Make sure the sqlite3_vfs_register() and sqlite3_vfs_unregister() APIs

work right even if not VFS is currently registered.  Ticket #2738. (CVS 4505)

FossilOrigin-Name: c36500871e85b55cb0804d5c9e88fa6861a507a9

manifest

@@ -1,5 +1,5 @@
-C Add\sspeed4.test,\swith\ssome\sspeed\stests\sfor\striggers,\ssub-selects,\sviews\sand\sjoins.\s(CVS\s4504)
-D 2007-10-23T10:25:30
+C Make\ssure\sthe\ssqlite3_vfs_register()\sand\ssqlite3_vfs_unregister()\sAPIs\nwork\sright\seven\sif\snot\sVFS\sis\scurrently\sregistered.\s\sTicket\s#2738.\s(CVS\s4505)
+D 2007-10-23T14:49:59
 F Makefile.in 30c7e3ba426ddb253b8ef037d1873425da6009a8
 F Makefile.linux-gcc 65241babba6faf1152bf86574477baab19190499
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -110,7 +110,7 @@ F src/mutex.h 079fa6fe9da18ceb89e79012c010594c6672addb
 F src/mutex_os2.c 7fe4773e98ed74a63b2e54fc557929eb155f6269
 F src/mutex_unix.c ff77650261a245035b79c5c8a174f4e05d3cae8a
 F src/mutex_w32.c 6e197765f283815496193e78e9548b5d0e53b68e
-F src/os.c 6a84b6ff284fa558e879d9b6a5809004aacc8195
+F src/os.c 8360932f1450b2b45edb608a3b184b031f7d00cc
 F src/os.h b75506ab40d222300f38023acb56fe08df5ffe33
 F src/os_common.h 98862f120ca6bf7a48ce8b16f158b77d00bc9d2f
 F src/os_os2.c 8d8ef4462cfa1b4d824ec55c486bce86fa0ac6fc
@@ -137,7 +137,7 @@ F src/sqliteInt.h 3fa9f4e9d2f07e162509f75d827d32f41fcd4f30
 F src/sqliteLimit.h 1bcbbdfa856f8b71b561abb31edb864b0eca1d12
 F src/table.c 1aeb9eab57b4235db86fe15a35dec76fb445a9c4
 F src/tclsqlite.c 29bb44a88e02ca4d2017113b7b1acc839582d57a
-F src/test1.c 738f9b4ab808dcfec1516ef699c416e3f4f1d119
+F src/test1.c e4785f9b339d27fb300da8bfb0ba27af8e7bcee0
 F src/test2.c 77b34303883b9d722c65a6879bb0163a400e3789
 F src/test3.c 73c1fd55d1ece61f295a6b9204fd97a139de86ae
 F src/test4.c c2c0f5dc907f1346f5d4b65eb5799f11eb9e4071
@@ -430,7 +430,7 @@ F test/table.test 13b1c2e2fb4727b35ee1fb7641fc469214fd2455
 F test/tableapi.test 92651a95c23cf955e92407928e640536402fa3cc
 F test/tclsqlite.test 3fac87cb1059c46b8fa8a60b553f4f1adb0fb6d9
 F test/temptable.test 19b851b9e3e64d91e9867619b2a3f5fffee6e125
-F test/tester.tcl 58a86ba2f93f76c728e7a338f8b7724c566ce708
+F test/tester.tcl 675147144b4e661e31277876bb1bb0d9f6afb442
 F test/thread001.test 8fbd9559da0bbdc273e00318c7fd66c162020af7
 F test/thread002.test 2c4ad2c386f60f6fe268cd91c769ee35b3c1fd0b
 F test/thread1.test 776c9e459b75ba905193b351926ac4019b049f35
@@ -584,7 +584,7 @@ F www/tclsqlite.tcl 8be95ee6dba05eabcd27a9d91331c803f2ce2130
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 2449e08069ef830f119203c4a3737d6756e73c63
-R 9ff5bb31431b0085b77a736c1e69245b
-U danielk1977
-Z 15cc286b9726040cda03d092104a36be
+P 3e3475b9e0f996841aa40419693c7c3eaa6c71aa
+R f5b08c77641b2a161a8d65b96bb2a7d8
+U drh
+Z 7b5ff5d5e516010e45b59cf86b7b1e00

