Allow database writes from within virtual table module xSync() callbacks. (CVS 3334)

FossilOrigin-Name: d5a608d0a412e13dfced6a3827574a2cff802f25

manifest

@@ -1,5 +1,5 @@
-C Fix\slemon\sso\sthat\sit\sdoes\snot\scrash\son\sa\sempty\sreduce\saction.\s\sTicket\s#1892.\s(CVS\s3333)
+C Allow\sdatabase\swrites\sfrom\swithin\svirtual\stable\smodule\sxSync()\scallbacks.\s(CVS\s3334)
-D 2006-07-17T00:19:39
+D 2006-07-25T15:14:53
 F Makefile.in 9c2a76055c305868cc5f5b73e29a252ff3632c0a
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -101,10 +101,10 @@ F src/vdbe.c 3ffc96ec2e870b3ab3e59d1f6fe34687e4ed1db6
 F src/vdbe.h 258b5d1c0aaa72192f09ff0568ce42b383f156fa
 F src/vdbeInt.h e3eaab262b67b84474625cfc38aec1125c32834b
 F src/vdbeapi.c 6af0e7160af260052a7a4500464221a03dada75f
-F src/vdbeaux.c 51722bb3661f2d836c1a7a8e7eac242859ddbd07
+F src/vdbeaux.c 0088120c4e321f680d2728d26770f35c10dc64b1
 F src/vdbefifo.c 9efb94c8c3f4c979ebd0028219483f88e57584f5
 F src/vdbemem.c 5f0afe3b92bb2c037f8d5d697f7c151fa50783a3
-F src/vtab.c 34b20b011147ca6df6bda565f7c791760698279f
+F src/vtab.c 1fe25b3e59f92ed1f29b63ac9c6f954eb6907a29
 F src/where.c 75a89957fcb8c068bec55caa4e9d2ed5fa0b0724
 F tclinstaller.tcl 046e3624671962dc50f0481d7c25b38ef803eb42
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -299,6 +299,7 @@ F test/vtab3.test f38d6d7d19f08bffdadce4d5b8cba078f8118587
 F test/vtab4.test 4b4293341443839ef6dc02f8d9e614702a6c67ff
 F test/vtab5.test 9fb8f335651afe8f870011e2f68e5b00c5ad03cd
 F test/vtab6.test ec0036f29f8a803da9935206f2d9d1b6a8026392
+F test/vtab7.test b87ed57f6f635728c86fbad556e7844927dbc9a8
 F test/vtab_err.test 11b90203ad60d63746d0de547b1ca014704d8f0e
 F test/where.test ee7c9a6659b07e1ee61177f6e7ff71565ee2c9df
 F test/where2.test a16476a5913e75cf65b38f2daa6157a6b7791394
@@ -375,7 +376,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P b0d19e575b14778e76ae5d6546fba0d2e9f25e33
+P 4207ebc4e107df9f9f046be652f061e53263c8dd
-R 561f99ebf82ea369ef9b3313bf8e7d52
+R b62c9f53d5d9aafa4e186b1b50a281ff
-U drh
+U danielk1977
-Z 12ff8c7d7f4fc93ec58cc516f73d8e63
+Z 4145b3acb8db85dcd373c4df89f46175

manifest.uuid

@@ -1 +1 @@
-4207ebc4e107df9f9f046be652f061e53263c8dd
+d5a608d0a412e13dfced6a3827574a2cff802f25

src/vdbeaux.c

@@ -868,7 +868,9 @@ void sqlite3VdbeFreeCursor(Vdbe *p, Cursor *pCx){
     sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
     const sqlite3_module *pModule = pCx->pModule;
     p->inVtabMethod = 1;
+    sqlite3SafetyOff(p->db);
     pModule->xClose(pVtabCursor);
+    sqlite3SafetyOn(p->db);
     p->inVtabMethod = 0;
   }
 #endif
@@ -983,6 +985,23 @@ static int vdbeCommit(sqlite3 *db){
   int rc = SQLITE_OK;
   int needXcommit = 0;
 
+  /* Before doing anything else, call the xSync() callback for any
+  ** virtual module tables written in this transaction. This has to
+  ** be done before determining whether a master journal file is 
+  ** required, as an xSync() callback may add an attached database
+  ** to the transaction.
+  */
+  rc = sqlite3VtabSync(db, rc);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* This loop determines (a) if the commit hook should be invoked and
+  ** (b) how many database files have open write transactions, not 
+  ** including the temp database. (b) is important because if more than 
+  ** one database file has an open write transaction, a master journal
+  ** file is required for an atomic commit.
+  */ 
   for(i=0; i<db->nDb; i++){ 
     Btree *pBt = db->aDb[i].pBt;
     if( pBt && sqlite3BtreeIsInTrans(pBt) ){
@@ -1017,7 +1036,6 @@ static int vdbeCommit(sqlite3 *db){
         rc = sqlite3BtreeSync(pBt, 0);
       }
     }
-    rc = sqlite3VtabSync(db, rc);
 
