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fix: prevent IPC socket fd leak into child processes #388

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fix: prevent IPC socket fd leak into child processes #388

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6 changes: 6 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,12 @@
All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).

## [Unreleased]

### Fixed

- Prevent IPC socket fd leak into child processes spawned by `$(...)` config commands, which caused `Binding control port failed` errors after restart ([#388](https://github.com/houmain/keymapper/pull/388)).

## [Version 5.6.0] - 2026-06-14

### Added
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22 changes: 19 additions & 3 deletions src/common/Host.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,15 @@ void make_non_blocking(Socket socket_fd) {

#else // !defined(_WIN32)

#include <features.h>
// accept4() requires _GNU_SOURCE on glibc >= 2.10.
// On musl it is available without any feature-test macro.
#if defined(__GLIBC__) && __GLIBC_PREREQ(2, 10)
#define HAVE_ACCEPT4 1
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#endif
#include <csignal>
#include <unistd.h>
#include <fcntl.h>
Expand Down Expand Up @@ -120,7 +129,7 @@ Host::~Host() {
}

bool Host::listen() {
m_listen_fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
m_listen_fd = ::socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
if (m_listen_fd == invalid_socket)
return false;

Expand Down Expand Up @@ -158,9 +167,16 @@ Connection Host::accept(std::optional<Duration> timeout) {
if (!block_until_readable(m_listen_fd, timeout))
return { };

# if defined(HAVE_ACCEPT4)
auto socket_fd = ::accept4(m_listen_fd, nullptr, nullptr, SOCK_CLOEXEC);
# else
auto socket_fd = ::accept(m_listen_fd, nullptr, nullptr);
# endif
if (socket_fd == invalid_socket)
return { };
# if !defined(HAVE_ACCEPT4)
::fcntl(socket_fd, F_SETFD, ::fcntl(socket_fd, F_GETFD) | FD_CLOEXEC);
# endif
make_blocking(socket_fd);
auto connection = Connection(socket_fd);

Expand Down Expand Up @@ -190,7 +206,7 @@ Connection Host::connect(std::optional<Duration> timeout) {
const auto retry_until_timepoint = (timeout ?
std::make_optional(Clock::now() + *timeout) : std::nullopt);

auto socket_fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
auto socket_fd = ::socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
for (;;) {
if (socket_fd == invalid_socket)
return { };
Expand All @@ -205,7 +221,7 @@ Connection Host::connect(std::optional<Duration> timeout) {
!connection.read(&versions_match)) {
// this fails regularly when reconnecting to a closing host
connection.disconnect();
socket_fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
socket_fd = ::socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
continue;
}
if (!versions_match)
Expand Down