From 8034ac37f89f8ff952c1d22edaf69cbe5c5ffdb3 Mon Sep 17 00:00:00 2001
From: Quinton Miller <nicetas.c@gmail.com>
Date: Tue, 18 Apr 2023 02:31:00 +0800
Subject: [PATCH 1/2] Allow `/SUBSYSTEM:WINDOWS` on Windows

---
 src/crystal/system/win32/file_descriptor.cr | 23 ++++++++++++++-------
 src/crystal/system/win32/process.cr         |  4 +---
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/crystal/system/win32/file_descriptor.cr b/src/crystal/system/win32/file_descriptor.cr
index f9c0d525bc72..4292dca12ab7 100644
--- a/src/crystal/system/win32/file_descriptor.cr
+++ b/src/crystal/system/win32/file_descriptor.cr
@@ -54,8 +54,18 @@ module Crystal::System::FileDescriptor
   end
 
   private def windows_handle
+    FileDescriptor.windows_handle!(fd)
+  end
+
+  def self.windows_handle(fd)
+    ret = LibC._get_osfhandle(fd)
+    return LibC::INVALID_HANDLE_VALUE if ret == -1 || ret == -2
+    LibC::HANDLE.new(ret)
+  end
+
+  def self.windows_handle!(fd)
     ret = LibC._get_osfhandle(fd)
-    raise RuntimeError.from_errno("_get_osfhandle") if ret == -1
+    raise RuntimeError.from_errno("_get_osfhandle") if ret == -1 || ret == -2
     LibC::HANDLE.new(ret)
   end
 
@@ -154,9 +164,7 @@ module Crystal::System::FileDescriptor
   end
 
   def self.pread(fd, buffer, offset)
-    handle = LibC._get_osfhandle(fd)
-    raise IO::Error.from_errno("_get_osfhandle") if handle == -1
-    handle = LibC::HANDLE.new(handle)
+    handle = windows_handle!(fd)
 
     overlapped = LibC::OVERLAPPED.new
     overlapped.union.offset.offset = LibC::DWORD.new(offset)
@@ -172,9 +180,8 @@ module Crystal::System::FileDescriptor
 
   def self.from_stdio(fd)
     console_handle = false
-    handle = LibC._get_osfhandle(fd)
-    if handle != -1
-      handle = LibC::HANDLE.new(handle)
+    handle = windows_handle(fd)
+    if handle != LibC::INVALID_HANDLE_VALUE
       # TODO: use `out old_mode` after implementing interpreter out closured var
       old_mode = uninitialized LibC::DWORD
       if LibC.GetConsoleMode(handle, pointerof(old_mode)) != 0
@@ -187,7 +194,7 @@ module Crystal::System::FileDescriptor
       end
     end
 
-    io = IO::FileDescriptor.new(fd)
+    io = IO::FileDescriptor.new(fd, blocking: true)
     # Set sync or flush_on_newline as described in STDOUT and STDERR docs.
     # See https://crystal-lang.org/api/toplevel.html#STDERR
     if console_handle
diff --git a/src/crystal/system/win32/process.cr b/src/crystal/system/win32/process.cr
index b887d8521c46..a9bb85e9aa5a 100644
--- a/src/crystal/system/win32/process.cr
+++ b/src/crystal/system/win32/process.cr
@@ -182,9 +182,7 @@ struct Crystal::System::Process
   end
 
   private def self.handle_from_io(io : IO::FileDescriptor, parent_io)
-    ret = LibC._get_osfhandle(io.fd)
-    raise RuntimeError.from_winerror("_get_osfhandle") if ret == -1
-    source_handle = LibC::HANDLE.new(ret)
+    source_handle = FileDescriptor.windows_handle!(io.fd)
 
     cur_proc = LibC.GetCurrentProcess
     if LibC.DuplicateHandle(cur_proc, source_handle, cur_proc, out new_handle, 0, true, LibC::DUPLICATE_SAME_ACCESS) == 0

From 5491612aa754786f9e18a3b728eaf747e08459cc Mon Sep 17 00:00:00 2001
From: Quinton Miller <nicetas.c@gmail.com>
Date: Tue, 18 Apr 2023 02:51:36 +0800
Subject: [PATCH 2/2] `-2` does not set errno

---
 src/crystal/system/win32/file_descriptor.cr | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/crystal/system/win32/file_descriptor.cr b/src/crystal/system/win32/file_descriptor.cr
index 4292dca12ab7..576fb64e53c8 100644
--- a/src/crystal/system/win32/file_descriptor.cr
+++ b/src/crystal/system/win32/file_descriptor.cr
@@ -65,7 +65,8 @@ module Crystal::System::FileDescriptor
 
   def self.windows_handle!(fd)
     ret = LibC._get_osfhandle(fd)
-    raise RuntimeError.from_errno("_get_osfhandle") if ret == -1 || ret == -2
+    raise RuntimeError.from_errno("_get_osfhandle") if ret == -1
+    raise RuntimeError.new("_get_osfhandle returned -2") if ret == -2
     LibC::HANDLE.new(ret)
   end