From 23a81b439638fee89054ad749f0348ab7d107619 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Mon, 24 Aug 2020 02:27:26 +1000
Subject: [PATCH 1/2] std: refactor fs.openFileZ flag handling

---
 lib/std/fs.zig | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index df368e070b..d9c949ef33 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -686,21 +686,25 @@ pub const Dir = struct {
             return self.openFileW(path_w.span(), flags);
         }
 
+        var os_flags: u32 = os.O_CLOEXEC;
         // Use the O_ locking flags if the os supports them
         // (Or if it's darwin, as darwin's `open` doesn't support the O_SYNC flag)
         const has_flock_open_flags = @hasDecl(os, "O_EXLOCK") and !is_darwin;
-        const nonblocking_lock_flag = if (has_flock_open_flags and flags.lock_nonblocking)
-            os.O_NONBLOCK | os.O_SYNC
-        else
-            @as(u32, 0);
-        const lock_flag: u32 = if (has_flock_open_flags) switch (flags.lock) {
-            .None => @as(u32, 0),
-            .Shared => os.O_SHLOCK | nonblocking_lock_flag,
-            .Exclusive => os.O_EXLOCK | nonblocking_lock_flag,
-        } else 0;
-
-        const O_LARGEFILE = if (@hasDecl(os, "O_LARGEFILE")) os.O_LARGEFILE else 0;
-        const os_flags = lock_flag | O_LARGEFILE | os.O_CLOEXEC | if (flags.write and flags.read)
+        if (has_flock_open_flags) {
+            const nonblocking_lock_flag = if (flags.lock_nonblocking)
+                os.O_NONBLOCK | os.O_SYNC
+            else
+                @as(u32, 0);
+            os_flags |= switch (flags.lock) {
+                .None => @as(u32, 0),
+                .Shared => os.O_SHLOCK | nonblocking_lock_flag,
+                .Exclusive => os.O_EXLOCK | nonblocking_lock_flag,
+            };
+        }
+        if (@hasDecl(os, "O_LARGEFILE")) {
+            os_flags |= os.O_LARGEFILE;
+        }
+        os_flags |= if (flags.write and flags.read)
             @as(u32, os.O_RDWR)
         else if (flags.write)
             @as(u32, os.O_WRONLY)

From 129d3e274dbc3e11a30e3d54c5da7a944ddcf4f0 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Mon, 24 Aug 2020 02:28:31 +1000
Subject: [PATCH 2/2] std: use O_NOCTTY flag

---
 lib/std/fs.zig      | 3 +++
 lib/std/fs/file.zig | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index d9c949ef33..21a00eeb1d 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -704,6 +704,9 @@ pub const Dir = struct {
         if (@hasDecl(os, "O_LARGEFILE")) {
             os_flags |= os.O_LARGEFILE;
         }
+        if (!flags.allow_ctty) {
+            os_flags |= os.O_NOCTTY;
+        }
         os_flags |= if (flags.write and flags.read)
             @as(u32, os.O_RDWR)
         else if (flags.write)
diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index 3e22528ea9..6fb2385a85 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -101,6 +101,10 @@ pub const File = struct {
         /// if `std.io.is_async`. It allows the use of `nosuspend` when calling functions
         /// related to opening the file, reading, writing, and locking.
         intended_io_mode: io.ModeOverride = io.default_mode,
+
+        /// Set this to allow the opened file to automatically become the
+        /// controlling TTY for the current process.
+        allow_ctty: bool = false,
     };
 
     /// TODO https://github.com/ziglang/zig/issues/3802