KOReader user patch, to limit the crash.log's filesize during run

2-limit-crashlog-size.lua

-- A KOReader patch for limiting the crash.log file size during run (and not only on KOReader start)

-- The menu entry can be found in Filemanager: Settings > More tools > Developer options > Limit log file size

-- Version 0.2
--   Kobo os.execute("truncate") is not available -> os.execute("busybox truncate")
-- Version 0.3
--   onSuspend and onResume work now
-- Version 0.4
--   unschedule tasks in onClose
-- Version 0.5
--   don't use onClose, but onExit (unschedule and close)

local FFIUtil = require("ffi/util")
local UIManager = require("ui/uimanager")
local _ = require("gettext")
local T = FFIUtil.template
local WidgetContainer = require("ui/widget/container/widgetcontainer")
local datetime = require("datetime")
local lfs = require("libs/libkoreader-lfs")
local logger = require("logger")
local util = require("util")

local truncate_cmd
if os.execute("which truncate") == 0 then
    truncate_cmd = "truncate -s 0 crash.log"
elseif os.execute("busybox truncate --help") == 0 then
    truncate_cmd = "busybox truncate -s 0 crash.log"
else
    logger.dbg("Crashlog: truncate command not found!")
    return
end

local function crashlog_exists()
    return lfs.attributes("crash.log", "mode") == "file"
end

if not crashlog_exists() then
    logger.dbg("Crashlog: crash.log does not exist on this device.")
    return
end

--- crash.log handling ---

local CRASHLOG_MAXSIZE = 500000 -- 500000 is the maximum filesize in koreader.sh startup
local CRASHLOG_OVERCOMMIT_FACTOR = 2.5 -- factor the file size can be overcomitted, before trimming should happen during KOReader running

local MINIMAL_TRIM_INTERVAL_S = 5*60 -- should be at least > a few minutes

local CrashLog =  WidgetContainer:extend{
    name = "limit_crashlog",
}

function CrashLog:init()
    self:maybeSchedule()
end

function CrashLog:exists()
    return crashlog_exists()
end

function CrashLog:size()
    return lfs.attributes("crash.log", "size")
end

--- Trim the crash.log file
function CrashLog:trim()
    if not CrashLog.exists() then
        return
    end

    local crashlog_size = CrashLog:size()
    logger.dbg("Crashlog: original filesize", util.getFriendlySize(crashlog_size))
    if crashlog_size > CRASHLOG_MAXSIZE * CRASHLOG_OVERCOMMIT_FACTOR then
        if os.execute("tail -c 500000 crash.log > crash.log.tail ") ~= 0 then return end
        if os.execute(truncate_cmd) ~= 0 then return end
        if os.execute("echo '... trimmed ...' >> crash.log") ~= 0 then return end
        if os.execute("cat crash.log.tail >> crash.log") ~= 0 then return end
        if os.execute("rm crash.log.tail") ~= 0 then return end
        if os.execute("sync") ~= 0 then return end

        logger.dbg("Crashlog: trimmed filesize", util.getFriendlySize(CrashLog:size()))
    end
end

--- Trim the logfile and schedule the next trim if necessary
-- @number time_s  if >= MINIMA_TRIM_INTERVAL_S then trim and schedule, else unschedule
function CrashLog:maybeSchedule(time_s)
    local schedule_time_s = time_s or G_reader_settings:readSetting("crashlog_autotrim_time_s", -1)
    if schedule_time_s >= MINIMAL_TRIM_INTERVAL_S then -- don't schedule, when time is within a minute
        self:trim()
        UIManager:scheduleIn(schedule_time_s, self.maybeSchedule, self)
    else
        UIManager:unschedule(self.maybeSchedule)
    end
end

function CrashLog:onSuspend()
    logger.dbg("Crashlog: onSuspend")
    if G_reader_settings:readSetting("crashlog_autotrim_time_s", -1) >= 0 then
        self:trim()
        self:maybeSchedule(0)
    end
end
function CrashLog:onResume()
    logger.dbg("Crashlog: onResume")
    self:maybeSchedule()
end

function CrashLog:onExit()
    logger.dbg("Crashlog: onExit")
    UIManager:unschedule(self.maybeSchedule)
    UIManager:close(self)
end

--- monkey patch the developer menu ---

local FileManagerMenu = require("apps/filemanager/filemanagermenu")
local setUpdateItemTable_orig = FileManagerMenu.setUpdateItemTable

FileManagerMenu.setUpdateItemTable = function(self)
    setUpdateItemTable_orig(self)

    local function find_table(table, id)
        for i, v in pairs(table) do
            if v.id == id then
                return v, true
            end
        end
    end

    local table_to_insert, found = find_table(self.tab_item_table, "tools")
    if not found then return end
    table_to_insert, found = find_table(table_to_insert, "more_tools")
    if not found then return end
    table_to_insert, found = find_table(table_to_insert.sub_item_table, "developer_options")
    if not found then return end

    table.insert(table_to_insert.sub_item_table, {
        text_func = function()
            local crashlog_autotrim_time_s = G_reader_settings:readSetting("crashlog_autotrim_time_s", -1)
            local size = util.getFriendlySize(CrashLog:size())
            if crashlog_autotrim_time_s < 0 then
                return T(_("Limit log file size (%1)"), size)
            elseif crashlog_autotrim_time_s == 0 then
                return T(_("Limit log file size (%1, %2)"), size, "only on suspend")
            else
                local time_string = datetime.secondsToClockDuration("letters", crashlog_autotrim_time_s, true, true, true)
                return T(_("Limit log file size (%1, %2)"), size, time_string)
            end
        end,
        enabled_func = function()
            return CrashLog:exists()
        end,
        checked_func = function()
            return G_reader_settings:readSetting("crashlog_autotrim_time_s", -1) >= 0
        end,
        callback = function()
            local crashlog_autotrim_time_s = G_reader_settings:readSetting("crashlog_autotrim_time_s")
            local time_table_s = {6*3600, 3600, 30*60, 15*60, 0, -1}
            if crashlog_autotrim_time_s >= time_table_s[1] then
                crashlog_autotrim_time_s = -1
            else
                for i = 2, #time_table_s do
                    if crashlog_autotrim_time_s >= time_table_s[i] then
                        crashlog_autotrim_time_s = time_table_s[i-1]
                        break
                    end
                end
            end
            G_reader_settings:saveSetting("crashlog_autotrim_time_s", crashlog_autotrim_time_s)
            CrashLog:maybeSchedule()
        end,
        keep_menu_open = true,
    })

end

--- initialisations

UIManager:show(CrashLog:new())

CHANGELOG

Version 0.5
don't use onClose, but onExit (unschedule and close)

Version 0.4
onSuspend and onResume work now

Version 0.3
unschedule tasks in onClose

Version 0.2
os.execute("truncate") is not available on Kobo, so check if truncate is available, if not try to use busybox truncate
works on emulator and Kobo

Version 0.1:
initial commit; works on the emulator