mount bind point support

src/main/resources/assets/opencomputers/loot/openos/bin/mount.lua

@@ -1,18 +1,37 @@
 local fs = require("filesystem")
 local shell = require("shell")
 
-local args, ops = shell.parse(...)
-local argc = #args
+local function usage()
+  io.stderr:write([==[
+Usage: mount [OPTIONS] [device path]")
+  If no args are given, all current mount points are printed.
+  <Options> Note that multiple options can be used together
+  -r, --ro    Mount the filesystem read only
+      --bind  Create a mount bind point, folder to folder
+  <Args>
+  device      Specify filesystem device by one of:
+              a. label
+              b. address (can be abbreviated)
+              c. folder path (requires --bind)
+  path        Target folder path to mount to
 
-if ops and (ops.h or ops.help) then
-  print("see `man mount` for help");
+See `man mount` for more details
+  ]==])
   os.exit(1)
 end
-    
-if argc == 0 then 
+
+-- smart parse, follow arg after -o
+local args, opts = shell.parse(...)
+opts.readonly = opts.r or opts.readonly
+
+if opts.h or opts.help then
+  usage()
+end
+
+local function print_mounts()
   -- for each mount
   local mounts = {}
-    
+  
   for proxy,path in fs.mounts() do
     local device = {}
 
@@ -25,7 +44,7 @@ if argc == 0 then
     local dev_mounts = mounts[device.dev_path]
     table.insert(dev_mounts, device)
   end
-  
+
   local smounts = {}
   for key,value in pairs(mounts) do
     smounts[#smounts+1] = {key, value}
@@ -38,29 +57,40 @@ if argc == 0 then
       local rw_ro = "(" .. device.rw_ro .. ")"
       local fs_label = "\"" .. device.fs_label .. "\""
             
-      io.write(string.format("%s on %-10s %s %s\n",
+      io.write(string.format("%-8s on %-10s %s %s\n",
         dev_path:sub(1,8),
         device.mount_path,
         rw_ro,
         fs_label))
     end
   end
-elseif argc ~= 2 then
-  print("Usage: mount [<label|address> <path>]")
-  print("Note that the address may be abbreviated.")
-  return 1 -- error code
-else
-  local proxy, reason = fs.proxy(args[1])
+end
+
+local function do_mount()
+  -- bind converts a path to a proxy
+  local proxy, reason = fs.proxy(args[1], opts)
   if not proxy then
-    io.stderr:write(reason,"\n")
-    return 1
-  elseif ops.r then
-    proxy = dofile("/lib/core/ro_wrapper.lua").wrap(proxy)
+    io.stderr:write("Failed to mount: ", tostring(reason), "\n")
+    os.exit(1)
   end
 
   local result, mount_failure = fs.mount(proxy, shell.resolve(args[2]))
   if not result then
     io.stderr:write(mount_failure, "\n")
-    return 2 -- error code
+    os.exit(2) -- error code
   end
 end
+
+if #args == 0 then
+  if next(opts) then
+    io.stderr:write("Missing argument\n")
+    usage()
+  else
+    print_mounts()
+  end
+elseif #args == 2 then
+  do_mount()
+else
+  io.stderr:write("wrong number of arguments: ", #args, "\n")
+  usage()
+end

src/main/resources/assets/opencomputers/loot/openos/lib/core/full_filesystem.lua

@@ -1,4 +1,5 @@
 local filesystem = require("filesystem")
+local component = require("component")
 
 function filesystem.makeDirectory(path)
   if filesystem.exists(path) then
@@ -136,3 +137,101 @@ function filesystem.copy(fromPath, toPath)
   return data == nil, reason
 end
 
