Fix the sqlite3_prepare() family of interfaces so that they zero the *ppStmt

value even on an SQLITE_MISUSE return.  Make it clear in the documentation
that the ppStmt parameter cannot be zero. (CVS 6441)

FossilOrigin-Name: 23bf9f266559603e37b2703715eaf8ef5af6bb17

3 files changed, 29 insertions, 18 deletions

diff --git a/src/prepare.c b/src/prepare.c
index c4d88a3be..e3479f3b8 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -13,7 +13,7 @@
 ** interface, and routines that contribute to loading the database schema
 ** from disk.
 **
-** $Id: prepare.c,v 1.115 2009/04/01 16:33:38 drh Exp $
+** $Id: prepare.c,v 1.116 2009/04/02 18:32:27 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -528,11 +528,8 @@ static int sqlite3Prepare(
   int rc = SQLITE_OK;
   int i;
 
-  assert( ppStmt );
-  *ppStmt = 0;
-  if( sqlite3SafetyOn(db) ){
-    return SQLITE_MISUSE;
-  }
+  if( sqlite3SafetyOn(db) ) return SQLITE_MISUSE;
+  assert( ppStmt && *ppStmt==0 );
   assert( !db->mallocFailed );
   assert( sqlite3_mutex_held(db->mutex) );
 
@@ -671,6 +668,8 @@ static int sqlite3LockAndPrepare(
   const char **pzTail       /* OUT: End of parsed string */
 ){
   int rc;
+  assert( ppStmt!=0 );
+  *ppStmt = 0;
   if( !sqlite3SafetyCheckOk(db) ){
     return SQLITE_MISUSE;
   }
@@ -773,6 +772,7 @@ static int sqlite3Prepare16(
   const char *zTail8 = 0;
   int rc = SQLITE_OK;
 
+  assert( ppStmt );
   *ppStmt = 0;
   if( !sqlite3SafetyCheckOk(db) ){
     return SQLITE_MISUSE;
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index d8f51e79c..1ecd14c23 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -30,7 +30,7 @@
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 **
-** @(#) $Id: sqlite.h.in,v 1.436 2009/03/20 13:15:30 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.437 2009/04/02 18:32:27 drh Exp $
 */
 #ifndef _SQLITE3_H_
 #define _SQLITE3_H_
@@ -2229,7 +2229,8 @@ int sqlite3_limit(sqlite3*, int id, int newVal);
 ** program using one of these routines.
 **
 ** The first argument, "db", is a [database connection] obtained from a
-** prior call to [sqlite3_open()], [sqlite3_open_v2()] or [sqlite3_open16()].
+** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
+** [sqlite3_open16()].  The database connection must not have been closed.
 **
 ** The second argument, "zSql", is the statement to be compiled, encoded
 ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
@@ -2246,17 +2247,18 @@ int sqlite3_limit(sqlite3*, int id, int newVal);
 ** is equal to the number of bytes in the input string <i>including</i>
 ** the nul-terminator bytes.
 **
-** *pzTail is made to point to the first byte past the end of the
-** first SQL statement in zSql.  These routines only compile the first
-** statement in zSql, so *pzTail is left pointing to what remains
-** uncompiled.
+** If pzTail is not NULL then *pzTail is made to point to the first byte
+** past the end of the first SQL statement in zSql.  These routines only
+** compile the first statement in zSql, so *pzTail is left pointing to
+** what remains uncompiled.
 **
 ** *ppStmt is left pointing to a compiled [prepared statement] that can be
 ** executed using [sqlite3_step()].  If there is an error, *ppStmt is set
 ** to NULL.  If the input text contains no SQL (if the input is an empty
 ** string or a comment) then *ppStmt is set to NULL.
-** {A13018} The calling procedure is responsible for deleting the compiled
+** The calling procedure is responsible for deleting the compiled
 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
+** ppStmt may not be NULL.
 **
 ** On success, [SQLITE_OK] is returned, otherwise an [error code] is returned.
 **
diff --git a/src/test9.c b/src/test9.c
index 2043da23f..222bdc390 100644
--- a/src/test9.c
+++ b/src/test9.c
@@ -14,7 +14,7 @@
 ** for completeness. Test code is written in C for these cases
 ** as there is not much point in binding to Tcl.
 **
-** $Id: test9.c,v 1.6 2008/07/11 13:53:55 drh Exp $
+** $Id: test9.c,v 1.7 2009/04/02 18:32:27 drh Exp $
 */
 #include "sqliteInt.h"
 #include "tcl.h"
@@ -114,6 +114,7 @@ static int c_misuse_test(
 ){
   const char *zErrFunction = "N/A";
   sqlite3 *db = 0;
+  sqlite3_stmt *pStmt;
   int rc;
 
   if( objc!=1 ){
@@ -138,29 +139,37 @@ static int c_misuse_test(
     goto error_out;
   }
 
-  rc = sqlite3_prepare(db, 0, 0, 0, 0);
+  pStmt = (sqlite3_stmt*)1234;
+  rc = sqlite3_prepare(db, 0, 0, &pStmt, 0);
   if( rc!=SQLITE_MISUSE ){
     zErrFunction = "sqlite3_prepare";
     goto error_out;
   }
+  assert( pStmt==0 ); /* Verify that pStmt is zeroed even on a MISUSE error */
 
-  rc = sqlite3_prepare_v2(db, 0, 0, 0, 0);
+  pStmt = (sqlite3_stmt*)1234;
+  rc = sqlite3_prepare_v2(db, 0, 0, &pStmt, 0);
   if( rc!=SQLITE_MISUSE ){
     zErrFunction = "sqlite3_prepare_v2";
     goto error_out;
   }
+  assert( pStmt==0 );
 
 #ifndef SQLITE_OMIT_UTF16
-  rc = sqlite3_prepare16(db, 0, 0, 0, 0);
+  pStmt = (sqlite3_stmt*)1234;
+  rc = sqlite3_prepare16(db, 0, 0, &pStmt, 0);
   if( rc!=SQLITE_MISUSE ){
     zErrFunction = "sqlite3_prepare16";
     goto error_out;
   }
-  rc = sqlite3_prepare16_v2(db, 0, 0, 0, 0);
+  assert( pStmt==0 );
+  pStmt = (sqlite3_stmt*)1234;
+  rc = sqlite3_prepare16_v2(db, 0, 0, &pStmt, 0);
   if( rc!=SQLITE_MISUSE ){
     zErrFunction = "sqlite3_prepare16_v2";
     goto error_out;
   }
+  assert( pStmt==0 );
 #endif
 
   return TCL_OK;