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-- Example Lua plugin.
--
-- This example can be freely used for any purpose.
-- Run it from the build directory like this:
--
-- ./nbdkit -f -v lua ./plugins/lua/example.lua file=disk.img
--
-- Or run it after installing nbdkit like this:
--
-- nbdkit -f -v lua ./plugins/lua/example.lua file=disk.img
--
-- The -f -v arguments are optional. They cause the server to stay in
-- the foreground and print debugging, which is useful when testing.
--
-- You can connect to the server using guestfish or qemu, eg:
--
-- guestfish --format=raw -a nbd://localhost
-- ><fs> run
-- ><fs> part-disk /dev/sda mbr
-- ><fs> mkfs ext2 /dev/sda1
-- ><fs> list-filesystems
-- ><fs> mount /dev/sda1 /
-- ><fs> [etc]
-- This is called from: nbdkit lua example.lua --dump-plugin
function dump_plugin ()
print ("example_lua=1")
end
-- We expect a file=... parameter pointing to the file to serve.
function config (key, value)
if key == "file" then
file = value
else
error ("unknown parameter " .. key .. "=" .. value)
end
end
-- Check the file parameter was passed.
function config_complete ()
if not file then
error ("file parameter missing")
end
end
-- Open a new client connection.
function open (readonly)
-- Open the file.
local flags
if readonly then
flags="rb"
else
flags="r+b"
end
local fh = assert (io.open (file, flags))
-- We can return any Lua object as the handle. In this
-- plugin it's convenient to return the file handle.
return fh
end
-- Close a client connection.
function close (fh)
assert (fh:close())
end
function get_size (fh)
local size = assert (fh:seek ("end"))
return size
end
function pread (fh, count, offset)
assert (fh:seek ("set", offset))
local data = assert (fh:read (count))
return data
end
function pwrite (fh, buf, offset)
assert (fh:seek ("set", offset))
assert (fh:write (buf))
end
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