+local function readonly_wrap(proxy)
+  checkArg(1, proxy, "table")
+  if proxy.isReadOnly() then
+    return proxy
+  end
+
+  local function roerr() return nil, "filesystem is readonly" end
+  return setmetatable({
+    rename = roerr,
+    open = function(path, mode)
+      checkArg(1, path, "string")
+      checkArg(2, mode, "string")
+      if mode:match("[wa]") then
+        return roerr()
+      end
+      return proxy.open(path, mode)
+    end,
+    isReadOnly = function()
+      return true
+    end,
+    write = roerr,
+    setLabel = roerr,
+    makeDirectory = roerr,
+    remove = roerr,
+  }, {__index=proxy})
+end
+
+local function bind_proxy(path)
+  local real, reason = filesystem.realPath(path)
+  if not real then
+    return nil, reason
+  end
+  local real_fs, real_fs_path = filesystem.get(real)
+  if real == real_fs_path then
+    return real_fs
+  end
+  -- turn /tmp/foo into foo
+  local rest = real:sub(#real_fs_path + 1)
+  local function wrap_relative(fp)
+    return function(path, ...)
+      return fp(filesystem.concat(rest, path), ...)
+    end
+  end
+  local bind = {
+    address = real,
+    isReadOnly = real_fs.isReadOnly,
+    list = wrap_relative(real_fs.list),
+    isDirectory = wrap_relative(real_fs.isDirectory),
+    size = wrap_relative(real_fs.size),
+    lastModified = wrap_relative(real_fs.lastModified),
+    exists = wrap_relative(real_fs.exists),
+    open = wrap_relative(real_fs.open),
+    read = real_fs.read,
+    write = real_fs.write,
+    close = real_fs.close,
+    getLabel = function() return "" end,
+    setLabel = function() return nil, "cannot set the label of a bind point" end,
+  }
+  setmetatable(bind, { __index = function(...)
+    print("missing bind method", ...)
+  end
+  })
+  return bind
+end
+
+filesystem.internal = {}
+function filesystem.internal.proxy(filter, options)
+  checkArg(1, filter, "string")
+  checkArg(2, options, "table", "nil")
+  options = options or {}
+  local address, proxy, reason
+  if options.bind then
+    proxy, reason = bind_proxy(filter)
+  else
+    -- no options: filter should be a label or partial address
+    for c in component.list("filesystem", true) do
+      if component.invoke(c, "getLabel") == filter then
+        address = c
+        break
+      end
+      if c:sub(1, filter:len()) == filter then
+        address = c
+        break
+      end
+    end
+    if not address then
+      return nil, "no such file system"
+    end
+    proxy, reason = component.proxy(address)
+  end
+  if not proxy then
+    return proxy, reason
+  end
+  if options.readonly then
+    proxy = readonly_wrap(proxy)
+  end
+  return proxy
+end

src/main/resources/assets/opencomputers/loot/openos/lib/core/ro_wrapper.lua

@@ -1,30 +0,0 @@
-local lib = {}
-
-function lib.wrap(proxy)
-  checkArg(1, proxy, "table")
-  if proxy.isReadOnly() then
-    return proxy
-  end
-
-  local function roerr() return nil, "filesystem is readonly" end
-  return setmetatable({
-    rename = roerr,
-    open = function(path, mode)
-      checkArg(1, path, "string")
-      checkArg(2, mode, "string")
-      if mode:match("[wa]") then
-        return roerr()
-      end
-      return proxy.open(path, mode)
-    end,
-    isReadOnly = function()
-      return true
-    end,
-    write = roerr,
-    setLabel = roerr,
-    makeDirectory = roerr,
-    remove = roerr,
-  }, {__index=proxy})
-end
-
-return lib

src/main/resources/assets/opencomputers/loot/openos/lib/filesystem.lua

@@ -234,23 +234,13 @@ function filesystem.name(path)
   return parts[#parts]
 end
 
-function filesystem.proxy(filter)
+function filesystem.proxy(filter, options)
   checkArg(1, filter, "string")
-  local address
-  for c in component.list("filesystem", true) do
-    if component.invoke(c, "getLabel") == filter then
-      address = c
-      break
-    end
-    if c:sub(1, filter:len()) == filter then
-      address = c
-      break
-    end
+  if not component.list("filesystem")[filter] then
+    -- if not, load fs full library, it has a smarter proxy that also supports options
+    return filesystem.internal.proxy(filter, options)
   end
-  if not address then
-    return nil, "no such file system"
-  end
-  return component.proxy(address)
+  return component.proxy(filter) -- it might be a perfect match
 end
 
 function filesystem.exists(path)

src/main/resources/assets/opencomputers/loot/openos/lib/package.lua

@@ -72,9 +72,9 @@ end
 function package.delay(lib, file)
   local mt = {
     __index = function(tbl, key)
-      dofile(file)
       setmetatable(lib, nil)
       setmetatable(lib.internal or {}, nil)
+      dofile(file)
       return tbl[key]
     end
   }

src/main/resources/assets/opencomputers/loot/openos/usr/man/mount

@@ -5,9 +5,12 @@ SYNOPSIS
   mount
   mount LABEL PATH
   mount ADDRESS PATH
+  mount --bind PATH PATH
 
 OPTIONS
-  -r  mount filesystem readonly 
+  -r, --readonly  mount filesystem readonly 
+      --bind      mount a bind point (folder to folder)
+  -h, --help      print help message
 
 DESCRIPTION
   All files accessible in OpenOS are arranged in one big tree, starting with the root node, '/'. The files are the leaves of the tree, directories are inner nodes of the tree. Files can be distributed across several devices (file system components, such as hard drives and floppies). The `mount` command is used to attach a file system to this tree. The `umount` command can be used to remove a mounted file system from the tree (note that `rm` works for this, too).
@@ -22,5 +25,8 @@ EXAMPLES
   mount 56f /var
     Mounts the file system of which the address starts with `56f` at `/var`.
 
-  mount -r tmpfs /tmp_ro
-    Mounts a readonly access path of tmpfs to /tmp_ro
+  mount --readonly tmpfs /tmp_ro
+    Mounts a readonly access path of tmpfs to /tmp_ro
+
+  mount --bind /mnt/fa4/home /home
+    Mounts /mnt/fa5/home to /home