SQLite

  pRet->pDbFd = pDbFd;
  pRet->readLock = -1;
  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);
  }else{
    *ppWal = pRet;

  }
}

#-------------------------------------------------------------------------
# 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 {} {
  foreach f [glob -nocomplain sv_test.db*] { file delete -force $f }
  foreach f [glob -nocomplain test.db*] {
    set f2 "sv_$f"
    file copy -force $f $f2
  }
}
proc faultsim_save_and_close {} {
  faultsim_save
  catch { db close }
  return ""
}
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
}

proc faultsim_integrity_check {{db db}} {
  set ic [$db eval { PRAGMA integrity_check }]

#-------------------------------------------------------------------------
# If a connection is required to create a WAL or SHM file, it creates 
# 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;
    }
    db close

    } [list $effective $effective]
    do_test wal2-12.2.$tn.5 {
      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