Add helper that checks GitHub for new dt releases

official/check_for_updates.lua

@@ -0,0 +1,89 @@
+--[[
+    This file is part of darktable,
+    copyright (c) 2015 Tobias Ellinghaus
+
+    darktable is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    darktable is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
+]]
+--[[
+CHECK FOR UPDATES
+a simple script that will automatically look for newer releases on github and inform
+when there is something. it will only check on startup and only once a week.
+
+USAGE
+* install luasec and cjson for Lua 5.2 on your system
+* require this script from your main lua file
+* restart darktable
+
+]]
+
+local dt = require "darktable"
+local https = require "ssl.https"
+local cjson = require "cjson"
+
+dt.configuration.check_version(...,{2,0,0})
+
+-- compare two version strings of the form "major.minor.patch"
+-- returns -1, 0, 1 if the first version is smaller, equal, greater than the second version,
+-- or nil if one or both are of the wrong format
+-- strings like "release-1.2.3" and "1.2.3+456~gb00b5" are fine, too
+local function compare_versions(a, b)
+  local a_major, a_minor, a_patch = a:match("(%d+)%.(%d+)%.(%d+)")
+  local b_major, b_minor, b_patch = b:match("(%d+)%.(%d+)%.(%d+)")
+  if a_major and a_minor and a_patch and b_major and b_minor and b_patch then
+    if a_major < b_major then return -1 end
+    if a_major > b_major then return 1 end
+
+    if a_minor < b_minor then return -1 end
+    if a_minor > b_minor then return 1 end
+
+    if a_patch < b_patch then return -1 end
+    if a_patch > b_patch then return 1 end
+
+    return 0
+  else
+    return
+  end
+end
+
+
+-- check stored timestamp and skip the check if the last time was not too long ago
+-- for now we are assuming that os.time() returns seconds. that's not guaranteed but the case on many systems.
+-- the reference date doesn't matter, as long as it's currently positive (we start with 0 the first time)
+-- see http://lua-users.org/wiki/DateAndTime
+local now = os.time()
+local back_then = dt.preferences.read("check_for_updates", "timestamp", "integer")
+
+-- check once a week
+if now > (back_then + 60 * 60 * 24 * 7) then
+
+  -- try to get the latest release's version from github and compare to what we are running
+  -- see https://developer.github.com/v3/repos/releases/ for the api docs
+  -- just ignore when anything fails and retry at some other time
+  local result, error_code = https.request("https://api.github.com/repos/darktable-org/darktable/releases/latest")
+
+  if error_code == 200 then
+    local name = cjson.decode(result)["name"]  -- http://www.kyne.com.au/~mark/software/lua-cjson-manual.html
+    if name then
+      local cmp = compare_versions(name, dt.configuration.version)
+      if cmp then
+        if cmp > 0 then
+          dt.print("there seems to be a newer release than what you are running. better update")
+        end
+        -- update timestamp to not check again for a while
+        dt.preferences.write("check_for_updates", "timestamp", "integer", now)
+      end
+    end
+  end
+
+end