Attempt to detect when two or more threads try to use the same database at

the same time and return an SQLITE_MISUSE error.  Also return this error
if an attempt is made to use a closed database. (CVS 558)

FossilOrigin-Name: a05fabd2df1cb38c555a7b2f31b0ca687db500c2

manifest

@@ -1,5 +1,5 @@
-C Fix\sfor\sticket\s#35:\sIgnore\sany\sORDER\sBY\sclause\son\sa\ssubquery\sin\sa\sFROM\sclause.\s(CVS\s557)
+C Attempt\sto\sdetect\swhen\stwo\sor\smore\sthreads\stry\sto\suse\sthe\ssame\sdatabase\sat\nthe\ssame\stime\sand\sreturn\san\sSQLITE_MISUSE\serror.\s\sAlso\sreturn\sthis\serror\nif\san\sattempt\sis\smade\sto\suse\sa\sclosed\sdatabase.\s(CVS\s558)
-D 2002-05-08T21:46:15
+D 2002-05-10T05:44:56
 F Makefile.in 50f1b3351df109b5774771350d8c1b8d3640130d
 F Makefile.template 89e373b2dad0321df00400fa968dc14b61a03296
 F README a4c0ba11354ef6ba0776b400d057c59da47a4cc0
@@ -28,7 +28,7 @@ F src/func.c a31dcba85bc2ecb9b752980289cf7e6cd0cafbce
 F src/hash.c cc259475e358baaf299b00a2c7370f2b03dda892
 F src/hash.h dca065dda89d4575f3176e75e9a3dc0f4b4fb8b9
 F src/insert.c 31233f44fc79edbb43523a830e54736a8e222ff4
-F src/main.c df43fe585d2bfb925c837b6822783c0ee3dd6e1c
+F src/main.c a7041c9a32515a33dea8150dd33f748ce6e57861
 F src/md5.c b2b1a34fce66ceca97f4e0dabc20be8be7933c92
 F src/os.c 5ab8b6b4590d0c1ab8e96c67996c170e4462e0fc
 F src/os.h 4a361fccfbc4e7609b3e1557f604f94c1e96ad10
@@ -40,18 +40,18 @@ F src/random.c 19e8e00fe0df32a742f115773f57651be327cabe
 F src/select.c 1b623a7d826ec7c245bc542b665d61724da2a62d
 F src/shell.c 5acbe59e137d60d8efd975c683dbea74ab626530
 F src/shell.tcl 27ecbd63dd88396ad16d81ab44f73e6c0ea9d20e
-F src/sqlite.h.in ffcacf73b5ed1a4939205d29a704a185758fa6a6
+F src/sqlite.h.in 0038faa6d642de06b91143ee65a131bd831d020b
-F src/sqliteInt.h e47ca9267a4c4a98e9f8d90c2df994a18f23d699
+F src/sqliteInt.h b850d1013577be1aa34ca3b7985fa8aca733709b
 F src/table.c eed2098c9b577aa17f8abe89313a9c4413f57d63
 F src/tclsqlite.c c9e9039762d9866eae70bf782237d0206a13f57e
 F src/test1.c d46ab7a82a9c16a3b1ee363cb4c0f98c5ff65743
-F src/test2.c d410dbd8a90faa466c3ab694fa0aa57f5a773aa6
+F src/test2.c 669cc22781c6461a273416ec1a7414d25c081730
 F src/test3.c 4e52fff8b01f08bd202f7633feda5639b7ba2b5e
 F src/threadtest.c 81f0598e0f031c1bd506af337fdc1b7e8dff263f
 F src/tokenize.c 5624d342601f616157ba266abccc1368a5afee70
 F src/update.c 7dd714a6a7fa47f849ebb36b6d915974d6c6accb
-F src/util.c b34cd91387bbfdc79319ea451a7d120cef478120
+F src/util.c 79bcc175e48662faa523d4d00d34bfa246ae219f
-F src/vdbe.c 0ed88fff32273c103a24396d491b71bc69b4b596
+F src/vdbe.c aa5d5f76f2d7f76b1f63d81c5fd2dc91e66c49a4
 F src/vdbe.h 67840a462e1daedb958cca0ccc97db140d3d9152
 F src/where.c 5e3e97adfa5800378f2ed45bb9312dd3a70e239c
 F test/all.test 6aa106eee4d7127afa5cee97c51a783a79694ead
@@ -114,7 +114,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F www/arch.fig d5f9752a4dbf242e9cfffffd3f5762b6c63b3bcf
 F www/arch.png 82ef36db1143828a7abc88b1e308a5f55d4336f4
 F www/arch.tcl 72a0c80e9054cc7025a50928d28d9c75c02c2b8b
-F www/c_interface.tcl 79f63ffa8c6e7adb9e3449ff325d093cfb0ce3e3
+F www/c_interface.tcl fbaddacc3fed376d4aebfddceb31a1fac00cf158
 F www/changes.tcl 2178c2f6a259885904f6406864006a1602d5d498
 F www/conflict.tcl 81dd21f9a679e60aae049e9dd8ab53d59570cda2
 F www/crosscompile.tcl 3622ebbe518927a3854a12de51344673eb2dd060
@@ -130,7 +130,7 @@ F www/speed.tcl da8afcc1d3ccc5696cfb388a68982bc3d9f7f00f
 F www/sqlite.tcl 8b5884354cb615049aed83039f8dfe1552a44279
 F www/tclsqlite.tcl 1db15abeb446aad0caf0b95b8b9579720e4ea331
 F www/vdbe.tcl 2013852c27a02a091d39a766bc87cff329f21218
-P 5f22d21571acedbd6348b61445a7c408cde8d229
+P 1b0ee944c9af10078aba628e85d79f8682afa2b6
-R 8bb0ddf73035f1de9a05b9cb9c9657bb
+R af1468ce6a17da4c94780c1e8568bbbf
 U drh
-Z 9f4be155fc56c5c79e292303d6e98925
+Z 8cea50e279e02e056a890661e5730afa

