backup B db2 main db main
+  B step 30
+} {SQLITE_OK}
+do_test pager1-9.1.2 {
+  execsql { UPDATE ab SET b = a_string(301) }
+  list [B step 10000] [B finish]
+} {SQLITE_DONE SQLITE_OK}
+do_test pager1-9.1.3 {
+ db one {SELECT md5sum(a, b) FROM ab}
+} [db2 one {SELECT md5sum(a, b) FROM ab}]
+do_test pager1-9.1.4 { execsql { SELECT count(*) FROM ab } } {128}
+
+do_test pager1-9.2.1 {
+  execsql { UPDATE ab SET a = a_string(202) }
+  sqlite3_backup B db2 main db main
+  B step 30
+} {SQLITE_OK}
+do_test pager1-9.2.2 {
+  execsql { 
+    BEGIN;
+      UPDATE ab SET b = a_string(301);
+    ROLLBACK;
+  }
+  list [B step 10000] [B finish]
+} {SQLITE_DONE SQLITE_OK}
+do_test pager1-9.2.3 {
+ db one {SELECT md5sum(a, b) FROM ab}
+} [db2 one {SELECT md5sum(a, b) FROM ab}]
+do_test pager1-9.2.4 { execsql { SELECT count(*) FROM ab } } {128}
 
 finish_test
 

Index: test/pagerfault.test
==================================================================
--- test/pagerfault.test
+++ test/pagerfault.test
@@ -305,10 +305,23 @@
 # } -test {
 #   faultsim_test_result {0 {5 6 7 8}}
 #   faultsim_integrity_check
 # }
 #
+
+# This is designed to provoke a special case in the pager code:
+#
+# If an error (specifically, a FULL or IOERR error) occurs while writing a
+# dirty page to the file-system in order to free up memory, the pager enters
+# the "error state". An IO error causes SQLite to roll back the current
+# transaction (exiting the error state). A FULL error, however, may only
+# rollback the current statement.
+#
+# This block tests that nothing goes wrong if a FULL error occurs while
+# writing a dirty page out to free memory from within a statement that has
+# opened a statement transaction.
+#
 do_test pagerfault-7-pre1 {
   faultsim_delete_and_reopen
   execsql {
     CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
     BEGIN;
@@ -333,12 +346,50 @@
     BEGIN;
       UPDATE t1 SET b = randomblob(1500);
   }
 } -body {
   execsql { UPDATE t1 SET a = 65, b = randomblob(1500) WHERE (a+1)>200 }
+  execsql COMMIT
+} -test {
+  faultsim_test_result {0 {}}
+  faultsim_integrity_check
+}
+
+do_test pagerfault-8-pre1 {
+  faultsim_delete_and_reopen
+  execsql {
+    PRAGMA auto_vacuum = 1;
+    CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+    BEGIN;
+      INSERT INTO t1 VALUES(NULL, randomblob(1500));
+      INSERT INTO t1 VALUES(NULL, randomblob(1500));
+      INSERT INTO t1 SELECT NULL, randomblob(1500) FROM t1;    --  4
+      INSERT INTO t1 SELECT NULL, randomblob(1500) FROM t1;    --  8
+      INSERT INTO t1 SELECT NULL, randomblob(1500) FROM t1;    -- 16
+      INSERT INTO t1 SELECT NULL, randomblob(1500) FROM t1;    -- 32
+      INSERT INTO t1 SELECT NULL, randomblob(1500) FROM t1;    -- 64
+    COMMIT;
+  }
+  faultsim_save_and_close
+  set filesize [file size test.db]
+  set {} {}
+} {}
+do_test pagerfault-8-pre2 {
+  faultsim_restore_and_reopen
+  execsql { DELETE FROM t1 WHERE a>32 }
+  expr {[file size test.db] < $filesize}
+} {1}
+breakpoint
+do_faultsim_test pagerfault-8 -prep {
+  faultsim_restore_and_reopen
+  execsql { 
+    BEGIN;
+    DELETE FROM t1 WHERE a>32;
+  }
+} -body {
   execsql COMMIT
 } -test {
   faultsim_test_result {0 {}}
   faultsim_integrity_check
 }
 
 finish_test