Add support for redirecting stderr to stdout.

app/controllers/submissions_controller.rb

@@ -116,7 +116,8 @@ def submission_params
       :max_processes_and_or_threads,
       :enable_per_process_and_thread_time_limit,
       :enable_per_process_and_thread_memory_limit,
-      :max_file_size
+      :max_file_size,
+      :redirect_stderr_to_stdout
     )
 
     params[:base64_encoded] == "true" ? decode_params(submission_params) : submission_params

app/helpers/config.rb

@@ -28,6 +28,7 @@ module Config
   MAX_MAX_FILE_SIZE = (ENV['MAX_MAX_FILE_SIZE'].presence || 4096).to_i
   NUMBER_OF_RUNS = (ENV['NUMBER_OF_RUNS'].presence || 1).to_i
   MAX_NUMBER_OF_RUNS = (ENV['MAX_NUMBER_OF_RUNS'].presence || 20).to_i
+  REDIRECT_STDERR_TO_STDOUT = ENV['REDIRECT_STDERR_TO_STDOUT'] == "true"
 
   def self.config_info
     @@default_confg ||= {
@@ -56,7 +57,8 @@ def self.config_info
       "max_file_size": MAX_FILE_SIZE,
       "max_max_file_size": MAX_MAX_FILE_SIZE,
       "number_of_runs": NUMBER_OF_RUNS,
-      "max_number_of_runs": MAX_NUMBER_OF_RUNS
+      "max_number_of_runs": MAX_NUMBER_OF_RUNS,
+      "redirect_stderr_to_stdout": REDIRECT_STDERR_TO_STDOUT
     }
   end
 end

app/jobs/isolate_job.rb

@@ -145,6 +145,7 @@ def run
     -s \
     -b #{box_id} \
     -M #{metadata_file} \
+    #{submission.redirect_stderr_to_stdout ? "--stderr-to-stdout" : ""} \
     -t #{submission.cpu_time_limit} \
     -x #{submission.cpu_extra_time} \
     -w #{submission.wall_time_limit} \

app/models/submission.rb

@@ -210,5 +210,9 @@ def set_defaults
       Config::ENABLE_PER_PROCESS_AND_THREAD_MEMORY_LIMIT
     )
     self.max_file_size ||= Config::MAX_FILE_SIZE
+    self.redirect_stderr_to_stdout = NilValue.value_or_default(
+      self.redirect_stderr_to_stdout,
+      Config::REDIRECT_STDERR_TO_STDOUT
+    )
   end
 end

db/migrate/20200113231131_add_redirect_stderr_to_stdout_to_submission.rb

@@ -0,0 +1,5 @@
+class AddRedirectStderrToStdoutToSubmission < ActiveRecord::Migration[5.0]
+  def change
+    add_column :submissions, :redirect_stderr_to_stdout, :boolean
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20191230001624) do
+ActiveRecord::Schema.define(version: 20200113231131) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -53,6 +53,7 @@
     t.decimal  "wall_time"
     t.string   "compiler_options"
     t.string   "command_line_arguments"
+    t.boolean  "redirect_stderr_to_stdout"
     t.index ["token"], name: "index_submissions_on_token", using: :btree
   end
 

judge0-api.conf.default

@@ -232,3 +232,7 @@ NUMBER_OF_RUNS=
 # Maximum custom NUMBER_OF_RUNS.
 # Default: 20
 MAX_NUMBER_OF_RUNS=
+
+# Redirect stderr to stdout.
+# Default: false
+REDIRECT_STDERR_TO_STDOUT=