Fetch Hex with wget or curl

This way we can use https and do peer verification without bundling
certificates with elixir.

Author: ericmj

lib/mix/lib/mix/tasks/archive.install.ex

@@ -30,7 +30,7 @@ defmodule Mix.Tasks.Archive.Install do
   """
   @spec run(OptionParser.argv) :: boolean
   def run(argv) do
-    {opts, argv, _} = OptionParser.parse(argv, switches: [force: :boolean])
+    {opts, argv, _} = OptionParser.parse(argv, switches: [force: :boolean, shell: :boolean])
 
     if src = List.first(argv) do
       %URI{path: path} = URI.parse(src)
@@ -58,7 +58,7 @@ defmodule Mix.Tasks.Archive.Install do
       dest = Mix.Local.archives_path()
       File.mkdir_p!(dest)
       archive = Path.join(dest, basename(src))
-      create_file archive, Mix.Utils.read_path!(src)
+      create_file archive, Mix.Utils.read_path!(src, opts)
       true = Code.append_path(Mix.Archive.ebin(archive))
     else
       false

lib/mix/lib/mix/tasks/local.hex.ex

@@ -18,7 +18,7 @@ defmodule Mix.Tasks.Local.Hex do
   """
   @spec run(OptionParser.argv) :: boolean
   def run(args) do
-    Mix.Tasks.Archive.Install.run [@hex_url|args]
+    Mix.Tasks.Archive.Install.run [@hex_url, "--shell" | args]
   end
 
   @doc false

lib/mix/lib/mix/utils.ex

@@ -359,22 +359,32 @@ defmodule Mix.Utils do
   Used by tasks like `archive.install` and `local.rebar` that support
   installation either from a URL or a local file.
 
-  Raises if the given path is not a url, nor a file or if the
-  file or url are invalid.
+  Raises if the given path is not a URL, nor a file or if the
+  file or URL are invalid.
+
+  ## Options
+
+    * `:shell` - Forces the use of `wget` or `curl` to fetch the file if the
+      given path is a URL.
   """
-  def read_path!(path) do
+  def read_path!(path, opts \\ []) do
     cond do
-      url?(path)  -> read_url(path)
-      file?(path) -> read_file(path)
-      :else       -> Mix.raise "Expected #{path} to be a url or a local file path"
+      url?(path) && opts[:shell] ->
+        read_shell(path)
+      url?(path) ->
+        read_httpc(path)
+      file?(path) ->
+        read_file(path)
+      true ->
+        Mix.raise "Expected #{path} to be a url or a local file path"
     end
   end
 
   defp read_file(path) do
     File.read!(path)
   end
 
-  defp read_url(path) do
+  defp read_httpc(path) do
     {:ok, _} = Application.ensure_all_started(:ssl)
     {:ok, _} = Application.ensure_all_started(:inets)
 
@@ -420,6 +430,33 @@ defmodule Mix.Utils do
     end
   end
 
+  defp read_shell(path) do
+    filename = URI.parse(path).path |> Path.basename
+    out_path = Path.join(System.tmp_dir!, filename)
+    File.rm(out_path)
+
+    cond do
+      System.find_executable("wget") ->
+        Mix.shell.cmd(~s(wget -O "#{out_path}" "#{path}"))
+      System.find_executable("curl") ->
+        Mix.shell.cmd(~s(curl -L -o "#{out_path}" "#{path}"))
+      windows? && System.find_executable("powershell") ->
+        command = ~s[$client = new-object System.Net.WebClient; ] <>
+                  ~s[$client.DownloadFile(\\"#{path}\\", \\"#{out_path}\\")]
+        Mix.shell.cmd(~s[powershell -Command "& {#{command}}"])
+      true ->
+        Mix.raise "wget or curl not installed, download manually: #{path}"
+    end
+
+    data = File.read!(out_path)
+    File.rm!(out_path)
+    data
+  end
+
+  def windows? do
+    match?({:win32, _}, :os.type)
+  end
+
   defp file?(path) do
     File.regular?(path)
   end