From 032a22fd8df47e683a486b4dfc6507b38a1020d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20M=C3=BCller?= <straightshoota@gmail.com>
Date: Tue, 11 Jun 2024 22:17:25 +0200
Subject: [PATCH] Fix `Process.run` with closed IO

---
 spec/std/process_spec.cr           | 8 ++++++++
 src/crystal/system/unix/process.cr | 5 +++++
 src/process.cr                     | 8 ++++++++
 3 files changed, 21 insertions(+)

diff --git a/spec/std/process_spec.cr b/spec/std/process_spec.cr
index d656e9353589..f067d2f5c775 100644
--- a/spec/std/process_spec.cr
+++ b/spec/std/process_spec.cr
@@ -181,6 +181,14 @@ pending_interpreted describe: Process do
       $?.exit_code.should eq(0)
     end
 
+    it "forwards closed io" do
+      closed_io = IO::Memory.new
+      closed_io.close
+      Process.run(*stdin_to_stdout_command, input: closed_io)
+      Process.run(*stdin_to_stdout_command, output: closed_io)
+      Process.run(*stdin_to_stdout_command, error: closed_io)
+    end
+
     it "sets working directory with string" do
       parent = File.dirname(Dir.current)
       command = {% if flag?(:win32) %}
diff --git a/src/crystal/system/unix/process.cr b/src/crystal/system/unix/process.cr
index 4fd2b658cd59..c9dd1925169a 100644
--- a/src/crystal/system/unix/process.cr
+++ b/src/crystal/system/unix/process.cr
@@ -292,6 +292,11 @@ struct Crystal::System::Process
   end
 
   private def self.reopen_io(src_io : IO::FileDescriptor, dst_io : IO::FileDescriptor)
+    if src_io.closed?
+      dst_io.close
+      return
+    end
+
     src_io = to_real_fd(src_io)
 
     dst_io.reopen(src_io)
diff --git a/src/process.cr b/src/process.cr
index a1b827d73754..045615c814a7 100644
--- a/src/process.cr
+++ b/src/process.cr
@@ -294,6 +294,14 @@ class Process
     when IO::FileDescriptor
       stdio
     when IO
+      if stdio.closed?
+        if dst_io == STDIN
+          return File.open(File::NULL, "r").tap(&.close)
+        else
+          return File.open(File::NULL, "w").tap(&.close)
+        end
+      end
+
       if dst_io == STDIN
         fork_io, process_io = IO.pipe(read_blocking: true)