Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -7073,11 +7073,12 @@
 */
 int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
   int rc = SQLITE_OK;
   if( pPager->pWal ){
     rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
-        pPager->xBusyHandler, pPager->pBusyHandlerArg,
+        (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
+        pPager->pBusyHandlerArg,
         pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
         pnLog, pnCkpt
     );
   }
   return rc;

Index: src/wal.c
==================================================================
--- src/wal.c
+++ src/wal.c
@@ -1687,11 +1687,11 @@
 ** time.
 */
 static int walCheckpoint(
   Wal *pWal,                      /* Wal connection */
   int eMode,                      /* One of PASSIVE, FULL or RESTART */
-  int (*xBusyCall)(void*),        /* Function to call when busy */
+  int (*xBusy)(void*),            /* Function to call when busy */
   void *pBusyArg,                 /* Context argument for xBusyHandler */
   int sync_flags,                 /* Flags for OsSync() (or 0) */
   u8 *zBuf                        /* Temporary buffer to use */
 ){
   int rc;                         /* Return code */
@@ -1701,11 +1701,10 @@
   u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
   u32 mxSafeFrame;                /* Max frame that can be backfilled */
   u32 mxPage;                     /* Max database page to write */
   int i;                          /* Loop counter */
   volatile WalCkptInfo *pInfo;    /* The checkpoint status information */
-  int (*xBusy)(void*) = 0;        /* Function to call when waiting for locks */
 
   szPage = walPagesize(pWal);
   testcase( szPage<=32768 );
   testcase( szPage>=65536 );
   pInfo = walCkptInfo(pWal);
@@ -1716,11 +1715,13 @@
   if( rc!=SQLITE_OK ){
     return rc;
   }
   assert( pIter );
 
-  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;
+  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
 
   /* Compute in mxSafeFrame the index of the last frame of the WAL that is
   ** safe to write into the database.  Frames beyond mxSafeFrame might
   ** overwrite database pages that are in use by active readers and thus
   ** cannot be backfilled from the WAL.
@@ -2941,11 +2942,11 @@
 ** If parameter xBusy is not NULL, it is a pointer to a busy-handler
 ** callback. In this case this function runs a blocking checkpoint.
 */
 int sqlite3WalCheckpoint(
   Wal *pWal,                      /* Wal connection */
-  int eMode,                      /* PASSIVE, FULL or RESTART */
+  int eMode,                      /* PASSIVE, FULL, RESTART, or TRUNCATE */
   int (*xBusy)(void*),            /* Function to call when busy */
   void *pBusyArg,                 /* Context argument for xBusyHandler */
   int sync_flags,                 /* Flags to sync db file with (or 0) */
   int nBuf,                       /* Size of temporary buffer */
   u8 *zBuf,                       /* Temporary buffer to use */
@@ -2953,40 +2954,54 @@
   int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
 ){
   int rc;                         /* Return code */
   int isChanged = 0;              /* True if a new wal-index header is loaded */
   int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */
+  int (*xBusy2)(void*) = xBusy;   /* Busy handler for eMode2 */
 
   assert( pWal->ckptLock==0 );
   assert( pWal->writeLock==0 );
 
+  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
   if( pWal->readOnly ) return SQLITE_READONLY;
   WALTRACE(("WAL%p: checkpoint begins\n", pWal));
+
+  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
+  ** "checkpoint" lock on the database file. */
   rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
   if( rc ){
-    /* Usually this is SQLITE_BUSY meaning that another thread or process
-    ** is already running a checkpoint, or maybe a recovery.  But it might
-    ** also be SQLITE_IOERR. */
+    /* EVIDENCE-OF: R-10421-19736 If any other process is running a
+    ** checkpoint operation at the same time, the lock cannot be obtained and
+    ** SQLITE_BUSY is returned.
+    ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+    ** it will not be invoked in this case.
+    */
+    testcase( rc==SQLITE_BUSY );
+    testcase( xBusy!=0 );
     return rc;
   }
   pWal->ckptLock = 1;
 
-  /* If this is a blocking-checkpoint, then obtain the write-lock as well
-  ** to prevent any writers from running while the checkpoint is underway.
-  ** This has to be done before the call to walIndexReadHdr() below.
+  /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
+  ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
+  ** file.
   **
-  ** If the writer lock cannot be obtained, then a passive checkpoint is
-  ** run instead. Since the checkpointer is not holding the writer lock,
-  ** there is no point in blocking waiting for any readers. Assuming no 
-  ** other error occurs, this function will return SQLITE_BUSY to the caller.
+  ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
+  ** immediately, and a busy-handler is configured, it is invoked and the
+  ** writer lock retried until either the busy-handler returns 0 or the
+  ** lock is successfully obtained.
   */
   if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
     rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
     if( rc==SQLITE_OK ){
       pWal->writeLock = 1;
     }else if( rc==SQLITE_BUSY ){
       eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+      xBusy2 = 0;
       rc = SQLITE_OK;
     }
   }
 
   /* Read the wal-index header. */
@@ -3000,11 +3015,11 @@
   /* Copy data from the log to the database file. */
   if( rc==SQLITE_OK ){
     if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
       rc = SQLITE_CORRUPT_BKPT;
     }else{
-      rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf);
+      rc = walCheckpoint(pWal, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
     }
 
     /* If no error occurred, set the output variables. */
     if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
       if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;