From fabd96552f3f690db8ff7651f6354057139f0557 Mon Sep 17 00:00:00 2001
From: Velikiy Kirill <velikoss@vk.com>
Date: Mon, 15 Sep 2025 14:41:35 +0300
Subject: [PATCH] Implement write_to_stdin() in std::os::process (#2482)

* SubProcess: Add write_to_stdin

* SubProcess: Change unit test for windows support
---
 lib/std/os/subprocess.c3          |  6 ++++++
 test/unit/stdlib/os/subprocess.c3 | 20 +++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/lib/std/os/subprocess.c3 b/lib/std/os/subprocess.c3
index a9be419c3..a9e610b49 100644
--- a/lib/std/os/subprocess.c3
+++ b/lib/std/os/subprocess.c3
@@ -531,3 +531,9 @@ fn bool? SubProcess.is_running(&self)
 		return false;
 	$endif
 }
+
+fn usz? SubProcess.write_to_stdin(&self, char[] buffer)
+{
+	if (!self.stdin_file) return FAILED_TO_OPEN_STDIN?;
+	return os::native_fwrite(self.stdin_file, buffer);
+}
diff --git a/test/unit/stdlib/os/subprocess.c3 b/test/unit/stdlib/os/subprocess.c3
index 3265a3f6d..841457a58 100644
--- a/test/unit/stdlib/os/subprocess.c3
+++ b/test/unit/stdlib/os/subprocess.c3
@@ -142,4 +142,22 @@ fn void test_inherit_stdio_redirect()
     
     assert(stdout_bytes == 0, "Should read 0 bytes from stdout");
     assert(stderr_bytes == 0, "Should read 0 bytes from stderr");
-}
\ No newline at end of file
+}
+
+fn void test_write_to_stdin() @test {
+$if env::WIN32:
+	SubProcess? subprocess = process::create({`powershell`, `-C`, `Read-Host`}, {.inherit_environment = true});
+$else
+	SubProcess? subprocess = process::create({"tee"}, {.read_async = true});
+$endif
+	test::eq(@ok(subprocess), true);
+	usz? write = subprocess!!.write_to_stdin(")");
+	test::eq(@ok(write), true);
+	test::eq(write!!, 1);
+	char buf;
+	test::eq(@ok(subprocess!!.join()), true);
+	usz? read = subprocess!!.read_stdout(&buf, 1);
+	test::eq(@ok(read), true);
+	test::eq(read!!, 1);
+	test::eq(buf, ')');
+}