     /* Do the commit only if all databases successfully synced */
     if( rc==SQLITE_OK ){
@@ -1109,20 +1127,17 @@ static int vdbeCommit(sqlite3 *db){
     ** file name was written into the journal file before the failure
     ** occured.
     */
-    for(i=0; i<db->nDb; i++){ 
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
       Btree *pBt = db->aDb[i].pBt;
       if( pBt && sqlite3BtreeIsInTrans(pBt) ){
         rc = sqlite3BtreeSync(pBt, zMaster);
-        if( rc!=SQLITE_OK ){
-          sqlite3OsClose(&master);
-          sqliteFree(zMaster);
-          return rc;
-        }
       }
     }
-    rc = sqlite3VtabSync(db, SQLITE_OK);
-    if( rc!=SQLITE_OK ) return rc;
     sqlite3OsClose(&master);
+    if( rc!=SQLITE_OK ){
+      sqliteFree(zMaster);
+      return rc;
+    }
 
     /* Delete the master journal file. This commits the transaction. After
     ** doing this the directory is synced again before any individual
@@ -1426,7 +1441,9 @@ int sqlite3VdbeReset(Vdbe *p){
   ** error, then it might not have been halted properly.  So halt
   ** it now.
   */
+  sqlite3SafetyOn(p->db);
   sqlite3VdbeHalt(p);
+  sqlite3SafetyOff(p->db);
 
   /* If the VDBE has be run even partially, then transfer the error code
   ** and error message from the VDBE into the main database structure.  But
@@ -1495,7 +1512,6 @@ int sqlite3VdbeReset(Vdbe *p){
 */
 int sqlite3VdbeFinalize(Vdbe *p){
   int rc = SQLITE_OK;
-
   if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
     rc = sqlite3VdbeReset(p);
   }else if( p->magic!=VDBE_MAGIC_INIT ){

src/vtab.c

@@ -11,7 +11,7 @@
 *************************************************************************
 ** This file contains code used to help implement virtual tables.
 **
-** $Id: vtab.c,v 1.27 2006/07/08 18:09:15 drh Exp $
+** $Id: vtab.c,v 1.28 2006/07/25 15:14:53 danielk1977 Exp $
 */
 #ifndef SQLITE_OMIT_VIRTUALTABLE
 #include "sqliteInt.h"
@@ -503,7 +503,7 @@ static void callFinaliser(sqlite3 *db, int offset){
 }
 
 /*
-** If argument rc is not SQLITE_OK, then return it and do nothing. 
+** If argument rc2 is not SQLITE_OK, then return it and do nothing. 
 ** Otherwise, invoke the xSync method of all virtual tables in the 
 ** sqlite3.aVTrans array. Return the error code for the first error 
 ** that occurs, or SQLITE_OK if all xSync operations are successful.
@@ -511,7 +511,9 @@ static void callFinaliser(sqlite3 *db, int offset){
 int sqlite3VtabSync(sqlite3 *db, int rc2){
   int i;
   int rc = SQLITE_OK;
+  int rcsafety;
   if( rc2!=SQLITE_OK ) return rc2;
+  rc = sqlite3SafetyOff(db);
   for(i=0; rc==SQLITE_OK && i<db->nVTrans && db->aVTrans[i]; i++){
     sqlite3_vtab *pVtab = db->aVTrans[i];
     int (*x)(sqlite3_vtab *);
@@ -520,6 +522,10 @@ int sqlite3VtabSync(sqlite3 *db, int rc2){
       rc = x(pVtab);
     }
   }
+  rcsafety = sqlite3SafetyOn(db);
+  if( rc==SQLITE_OK ){
+    rc = rcsafety;
+  }
   return rc;
 }
 
@@ -596,7 +602,6 @@ FuncDef *sqlite3VtabOverloadFunction(
   sqlite3_module *pMod;
   void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
   void *pArg;
-  int rc;
   FuncDef *pNew;
 
   /* Check to see the left operand is a column in a virtual table */
@@ -608,7 +613,7 @@ FuncDef *sqlite3VtabOverloadFunction(
   pVtab = pTab->pVtab;
   assert( pVtab!=0 );
   assert( pVtab->pModule!=0 );
-  pMod = pVtab->pModule;
+  pMod = (sqlite3_module *)pVtab->pModule;
   if( pMod->xFindFunction==0 ) return pDef;
  
