/*

 ** 2003 December 18

 **

 ** 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.

 **

 *************************************************************************

 ** Code for testing the the SQLite library in a multithreaded environment.

 **

 ** $Id: test4.c,v 1.23 2008/07/28 19:34:54 drh Exp $

 */

 #include "sqliteInt.h"

 #include "tcl.h"

 #if defined(SQLITE_OS_UNIX) && OS_UNIX==1 && SQLITE_THREADSAFE

 #include <stdlib.h>

 #include <string.h>

 #include <pthread.h>

 #include <sched.h>

 #include <ctype.h>

 /*

 ** Each thread is controlled by an instance of the following

 ** structure.

 */

 typedef struct Thread Thread;

 struct Thread {

   /* The first group of fields are writable by the master and read-only

   ** to the thread. */

   char *zFilename;       /* Name of database file */

   void (*xOp)(Thread*);  /* next operation to do */

   char *zArg;            /* argument usable by xOp */

   int opnum;             /* Operation number */

   int busy;              /* True if this thread is in use */

   /* The next group of fields are writable by the thread but read-only to the

   ** master. */

   int completed;        /* Number of operations completed */

   sqlite3 *db;           /* Open database */

   sqlite3_stmt *pStmt;     /* Pending operation */

   char *zErr;           /* operation error */

   char *zStaticErr;     /* Static error message */

   int rc;               /* operation return code */

   int argc;             /* number of columns in result */

   const char *argv[100];    /* result columns */

   const char *colv[100];    /* result column names */

 };

 /*

 ** There can be as many as 26 threads running at once.  Each is named

 ** by a capital letter: A, B, C, ..., Y, Z.

 */

 #define N_THREAD 26

 static Thread threadset[N_THREAD];

 /*

 ** The main loop for a thread.  Threads use busy waiting. 

 */

 static void *thread_main(void *pArg){

   Thread *p = (Thread*)pArg;

   if( p->db ){

     sqlite3_close(p->db);

   }

   sqlite3_open(p->zFilename, &p->db);

   if( SQLITE_OK!=sqlite3_errcode(p->db) ){

     p->zErr = strdup(sqlite3_errmsg(p->db));

     sqlite3_close(p->db);

     p->db = 0;

   }

   p->pStmt = 0;

   p->completed = 1;

   while( p->opnum<=p->completed ) sched_yield();

   while( p->xOp ){

     if( p->zErr && p->zErr!=p->zStaticErr ){

       sqlite3_free(p->zErr);

       p->zErr = 0;

     }

     (*p->xOp)(p);

     p->completed++;

     while( p->opnum<=p->completed ) sched_yield();

   }

   if( p->pStmt ){

     sqlite3_finalize(p->pStmt);

     p->pStmt = 0;

   }

   if( p->db ){

     sqlite3_close(p->db);

     p->db = 0;

   }

   if( p->zErr && p->zErr!=p->zStaticErr ){

     sqlite3_free(p->zErr);

     p->zErr = 0;

   }

   p->completed++;

   sqlite3_thread_cleanup();

   return 0;

 }

 /*

 ** Get a thread ID which is an upper case letter.  Return the index.

 ** If the argument is not a valid thread ID put an error message in

 ** the interpreter and return -1.

 */

 static int parse_thread_id(Tcl_Interp *interp, const char *zArg){

   if( zArg==0 || zArg[0]==0 || zArg[1]!=0 || !isupper((unsigned char)zArg[0]) ){

     Tcl_AppendResult(interp, "thread ID must be an upper case letter", 0);

     return -1;

   }

   return zArg[0] - 'A';

 }

 /*

 ** Usage:    thread_create NAME  FILENAME

 **

 ** NAME should be an upper case letter.  Start the thread running with

 ** an open connection to the given database.

 */

 static int tcl_thread_create(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   pthread_t x;

   int rc;

   if( argc!=3 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID FILENAME", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( threadset[i].busy ){

     Tcl_AppendResult(interp, "thread ", argv[1], " is already running", 0);

     return TCL_ERROR;