manifest.uuid

@@ -1 +1 @@
-3e3475b9e0f996841aa40419693c7c3eaa6c71aa
+c36500871e85b55cb0804d5c9e88fa6861a507a9

src/os.c

@@ -214,7 +214,7 @@ static sqlite3_vfs *vfsList = 0;
 */
 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
   sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
-  sqlite3_vfs *pVfs;
+  sqlite3_vfs *pVfs = 0;
   static int isInit = 0;
   sqlite3_mutex_enter(mutex);
   if( !isInit ){
@@ -234,9 +234,11 @@ sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 */
 static void vfsUnlink(sqlite3_vfs *pVfs){
   assert( sqlite3_mutex_held(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER)) );
-  if( vfsList==pVfs ){
+  if( pVfs==0 ){
+    /* No-op */
+  }else if( vfsList==pVfs ){
     vfsList = pVfs->pNext;
-  }else{
+  }else if( vfsList ){
     sqlite3_vfs *p = vfsList;
     while( p->pNext && p->pNext!=pVfs ){
       p = p->pNext;
@@ -276,7 +278,6 @@ int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
   sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
   sqlite3_mutex_enter(mutex);
   vfsUnlink(pVfs);
-  assert(vfsList);
   sqlite3_mutex_leave(mutex);
   return SQLITE_OK;
 }

src/test1.c

@@ -13,7 +13,7 @@
 ** is not included in the SQLite library.  It is used for automated
 ** testing of the SQLite library.
 **
-** $Id: test1.c,v 1.277 2007/09/03 17:30:07 danielk1977 Exp $
+** $Id: test1.c,v 1.278 2007/10/23 14:49:59 drh Exp $
 */
 #include "sqliteInt.h"
 #include "tcl.h"
@@ -4205,6 +4205,43 @@ static int working_64bit_int(
 }
 
 
+/*
+** tclcmd:   vfs_unlink_test
+**
+** This TCL command unregisters the primary VFS and then registers
+** it back again.  This is used to test the ability to register a
+** VFS when none are previously registered, and the ability to 
+** unregister the only available VFS.  Ticket #2738
+*/
+static int vfs_unlink_test(
+  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
+  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
+  int objc,              /* Number of arguments */
+  Tcl_Obj *CONST objv[]  /* Command arguments */
+){
+  int i;
+  sqlite3_vfs *apVfs[20];
+
+  for(i=0; i<sizeof(apVfs)/sizeof(apVfs[0]); i++){
+    apVfs[i] = sqlite3_vfs_find(0);
+    if( apVfs[i] ){
+      assert( apVfs[i]==sqlite3_vfs_find(apVfs[i]->zName) );
+      sqlite3_vfs_unregister(apVfs[i]);
+      assert( 0==sqlite3_vfs_find(apVfs[i]->zName) );
+    }
+  }
+  assert( 0==sqlite3_vfs_find(0) );
+  for(i=sizeof(apVfs)/sizeof(apVfs[0])-1; i>=0; i--){
+    if( apVfs[i] ){
+      sqlite3_vfs_register(apVfs[i], 1);
+      assert( apVfs[i]==sqlite3_vfs_find(0) );
+      assert( apVfs[i]==sqlite3_vfs_find(apVfs[i]->zName) );
+    }
+  }
+  return TCL_OK;
+}
+
+
 /*
 ** Register commands with the TCL interpreter.
 */
@@ -4340,6 +4377,7 @@ int Sqlitetest1_Init(Tcl_Interp *interp){
      { "sqlite3_create_collation_v2", test_create_collation_v2, 0 },
      { "sqlite3_global_recover",     test_global_recover, 0   },
      { "working_64bit_int",          working_64bit_int,   0   },
+     { "vfs_unlink_test",            vfs_unlink_test,     0   },
 
      /* Functions from os.h */
 #ifndef SQLITE_OMIT_DISKIO

test/tester.tcl

@@ -11,7 +11,7 @@
 # This file implements some common TCL routines used for regression
 # testing the SQLite library
 #
-# $Id: tester.tcl,v 1.93 2007/10/20 15:41:58 drh Exp $
+# $Id: tester.tcl,v 1.94 2007/10/23 14:49:59 drh Exp $
 
 
 set tcl_precision 15
@@ -166,6 +166,7 @@ proc finalize_testing {} {
   catch {db2 close}
   catch {db3 close}
 
+  vfs_unlink_test
   sqlite3 db {}
   # sqlite3_clear_tsd_memdebug
   db close