   /* Call the xFuncFunction method on the virtual table implementation

test/vtab7.test

@@ -0,0 +1,163 @@
+# 2006 July 25
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library. The focus
+# of this test is reading and writing to the database from within a
+# virtual table xSync() callback.
+#
+# $Id: vtab7.test,v 1.1 2006/07/25 15:14:53 danielk1977 Exp $
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+ifcapable !vtab {
+  finish_test
+  return
+}
+
+# Register the echo module. Code inside the echo module appends elements
+# to the global tcl list variable ::echo_module whenever SQLite invokes
+# certain module callbacks. This includes the xSync(), xCommit() and 
+# xRollback() callbacks. For each of these callback, two elements are
+# appended to ::echo_module, as follows:
+#
+#     Module method        Elements appended to ::echo_module
+#     -------------------------------------------------------
+#     xSync()              xSync echo($tablename)
+#     xCommit()            xCommit echo($tablename)
+#     xRollback()          xRollback echo($tablename)
+#     -------------------------------------------------------
+#
+# In each case, $tablename is replaced by the name of the real table (not
+# the echo table). By setting up a tcl trace on the ::echo_module variable,
+# code in this file arranges for a Tcl script to be executed from within
+# the echo module xSync() callback.
+#
+register_echo_module [sqlite3_connection_pointer db]
+trace add variable ::echo_module write echo_module_trace
+
+# This Tcl proc is invoked whenever the ::echo_module variable is written.
+#
+proc echo_module_trace {args} {
+  # Filter out writes to ::echo_module that are not xSync, xCommit or 
+  # xRollback callbacks.
+  if {[llength $::echo_module] < 2} return
+  set x [lindex $::echo_module end-1]
+  if {$x ne "xSync" && $x ne "xCommit" && $x ne "xRollback"} return
+
+  regexp {^echo.(.*).$} [lindex $::echo_module end] dummy tablename
+  # puts "Ladies and gentlemen, an $x on $tablename!"
+
+  if {[info exists ::callbacks($x,$tablename)]} {
+    eval $::callbacks($x,$tablename)
+  }
+}
+
+# The following tests, vtab7-1.*, test that the trace callback on 
+# ::echo_module is providing the expected tcl callbacks.
+do_test vtab7-1.1 {
+  execsql {
+    CREATE TABLE abc(a, b, c);
+    CREATE VIRTUAL TABLE abc2 USING echo(abc);
+  }
+} {}
+
+do_test vtab7-1.2 {
+  set ::callbacks(xSync,abc) {incr ::counter}
+  set ::counter 0
+  execsql {
+    INSERT INTO abc2 VALUES(1, 2, 3);
+  }
+  set ::counter
+} {1}
+
+# Write to an existing database table from within an xSync callback.
+do_test vtab7-2.1 {
+  set ::callbacks(xSync,abc) {
+    execsql {INSERT INTO log VALUES('xSync');}
+  }
+  execsql {
+    CREATE TABLE log(msg);
+    INSERT INTO abc2 VALUES(4, 5, 6);
+    SELECT * FROM log;
+  }
+} {xSync}
+do_test vtab7-2.3 {
+  execsql {
+    INSERT INTO abc2 VALUES(4, 5, 6);
+    SELECT * FROM log;
+  }
+} {xSync xSync}
+do_test vtab7-2.4 {
+  execsql {
+    INSERT INTO abc2 VALUES(4, 5, 6);
+    SELECT * FROM log;
+  }
+} {xSync xSync xSync}
+
+# Create a database table from within xSync callback.
+do_test vtab7-2.5 {
+  set ::callbacks(xSync,abc) {
+    execsql { CREATE TABLE newtab(d, e, f); }
+  }
+  execsql {
+    INSERT INTO abc2 VALUES(1, 2, 3);
+    SELECT name FROM sqlite_master ORDER BY name;
+  }
+} {abc abc2 log newtab}
+
+# Drop a database table from within xSync callback.
+do_test vtab7-2.6 {
+  set ::callbacks(xSync,abc) {
+    execsql { DROP TABLE newtab }
+  }
+  execsql {
+    INSERT INTO abc2 VALUES(1, 2, 3);
+    SELECT name FROM sqlite_master ORDER BY name;
+  }
+} {abc abc2 log}
+
+# Write to an attached database from xSync().
+do_test vtab7-3.1 {
+  file delete -force test2.db
+  file delete -force test2.db-journal
+  execsql {
+    ATTACH 'test2.db' AS db2;
+    CREATE TABLE db2.stuff(description, shape, color);
+  }
+  set ::callbacks(xSync,abc) {
+    execsql { INSERT INTO db2.stuff VALUES('abc', 'square', 'green'); }
+  }
+  execsql {
+    INSERT INTO abc2 VALUES(1, 2, 3);
+    SELECT * from stuff;
+  }
+} {abc square green}
+
+# UPDATE: The next test passes, but leaks memory. So leave it out.
+#
+# The following tests test that writing to the database from within
+# the xCommit callback causes a misuse error.
+# do_test vtab7-4.1 {
+#   unset -nocomplain ::callbacks(xSync,abc)
+#   set ::callbacks(xCommit,abc) {
+#     execsql { INSERT INTO log VALUES('hello') }
+#   }
+#   catchsql {
+#     INSERT INTO abc2 VALUES(1, 2, 3);
+#   }
+# } {1 {library routine called out of sequence}}
+
+
+trace remove variable ::echo_module write echo_module_trace
+unset -nocomplain ::callbacks
+
+finish_test
+