   }

   threadset[i].busy = 1;

   sqlite3_free(threadset[i].zFilename);

   threadset[i].zFilename = sqlite3DbStrDup(0, argv[2]);

   threadset[i].opnum = 1;

   threadset[i].completed = 0;

   rc = pthread_create(&x, 0, thread_main, &threadset[i]);

   if( rc ){

     Tcl_AppendResult(interp, "failed to create the thread", 0);

     sqlite3_free(threadset[i].zFilename);

     threadset[i].busy = 0;

     return TCL_ERROR;

   }

   pthread_detach(x);

   return TCL_OK;

 }

 /*

 ** Wait for a thread to reach its idle state.

 */

 static void thread_wait(Thread *p){

   while( p->opnum>p->completed ) sched_yield();

 }

 /*

 ** Usage:  thread_wait ID

 **

 ** Wait on thread ID to reach its idle state.

 */

 static int tcl_thread_wait(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   return TCL_OK;

 }

 /*

 ** Stop a thread.

 */

 static void stop_thread(Thread *p){

   thread_wait(p);

   p->xOp = 0;

   p->opnum++;

   thread_wait(p);

   sqlite3_free(p->zArg);

   p->zArg = 0;

   sqlite3_free(p->zFilename);

   p->zFilename = 0;

   p->busy = 0;

 }

 /*

 ** Usage:  thread_halt ID

 **

 ** Cause a thread to shut itself down.  Wait for the shutdown to be

 ** completed.  If ID is "*" then stop all threads.

 */

 static int tcl_thread_halt(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   if( argv[1][0]=='*' && argv[1][1]==0 ){

     for(i=0; i<N_THREAD; i++){

       if( threadset[i].busy ) stop_thread(&threadset[i]);

     }

   }else{

     i = parse_thread_id(interp, argv[1]);

     if( i<0 ) return TCL_ERROR;

     if( !threadset[i].busy ){

       Tcl_AppendResult(interp, "no such thread", 0);

       return TCL_ERROR;

     }

     stop_thread(&threadset[i]);

   }

   return TCL_OK;

 }

 /*

 ** Usage: thread_argc  ID

 **

 ** Wait on the most recent thread_step to complete, then return the

 ** number of columns in the result set.

 */

 static int tcl_thread_argc(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   char zBuf[100];

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   sprintf(zBuf, "%d", threadset[i].argc);

   Tcl_AppendResult(interp, zBuf, 0);

   return TCL_OK;

 }

 /*

 ** Usage: thread_argv  ID   N

 **

 ** Wait on the most recent thread_step to complete, then return the

 ** value of the N-th columns in the result set.

 */

 static int tcl_thread_argv(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   int n;

   if( argc!=3 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID N", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;

   thread_wait(&threadset[i]);

   if( n<0 || n>=threadset[i].argc ){

     Tcl_AppendResult(interp, "column number out of range", 0);

     return TCL_ERROR;

   }

   Tcl_AppendResult(interp, threadset[i].argv[n], 0);

   return TCL_OK;

 }

 /*

 ** Usage: thread_colname  ID   N

 **

 ** Wait on the most recent thread_step to complete, then return the

 ** name of the N-th columns in the result set.

 */

 static int tcl_thread_colname(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   int n;

   if( argc!=3 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID N", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;

   thread_wait(&threadset[i]);

   if( n<0 || n>=threadset[i].argc ){

     Tcl_AppendResult(interp, "column number out of range", 0);

     return TCL_ERROR;

   }

   Tcl_AppendResult(interp, threadset[i].colv[n], 0);

   return TCL_OK;

 }

 /*

 ** Usage: thread_result  ID

 **

 ** Wait on the most recent operation to complete, then return the

 ** result code from that operation.

 */

 static int tcl_thread_result(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   const char *zName;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   switch( threadset[i].rc ){

     case SQLITE_OK:         zName = "SQLITE_OK";          break;

     case SQLITE_ERROR:      zName = "SQLITE_ERROR";       break;

     case SQLITE_PERM:       zName = "SQLITE_PERM";        break;

     case SQLITE_ABORT:      zName = "SQLITE_ABORT";       break;

     case SQLITE_BUSY:       zName = "SQLITE_BUSY";        break;

     case SQLITE_LOCKED:     zName = "SQLITE_LOCKED";      break;

     case SQLITE_NOMEM:      zName = "SQLITE_NOMEM";       break;

     case SQLITE_READONLY:   zName = "SQLITE_READONLY";    break;

     case SQLITE_INTERRUPT:  zName = "SQLITE_INTERRUPT";   break;

