func Unlink(rip *common.Inode, name string) error {
if !rip.IsDirectory() {
return common.ENOTDIR
}
dirp := rip
inum := 0
err := search_dir(dirp, name, &inum, DELETE)
return err
}
func Link(rip *common.Inode, name string, inum int) error {
if !rip.IsDirectory() {
return common.ENOTDIR
}
dirp := rip
// Add the entry to the directory
err := search_dir(dirp, name, &inum, ENTER)
return err
}
func IsEmpty(rip *common.Inode) bool {
if !rip.IsDirectory() {
return false
}
dirp := rip
zeroinode := 0
if err := search_dir(dirp, "", &zeroinode, IS_EMPTY); err != nil {
return false
}
return true
}
func Lookup(rip *common.Inode, name string) (bool, int, int) {
if !rip.IsDirectory() {
return false, common.NO_DEV, common.NO_INODE
}
dirp := rip
inum := 0
err := search_dir(dirp, name, &inum, LOOKUP)
if err != nil {
return false, common.NO_DEV, common.NO_INODE
}
return true, dirp.Devinfo.Devnum, inum
}
func (fs *FileSystem) do_mount(proc *Process, dev common.BlockDevice, path string) error {
if dev == nil {
return common.EINVAL
}
// scan bitmap block table to see if 'dev' is already mounted
found := false
freeIndex := -1
for i := 0; i < common.NR_DEVICES; i++ {
if fs.devices[i] == dev {
found = true
} else if fs.devices[i] == nil {
freeIndex = i
}
}
if found {
return common.EBUSY // already mounted
}
if freeIndex == -1 {
return common.ENFILE // no device slot available
}
// Invalidate the cache for this index to be sure
fs.bcache.Invalidate(freeIndex)
// Fill in the device info
devinfo, err := common.GetDeviceInfo(dev)
// If it a recognized Minix filesystem
if err != nil {
return err
}
// Create a new allocation table for this device
alloc := alloctbl.NewAllocTbl(devinfo, fs.bcache, freeIndex)
// Update the device number/alloc table
devinfo.Devnum = freeIndex
devinfo.AllocTbl = alloc
// Add the device to the block cache/inode table
fs.bcache.MountDevice(freeIndex, dev, devinfo)
fs.itable.MountDevice(freeIndex, devinfo)
fs.devices[freeIndex] = dev
fs.devinfo[freeIndex] = devinfo
// Get the inode of the file to be mounted on
rip, err := fs.eatPath(fs.procs[common.ROOT_PROCESS], path)
if err != nil {
// Perform lots of cleanup
fs.devices[freeIndex] = nil
fs.devinfo[freeIndex] = nil
fs.bcache.UnmountDevice(freeIndex)
fs.itable.UnmountDevice(freeIndex)
return err
}
var r error = nil
// It may not be busy
if rip.Count > 1 {
r = common.EBUSY
}
// It may not be spacial
bits := rip.Type()
if bits == common.I_BLOCK_SPECIAL || bits == common.I_CHAR_SPECIAL {
r = common.ENOTDIR
}
// Get the root inode of the mounted file system
var root_ip *common.Inode
if r == nil {
root_ip, err = fs.itable.GetInode(freeIndex, common.ROOT_INODE)
if err != nil {
r = err
}
}
if root_ip != nil && root_ip.Mode == 0 {
r = common.EINVAL
}
// File types of 'rip' and 'root_ip' may not conflict
if r == nil {
if !rip.IsDirectory() && root_ip.IsDirectory() {
r = common.EISDIR
}
}
// If error, return the bitmap and both inodes; release the maps
if r != nil {
// TODO: Refactor this error handling code?
// Perform lots of cleanup
fs.devices[freeIndex] = nil
fs.devinfo[freeIndex] = nil
fs.bcache.UnmountDevice(freeIndex)
fs.itable.UnmountDevice(freeIndex)
return r
}
// Nothing else can go wrong, so perform the mount
minfo := &common.MountInfo{
MountPoint: rip,
MountTarget: root_ip,
}
rip.Mounted = minfo // so we can find the root inode during lookup
root_ip.Mounted = minfo // so we can easily resolve from a mount target to the mount point
// Store the mountinfo in the device info table for easy mapping
devinfo.MountInfo = minfo
return nil
}