1 files changed, 72 insertions, 0 deletions
diff --git a/lualibs-md5.lua b/lualibs-md5.lua
new file mode 100644
index 0000000..27955ef
--- /dev/null
+++ b/lualibs-md5.lua
@@ -0,0 +1,72 @@
+if not modules then modules = { } end modules ['l-md5'] = {
+    version   = 1.001,
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+-- This also provides file checksums and checkers.
+
+local gsub, format, byte = string.gsub, string.format, string.byte
+
+local function convert(str,fmt)
+    return (gsub(md5.sum(str),".",function(chr) return format(fmt,byte(chr)) end))
+end
+
+if not md5.HEX then function md5.HEX(str) return convert(str,"%02X") end end
+if not md5.hex then function md5.hex(str) return convert(str,"%02x") end end
+if not md5.dec then function md5.dec(str) return convert(str,"%03i") end end
+
+--~ if not md5.HEX then
+--~     local function remap(chr) return format("%02X",byte(chr)) end
+--~     function md5.HEX(str) return (gsub(md5.sum(str),".",remap)) end
+--~ end
+--~ if not md5.hex then
+--~     local function remap(chr) return format("%02x",byte(chr)) end
+--~     function md5.hex(str) return (gsub(md5.sum(str),".",remap)) end
+--~ end
+--~ if not md5.dec then
+--~     local function remap(chr) return format("%03i",byte(chr)) end
+--~     function md5.dec(str) return (gsub(md5.sum(str),".",remap)) end
+--~ end
+
+file.needs_updating_threshold = 1
+
+function file.needs_updating(oldname,newname) -- size modification access change
+    local oldtime = lfs.attributes(oldname, modification)
+    local newtime = lfs.attributes(newname, modification)
+    if newtime >= oldtime then
+        return false
+    elseif oldtime - newtime < file.needs_updating_threshold then
+        return false
+    else
+        return true
+    end
+end
+
+function file.checksum(name)
+    if md5 then
+        local data = io.loaddata(name)
+        if data then
+            return md5.HEX(data)
+        end
+    end
+    return nil
+end
+
+function file.loadchecksum(name)
+    if md5 then
+        local data = io.loaddata(name .. ".md5")
+        return data and (gsub(data,"%s",""))
+    end
+    return nil
+end
+
+function file.savechecksum(name, checksum)
+    if not checksum then checksum = file.checksum(name) end
+    if checksum then
+        io.savedata(name .. ".md5",checksum)
+        return checksum
+    end
+    return nil
+end