-- This is intended to be run as an RPM scriptlet.

-- Keep this file in sync with the convert-to-edition

-- shell script

local VARIANT_FILE = "/usr/lib/variant"

-- Read in /usr/lib/variant and determine the edition

local function read_variant()

  local variant

  local f = io.open(VARIANT_FILE, "r")

  if f ~= nil then

    while true do

      local line = f:read()

      if line == nil then

        break

      end

      local m = line:match("^VARIANT_ID=([^\n]+)")

      if m ~= nil then

        variant = m

      end

    end

    f:close()

  end

  return variant

end

-- Atomically replace a file with new contents

local function writefile(path, data)

  local tmp = path .. ".convert-to-edition"

  local f = io.open(tmp, "w+")

  if f == nil then

    return

  end

  f:write(data)

  f:close()

  if not os.rename(tmp, path) then

    os.remove(tmp)

  end

end

-- Forcibly replace a symlink

local function symlink(from, to)

  os.remove(to)

  assert(posix.symlink(from, to))

end

-- Run a subroutine in a child process

local function execute(...)

  local pid = posix.fork()

  if pid == 0 then

    posix.exec(...)

    posix.exit(1)

  elseif pid ~= -1 then

    local status = posix.wait(pid)

    if status ~= 0 then

      local program = ...

      error(program .. " exited with status " .. status)

    end

  end

end

-- Remove preset files for other editions

-- This should never be necessary, but it's best to be safe

local function clear_presets()

  local path = "/usr/lib/systemd/system-preset"

  for file in posix.files(path) do

    if file:match("^80-.*%.preset$") then

      os.remove(path .. "/" .. file)

    end

  end

end

-- Get a list of presets that need to be enabled or disabled

-- as part of the installation of this edition

local function read_presets(path)

  local result = {}

  local f = assert(io.open(path))

  if f ~= nil then

    while true do

      local line = f:read()

      if line == nil then

        break

      end

      local cmd, arg = line:match("^([^ \t]+)[ \t]+([^\n \t]+)")

      if cmd == "enable" or cmd == "disable" then

        result[#result + 1] = arg

      end

    end

    f:close()

  end

  return result

end

local function set_variant(variant)

  writefile(VARIANT_FILE, "VARIANT_ID=" .. variant .. "\n")

end

local function set_release(release)

  symlink("./os.release.d/os-release-" .. release, "/usr/lib/os-release")

end

local function set_issue(release)

  symlink("./os.release.d/issue-" .. release, "/usr/lib/issue")

end

-- release: the VARIANT_ID for os-release

-- issue: which /etc/issue file to install

-- presets: whether this edition has extra presets beyond the

--          defaults to enable or disable

local variants = {

  atomichost = {release = "atomichost", issue = "fedora", presets = false},

  cloud = {release = "cloud", issue = "fedora", presets = false},

  nonproduct = {release = "fedora", issue = "fedora", presets = false},

  server = {release = "server", issue = "server", presets = true},

  workstation = {release = "workstation", issue = "fedora", presets = true},

}

-- Call out to systemctl to enable or disable presets

local function set_presets(edition, apply_presets)

  if variants[edition].presets then

    local target = "/usr/lib/systemd/system-preset/80-" .. edition .. ".preset"

    symlink("../../os.release.d/presets/80-" .. edition .. ".preset", target)

    if apply_presets then

      local presets = read_presets(target)

      local systemctl = "/usr/bin/systemctl"

      if posix.access(systemctl, "x") then

        --fork off a systemctl call

        local pid = assert(posix.fork())

        if pid == 0 then

          -- Child

          posix.exec(systemctl, "preset", "-q", table.unpack(presets))

          -- In case exec() fails

          os.exit(17)

        else

          -- RPM

          assert(posix.wait(pid))

        end

      end

    end

  end

end

local function convert_to_edition(edition, apply_presets)

  local variant = variants[edition]

  if variant == nil then

    error("undefined edition: " .. edition)

  end

  set_release(variant.release)

  set_issue(variant.issue)

  clear_presets()

  set_presets(edition, apply_presets)

end

local function install_edition(edition)

  -- Create the variant file if it does not already exist. This needs

  -- to be done on both installation and upgrade, to ensure that we

  -- upgrade from F23 and earlier properly.

  if not posix.access(VARIANT_FILE, "f") then

    set_variant(edition)

  end

  if read_variant() == edition then

    -- (On initial installation only), fix up after %%systemd_post

    -- in packages possibly installed before our preset file was

    -- added

    -- On upgrades, do not enable or disable presets to avoid

    -- surprising the user

    local initial_install = arg[2] == 1

    convert_to_edition(edition, initial_install)

  end

end

local function uninstall_edition(edition)

  -- If we are uninstalling, we need to reset the variant file and

  -- force the os-release file back to os-release-fedora.  We do this

  -- in %%preun so that we don't have any time where the os-release

  -- symlink is dangling (since in %%postun, the os-release-$EDITION

  -- file will have already been removed)

  if arg[2] == 0 then

    if read_variant() == edition then

      set_variant("nonproduct")

      convert_to_edition("nonproduct", false)

    end

  end

end