From 9884c9dd9bcec7008676f0590050b194dcff5d6d Mon Sep 17 00:00:00 2001
From: fffe <fffe@users.noreply.github.com>
Date: Fri, 3 Jul 2026 04:52:26 -0700
Subject: [PATCH] Add support for posix_spawn_file_actions_addclosefrom_np by
 @fffe

---
 configure.ac         |  1 +
 scripts/checks.m4    | 18 ++++++++++++++++++
 src/rpc/exec_file.cc | 25 ++++++++++++++++---------
 3 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/configure.ac b/configure.ac
index 100e2bea..4419c083 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,6 +73,7 @@ CFLAGS="$CFLAGS $PTHREAD_CFLAGS $CURSES_CFLAGS $ZLIB_CFLAGS $DEPENDENCIES_CFLAGS
 CXXFLAGS="$CXXFLAGS $PTHREAD_CFLAGS $CURSES_CFLAGS $ZLIB_CFLAGS $DEPENDENCIES_CFLAGS"
 
 TORRENT_CHECK_CACHELINE
+TORRENT_CHECK_POSIX_SPAWN_ADDCLOSEFROM_NP
 
 AC_CONFIG_FILES([
   Makefile
diff --git a/scripts/checks.m4 b/scripts/checks.m4
index c3ff3af7..c46f72ac 100644
--- a/scripts/checks.m4
+++ b/scripts/checks.m4
@@ -298,6 +298,24 @@ AC_DEFUN([TORRENT_DISABLE_PTHREAD_SETNAME_NP], [
 ])
 
 
+AC_DEFUN([TORRENT_CHECK_POSIX_SPAWN_ADDCLOSEFROM_NP], [
+  AC_MSG_CHECKING(for posix_spawn_file_actions_addclosefrom_np)
+
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+    #define _GNU_SOURCE
+    #include <spawn.h>
+  ]], [[
+    posix_spawn_file_actions_t actions;
+    posix_spawn_file_actions_addclosefrom_np(&actions, 3);
+  ]])],[
+    AC_DEFINE(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSEFROM_NP, 1, [Define if posix_spawn_file_actions_addclosefrom_np is available.])
+    AC_MSG_RESULT(yes)
+  ],[
+    AC_MSG_RESULT(no)
+  ])
+])
+
+
 AC_DEFUN([TORRENT_WITH_SYSTEMD], [
   AC_ARG_WITH(systemd,
     AS_HELP_STRING([--with-systemd],[enable systemd socket activation support [[default=no]]]),
diff --git a/src/rpc/exec_file.cc b/src/rpc/exec_file.cc
index f6fce9da..1a4e053e 100644
--- a/src/rpc/exec_file.cc
+++ b/src/rpc/exec_file.cc
@@ -43,6 +43,22 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
   if (posix_spawn_file_actions_init(&actions) != 0)
     throw torrent::internal_error("ExecFile::execute(...) posix_spawn_file_actions_init failed.");
 
+  posix_spawnattr_t attr;
+  posix_spawnattr_init(&attr);
+
+  short spawn_flags = 0;
+
+  // Try to avoid leaking open fds to the spawned process. Prefer POSIX_SPAWN_CLOEXEC_DEFAULT
+  // (macOS-only) or posix_spawn_file_actions_addclosefrom_np (glibc >= 2.34, FreeBSD >= 13.1).
+  //
+  // Other platforms like musl libc, OpenBSD and NetBSD must rely on explicit O_CLOEXEC.
+
+#if defined(POSIX_SPAWN_CLOEXEC_DEFAULT)
+  spawn_flags |= POSIX_SPAWN_CLOEXEC_DEFAULT;
+#elif defined(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSEFROM_NP)
+  posix_spawn_file_actions_addclosefrom_np(&actions, 3);
+#endif
+
   // Handle standard input redirection (/dev/null), posix_spawn_file_actions_addopen handles opening
   // and dup2 natively
   if (posix_spawn_file_actions_addopen(&actions, 0, "/dev/null", O_RDWR, 0) != 0) {
@@ -76,15 +92,6 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
     posix_spawn_file_actions_addopen(&actions, 2, "/dev/null", O_RDWR, 0);
   }
 
-  posix_spawnattr_t attr;
-  posix_spawnattr_init(&attr);
-
-  short spawn_flags = 0;
-
-#ifdef POSIX_SPAWN_CLOEXEC_DEFAULT
-  spawn_flags |= POSIX_SPAWN_CLOEXEC_DEFAULT;
-#endif
-
   if (flags & flag_background) {
 #ifdef POSIX_SPAWN_SETSID
     spawn_flags |= POSIX_SPAWN_SETSID;