# HG changeset patch
# Parent  b47c6fffbd04edcc55de5424d38e8bacba811f68
When parsing addresses returned by accept(), etc., do not assume
null termination of sun_path in AF_UNIX addresses: rely instead
on the returned address length.  If this is longer then the
original buffer, ignore it and use the original length.

diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -983,13 +983,22 @@ makebdaddr(bdaddr_t *bdaddr)
 
 /*ARGSUSED*/
 static PyObject *
-makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
+makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, socklen_t addrlen,
+             socklen_t buflen, int proto)
 {
     if (addrlen == 0) {
         /* No address -- may be recvfrom() from known socket */
         Py_INCREF(Py_None);
         return Py_None;
     }
+    /* buflen is the length of the buffer containing the address, and
+       addrlen is either the same, or is the length returned by the OS
+       after writing an address into the buffer.  Some systems return
+       the length they would have written if there had been space
+       (e.g. when an oversized AF_UNIX address has its sun_path
+       truncated). */
+    if (addrlen > buflen)
+        addrlen = buflen;
 
     switch (addr->sa_family) {
 
@@ -1009,18 +1018,28 @@ makesockaddr(SOCKET_T sockfd, struct soc
 #if defined(AF_UNIX)
     case AF_UNIX:
     {
+        Py_ssize_t len, splen;
         struct sockaddr_un *a = (struct sockaddr_un *) addr;
+
+        if (addrlen < offsetof(struct sockaddr_un, sun_path))
+            Py_RETURN_NONE;
+        else
+            splen = addrlen - offsetof(struct sockaddr_un, sun_path);
 #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);
+        /* Backwards compatibility: return empty addresses as bytes */
+        if (splen == 0 || (splen > 0 && a->sun_path[0] == 0)) {
+            /* Linux abstract namespace */
+            return PyBytes_FromStringAndSize(a->sun_path, splen);
         }
         else
 #endif /* linux */
         {
-            /* regular NULL-terminated string */
-            return PyUnicode_DecodeFSDefault(a->sun_path);
+            /* Path text can occupy all of sun_path[], and therefore
+               lack null termination */
+            for (len = 0; len < splen && a->sun_path[len] != 0; len++)
+                ;
         }
+        return PyUnicode_DecodeFSDefaultAndSize(a->sun_path, len);
     }
 #endif /* AF_UNIX */
 
@@ -1952,6 +1971,7 @@ sock_accept(PySocketSockObject *s)
     sock_addr_t addrbuf;
     SOCKET_T newfd = INVALID_SOCKET;
     socklen_t addrlen;
+    socklen_t buflen;
     PyObject *sock = NULL;
     PyObject *addr = NULL;
     PyObject *res = NULL;
@@ -1963,6 +1983,7 @@ sock_accept(PySocketSockObject *s)
 
     if (!getsockaddrlen(s, &addrlen))
         return NULL;
+    buflen = addrlen;
     memset(&addrbuf, 0, addrlen);
 
     if (!IS_SELECTABLE(s))
@@ -2025,7 +2046,7 @@ sock_accept(PySocketSockObject *s)
     }
 
     addr = makesockaddr(s->sock_fd, SAS2SA(&addrbuf),
-                        addrlen, s->sock_proto);
+                        addrlen, buflen, s->sock_proto);
     if (addr == NULL)
         goto finally;
 
@@ -2469,16 +2490,18 @@ sock_getsockname(PySocketSockObject *s)
     sock_addr_t addrbuf;
     int res;
     socklen_t addrlen;
+    socklen_t buflen;
 
     if (!getsockaddrlen(s, &addrlen))
         return NULL;
+    buflen = addrlen;
     memset(&addrbuf, 0, addrlen);
     Py_BEGIN_ALLOW_THREADS
     res = getsockname(s->sock_fd, SAS2SA(&addrbuf), &addrlen);
     Py_END_ALLOW_THREADS
     if (res < 0)
         return s->errorhandler();
-    return makesockaddr(s->sock_fd, SAS2SA(&addrbuf), addrlen,
+    return makesockaddr(s->sock_fd, SAS2SA(&addrbuf), addrlen, buflen,
                         s->sock_proto);
 }
 
@@ -2498,16 +2521,18 @@ sock_getpeername(PySocketSockObject *s)
     sock_addr_t addrbuf;
     int res;
     socklen_t addrlen;
+    socklen_t buflen;
 
     if (!getsockaddrlen(s, &addrlen))
         return NULL;
+    buflen = addrlen;
     memset(&addrbuf, 0, addrlen);
     Py_BEGIN_ALLOW_THREADS
     res = getpeername(s->sock_fd, SAS2SA(&addrbuf), &addrlen);
     Py_END_ALLOW_THREADS
     if (res < 0)
         return s->errorhandler();
-    return makesockaddr(s->sock_fd, SAS2SA(&addrbuf), addrlen,
+    return makesockaddr(s->sock_fd, SAS2SA(&addrbuf), addrlen, buflen,
                         s->sock_proto);
 }
 
@@ -2736,11 +2761,13 @@ sock_recvfrom_guts(PySocketSockObject *s
     int timeout;
     Py_ssize_t n = -1;
     socklen_t addrlen;
+    socklen_t buflen;
 
     *addr = NULL;
 
     if (!getsockaddrlen(s, &addrlen))
         return -1;
+    buflen = addrlen;
 
     if (!IS_SELECTABLE(s)) {
         select_error();
@@ -2775,7 +2802,7 @@ sock_recvfrom_guts(PySocketSockObject *s
     }
 
     if (!(*addr = makesockaddr(s->sock_fd, SAS2SA(&addrbuf),
-                               addrlen, s->sock_proto)))
+                               addrlen, buflen, s->sock_proto)))
         return -1;
 
     return n;
@@ -3011,8 +3038,7 @@ sock_recvmsg_guts(PySocketSockObject *s,
                            cmsg_list,
                            (int)msg.msg_flags,
                            makesockaddr(s->sock_fd, SAS2SA(&addrbuf),
-                                        ((msg.msg_namelen > addrbuflen) ?
-                                         addrbuflen : msg.msg_namelen),
+                                        msg.msg_namelen, addrbuflen,
                                         s->sock_proto));
     if (retval == NULL)
         goto err_closefds;
@@ -5264,7 +5290,8 @@ socket_getaddrinfo(PyObject *self, PyObj
     for (res = res0; res; res = res->ai_next) {
         PyObject *single;
         PyObject *addr =
-            makesockaddr(-1, res->ai_addr, res->ai_addrlen, protocol);
+            makesockaddr(-1, res->ai_addr, res->ai_addrlen, res->ai_addrlen,
+                         protocol);
         if (addr == NULL)
             goto err;
         single = Py_BuildValue("iiisO", res->ai_family,