From e45c504ab04c21da47bf6dbfde27d6ebc824ae23 Mon Sep 17 00:00:00 2001
From: Leonard Hecker <leonard@hecker.io>
Date: Thu, 3 Apr 2025 23:58:06 +0200
Subject: [PATCH] Don't reopen stdout on startup

If it's not a TTY we should just exit, because then the user probably
ran edit by accident anyway. It doesn't make much sense to redirect
the output of any interactive application.
---
 src/sys/unix.rs    |  6 ++----
 src/sys/windows.rs | 49 ++++++++++++++++++++++++----------------------
 2 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/src/sys/unix.rs b/src/sys/unix.rs
index a712908..081f776 100644
--- a/src/sys/unix.rs
+++ b/src/sys/unix.rs
@@ -45,9 +45,6 @@ pub fn init() -> apperr::Result<Deinit> {
         if libc::isatty(STATE.stdin) == 0 {
             STATE.stdin = check_int_return(libc::open(c"/dev/tty".as_ptr(), libc::O_RDONLY))?;
         }
-        if libc::isatty(STATE.stdout) == 0 {
-            STATE.stdout = check_int_return(libc::open(c"/dev/tty".as_ptr(), libc::O_WRONLY))?;
-        }
 
         // Store the stdin flags so we can more easily toggle `O_NONBLOCK` later on.
         STATE.stdin_flags = check_int_return(libc::fcntl(STATE.stdin, libc::F_GETFL))?;
@@ -288,7 +285,8 @@ pub fn write_stdout(text: &str) {
 
 pub fn open_stdin_if_redirected() -> Option<File> {
     unsafe {
-        if libc::isatty(libc::STDIN_FILENO) == 0 {
+        // Did we reopen stdin during `init()`?
+        if STATE.stdin != libc::STDIN_FILENO {
             Some(File::from_raw_fd(libc::STDIN_FILENO))
         } else {
             None
diff --git a/src/sys/windows.rs b/src/sys/windows.rs
index 1168d4c..097c08e 100644
--- a/src/sys/windows.rs
+++ b/src/sys/windows.rs
@@ -80,24 +80,27 @@ pub fn init() -> apperr::Result<Deinit> {
         let kernel32 = LibraryLoader::GetModuleHandleW(w!("kernel32.dll"));
         STATE.read_console_input_ex = get_proc_address(kernel32, c"ReadConsoleInputExW")?;
 
-        STATE.stdin = FileSystem::CreateFileW(
-            w!("CONIN$"),
-            Foundation::GENERIC_READ | Foundation::GENERIC_WRITE,
-            FileSystem::FILE_SHARE_READ | FileSystem::FILE_SHARE_WRITE,
-            null_mut(),
-            FileSystem::OPEN_EXISTING,
-            0,
-            null_mut(),
-        );
-        STATE.stdout = FileSystem::CreateFileW(
-            w!("CONOUT$"),
-            Foundation::GENERIC_READ | Foundation::GENERIC_WRITE,
-            FileSystem::FILE_SHARE_READ | FileSystem::FILE_SHARE_WRITE,
-            null_mut(),
-            FileSystem::OPEN_EXISTING,
-            0,
-            null_mut(),
-        );
+        STATE.stdin = Console::GetStdHandle(Console::STD_INPUT_HANDLE);
+        STATE.stdout = Console::GetStdHandle(Console::STD_OUTPUT_HANDLE);
+
+        // Reopen stdin if it's redirected (= piped input).
+        if !ptr::eq(STATE.stdin, Foundation::INVALID_HANDLE_VALUE)
+            && matches!(
+                FileSystem::GetFileType(STATE.stdin),
+                FileSystem::FILE_TYPE_DISK | FileSystem::FILE_TYPE_PIPE
+            )
+        {
+            STATE.stdin = FileSystem::CreateFileW(
+                w!("CONIN$"),
+                Foundation::GENERIC_READ | Foundation::GENERIC_WRITE,
+                FileSystem::FILE_SHARE_READ | FileSystem::FILE_SHARE_WRITE,
+                null_mut(),
+                FileSystem::OPEN_EXISTING,
+                0,
+                null_mut(),
+            );
+        }
+
         if ptr::eq(STATE.stdin, Foundation::INVALID_HANDLE_VALUE)
             || ptr::eq(STATE.stdout, Foundation::INVALID_HANDLE_VALUE)
         {
@@ -379,11 +382,11 @@ pub fn write_stdout(text: &str) {
 pub fn open_stdin_if_redirected() -> Option<File> {
     unsafe {
         let handle = Console::GetStdHandle(Console::STD_INPUT_HANDLE);
-        match FileSystem::GetFileType(handle) {
-            FileSystem::FILE_TYPE_DISK | FileSystem::FILE_TYPE_PIPE => {
-                Some(File::from_raw_handle(handle))
-            }
-            _ => None,
+        // Did we reopen stdin during `init()`?
+        if !std::ptr::eq(STATE.stdin, handle) {
+            Some(File::from_raw_handle(handle))
+        } else {
+            None
         }
     }
 }