     case SQLITE_IOERR:      zName = "SQLITE_IOERR";       break;

     case SQLITE_CORRUPT:    zName = "SQLITE_CORRUPT";     break;

     case SQLITE_FULL:       zName = "SQLITE_FULL";        break;

     case SQLITE_CANTOPEN:   zName = "SQLITE_CANTOPEN";    break;

     case SQLITE_PROTOCOL:   zName = "SQLITE_PROTOCOL";    break;

     case SQLITE_EMPTY:      zName = "SQLITE_EMPTY";       break;

     case SQLITE_SCHEMA:     zName = "SQLITE_SCHEMA";      break;

     case SQLITE_CONSTRAINT: zName = "SQLITE_CONSTRAINT";  break;

     case SQLITE_MISMATCH:   zName = "SQLITE_MISMATCH";    break;

     case SQLITE_MISUSE:     zName = "SQLITE_MISUSE";      break;

     case SQLITE_NOLFS:      zName = "SQLITE_NOLFS";       break;

     case SQLITE_AUTH:       zName = "SQLITE_AUTH";        break;

     case SQLITE_FORMAT:     zName = "SQLITE_FORMAT";      break;

     case SQLITE_RANGE:      zName = "SQLITE_RANGE";       break;

     case SQLITE_ROW:        zName = "SQLITE_ROW";         break;

     case SQLITE_DONE:       zName = "SQLITE_DONE";        break;

     default:                zName = "SQLITE_Unknown";     break;

   }

   Tcl_AppendResult(interp, zName, 0);

   return TCL_OK;

 }

 /*

 ** Usage: thread_error  ID

 **

 ** Wait on the most recent operation to complete, then return the

 ** error string.

 */

 static int tcl_thread_error(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   Tcl_AppendResult(interp, threadset[i].zErr, 0);

   return TCL_OK;

 }

 /*

 ** This procedure runs in the thread to compile an SQL statement.

 */

 static void do_compile(Thread *p){

   if( p->db==0 ){

     p->zErr = p->zStaticErr = "no database is open";

     p->rc = SQLITE_ERROR;

     return;

   }

   if( p->pStmt ){

     sqlite3_finalize(p->pStmt);

     p->pStmt = 0;

   }

   p->rc = sqlite3_prepare(p->db, p->zArg, -1, &p->pStmt, 0);

 }

 /*

 ** Usage: thread_compile ID SQL

 **

 ** Compile a new virtual machine.

 */

 static int tcl_thread_compile(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=3 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID SQL", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   threadset[i].xOp = do_compile;

   sqlite3_free(threadset[i].zArg);

   threadset[i].zArg = sqlite3DbStrDup(0, argv[2]);

   threadset[i].opnum++;

   return TCL_OK;

 }

 /*

 ** This procedure runs in the thread to step the virtual machine.

 */

 static void do_step(Thread *p){

   int i;

   if( p->pStmt==0 ){

     p->zErr = p->zStaticErr = "no virtual machine available";

     p->rc = SQLITE_ERROR;

     return;

   }

   p->rc = sqlite3_step(p->pStmt);

   if( p->rc==SQLITE_ROW ){

     p->argc = sqlite3_column_count(p->pStmt);

     for(i=0; i<sqlite3_data_count(p->pStmt); i++){

       p->argv[i] = (char*)sqlite3_column_text(p->pStmt, i);

     }

     for(i=0; i<p->argc; i++){

       p->colv[i] = sqlite3_column_name(p->pStmt, i);

     }

   }

 }

 /*

 ** Usage: thread_step ID

 **

 ** Advance the virtual machine by one step

 */

 static int tcl_thread_step(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " IDL", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   threadset[i].xOp = do_step;

   threadset[i].opnum++;

   return TCL_OK;

 }

 /*

 ** This procedure runs in the thread to finalize a virtual machine.

 */

 static void do_finalize(Thread *p){

   if( p->pStmt==0 ){

     p->zErr = p->zStaticErr = "no virtual machine available";

     p->rc = SQLITE_ERROR;

     return;

   }

   p->rc = sqlite3_finalize(p->pStmt);

   p->pStmt = 0;

