#38 handle out of space when logging

scada-common/log.lua

@@ -6,13 +6,42 @@
 -- underscores are used since some of these names are used elsewhere (e.g. 'debug' is a lua table)
 
 local LOG_DEBUG = true
+local LOG_PATH = "/log.txt"
 
-local file_handle = fs.open("/log.txt", "a")
+local file_handle = fs.open(LOG_PATH, "a")
 
 local _log = function (msg)
     local stamped = os.date("[%c] ") .. msg
-    file_handle.writeLine(stamped)
-    file_handle.flush()
+
+    -- attempt to write log
+    local status, result = pcall(function () 
+        file_handle.writeLine(stamped)
+        file_handle.flush()
+    end)
+
+    -- if we don't have much space, we need to create a new log file
+    local delete_log = fs.getFreeSpace(LOG_PATH) < 100
+
+    if not status then
+        if result == "Out of space" then
+            delete_log = true
+        elseif result ~= nil then
+            print("unknown error writing to logfile: " .. result)
+        end
+    end
+
+    if delete_log then
+        -- delete the old log file and open a new one
+        file_handle.close()
+        fs.delete(LOG_PATH)
+        file_handle = fs.open(LOG_PATH, "a")
+
+        -- leave a message
+        local notif = os.date("[%c] ") .. "recycled log file"
+        file_handle.writeLine(notif)
+        file_handle.writeLine(stamped)
+        file_handle.flush()
+    end
 end
 
 function _debug(msg, trace)