adjust file metatables even in compat53.module mode (#67)

* adjust file metatables even in compat53.module mode

* apply tweaks only to LuaJIT; file:write() only to compat=none

3 files changed, 143 insertions, 56 deletions

diff --git a/compat53/file_mt.lua b/compat53/file_mt.lua
new file mode 100644
index 0000000..6433619
--- /dev/null
+++ b/compat53/file_mt.lua
@@ -0,0 +1,71 @@
+local lua_version = _VERSION:sub(-3)
+
+local M = {}
+
+local unpack = lua_version == "5.1" and unpack or table.unpack
+
+local function addasterisk(fmt)
+   if type(fmt) == "string" and fmt:sub(1, 1) ~= "*" then
+      return "*"..fmt
+   else
+      return fmt
+   end
+end
+
+function M.update_file_meta(file_meta, is_luajit52)
+
+   -- make '*' optional for file:read and file:lines
+
+   local file_lines = file_meta.__index.lines
+   file_meta.__index.lines = function(self, ...)
+      local n = select('#', ...)
+      for i = 1, n do
+         local a = select(i, ...)
+         local b = addasterisk(a)
+         -- as an optimization we only allocate a table for the
+         -- modified format arguments when we have a '*' somewhere
+         if a ~= b then
+            local args = { ... }
+            args[i] = b
+            for j = i+1, n do
+               args[j] = addasterisk(args[j])
+            end
+            return file_lines(self, unpack(args, 1, n))
+         end
+      end
+      return file_lines(self, ...)
+   end
+
+   local file_read = file_meta.__index.read
+   file_meta.__index.read = function(self, ...)
+      local n = select('#', ...)
+      for i = 1, n do
+         local a = select(i, ...)
+         local b = addasterisk(a)
+         -- as an optimization we only allocate a table for the
+         -- modified format arguments when we have a '*' somewhere
+         if a ~= b then
+            local args = { ... }
+            args[i] = b
+            for j = i+1, n do
+               args[j] = addasterisk(args[j])
+            end
+            return file_read(self, unpack(args, 1, n))
+         end
+      end
+      return file_read(self, ...)
+   end
+
+   if not is_luajit52 then
+      local file_write = file_meta.__index.write
+      file_meta.__index.write = function(self, ...)
+         local ret, err = file_write(self, ...)
+         if ret then
+            return self
+         end
+         return ret, err
+      end
+   end
+end
+
+return M
diff --git a/compat53/init.lua b/compat53/init.lua
index a7f0c80..b507571 100644
--- a/compat53/init.lua
+++ b/compat53/init.lua
@@ -17,57 +17,15 @@ if lua_version < "5.3" then
    local file_meta = gmt(io.stdout)
 
 
-   -- make '*' optional for file:read and file:lines
-   if type(file_meta) == "table" and type(file_meta.__index) == "table" then
-
-      local function addasterisk(fmt)
-         if type(fmt) == "string" and fmt:sub(1, 1) ~= "*" then
-            return "*"..fmt
-         else
-            return fmt
-         end
-      end
-
-      local file_lines = file_meta.__index.lines
-      file_meta.__index.lines = function(self, ...)
-         local n = select('#', ...)
-         for i = 1, n do
-            local a = select(i, ...)
-            local b = addasterisk(a)
-            -- as an optimization we only allocate a table for the
-            -- modified format arguments when we have a '*' somewhere
-            if a ~= b then
-               local args = { ... }
-               args[i] = b
-               for j = i+1, n do
-                  args[j] = addasterisk(args[j])
-               end
-               return file_lines(self, unpack(args, 1, n))
-            end
-         end
-         return file_lines(self, ...)
-      end
+   -- detect LuaJIT (including LUAJIT_ENABLE_LUA52COMPAT compilation flag)
+   local is_luajit = (string.dump(function() end) or ""):sub(1, 3) == "\027LJ"
+   local is_luajit52 = is_luajit and
+     #setmetatable({}, { __len = function() return 1 end }) == 1
 