 }

 /*

 ** Usage: thread_finalize ID

 **

 ** Finalize the virtual machine.

 */

 static int tcl_thread_finalize(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " IDL", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   threadset[i].xOp = do_finalize;

   sqlite3_free(threadset[i].zArg);

   threadset[i].zArg = 0;

   threadset[i].opnum++;

   return TCL_OK;

 }

 /*

 ** Usage: thread_swap ID ID

 **

 ** Interchange the sqlite* pointer between two threads.

 */

 static int tcl_thread_swap(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i, j;

   sqlite3 *temp;

   if( argc!=3 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID1 ID2", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   j = parse_thread_id(interp, argv[2]);

   if( j<0 ) return TCL_ERROR;

   if( !threadset[j].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[j]);

   temp = threadset[i].db;

   threadset[i].db = threadset[j].db;

   threadset[j].db = temp;

   return TCL_OK;

 }

 /*

 ** Usage: thread_db_get ID

 **

 ** Return the database connection pointer for the given thread.  Then

 ** remove the pointer from the thread itself.  Afterwards, the thread

 ** can be stopped and the connection can be used by the main thread.

 */

 static int tcl_thread_db_get(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   char zBuf[100];

   extern int sqlite3TestMakePointerStr(Tcl_Interp*, char*, void*);

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   sqlite3TestMakePointerStr(interp, zBuf, threadset[i].db);

   threadset[i].db = 0;

   Tcl_AppendResult(interp, zBuf, (char*)0);

   return TCL_OK;

 }

 /*

 ** Usage: thread_stmt_get ID

 **

 ** Return the database stmt pointer for the given thread.  Then

 ** remove the pointer from the thread itself. 

 */

 static int tcl_thread_stmt_get(

   void *NotUsed,

   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

   int argc,              /* Number of arguments */

   const char **argv      /* Text of each argument */

 ){

   int i;

   char zBuf[100];

   extern int sqlite3TestMakePointerStr(Tcl_Interp*, char*, void*);

   if( argc!=2 ){

     Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

        " ID", 0);

     return TCL_ERROR;

   }

   i = parse_thread_id(interp, argv[1]);

   if( i<0 ) return TCL_ERROR;

   if( !threadset[i].busy ){

     Tcl_AppendResult(interp, "no such thread", 0);

     return TCL_ERROR;

   }

   thread_wait(&threadset[i]);

   sqlite3TestMakePointerStr(interp, zBuf, threadset[i].pStmt);

   threadset[i].pStmt = 0;

   Tcl_AppendResult(interp, zBuf, (char*)0);

   return TCL_OK;

 }

 /*

 ** Register commands with the TCL interpreter.

 */

 int Sqlitetest4_Init(Tcl_Interp *interp){

   static struct {

      char *zName;

      Tcl_CmdProc *xProc;

   } aCmd[] = {

      { "thread_create",     (Tcl_CmdProc*)tcl_thread_create     },

      { "thread_wait",       (Tcl_CmdProc*)tcl_thread_wait       },

      { "thread_halt",       (Tcl_CmdProc*)tcl_thread_halt       },

      { "thread_argc",       (Tcl_CmdProc*)tcl_thread_argc       },

      { "thread_argv",       (Tcl_CmdProc*)tcl_thread_argv       },

      { "thread_colname",    (Tcl_CmdProc*)tcl_thread_colname    },

      { "thread_result",     (Tcl_CmdProc*)tcl_thread_result     },

      { "thread_error",      (Tcl_CmdProc*)tcl_thread_error      },

      { "thread_compile",    (Tcl_CmdProc*)tcl_thread_compile    },

      { "thread_step",       (Tcl_CmdProc*)tcl_thread_step       },

      { "thread_finalize",   (Tcl_CmdProc*)tcl_thread_finalize   },

      { "thread_swap",       (Tcl_CmdProc*)tcl_thread_swap       },

      { "thread_db_get",     (Tcl_CmdProc*)tcl_thread_db_get     },

      { "thread_stmt_get",   (Tcl_CmdProc*)tcl_thread_stmt_get   },

   };

   int i;

   for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){

     Tcl_CreateCommand(interp, aCmd[i].zName, aCmd[i].xProc, 0, 0);

   }

   return TCL_OK;

 }

 #else

 int Sqlitetest4_Init(Tcl_Interp *interp){ return TCL_OK; }

 #endif /* SQLITE_OS_UNIX */