manifest.uuid

@@ -1 +1 @@
-1b0ee944c9af10078aba628e85d79f8682afa2b6
+a05fabd2df1cb38c555a7b2f31b0ca687db500c2

src/main.c

@@ -14,7 +14,7 @@
 ** other files are for internal use by SQLite and should not be
 ** accessed by users of the library.
 **
-** $Id: main.c,v 1.69 2002/04/12 10:08:59 drh Exp $
+** $Id: main.c,v 1.70 2002/05/10 05:44:56 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
@@ -332,6 +332,7 @@ sqlite *sqlite_open(const char *zFilename, int mode, char **pzErrMsg){
   sqliteRegisterBuildinFunctions(db);
   db->onError = OE_Default;
   db->priorNewRowid = 0;
+  db->magic = SQLITE_MAGIC_BUSY;
   
   /* Open the backend database driver */
   rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
@@ -359,6 +360,7 @@ sqlite *sqlite_open(const char *zFilename, int mode, char **pzErrMsg){
     sqliteFree(*pzErrMsg);
     *pzErrMsg = 0;
   }
+  db->magic = SQLITE_MAGIC_OPEN;
   return db;
 
 no_mem_on_open:
@@ -433,6 +435,8 @@ int sqlite_changes(sqlite *db){
 */
 void sqlite_close(sqlite *db){
   HashElem *i;
+  if( sqliteSafetyOn(db) ){ return; }
+  db->magic = SQLITE_MAGIC_CLOSED;
   sqliteBtreeClose(db->pBe);
   clearHashTable(db, 0);
   if( db->pBeTemp ){
@@ -526,10 +530,12 @@ int sqlite_exec(
   Parse sParse;
 
   if( pzErrMsg ) *pzErrMsg = 0;
+  if( sqliteSafetyOn(db) ){ return SQLITE_MISUSE; }
   if( (db->flags & SQLITE_Initialized)==0 ){
     int rc = sqliteInit(db, pzErrMsg);
     if( rc!=SQLITE_OK ){
       sqliteStrRealloc(pzErrMsg);
+      sqliteSafetyOff(db);
       return rc;
     }
   }
@@ -554,9 +560,49 @@ int sqlite_exec(
     clearHashTable(db, 1);
   }
   db->recursionDepth--;
+  if( sqliteSafetyOff(db) ){ sParse.rc = SQLITE_MISUSE; }
   return sParse.rc;
 }
 
+/*
+** Change the magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
+** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
+** when this routine is called.
+**
+** This routine is a attempt to detect if two threads attempt
+** to use the same sqlite* pointer at the same time.  There is a
+** race condition so it is possible that the error is not detected.
+** But usually the problem will be seen.  The result will be an
+** error which can be used to debugging the application that is
+** using SQLite incorrectly.
+*/
+int sqliteSafetyOn(sqlite *db){
+  if( db->magic==SQLITE_MAGIC_OPEN ){
+    db->magic = SQLITE_MAGIC_BUSY;
+    return 0;
+  }else{
+    db->magic = SQLITE_MAGIC_ERROR;
+    db->flags |= SQLITE_Interrupt;
+    return 1;
+  }
+}
+
+/*
+** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
+** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
+** when this routine is called.
+*/
+int sqliteSafetyOff(sqlite *db){
+  if( db->magic==SQLITE_MAGIC_BUSY ){
+    db->magic = SQLITE_MAGIC_OPEN;
+    return 0;
+  }else{
+    db->magic = SQLITE_MAGIC_ERROR;
+    db->flags |= SQLITE_Interrupt;
+    return 1;
+  }
+}
+
 /*
 ** This routine implements a busy callback that sleeps and tries
 ** again until a timeout value is reached.  The timeout value is

