Correctly check unix socket path length

Before this patch, the length of the entire URI was compared to the
maximum Unix socket path length. This is problematic because the URI
includes more than just the path, such as the login and parameters.
After this patch, only the path will be checked.

Closes #341

Author: ImeevMA

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+  * Fixed incorrent unix socket path length check (gh-341).
+
 ## 1.0.0
 
 - Extend `server.lua` API:

luatest/server.lua

@@ -156,12 +156,13 @@ function Server:initialize()
             self.net_box_uri = 'localhost:' .. self.net_box_port
         end
     end
-    if uri.parse(self.net_box_uri).host == 'unix/' then
+    local parsed_net_box_uri = uri.parse(self.net_box_uri)
+    if parsed_net_box_uri.host == 'unix/' then
         -- Linux uses max 108 bytes for Unix domain socket paths, which means a 107 characters
         -- string ended by a null terminator. Other systems use 104 bytes and 103 characters strings.
         local max_unix_socket_path = {linux = 107, other = 103}
         local system = os.execute('[ $(uname) = Linux ]') == 0 and 'linux' or 'other'
-        if self.net_box_uri:len() > max_unix_socket_path[system] then
+        if parsed_net_box_uri.unix:len() > max_unix_socket_path[system] then
             error(('Net box URI must be <= max Unix domain socket path length (%d chars)')
                 :format(max_unix_socket_path[system]))
         end

test/server_test.lua

@@ -296,6 +296,31 @@ g.test_max_unix_socket_path_exceeded = function()
     )
 end
 
+g.test_unix_socket_not_include_uri_fields = function()
+    local max_unix_socket_path = {linux = 107, other = 103}
+    local system = os.execute('[ $(uname) = Linux ]') == 0 and 'linux' or
+                   'other'
+    local workdir = fio.pathjoin(datadir, 'unix_socket')
+    fio.mktree(workdir)
+    local workdir_len = string.len(workdir)
+    local socket_name_len = max_unix_socket_path[system] + 1 - workdir_len
+    local socket_name = string.format('test_socket%s.sock',
+                                      string.rep('t', socket_name_len - 18))
+    local socket_path = fio.pathjoin(workdir, socket_name)
+    t.assert_equals(string.len(socket_path), max_unix_socket_path[system])
+    local net_box_uri = 'unix/:' .. socket_path .. '?three=1&four=2'
+    local s = Server:new({
+        command = command,
+        workdir = workdir,
+        net_box_uri = net_box_uri,
+        http_port = 0, -- unused
+    })
+    s:start()
+    t.helpers.retrying({}, function() s:connect_net_box() end)
+    t.assert_equals(s:exec(function() return box.cfg.listen end), net_box_uri)
+    s:stop()
+end
+
 g.test_server_start_with_coverage_enabled = function()
     t.skip_if(server.coverage_report, 'Coverage is already enabled. Nothing to test')
     server:restart({coverage_report = true})