[PATCH] runtests: check ports on IPv6 address

[Jun Wu]

# HG changeset patch
# User Jun Wu <quark at fb.com>
# Date 1486648674 28800
#      Thu Feb 09 05:57:54 2017 -0800
# Node ID 93e23f7b87a4ab456053b6ba573615be16c6c4b0
# Parent  a68510b69f413545722c086eaeb840dd5e8305b4
# Available At https://bitbucket.org/quark-zju/hg-draft
#              hg pull https://bitbucket.org/quark-zju/hg-draft -r 93e23f7b87a4
runtests: check ports on IPv6 address

Previously, checkportisavailable only checks ports on the IPv4 address. This
patch makes it check IPv6 as well. It'll be useful if "localhost" does not
have an IPv4 address, or its IPv4 address does not exist somehow.

diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -115,13 +115,17 @@ wifexited = getattr(os, "WIFEXITED", lam
 def checkportisavailable(port):
     """return true if a port seems free to bind on localhost"""
-    try:
-        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        s.bind(('localhost', port))
-        s.close()
-        return True
-    except socket.error as exc:
-        if not exc.errno == errno.EADDRINUSE:
-            raise
-        return False
+    families = [getattr(socket, i, None)
+                for i in ('AF_INET', 'AF_INET6')
+                if getattr(socket, i, None) is not None]
+    for family in families:
+        try:
+            s = socket.socket(family, socket.SOCK_STREAM)
+            s.bind(('localhost', port))
+            s.close()
+            return True
+        except socket.error as exc:
+            if exc.errno not in (errno.EADDRINUSE, errno.EADDRNOTAVAIL):
+                raise
+    return False
 
 closefds = os.name == 'posix'