src/sqlite.h.in

@@ -12,7 +12,7 @@
 ** This header file defines the interface that the SQLite library
 ** presents to client programs.
 **
-** @(#) $Id: sqlite.h.in,v 1.30 2002/04/12 10:08:59 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.31 2002/05/10 05:44:56 drh Exp $
 */
 #ifndef _SQLITE_H_
 #define _SQLITE_H_
@@ -161,6 +161,7 @@ int sqlite_exec(
 #define SQLITE_TOOBIG      18   /* Too much data for one row of a table */
 #define SQLITE_CONSTRAINT  19   /* Abort due to contraint violation */
 #define SQLITE_MISMATCH    20   /* Data type mismatch */
+#define SQLITE_MISUSE      21   /* Library used incorrectly */
 
 /*
 ** Each entry in an SQLite table has a unique integer key.  (The key is

src/sqliteInt.h

@@ -11,7 +11,7 @@
 *************************************************************************
 ** Internal interface definitions for SQLite.
 **
-** @(#) $Id: sqliteInt.h,v 1.105 2002/04/12 10:08:59 drh Exp $
+** @(#) $Id: sqliteInt.h,v 1.106 2002/05/10 05:44:56 drh Exp $
 */
 #include "sqlite.h"
 #include "hash.h"
@@ -167,6 +167,7 @@ struct sqlite {
   int lastRowid;                /* ROWID of most recent insert */
   int priorNewRowid;            /* Last randomly generated ROWID */
   int onError;                  /* Default conflict algorithm */
+  int magic;                    /* Magic number for detect library misuse */
   int nChange;                  /* Number of rows changed */
   int recursionDepth;           /* Number of nested calls to sqlite_exec() */
 };
@@ -189,6 +190,16 @@ struct sqlite {
 #define SQLITE_UnresetViews   0x00000200  /* True if one or more views have */
                                           /*   defined column names */
 
+/*
+** Possible values for the sqlite.magic field.
+** The numbers are obtained at random and have no special meaning, other
+** than being distinct from one another.
+*/
+#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
+#define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
+#define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
+#define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */
+
 /*
 ** Each SQL function is defined by an instance of the following
 ** structure.  A pointer to this structure is stored in the sqlite.aFunc
@@ -648,3 +659,5 @@ IdList *sqliteIdListDup(IdList*);
 Select *sqliteSelectDup(Select*);
 FuncDef *sqliteFindFunction(sqlite*,const char*,int,int,int);
 void sqliteRegisterBuildinFunctions(sqlite*);
+int sqliteSafetyOn(sqlite*);
+int sqliteSafetyOff(sqlite*);

src/test2.c

@@ -13,7 +13,7 @@
 ** is not included in the SQLite library.  It is used for automated
 ** testing of the SQLite library.
 **
-** $Id: test2.c,v 1.7 2002/02/02 15:01:16 drh Exp $
+** $Id: test2.c,v 1.8 2002/05/10 05:44:56 drh Exp $
 */
 #include "sqliteInt.h"
 #include "pager.h"
@@ -42,6 +42,12 @@ static char *errorName(int rc){
     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_TOOBIG:     zName = "SQLITE_TOOBIG";      break;
+    case SQLITE_CONSTRAINT: zName = "SQLITE_CONSTRAINT";  break;
+    case SQLITE_MISMATCH:   zName = "SQLITE_MISMATCH";    break;
+    case SQLITE_MISUSE:     zName = "SQLITE_MISUSE";      break;
     default:                zName = "SQLITE_Unknown";     break;
   }
   return zName;

src/util.c

@@ -14,7 +14,7 @@
 ** This file contains functions for allocating memory, comparing
 ** strings, and stuff like that.
 **
-** $Id: util.c,v 1.41 2002/03/06 03:08:26 drh Exp $
+** $Id: util.c,v 1.42 2002/05/10 05:44:56 drh Exp $
 */
 #include "sqliteInt.h"
 #include <stdarg.h>
@@ -1096,6 +1096,7 @@ const char *sqlite_error_string(int rc){
     case SQLITE_TOOBIG:     z = "too much data for one table row";       break;
     case SQLITE_CONSTRAINT: z = "constraint failed";                     break;
     case SQLITE_MISMATCH:   z = "datatype mismatch";                     break;
+    case SQLITE_MISUSE:     z = "SQLite library used incorrectly";       break;
     default:                z = "unknown error";                         break;
   }
   return z;

