1 files changed, 99 insertions, 36 deletions
diff --git a/tex/context/base/mkiv/l-gzip.lua b/tex/context/base/mkiv/l-gzip.lua
index 5100e4722..31466bde8 100644
--- a/tex/context/base/mkiv/l-gzip.lua
+++ b/tex/context/base/mkiv/l-gzip.lua
@@ -5,50 +5,113 @@ if not modules then modules = { } end modules ['l-gzip'] = {
     license   = "see context related readme files"
 }
 
-if not gzip then
+if gzip then
 
-    -- no fallback yet
+    local suffix, suffixes = file.suffix, file.suffixes
 
-    return
-
-end
-
-local suffix, suffixes = file.suffix, file.suffixes
-
-function gzip.load(filename)
-    local f = io.open(filename,"rb")
-    if not f then
-        -- invalid file
-    elseif suffix(filename) == "gz" then
-        f:close()
-        local g = gzip.open(filename,"rb")
-        if g then
-            local str = g:read("*all")
-            g:close()
+    function gzip.load(filename)
+        local f = io.open(filename,"rb")
+        if not f then
+            -- invalid file
+        elseif suffix(filename) == "gz" then
+            f:close()
+            local g = gzip.open(filename,"rb")
+            if g then
+                local str = g:read("*all")
+                g:close()
+                return str
+            end
+        else
+            local str = f:read("*all")
+            f:close()
             return str
         end
-    else
-        local str = f:read("*all")
-        f:close()
-        return str
     end
-end
 
-function gzip.save(filename,data)
-    if suffix(filename) ~= "gz" then
-        filename = filename .. ".gz"
+    function gzip.save(filename,data)
+        if suffix(filename) ~= "gz" then
+            filename = filename .. ".gz"
+        end
+        local f = io.open(filename,"wb")
+        if f then
+            local s = zlib.compress(data or "",9,nil,15+16)
+            f:write(s)
+            f:close()
+            return #s
+        end
     end
-    local f = io.open(filename,"wb")
-    if f then
-        local s = zlib.compress(data or "",9,nil,15+16)
-        f:write(s)
-        f:close()
-        return #s
+
+    function gzip.suffix(filename)
+        local suffix, extra = suffixes(filename)
+        local gzipped = extra == "gz"
+        return suffix, gzipped
     end
+
+else
+
+    -- todo: fallback on flate
+
 end
 
-function gzip.suffix(filename)
-    local suffix, extra = suffixes(filename)
-    local gzipped = extra == "gz"
-    return suffix, gzipped
+if flate then
+
+    local type = type
+    local find = string.find
+
+    local compress   = flate.gz_compress
+    local decompress = flate.gz_decompress
+
+    local absmax     = 128*1024*1024
+    local initial    =       64*1024
+    local identifier = "^\x1F\x8B\x08"
+
+    function gzip.compressed(s)
+        return s and find(s,identifier)
+    end
+
+    function gzip.compress(s,level)
+        if s and not find(s,identifier) then -- the find check might go away
+            if not level then
+                level = 3
+            elseif level <= 0 then
+                return s
+            elseif level > 9 then
+                level = 9
+            end
+            return compress(s,level) or s
+        end
+    end
+
+    function gzip.decompress(s,size,iterate)
+        if s and find(s,identifier) then
+            if type(size) ~= "number" then
+                size = initial
+            end
+            if size > absmax then
+                size = absmax
+            end
+            if type(iterate) == "number" then
+                max = size * iterate
+            elseif iterate == nil or iterate == true then
+                iterate = true
+                max     = absmax
+            end
+            if max > absmax then
+                max = absmax
+            end
+            while true do
+                local d = decompress(s,size)
+                if d then
+                    return d
+                end
+                size = 2 * size
+                if not iterate or size > max then
+                    return false
+                end
+            end
+        else
+            return s
+        end
+    end
+
 end