Index: src/wal.c
==================================================================
--- src/wal.c
+++ src/wal.c
@@ -1224,10 +1224,13 @@
   pRet->zWalName = zWalName;
 
   /* Open file handle on the write-ahead log file. */
   flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
   rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
+  if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
+    rc = SQLITE_CANTOPEN;
+  }
 
   if( rc!=SQLITE_OK ){
     walIndexClose(pRet, 0);
     sqlite3OsClose(pRet->pWalFd);
     sqlite3_free(pRet);

Index: test/malloc_common.tcl
==================================================================
--- test/malloc_common.tcl
+++ test/malloc_common.tcl
@@ -135,10 +135,11 @@
 
 #-------------------------------------------------------------------------
 # Procedures to save and restore the current file-system state:
 #
 #   faultsim_save
+#   faultsim_restore
 #   faultsim_save_and_close
 #   faultsim_restore_and_reopen
 #   faultsim_delete_and_reopen
 #
 proc faultsim_save {} {
@@ -151,17 +152,20 @@
 proc faultsim_save_and_close {} {
   faultsim_save
   catch { db close }
   return ""
 }
-proc faultsim_restore_and_reopen {{dbfile test.db}} {
-  catch { db close }
+proc faultsim_restore {} {
   foreach f [glob -nocomplain test.db*] { file delete -force $f }
   foreach f2 [glob -nocomplain sv_test.db*] {
     set f [string range $f2 3 end]
     file copy -force $f2 $f
   }
+}
+proc faultsim_restore_and_reopen {{dbfile test.db}} {
+  catch { db close }
+  faultsim_restore
   sqlite3 db $dbfile
   sqlite3_extended_result_codes db 1
   sqlite3_db_config_lookaside db 0 0 0
 }
 

Index: test/wal2.test
==================================================================
--- test/wal2.test
+++ test/wal2.test
@@ -1003,12 +1003,12 @@
 # the new files with the same file-system permissions as the database 
 # file itself. Test this.
 #
 if {$::tcl_platform(platform) == "unix"} {
   faultsim_delete_and_reopen
-
   set umask [exec /bin/sh -c umask]
+
   do_test wal2-12.1 {
     sqlite3 db test.db
     execsql { 
       CREATE TABLE tx(y, z);
       PRAGMA journal_mode = WAL;
@@ -1043,8 +1043,99 @@
       db close
       list [file exists test.db-wal] [file exists test.db-shm]
     } {0 0}
   }
 }
+
+#-------------------------------------------------------------------------
+# Test the libraries response to discovering that one or more of the
+# database, wal or shm files cannot be opened, or can only be opened
+# read-only.
+#
+if {$::tcl_platform(platform) == "unix"} {
+  proc perm {} {
+    set L [list]
+    foreach f {test.db test.db-wal test.db-shm} {
+      if {[file exists $f]} {
+        lappend L [file attr $f -perm]
+      } else {
+        lappend L {}
+      }
+    }
+    set L
+  }
+
+  faultsim_delete_and_reopen
+  execsql {
+    PRAGMA journal_mode = WAL;
+    CREATE TABLE t1(a, b);
+    PRAGMA wal_checkpoint;
+    INSERT INTO t1 VALUES('3.14', '2.72');
+  }
+  do_test wal2-13.1.1 {
+    list [file exists test.db-shm] [file exists test.db-wal]
+  } {1 1}
+  faultsim_save_and_close
+
+  foreach {tn db_perm wal_perm shm_perm can_open can_read can_write} {
+    2   00644   00644   00644   1   1   1
+    3   00644   00400   00644   1   0   0
+    4   00644   00644   00400   1   0   0
+    5   00400   00644   00644   1   1   0
+
+    7   00644   00000   00644   1   0   0
+    8   00644   00644   00000   1   0   0
+    9   00000   00644   00644   0   0   0
+  } {
+    faultsim_restore
+    do_test wal2-13.$tn.1 {
+      file attr test.db     -perm $db_perm
+      file attr test.db-wal -perm $wal_perm
+      file attr test.db-shm -perm $shm_perm
+
+      set     L [file attr test.db -perm]
+      lappend L [file attr test.db-wal -perm]
+      lappend L [file attr test.db-shm -perm]
+    } [list $db_perm $wal_perm $shm_perm]
+
+    # If $can_open is true, then it should be possible to open a database
+    # handle. Otherwise, if $can_open is 0, attempting to open the db
+    # handle throws an "unable to open database file" exception.
+    #
+    set r(1) {0 ok}
+    set r(0) {1 {unable to open database file}}
+    do_test wal2-13.$tn.2 {
+      list [catch {sqlite3 db test.db ; set {} ok} msg] $msg
+    } $r($can_open)
+
+    if {$can_open} {
+
+      # If $can_read is true, then the client should be able to read from
+      # the database file. If $can_read is false, attempting to read should
+      # throw the "unable to open database file" exception. 
+      #
+      set a(0) {1 {unable to open database file}}
+      set a(1) {0 {3.14 2.72}}
+      do_test wal2-13.$tn.3 {
+        catchsql { SELECT * FROM t1 }
+      } $a($can_read)
+  
+      # Now try to write to the db file. If the client can read but not
+      # write, then it should throw the familiar "unable to open db file"
+      # exception. If it can read but not write, the exception should
+      # be "attempt to write a read only database".
+      #
+      # If the client can read and write, the operation should succeed.
+      #
+      set b(0,0) {1 {unable to open database file}}
+      set b(1,0) {1 {attempt to write a readonly database}}
+      set b(1,1) {0 {}}
+      do_test wal2-13.$tn.4 {
+        catchsql { INSERT INTO t1 DEFAULT VALUES }
+      } $b($can_read,$can_write)
+    }
+    catch { db close }
+  }
+}
 
 finish_test