Add the SQLITE_FCNTL_TEMPFILENAME file control that asks the underlying VFS

to return a new temporary filename.  Per request from NSS team at Mozilla.

FossilOrigin-Name: 1a63b1d5fa5d79f96eddbda6d94bc10248863710

6 files changed, 70 insertions, 3 deletions

diff --git a/src/os_unix.c b/src/os_unix.c
index a3a012126..315f15018 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -3581,6 +3581,9 @@ static void unixModeBit(unixFile *pFile, unsigned char mask, int *pArg){
   }
 }
 
+/* Forward declaration */
+static int unixGetTempname(int nBuf, char *zBuf);
+
 /*
 ** Information and control of an open file handle.
 */
@@ -3618,6 +3621,14 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){
       *(char**)pArg = sqlite3_mprintf("%s", pFile->pVfs->zName);
       return SQLITE_OK;
     }
+    case SQLITE_FCNTL_TEMPFILENAME: {
+      char *zTFile = sqlite3_malloc( pFile->pVfs->mxPathname );
+      if( zTFile ){
+        unixGetTempname(pFile->pVfs->mxPathname, zTFile);
+        *(char**)pArg = zTFile;
+      }
+      return SQLITE_OK;
+    }
 #ifdef SQLITE_DEBUG
     /* The pager calls this method to signal that it has done
     ** a rollback and that the database is therefore unchanged and
diff --git a/src/os_win.c b/src/os_win.c
index 6f4925770..107370c41 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -2691,6 +2691,9 @@ static void winModeBit(winFile *pFile, unsigned char mask, int *pArg){
   }
 }
 
+/* Forward declaration */
+static int getTempname(int nBuf, char *zBuf);
+
 /*
 ** Control and query of the open file handle.
 */
@@ -2751,6 +2754,14 @@ static int winFileControl(sqlite3_file *id, int op, void *pArg){
       }
       return SQLITE_OK;
     }
+    case SQLITE_FCNTL_TEMPFILENAME: {
+      char *zTFile = sqlite3_malloc( pFile->pVfs->mxPathname );
+      if( zTFile ){
+        getTempname(pFile->pVfs->mxPathname, zTFile);
+        *(char**)pArg = zTFile;
+      }
+      return SQLITE_OK;
+    }
   }
   return SQLITE_NOTFOUND;
 }
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index ba97cd7d4..0bf0be5fc 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -852,7 +852,6 @@ struct sqlite3_io_methods {
 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
 ** file control occurs at the beginning of pragma statement analysis and so
 ** it is able to override built-in [PRAGMA] statements.
-** </ul>
 **
 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
 ** ^This file-control may be invoked by SQLite on the database file handle
@@ -864,6 +863,16 @@ struct sqlite3_io_methods {
 ** the array as the only argument. If it returns non-zero, then the operation
 ** should be retried. If it returns zero, the custom VFS should abandon the
 ** current operation.
+**
+** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
+** ^Application can invoke this file-control to have SQLite generate a
+** temporary filename using the same algorithm that is followed to generate
+** temporary filenames for TEMP tables and other internal uses.  The
+** argument should be a char** which will be filled with the filename
+** written into memory obtained from [sqlite3_malloc()].  The caller should
+** invoke [sqlite3_free()] on the result to avoid a memory leak.
+**
+** </ul>
 */
 #define SQLITE_FCNTL_LOCKSTATE               1
 #define SQLITE_GET_LOCKPROXYFILE             2
@@ -880,6 +889,7 @@ struct sqlite3_io_methods {
 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
 #define SQLITE_FCNTL_PRAGMA                 14
 #define SQLITE_FCNTL_BUSYHANDLER            15
+#define SQLITE_FCNTL_TEMPFILENAME           16
 
 /*
 ** CAPI3REF: Mutex Handle
diff --git a/src/test1.c b/src/test1.c
index e7a224221..bb8d186c1 100644
--- a/src/test1.c
+++ b/src/test1.c
@@ -5321,6 +5321,38 @@ static int file_control_vfsname(
   return TCL_OK;  
 }
 
