Improve writability checks.

LuaRocks does `mkdir -p` (or equivalent), so we can check
for the entire chain of parents for a writable directory.
Closes #449.

3 files changed, 33 insertions, 10 deletions

diff --git a/src/luarocks/fs/lua.lua b/src/luarocks/fs/lua.lua
index 18e6b01a..a444f014 100644
--- a/src/luarocks/fs/lua.lua
+++ b/src/luarocks/fs/lua.lua
@@ -833,10 +833,19 @@ function fs_lua.check_command_permissions(flags)
          break
       end
    end
-   local root_parent = dir.dir_name(root_dir)
-   if ok and not fs.exists(root_dir) and not fs.is_writable(root_parent) then
-      ok = false
-      err = root_dir.." does not exist and your user does not have write permissions in " .. root_parent
+   if ok and not fs.exists(root_dir) then
+      local root = fs.root_of(root_dir)
+      local parent = root_dir
+      repeat
+         parent = dir.dir_name(parent)
+         if parent == "" then
+            parent = root
+         end
+      until parent == root or fs.exists(parent)
+      if not fs.is_writable(parent) then
+         ok = false
+         err = root_dir.." does not exist and your user does not have write permissions in " .. parent
+      end
    end
    if ok then
       return true
diff --git a/src/luarocks/fs/unix.lua b/src/luarocks/fs/unix.lua
index 6ad5a678..8eb3386a 100644
--- a/src/luarocks/fs/unix.lua
+++ b/src/luarocks/fs/unix.lua
@@ -36,6 +36,14 @@ function unix.absolute_name(pathname, relative_to)
    end
 end
 
+--- Return the root directory for the given path.
+-- In Unix, root is always "/".
+-- @param pathname string: pathname to use.
+-- @return string: The root of the given pathname.
+function unix.root_of(_)
+   return "/"
+end
+
 --- Create a wrapper to make a script executable from the command-line.
 -- @param file string: Pathname of script to be made executable.
 -- @param dest string: Directory where to put the wrapper.
diff --git a/src/luarocks/fs/win32.lua b/src/luarocks/fs/win32.lua
index 32766e53..0c8cc9e9 100644
--- a/src/luarocks/fs/win32.lua
+++ b/src/luarocks/fs/win32.lua
@@ -18,7 +18,6 @@ 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.
@@ -26,6 +25,7 @@ function win32.quiet(cmd)
    return cmd.." 2> NUL 1> NUL"
 end
 
+local drive_letter = "[%.a-zA-Z]?:?[\\/]"
 
 local win_escape_chars = {
   ["%"] = "%%",
@@ -47,7 +47,7 @@ end
 function win32.Q(arg)
    assert(type(arg) == "string")
    -- Quote DIR for Windows
-   if arg:match("^[%.a-zA-Z]?:?[\\/]")  then
+   if arg:match("^"..drive_letter)  then
       arg = arg:gsub("/", "\\")
    end
    if arg == "\\" then
@@ -68,7 +68,7 @@ end
 function win32.Qb(arg)
    assert(type(arg) == "string")
    -- Quote DIR for Windows
-   if arg:match("^[%.a-zA-Z]?:?[\\/]")  then
+   if arg:match("^"..drive_letter)  then
       arg = arg:gsub("/", "\\")
    end
    if arg == "\\" then
@@ -92,15 +92,21 @@ function win32.absolute_name(pathname, relative_to)
    assert(type(relative_to) == "string" or not relative_to)
 
    relative_to = relative_to or fs.current_dir()
-   -- FIXME I'm not sure this first \\ should be there at all.
-   -- What are the Windows rules for drive letters?
-   if pathname:match("^[\\.a-zA-Z]?:?[\\/]") then
+   if pathname:match("^"..drive_letter) then
       return pathname
    else
       return relative_to .. "/" .. pathname
    end
 end
 
+--- Return the root directory for the given path.
+-- For example, for "c:\hello", returns "c:\"
+-- @param pathname string: pathname to use.
+-- @return string: The root of the given pathname.
+function win32.root_of(pathname)
+   return (fs.absolute_name(pathname):match("^("..drive_letter..")"))
+end
+
 --- Create a wrapper to make a script executable from the command-line.
 -- @param file string: Pathname of script to be made executable.
 -- @param dest string: Directory where to put the wrapper.