-      local file_read = file_meta.__index.read
-      file_meta.__index.read = function(self, ...)
-         local n = select('#', ...)
-         for i = 1, n do
-            local a = select(i, ...)
-            local b = addasterisk(a)
-            -- as an optimization we only allocate a table for the
-            -- modified format arguments when we have a '*' somewhere
-            if a ~= b then
-               local args = { ... }
-               args[i] = b
-               for j = i+1, n do
-                  args[j] = addasterisk(args[j])
-               end
-               return file_read(self, unpack(args, 1, n))
-            end
-         end
-         return file_read(self, ...)
-      end
 
+   if type(file_meta) == "table" and type(file_meta.__index) == "table" then
+      local file_mt = require("compat53.file_mt")
+      file_mt.update_file_meta(file_meta, is_luajit52)
    end -- got a valid metatable for file objects
 
 
@@ -85,12 +43,6 @@ if lua_version < "5.3" then
       local io_type = io.type
 
 
-      -- detect LuaJIT (including LUAJIT_ENABLE_LUA52COMPAT compilation flag)
-      local is_luajit = (string.dump(function() end) or ""):sub(1, 3) == "\027LJ"
-      local is_luajit52 = is_luajit and
-        #setmetatable({}, { __len = function() return 1 end }) == 1
-
-
       -- make package.searchers available as an alias for package.loaders
       local p_index = { searchers = package.loaders }
       setmetatable(package, {
diff --git a/compat53/module.lua b/compat53/module.lua
index 67b2a4a..90b2f06 100644
--- a/compat53/module.lua
+++ b/compat53/module.lua
@@ -13,7 +13,11 @@ if lua_version < "5.3" then
          debug, io, math, package, string, table
    local io_lines = io.lines
    local io_read = io.read
+   local io_open = io.open
+   local io_popen = io.popen
+   local io_tmpfile = io.tmpfile
    local unpack = lua_version == "5.1" and unpack or table.unpack
+   local debug_setmetatable = type(debug) == "table" and debug.setmetatable
 
    -- create module table
    M = {}
@@ -451,7 +455,6 @@ if lua_version < "5.3" then
       if type(debug) == "table" then
          local debug_setfenv = debug.setfenv
          local debug_getfenv = debug.getfenv
-         local debug_setmetatable = debug.setmetatable
 
          M.debug = setmetatable({}, { __index = debug })
 
@@ -823,6 +826,67 @@ if lua_version < "5.3" then
          end
       end -- not luajit
 
+      if is_luajit then
+         local compat_file_meta = {}
+         local compat_file_meta_loaded = false
+
+         local function load_compat_file_meta(file_meta)
+            -- fill compat_file_meta with original entries
+            for k, v in pairs(file_meta) do
+               compat_file_meta[k] = v
+            end
+            compat_file_meta.__index = {}
+            for k, v in pairs(file_meta.__index) do
+               compat_file_meta.__index[k] = v
+            end
+
+            -- update it with compatibility functions
+            local file_mt = require("compat53.file_mt")
+            file_mt.update_file_meta(compat_file_meta, is_luajit52)
+
+            compat_file_meta_loaded = true
+         end
+
+         function M.io.open(...)
+            local fd, err = io_open(...)
+            if fd and debug_setmetatable then
+               if not compat_file_meta_loaded then
+                  local file_meta = gmt(fd)
+                  load_compat_file_meta(file_meta)
+               end
+               debug_setmetatable(fd, compat_file_meta)
+            end
+
+            return fd, err
+         end
+
+         function M.io.popen(...)
+            local fd, err = io_popen(...)
+            if fd and debug_setmetatable then
+               if not compat_file_meta_loaded then
+                  local file_meta = gmt(fd)
+                  load_compat_file_meta(file_meta)
+               end
+               debug_setmetatable(fd, compat_file_meta)
+            end
+
+            return fd, err
+         end
+
+         function M.io.tmpfile(...)
+            local fd, err = io_tmpfile(...)
+            if fd and debug_setmetatable then
+               if not compat_file_meta_loaded then
+                  local file_meta = gmt(fd)
+                  load_compat_file_meta(file_meta)
+               end
+               debug_setmetatable(fd, compat_file_meta)
+            end
+
+            return fd, err
+         end
+      end
+
    end -- lua 5.1
 
    -- further write should be forwarded to _G