+/*
+** tclcmd:   file_control_tempfilename DB ?AUXDB?
+**
+** Return a string that is a temporary filename
+*/
+static int file_control_tempfilename(
+  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 */
+){
+  sqlite3 *db;
+  const char *zDbName = "main";
+  char *zTName = 0;
+
+  if( objc!=2 && objc!=3 ){
+    Tcl_AppendResult(interp, "wrong # args: should be \"",
+        Tcl_GetStringFromObj(objv[0], 0), " DB ?AUXDB?", 0);
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ){
+    return TCL_ERROR;
+  }
+  if( objc==3 ){
+    zDbName = Tcl_GetString(objv[2]);
+  }
+  sqlite3_file_control(db, zDbName, SQLITE_FCNTL_TEMPFILENAME, (void*)&zTName);
+  Tcl_AppendResult(interp, zTName, (char*)0);
+  sqlite3_free(zTName);
+  return TCL_OK;  
+}
+
 
 /*
 ** tclcmd:   sqlite3_vfs_list
@@ -6150,6 +6182,7 @@ int Sqlitetest1_Init(Tcl_Interp *interp){
      { "file_control_persist_wal",    file_control_persist_wal,     0   },
      { "file_control_powersafe_overwrite",file_control_powersafe_overwrite,0},
      { "file_control_vfsname",        file_control_vfsname,         0   },
+     { "file_control_tempfilename",   file_control_tempfilename,    0   },
      { "sqlite3_vfs_list",           vfs_list,     0   },
      { "sqlite3_create_function_v2", test_create_function_v2, 0 },
 
diff --git a/src/test_sqllog.c b/src/test_sqllog.c
index 49569a39f..7cb570bcf 100644
--- a/src/test_sqllog.c
+++ b/src/test_sqllog.c
@@ -390,7 +390,7 @@ static void testSqllogStmt(struct SLConn *p, const char *zSql){
 ** The SQLITE_CONFIG_SQLLOG callback registered by sqlite3_init_sqllog().
 */
 static void testSqllog(void *pCtx, sqlite3 *db, const char *zSql, int eType){
-  struct SLConn *p;
+  struct SLConn *p = 0;
   sqlite3_mutex *master = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
 
   assert( eType==0 || eType==1 || eType==2 );
diff --git a/src/test_vfstrace.c b/src/test_vfstrace.c
index d2f7455e3..0aacc01fe 100644
--- a/src/test_vfstrace.c
+++ b/src/test_vfstrace.c
@@ -475,6 +475,7 @@ static int vfstraceFileControl(sqlite3_file *pFile, int op, void *pArg){
     case SQLITE_FCNTL_PERSIST_WAL:  zOp = "PERSIST_WAL";        break;
     case SQLITE_FCNTL_OVERWRITE:    zOp = "OVERWRITE";          break;
     case SQLITE_FCNTL_VFSNAME:      zOp = "VFSNAME";            break;
+    case SQLITE_FCNTL_TEMPFILENAME: zOp = "TEMPFILENAME";       break;
     case 0xca093fa0:                zOp = "DB_UNCHANGED";       break;
     case SQLITE_FCNTL_PRAGMA: {
       const char *const* a = (const char*const*)pArg;
@@ -496,7 +497,8 @@ static int vfstraceFileControl(sqlite3_file *pFile, int op, void *pArg){
     *(char**)pArg = sqlite3_mprintf("vfstrace.%s/%z",
                                     pInfo->zVfsName, *(char**)pArg);
   }
-  if( op==SQLITE_FCNTL_PRAGMA && rc==SQLITE_OK && *(char**)pArg ){
+  if( (op==SQLITE_FCNTL_PRAGMA || op==SQLITE_FCNTL_TEMPFILENAME)
+   && rc==SQLITE_OK && *(char**)pArg ){
     vfstrace_printf(pInfo, "%s.xFileControl(%s,%s) returns %s",
                     pInfo->zVfsName, p->zFName, zOp, *(char**)pArg);
   }