Backport bpo-30205 to 3.5 (#1404)

pitrou · web-flow · commit 0d9d61828bbd · 2017-05-03T00:22:28.000+02:00
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
@@ -4589,6 +4589,10 @@ def bind(self, sock, path):
             else:
                 raise
 
+    def testUnbound(self):
+        # Issue #30205
+        self.assertIn(self.sock.getsockname(), (None, ''))
+
     def testStrAddr(self):
         # Test binding to and retrieving a normal string pathname.
         path = os.path.abspath(support.TESTFN)
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -49,6 +49,8 @@ Extension Modules
 Library
 -------
 
+- bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.
+
 - bpo-30070: Fixed leaks and crashes in errors handling in the parser module.
 
 - bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() when
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
@@ -1183,9 +1183,9 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
     {
         struct sockaddr_un *a = (struct sockaddr_un *) addr;
 #ifdef linux
-        if (a->sun_path[0] == 0) {  /* Linux abstract namespace */
-            addrlen -= offsetof(struct sockaddr_un, sun_path);
-            return PyBytes_FromStringAndSize(a->sun_path, addrlen);
+        size_t linuxaddrlen = addrlen - offsetof(struct sockaddr_un, sun_path);
+        if (linuxaddrlen > 0 && a->sun_path[0] == 0) {  /* Linux abstract namespace */
+            return PyBytes_FromStringAndSize(a->sun_path, linuxaddrlen);
         }
         else
 #endif /* linux */

Original file line number	Diff line number	Diff line change
`@@ -1183,9 +1183,9 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)`
`1183`	`1183`	`{`
`1184`	`1184`	`struct sockaddr_un a = (struct sockaddr_un ) addr;`
`1185`	`1185`	`#ifdef linux`
`1186`		`- if (a->sun_path[0] == 0) { /* Linux abstract namespace */`
`1187`		`- addrlen -= offsetof(struct sockaddr_un, sun_path);`
`1188`		`- return PyBytes_FromStringAndSize(a->sun_path, addrlen);`
	`1186`	`+ size_t linuxaddrlen = addrlen - offsetof(struct sockaddr_un, sun_path);`
	`1187`	`+ if (linuxaddrlen > 0 && a->sun_path[0] == 0) { /* Linux abstract namespace */`
	`1188`	`+ return PyBytes_FromStringAndSize(a->sun_path, linuxaddrlen);`
`1189`	`1189`	`}`
`1190`	`1190`	`else`
`1191`	`1191`	`#endif /* linux */`