socket.tcp_server removes old socket if it exists and dead. closes #414

src/lua/bsdsocket.lua

@@ -6,6 +6,7 @@ local TIMEOUT_INFINITY      = 500 * 365 * 86400
 
 local ffi = require 'ffi'
 local os_remove = os.remove
+local boxerrno  = box.errno
 local internal = box.socket.internal
 box.socket.internal = nil
 package.loaded['box.socket.internal'] = nil
@@ -1003,6 +1004,38 @@ local function tcp_server_usage()
     error('Usage: socket.tcp_server(host, port, handler | opts)')
 end
 
+local function tcp_server_bind(s, addr)
+    if s:bind(addr.host, addr.port) then
+        return true
+    end
+
+    if addr.family ~= 'AF_UNIX' then
+        return false
+    end
+
+    if boxerrno() ~= boxerrno.EADDRINUSE then
+        return false
+    end
+
+    local save_errno = boxerrno()
+
+    local sc = tcp_connect(addr.host, addr.port)
+    if sc ~= nil then
+        sc:close()
+        boxerrno(save_errno)
+        return false
+    end
+
+    if boxerrno() ~= boxerrno.ECONNREFUSED then
+        boxerrno(save_errno)
+        return false
+    end
+
+    os_remove(addr.port)
+    return s:bind(addr.host, addr.port)
+end
+
+
 local function tcp_server(host, port, opts, timeout)
     local server = {}
     if type(opts) == 'function' then
@@ -1040,7 +1073,7 @@ local function tcp_server(host, port, opts, timeout)
             else
                 s:setsockopt('SOL_SOCKET', 'SO_REUSEADDR', 1) -- ignore error
             end
-            if not s:bind(addr.host, addr.port) or not s:listen(backlog) then
+            if not tcp_server_bind(s, addr) or not s:listen(backlog) then
                 local save_errno = box.errno()
                 s:close()
                 box.errno(save_errno)

test/box/bsdsocket.result

@@ -222,7 +222,7 @@ lua s:getsockopt('SOL_SOCKET', 'SO_DEBUG')
 ...
 lua s:setsockopt('SOL_SOCKET', 'SO_ACCEPTCONN', 1)
 ---
-error: '[string "-- bsdsocket.lua (internal file)..."]:347: Socket option SO_ACCEPTCONN is read only'
+error: '[string "-- bsdsocket.lua (internal file)..."]:348: Socket option SO_ACCEPTCONN is read only'
 ...
 lua s:getsockopt('SOL_SOCKET', 'SO_RCVBUF') > 32
 ---
@@ -1149,3 +1149,37 @@ lua errno == box.errno.ECONNREFUSED
 ---
  - true
 ...
+test bind unix socket if old socket is exists
+lua s = box.socket('AF_UNIX', 'SOCK_STREAM', 0)
+---
+...
+lua s:bind('unix/', '/tmp/tarantool-test-socket')
+---
+ - true
+...
+lua s:listen()
+---
+ - true
+...
+lua s:close()
+---
+ - true
+...
+lua s = box.socket('AF_UNIX', 'SOCK_STREAM', 0)
+---
+...
+lua s:bind('unix/', '/tmp/tarantool-test-socket')
+---
+ - false
+...
+lua s = box.socket.tcp_server('unix/', '/tmp/tarantool-test-socket', function() end)
+---
+...
+lua s ~= nil
+---
+ - true
+...
+lua s:close()
+---
+ - true
+...

test/box/bsdsocket.test

@@ -370,3 +370,18 @@ exec admin "lua collectgarbage('collect')"
 exec admin "lua client, errno = box.socket.tcp_connect('unix/', '{}'), box.errno()".format(path)
 exec admin "lua errno == box.errno.ECONNREFUSED"
 os.unlink(path)
+
+print 'test bind unix socket if old socket is exists'
+exec admin "lua s = box.socket('AF_UNIX', 'SOCK_STREAM', 0)"
+exec admin "lua s:bind('unix/', '{}')".format(path)
+exec admin "lua s:listen()"
+exec admin "lua s:close()"
+if not os.path.exists(path):
+    print 'unix socket was removed: test failed'
+exec admin "lua s = box.socket('AF_UNIX', 'SOCK_STREAM', 0)"
+exec admin "lua s:bind('unix/', '{}')".format(path)
+exec admin "lua s = box.socket.tcp_server('unix/', '{}', function() end)".format(path)
+exec admin "lua s ~= nil"
+exec admin "lua s:close()"
+if os.path.exists(path):
+    print 'unix socket was not removed: test failed'