From 1d167a6b9fcc8c9ed494a0cf8d4e2b8406934f8a Mon Sep 17 00:00:00 2001
From: Markus Reiter <me@reitermark.us>
Date: Tue, 24 Jul 2018 00:09:11 +0200
Subject: [PATCH] Reraise `SystemCallError` as `ErrorDuringExecution`.

---
 Library/Homebrew/system_command.rb           | 24 +++++++++++---------
 Library/Homebrew/test/system_command_spec.rb |  8 +++++++
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/Library/Homebrew/system_command.rb b/Library/Homebrew/system_command.rb
index cdd74b0c77..c49d773a90 100644
--- a/Library/Homebrew/system_command.rb
+++ b/Library/Homebrew/system_command.rb
@@ -1,4 +1,5 @@
 require "open3"
+require "ostruct"
 require "vendor/plist/plist"
 require "shellwords"
 
@@ -28,18 +29,15 @@ class SystemCommand
 
   def run!
     @merged_output = []
-    @processed_output = { stdout: "", stderr: "" }
     odebug command.shelljoin
 
     each_output_line do |type, line|
       case type
       when :stdout
         puts line.chomp if print_stdout?
-        processed_output[:stdout] << line
         @merged_output << [:stdout, line]
       when :stderr
         $stderr.puts Formatter.error(line.chomp) if print_stderr?
-        processed_output[:stderr] << line
         @merged_output << [:stderr, line]
       end
     end
@@ -71,7 +69,7 @@ class SystemCommand
 
   private
 
-  attr_reader :executable, :args, :input, :options, :processed_output, :processed_status, :env
+  attr_reader :executable, :args, :input, :options, :env
 
   attr_predicate :sudo?, :print_stdout?, :print_stderr?, :must_succeed?
 
@@ -94,9 +92,9 @@ class SystemCommand
   end
 
   def assert_success
-    return if processed_status&.success?
+    return if @status.success?
     raise ErrorDuringExecution.new(command,
-                                   status: processed_status,
+                                   status: @status,
                                    output: @merged_output)
   end
 
@@ -122,7 +120,10 @@ class SystemCommand
     raw_stdin.close_write
     each_line_from [raw_stdout, raw_stderr], &b
 
-    @processed_status = raw_wait_thr.value
+    @status = raw_wait_thr.value
+  rescue SystemCallError => e
+    @status = $CHILD_STATUS
+    @merged_output << [:stderr, e.message]
   end
 
   def write_input_to(raw_stdin)
@@ -152,10 +153,11 @@ class SystemCommand
   end
 
   def result
-    Result.new(command,
-               processed_output[:stdout],
-               processed_output[:stderr],
-               processed_status.exitstatus)
+    output = @merged_output.each_with_object(stdout: "", stderr: "") do |(type, line), hash|
+      hash[type] << line
+    end
+
+    Result.new(command, output[:stdout], output[:stderr], @status.exitstatus)
   end
 
   class Result
diff --git a/Library/Homebrew/test/system_command_spec.rb b/Library/Homebrew/test/system_command_spec.rb
index f57d22f612..0b74d1fbfe 100644
--- a/Library/Homebrew/test/system_command_spec.rb
+++ b/Library/Homebrew/test/system_command_spec.rb
@@ -208,4 +208,12 @@ describe SystemCommand do
       expect(described_class.run("tool", env: { "PATH" => path }).stdout).to include "Hello, world!"
     end
   end
+
+  describe "#run" do
+    it "does not raise a `SystemCallError` when the executable does not exist" do
+      expect {
+        described_class.run("non_existent_executable")
+      }.not_to raise_error
+    end
+  end
 end