win32: generate proper temp filename

Closes #1224.

See https://github.com/luarocks/luarocks/pull/1224/files#r493011698

Co-authored-by: dwenegar <simone.livieri@gmail.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/luarocks/fs/win32.lua b/src/luarocks/fs/win32.lua
index f544393d..8ae62cf0 100644
--- a/src/luarocks/fs/win32.lua
+++ b/src/luarocks/fs/win32.lua
@@ -336,7 +336,12 @@ function win32.make_temp_dir(name_pattern)
 end
 
 function win32.tmpname()
-   return os.getenv("TMP")..os.tmpname()
+   local name = os.tmpname()
+   local tmp = os.getenv("TMP")
+   if tmp and name:sub(1, #tmp) ~= tmp then
+      name = (tmp .. "\\" .. name):gsub("\\+", "\\")
+   end
+   return name
 end
 
 function win32.current_user()