commit bfe9fa0f8e937a4172d6fabfa209633c9f160698
parent 0712a9c87bfe1ce08ae95a0cb30e5857c28e861c
Author: James Fotherby <Fotherby1@gmail.com>
Date: Mon, 19 Jan 2026 21:59:43 -0800
fix(socket): remove stale socket files (#37378)
Problem:
Crashed Nvim leaves socket files. Subsequent starts fail with "address already in use".
Solution:
On bind failure, test socket liveness via connect(). Remove if stale, retry bind().
Fixes #36581
Diffstat:
2 files changed, 110 insertions(+), 0 deletions(-)
diff --git a/src/nvim/event/socket.c b/src/nvim/event/socket.c
@@ -77,6 +77,37 @@ int socket_watcher_init(Loop *loop, SocketWatcher *watcher, const char *endpoint
return 0;
}
+/// Callback for closing probe connection handle
+static void probe_close_cb(uv_handle_t *handle)
+{
+ bool *closed = handle->data;
+ *closed = true;
+}
+
+/// Check if a socket is alive by attempting to connect to it.
+/// @param loop Event loop
+/// @param addr Socket address to probe
+/// @return true if socket is alive (connection succeeded), false otherwise
+static bool socket_alive(Loop *loop, const char *addr)
+{
+ RStream stream;
+ const char *error = NULL;
+
+ // Try to connect with a 500ms timeout (fast failure for dead sockets)
+ bool connected = socket_connect(loop, &stream, false, addr, 500, &error);
+ if (!connected) {
+ return false;
+ }
+
+ // Connection succeeded - socket is alive. Close the probe connection properly.
+ bool closed = false;
+ stream.s.uv.pipe.data = &closed;
+ uv_close((uv_handle_t *)&stream.s.uv.pipe, probe_close_cb);
+ LOOP_PROCESS_EVENTS_UNTIL(&main_loop, NULL, -1, closed);
+
+ return true;
+}
+
int socket_watcher_start(SocketWatcher *watcher, int backlog, socket_cb cb)
FUNC_ATTR_NONNULL_ALL
{
@@ -112,6 +143,40 @@ int socket_watcher_start(SocketWatcher *watcher, int backlog, socket_cb cb)
uv_freeaddrinfo(watcher->uv.tcp.addrinfo);
} else {
result = uv_pipe_bind(&watcher->uv.pipe.handle, watcher->addr);
+
+ // If bind failed with EACCES/EADDRINUSE, check if socket is stale
+ if (result == UV_EACCES || result == UV_EADDRINUSE) {
+ Loop *loop = watcher->stream->loop->data;
+
+ if (!socket_alive(loop, watcher->addr)) {
+ // Socket exists but is dead - remove it
+ ILOG("Removing stale socket: %s", watcher->addr);
+ int rm_result = os_remove(watcher->addr);
+
+ if (rm_result != 0) {
+ WLOG("Failed to remove stale socket %s: %s",
+ watcher->addr, uv_strerror(rm_result));
+ } else {
+ // Close and reinit the pipe handle before retrying bind
+ uv_loop_t *uv_loop = watcher->uv.pipe.handle.loop;
+ bool closed = false;
+ watcher->uv.pipe.handle.data = &closed;
+ uv_close((uv_handle_t *)&watcher->uv.pipe.handle, probe_close_cb);
+ LOOP_PROCESS_EVENTS_UNTIL(&main_loop, NULL, -1, closed);
+
+ uv_pipe_init(uv_loop, &watcher->uv.pipe.handle, 0);
+ watcher->stream = (uv_stream_t *)(&watcher->uv.pipe.handle);
+ watcher->stream->data = watcher;
+
+ // Retry bind with fresh handle
+ result = uv_pipe_bind(&watcher->uv.pipe.handle, watcher->addr);
+ }
+ } else {
+ // Socket is alive - this is a real error
+ ELOG("Socket already in use by another Nvim instance: %s", watcher->addr);
+ }
+ }
+
if (result == 0) {
result = uv_listen(watcher->stream, backlog, connection_cb);
}
diff --git a/test/functional/core/server_spec.lua b/test/functional/core/server_spec.lua
@@ -218,6 +218,51 @@ describe('server', function()
eq(true, old_servs_num < #new_servs)
client:close()
end)
+
+ it('removes stale socket files automatically #26053', function()
+ if is_os('win') then
+ -- Windows named pipes are ephemeral kernel objects that are automatically
+ -- cleaned up when the process terminates. Unix domain sockets persist as
+ -- files on the filesystem and can become stale after crashes.
+ return
+ end
+
+ clear()
+ clear_serverlist()
+ local socket_path = './Xtest-stale-socket'
+
+ -- Create stale socket file (simulate crash)
+ vim.uv.fs_close(vim.uv.fs_open(socket_path, 'w', 438))
+
+ -- serverstart() should detect and remove stale socket
+ eq(socket_path, fn.serverstart(socket_path))
+ fn.serverstop(socket_path)
+
+ -- Same test with --listen flag
+ vim.uv.fs_close(vim.uv.fs_open(socket_path, 'w', 438))
+ clear({ args = { '--listen', socket_path } })
+ eq(socket_path, api.nvim_get_vvar('servername'))
+ fn.serverstop(socket_path)
+ end)
+
+ it('does not remove live sockets #26053', function()
+ if is_os('win') then
+ return
+ end
+
+ clear()
+ local socket_path = './Xtest-live-socket'
+ eq(socket_path, fn.serverstart(socket_path))
+
+ -- Second instance should fail without removing live socket
+ local result = n.exec_lua(function(sock)
+ return vim.system({ vim.v.progpath, '--headless', '--listen', sock }, { text = true }):wait()
+ end, socket_path)
+
+ neq(0, result.code)
+ matches('Failed.*listen', result.stderr)
+ fn.serverstop(socket_path)
+ end)
end)
describe('startup --listen', function()