src/vdbe.c

@@ -30,7 +30,7 @@
 ** But other routines are also provided to help in building up
 ** a program instruction by instruction.
 **
-** $Id: vdbe.c,v 1.139 2002/04/20 14:24:42 drh Exp $
+** $Id: vdbe.c,v 1.140 2002/05/10 05:44:56 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -1092,6 +1092,7 @@ int sqliteVdbeList(
   void *pArg,                /* 1st argument to callback */
   char **pzErrMsg            /* Error msg written here */
 ){
+  sqlite *db = p->db;
   int i, rc;
   char *azValue[6];
   char zAddr[20];
@@ -1109,8 +1110,8 @@ int sqliteVdbeList(
   azValue[5] = 0;
   rc = SQLITE_OK;
   for(i=0; rc==SQLITE_OK && i<p->nOp; i++){
-    if( p->db->flags & SQLITE_Interrupt ){
+    if( db->flags & SQLITE_Interrupt ){
-      p->db->flags &= ~SQLITE_Interrupt;
+      db->flags &= ~SQLITE_Interrupt;
       sqliteSetString(pzErrMsg, "interrupted", 0);
       rc = SQLITE_INTERRUPT;
       break;
@@ -1125,9 +1126,16 @@ int sqliteVdbeList(
       azValue[4] = p->aOp[i].p3;
     }
     azValue[1] = zOpName[p->aOp[i].opcode];
+    if( sqliteSafetyOff(db) ){
+      rc = SQLITE_MISUSE;
+      break;
+    }
     if( xCallback(pArg, 5, azValue, azColumnNames) ){
       rc = SQLITE_ABORT;
     }
+    if( sqliteSafetyOn(db) ){
+      rc = SQLITE_MISUSE;
+    }
   }
   return rc;
 }
@@ -1577,9 +1585,11 @@ case OP_Callback: {
     if( p->iOffset>0 ){
       p->iOffset--;
     }else{
+      if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
       if( xCallback(pArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
         rc = SQLITE_ABORT;
       }
+      if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
       p->nCallback++;
       if( p->iLimit>0 ){
         p->iLimit--;
@@ -1612,9 +1622,11 @@ case OP_Callback: {
 */
 case OP_NullCallback: {
   if( xCallback!=0 && p->nCallback==0 ){
+    if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
     if( xCallback(pArg, pOp->p1, 0, p->azColName)!=0 ){
       rc = SQLITE_ABORT;
     }
+    if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
     p->nCallback++;
   }
   if( sqlite_malloc_failed ) goto no_mem;
@@ -3988,9 +4000,11 @@ case OP_SortCallback: {
     if( p->iOffset>0 ){
       p->iOffset--;
     }else{
+      if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
       if( xCallback(pArg, pOp->p1, (char**)zStack[i], p->azColName)!=0 ){
         rc = SQLITE_ABORT;
       }
+      if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
       p->nCallback++;
       if( p->iLimit>0 ){
         p->iLimit--;
@@ -4655,6 +4669,12 @@ no_mem:
   rc = SQLITE_NOMEM;
   goto cleanup;
 
+  /* Jump to here for an SQLITE_MISUSE error.
+  */
+abort_due_to_misuse:
+  rc = SQLITE_MISUSE;
+  /* Fall thru into abort_due_to_error */
+
   /* Jump to here for any other kind of fatal error.  The "rc" variable
   ** should hold the error number.
   */

www/c_interface.tcl

@@ -1,7 +1,7 @@
 #
 # Run this Tcl script to generate the sqlite.html file.
 #
-set rcsid {$Id: c_interface.tcl,v 1.26 2002/04/12 10:09:00 drh Exp $}
+set rcsid {$Id: c_interface.tcl,v 1.27 2002/05/10 05:44:57 drh Exp $}
 
 puts {<html>
 <head>
@@ -186,6 +186,7 @@ the type of error.  Here is a complete list of the return codes:
 #define SQLITE_TOOBIG      18   /* Too much data for one row of a table */
 #define SQLITE_CONSTRAINT  19   /* Abort due to contraint violation */
 #define SQLITE_MISMATCH    20   /* Data type mismatch */
+#define SQLITE_MISUSE      21   /* Library used incorrectly */
 </pre></blockquote>
 
 <p>
@@ -294,6 +295,15 @@ data into a column labeled INTEGER PRIMARY KEY.  For most columns, SQLite
 ignores the data type and allows any kind of data to be stored.  But
 an INTEGER PRIMARY KEY column is only allowed to store integer data.
 </p></dd>
+<dt>SQLITE_MISUSE</dt>
+<dd><p>This error might occur if one or more of the SQLite API routines
+is used incorrectly.  Examples of incorrect usage include calling
+<b>sqlite_exec()</b> after the database has been closed using
+<b>sqlite_close()</b> or calling <b>sqlite_exec()</b> with the same
+database pointer simultaneously from two separate threads.  The
+library makes an effort to detect these sorts of problems, but it
+cannot detect them with 100% accuracy.
+</p></dd>
 </dl>
 </blockquote>