1 files changed, 43 insertions, 4 deletions
diff --git a/tex/context/base/l-io.lua b/tex/context/base/l-io.lua
index 4f27dc1dc..657b755b8 100644
--- a/tex/context/base/l-io.lua
+++ b/tex/context/base/l-io.lua
@@ -17,14 +17,14 @@ else
     io.fileseparator, io.pathseparator = "/" , ":"
 end
 
-function io.loaddata(filename,textmode)
+function io.loaddata(filename,textmode) -- return nil if empty
     local f = io.open(filename,(textmode and 'r') or 'rb')
     if f then
         local data = f:read('*all')
         f:close()
-        return data
-    else
-        return nil
+        if #data > 0 then
+            return data
+        end
     end
 end
 
@@ -46,6 +46,45 @@ function io.savedata(filename,data,joiner)
     end
 end
 
+function io.loadlines(filename,n) -- return nil if empty
+    local f = io.open(filename,'r')
+    if f then
+        if n then
+            local lines = { }
+            for i=1,n do
+                local line = f:read("*lines")
+                if line then
+                    lines[#lines+1] = line
+                else
+                    break
+                end
+            end
+            f:close()
+            lines = concat(lines,"\n")
+            if #lines > 0 then
+                return lines
+            end
+        else
+            local line = f:read("*line") or ""
+            assert(f:close())
+            if #line > 0 then
+                return line
+            end
+        end
+    end
+end
+
+function io.loadchunk(filename,n)
+    local f = io.open(filename,'rb')
+    if f then
+        local data = f:read(n or 1024)
+        f:close()
+        if #data > 0 then
+            return data
+        end
+    end
+end
+
 function io.exists(filename)
     local f = io.open(filename)
     if f == nil then