fix failure on missing OTP_VERSION file #403

1 files changed, 24 insertions, 21 deletions

diff --git a/src/rebar_utils.erl b/src/rebar_utils.erl
index 4f0bc80..160d547 100644
--- a/src/rebar_utils.erl
+++ b/src/rebar_utils.erl
@@ -304,27 +304,30 @@ otp_release1([$R,N|_]=Rel) when is_integer(N) ->
 %% the "\n".
 otp_release1(Rel) ->
     File = filename:join([code:root_dir(), "releases", Rel, "OTP_VERSION"]),
-    {ok, Vsn} = file:read_file(File),
-
-    %% It's fine to rely on the binary module here because we can
-    %% be sure that it's available when the otp_release string does
-    %% not begin with $R.
-    Size = byte_size(Vsn),
-    %% The shortest vsn string consists of at least two digits
-    %% followed by "\n". Therefore, it's safe to assume Size >= 3.
-    case binary:part(Vsn, {Size, -3}) of
-        <<"**\n">> ->
-            %% The OTP documentation mentions that a system patched
-            %% using the otp_patch_apply tool available to licensed
-            %% customers will leave a '**' suffix in the version as a
-            %% flag saying the system consists of application versions
-            %% from multiple OTP versions. We ignore this flag and
-            %% drop the suffix, given for all intents and purposes, we
-            %% cannot obtain relevant information from it as far as
-            %% tooling is concerned.
-            binary:bin_to_list(Vsn, {0, Size - 3});
-        _ ->
-            binary:bin_to_list(Vsn, {0, Size - 1})
+    case file:read_file(File) of
+        {error, _} ->
+            Rel;
+        {ok, Vsn} ->
+            %% It's fine to rely on the binary module here because we can
+            %% be sure that it's available when the otp_release string does
+            %% not begin with $R.
+            Size = byte_size(Vsn),
+            %% The shortest vsn string consists of at least two digits
+            %% followed by "\n". Therefore, it's safe to assume Size >= 3.
+            case binary:part(Vsn, {Size, -3}) of
+                <<"**\n">> ->
+                    %% The OTP documentation mentions that a system patched
+                    %% using the otp_patch_apply tool available to licensed
+                    %% customers will leave a '**' suffix in the version as a
+                    %% flag saying the system consists of application versions
+                    %% from multiple OTP versions. We ignore this flag and
+                    %% drop the suffix, given for all intents and purposes, we
+                    %% cannot obtain relevant information from it as far as
+                    %% tooling is concerned.
+                    binary:bin_to_list(Vsn, {0, Size - 3});
+                _ ->
+                    binary:bin_to_list(Vsn, {0, Size - 1})
+            end
     end.
 
 %% We do the shell variable substitution ourselves on Windows and hope that the