inefficient way, but safer, of checking if an app is already downloaded

src/rebar_app_discover.erl

@@ -55,6 +55,7 @@ find_apps(LibDirs, Validate) ->
                                   find_app(AppDir, Validate)
                           end, all_app_dirs(LibDirs)).
 
+-spec find_app(list(), boolean()) -> rebar_app_info:t() | false.
 find_app(AppDir, Validate) ->
     AppFile = filelib:wildcard(filename:join([AppDir, "ebin", "*.app"])),
     AppSrcFile = filelib:wildcard(filename:join([AppDir, "src", "*.app.src"])),

src/rebar_app_utils.erl

@@ -26,7 +26,8 @@
 %% -------------------------------------------------------------------
 -module(rebar_app_utils).
 
--export([is_app_dir/0, is_app_dir/1,
+-export([find/2,
+         is_app_dir/0, is_app_dir/1,
          is_app_src/1,
          app_src_to_app/1,
          app_name/2,
@@ -42,6 +43,17 @@
 %% Public API
 %% ===================================================================
 
+-spec find(binary(), [rebar_app_info:t()]) -> {ok, rebar_app_info:t()} | error.
+find(Name, Apps) ->
+    ec_lists:find(fun(App) -> rebar_app_info:name(App) =:= Name end, Apps).
+
+-spec find(binary(), binary(), [rebar_app_info:t()]) -> {ok, rebar_app_info:t()} | error.
+find(Name, Vsn, Apps) ->
+    ec_lists:find(fun(App) ->
+                          rebar_app_info:name(App) =:= Name
+                              andalso rebar_app_info:original_vsn(App) =:= Vsn
+                  end, Apps).
+
 is_app_dir() ->
     is_app_dir(rebar_utils:get_cwd()).
 

src/rebar_prv_install_deps.erl

@@ -114,7 +114,7 @@ handle_deps(State, Deps) ->
                                                                ,Packages
                                                                ,Name
                                                                ,Vsn),
-                                       ok = maybe_fetch(AppInfo),
+                                       ok = maybe_fetch(AppInfo, State2),
                                        AppInfo
                                end, S)
              end,
@@ -154,7 +154,7 @@ update_src_deps(State) ->
     SrcDeps = rebar_state:src_deps(State),
     DepsDir = get_deps_dir(State),
     case lists:foldl(fun(AppInfo, {SrcDepsAcc, BinaryDepsAcc}) ->
-                             ok = maybe_fetch(AppInfo),
+                             ok = maybe_fetch(AppInfo, State),
                              {AppInfo1, NewSrcDeps, NewBinaryDeps} = handle_dep(DepsDir, AppInfo),
                              {ordsets:union(ordsets:add_element(AppInfo1, SrcDepsAcc), NewSrcDeps)
                              ,NewBinaryDeps++BinaryDepsAcc}
@@ -175,16 +175,17 @@ handle_dep(DepsDir, AppInfo) ->
     {SrcDeps, BinaryDeps} = parse_deps(DepsDir, Deps),
     {AppInfo1, SrcDeps, BinaryDeps}.
 
--spec maybe_fetch(rebar_app_info:t()) -> ok.
-maybe_fetch(AppInfo) ->
+-spec maybe_fetch(rebar_app_info:t(), rebar_state:t()) -> ok.
+maybe_fetch(AppInfo, State) ->
     AppDir = rebar_app_info:dir(AppInfo),
-    case filelib:is_dir(AppDir) of
-        false ->
+    Apps = rebar_app_discover:find_apps([get_deps_dir(State)], all),
+    case rebar_app_utils:find(rebar_app_info:name(AppInfo), Apps) of
+        {ok, _} ->
+            ok;
+        _ ->
             ?INFO("Fetching ~s~n", [rebar_app_info:name(AppInfo)]),
             Source = rebar_app_info:source(AppInfo),
-            rebar_fetch:download_source(AppDir, Source);
-        true ->
-            ok
+            rebar_fetch:download_source(AppDir, Source)
     end.
 
 -spec parse_deps(binary(), [dep()]) -> {ordsets:ordset(rebar_app_info:t()), [binary_dep()]}.

src/rebar_prv_update.erl

@@ -11,7 +11,7 @@
 -include("rebar.hrl").
 
 -define(PROVIDER, update).
--define(DEPS, []).
+-define(DEPS, [install_deps]).
 
 %% ===================================================================
 %% Public API
@@ -29,11 +29,14 @@ init(State) ->
                                                        opts = []}),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | rebar:error().
 do(State) ->
     case rebar_state:command_args(State) of
         [Name] ->
             ?ERROR("NOT IMPLEMENTED: Updating ~s~n", [Name]),
+            AllDeps = rebar_state:get(State, all_deps, []),
+            {ok, App} = rebar_app_utils:find(list_to_binary(Name), AllDeps),
+            rebar_prv_install_deps:handle_deps(State, [list_to_binary(Name)]),
             {ok, State};
         [] ->
             ?INFO("Updating package index...~n", []),