From cbf33fa14b181362598dd98fb45332d012b6f0a2 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 23 Apr 2021 16:23:13 +0530
Subject: [PATCH] Fix #3523

---
 docs/changelog.rst |  3 +++
 kitty/main.py      |  3 +++
 kitty/session.py   | 21 ++++++++++++++++-----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 2ff322d65..4f723464c 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -29,6 +29,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - GNOME: Fix maximize state not being remembered when focus changes and window
   decorations are hidden (:iss:`3507`)
 
+- Fix reading :option:`kitty --session` from ``STDIN`` not working when the
+  :option:`kitty --detach` option is used (:iss:`3523`)
+
 
 0.20.1 [2021-04-19]
 ----------------------
diff --git a/kitty/main.py b/kitty/main.py
index 567ed224d..98ac20b3b 100644
--- a/kitty/main.py
+++ b/kitty/main.py
@@ -306,6 +306,9 @@ def _main() -> None:
         create_opts(cli_opts, debug_config=True)
         return
     if cli_opts.detach:
+        if cli_opts.session == '-':
+            from .session import PreReadSession
+            cli_opts.session = PreReadSession(sys.stdin.read())
         detach()
     if cli_opts.replay_commands:
         from kitty.client import main as client_main
diff --git a/kitty/session.py b/kitty/session.py
index 1f2ab8fc7..2564a7b6b 100644
--- a/kitty/session.py
+++ b/kitty/session.py
@@ -137,6 +137,14 @@ def parse_session(raw: str, opts: Options, default_title: Optional[str] = None)
     yield finalize_session(ans)
 
 
+class PreReadSession(str):
+
+    def __new__(cls, val: str) -> 'PreReadSession':
+        ans: PreReadSession = str.__new__(cls, val)
+        ans.pre_read = True  # type: ignore
+        return ans
+
+
 def create_sessions(
     opts: Options,
     args: Optional[CLIOptions] = None,
@@ -146,12 +154,15 @@ def create_sessions(
     default_session: Optional[str] = None
 ) -> Generator[Session, None, None]:
     if args and args.session:
-        if args.session == '-':
-            f = sys.stdin
+        if isinstance(args.session, PreReadSession):
+            session_data = '' + str(args.session)
         else:
-            f = open(args.session)
-        with f:
-            session_data = f.read()
+            if args.session == '-':
+                f = sys.stdin
+            else:
+                f = open(args.session)
+            with f:
+                session_data = f.read()
         yield from parse_session(session_data, opts, getattr(args, 'title', None))
         return
     if default_session and default_session != 'none':