[chore] Update MD5 calls with new sha2 library (#6411)

Depends on <https://github.com/koreader/koreader-base/pull/1149>.

frontend/cache.lua

@@ -5,7 +5,7 @@ A global LRU cache
 local DataStorage = require("datastorage")
 local lfs = require("libs/libkoreader-lfs")
 local logger = require("logger")
-local md5 = require("ffi/MD5")
+local md5 = require("ffi/sha2").md5
 
 local CanvasContext = require("document/canvascontext")
 if CanvasContext.should_restrict_JIT then
@@ -129,7 +129,7 @@ function Cache:check(key, ItemClass)
         end
         return self.cache[key]
     elseif ItemClass then
-        local cached = self.cached[md5.sum(key)]
+        local cached = self.cached[md5(key)]
         if cached then
             local item = ItemClass:new{}
             local ok, msg = pcall(item.load, item, cached)
@@ -166,7 +166,7 @@ function Cache:serialize()
 
         -- only dump cache item that requests serialization explicitly
         if cache_item.persistent and cache_item.dump then
-            local cache_full_path = cache_path..md5.sum(key)
+            local cache_full_path = cache_path..md5(key)
             local cache_file_exists = lfs.attributes(cache_full_path)
 
             if cache_file_exists then break end

frontend/document/document.lua

@@ -135,20 +135,20 @@ function Document:fastDigest(docsettings)
         if not result then
             logger.dbg("computing and storing partial_md5_checksum")
             local bit = require("bit")
-            local md5 = require("ffi/MD5")
+            local md5 = require("ffi/sha2").md5
             local lshift = bit.lshift
             local step, size = 1024, 1024
-            local m = md5.new()
+            local update = md5()
             for i = -1, 10 do
                 file:seek("set", lshift(step, 2*i))
                 local sample = file:read(size)
                 if sample then
-                    m:update(sample)
+                    update(sample)
                 else
                     break
                 end
             end
-            result = m:sum()
+            result = update()
             docsettings:saveSetting("partial_md5_checksum", result)
         end
         if tmp_docsettings then

plugins/evernote.koplugin/clip.lua

@@ -2,7 +2,7 @@ local DocumentRegistry = require("document/documentregistry")
 local DocSettings = require("docsettings")
 local ReadHistory = require("readhistory")
 local logger = require("logger")
-local md5 = require("ffi/MD5")
+local md5 = require("ffi/sha2").md5
 local util = require("util")
 
 local MyClipping = {
@@ -222,7 +222,7 @@ function MyClipping:getImage(image)
         --doc:clipPagePNGFile(image.pos0, image.pos1,
                 --image.pboxes, image.drawer, "/tmp/"..md5(png)..".png")
         doc:close()
-        if png then return { png = png, hash = md5.sum(png) } end
+        if png then return { png = png, hash = md5(png) } end
     end
 end
 

plugins/kosync.koplugin/main.lua

@@ -9,7 +9,7 @@ local Event = require("ui/event")
 local Math = require("optmath")
 local Screen = Device.screen
 local logger = require("logger")
-local md5 = require("ffi/MD5")
+local md5 = require("ffi/sha2").md5
 local random = require("random")
 local T = require("ffi/util").template
 local _ = require("gettext")
@@ -386,7 +386,7 @@ function KOSync:doRegister(username, password)
     }
     -- on Android to avoid ANR (no-op on other platforms)
     Device:setIgnoreInput(true)
-    local userkey = md5.sum(password)
+    local userkey = md5(password)
     local ok, status, body = pcall(client.register, client, username, userkey)
     if not ok then
         if status then
@@ -422,7 +422,7 @@ function KOSync:doLogin(username, password)
         service_spec = self.path .. "/api.json"
     }
     Device:setIgnoreInput(true)
-    local userkey = md5.sum(password)
+    local userkey = md5(password)
     local ok, status, body = pcall(client.authorize, client, username, userkey)
     if not ok then
         if status then

plugins/statistics.koplugin/main.lua

@@ -288,21 +288,21 @@ function ReaderStatistics:partialMd5(file)
         return nil
     end
     local bit = require("bit")
-    local md5 = require("ffi/MD5")
+    local md5 = require("ffi/sha2").md5
     local lshift = bit.lshift
     local step, size = 1024, 1024
-    local m = md5.new()
+    local update = md5()
     local file_handle = io.open(file, 'rb')
     for i = -1, 10 do
         file_handle:seek("set", lshift(step, 2*i))
         local sample = file_handle:read(size)
         if sample then
-            m:update(sample)
+            update(sample)
         else
             break
         end
     end
-    return m:sum()
+    return update()
 end
 
 function ReaderStatistics:createDB(conn)