From 4c650b92ab48b0f50b41f26fbc9e895f34a4fc53 Mon Sep 17 00:00:00 2001
From: Thijs Schreijer <thijs@thijsschreijer.nl>
Date: Thu, 28 Nov 2013 21:06:40 +0100
Subject: fixes permission checks on Windows with VirtualStore redirection

---
 src/luarocks/fs/win32.lua | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/luarocks/fs/win32.lua b/src/luarocks/fs/win32.lua
index 0280b3f0..b6ea25e4 100644
--- a/src/luarocks/fs/win32.lua
+++ b/src/luarocks/fs/win32.lua
@@ -9,6 +9,15 @@ local cfg = require("luarocks.cfg")
 local dir = require("luarocks.dir")
 local util = require("luarocks.util")
 
+-- Monkey patch io.popen and os.execute to make sure quoting
+-- works as expected.
+-- See http://lua-users.org/lists/lua-l/2013-11/msg00367.html
+local _prefix = "type NUL && "
+local _popen, _execute = io.popen, os.execute
+io.popen = function(cmd, ...) return _popen(_prefix..cmd, ...) end
+os.execute = function(cmd, ...) return _execute(_prefix..cmd, ...) end
+
+
 --- Annotate command string for quiet execution.
 -- @param cmd string: A command-line string.
 -- @return string: The command-line, with silencing annotation.
@@ -173,3 +182,36 @@ function replace_file(old_file, new_file)
    return os.rename(new_file, old_file)
 end
 
+--- Test is file/dir is writable.
+-- Warning: testing if a file/dir is writable does not guarantee
+-- that it will remain writable and therefore it is no replacement
+-- for checking the result of subsequent operations.
+-- @param file string: filename to test
+-- @return boolean: true if file exists, false otherwise.
+function is_writable(file)
+   assert(file)
+   file = dir.normalize(file)
+   local result
+   local tmpname = 'tmpluarockstestwritable.deleteme'
+   if fs.is_dir(file) then
+      local file2 = dir.path(file, tmpname)
+      local fh = io.open(file2, 'wb')
+      result = fh ~= nil
+      if fh then fh:close() end
+      if result then
+         -- the above test might give a false positive when writing to
+         -- c:\program files\ because of VirtualStore redirection on Vista and up
+         -- So get a directory listing and check whether it's really there
+         local pipe = io.popen("dir "..fs.Q(file))
+         local dir_list = pipe:read("*a")
+         pipe:close()
+         result = (nil ~= string.find(dir_list, tmpname, 1, true))
+      end
+      os.remove(file2)
+   else
+      local fh = io.open(file, 'r+b')
+      result = fh ~= nil
+      if fh then fh:close() end
+   end
+   return result
+end
-- 
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