From 5114d70be6c52e2fb793b2f5ee4fe5871276804c Mon Sep 17 00:00:00 2001
From: Giel van Schijndel <me@mortis.eu>
Date: Wed, 9 Jul 2014 22:15:57 +0200
Subject: [PATCH] unix connect/bind: compute addr size the same regardless of
 extra fields

I.e. taking a Unix sockaddr's maximum size, subtracting the one variable
field's max size and adding the size of that field's content gets us the
actual size anytime. This gives us less duplication and only a single
piece of code used across all Unices: i.e. the same code gets tested on
all.

In particular the current makefile, when used on FreeBSD (which *does*
have the sun_len field, but appears to ignore its contents) the
addr-length passed to connect() and bind() is one to small because the
sun_len field's space is neglected in the previous size computation.
This change removes the unnecessary dependency on the build system for
the correctness of the addr length computation.

Signed-off-by: Giel van Schijndel <me@mortis.eu>
---
 src/unix.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/src/unix.c b/src/unix.c
index 91aaaf8..76104fb 100644
--- a/src/unix.c
+++ b/src/unix.c
@@ -191,20 +191,17 @@ static int meth_accept(lua_State *L) {
 static const char *unix_trybind(p_unix un, const char *path) {
     struct sockaddr_un local;
     size_t len = strlen(path);
+    size_t addrlen;
     int err;
     if (len >= sizeof(local.sun_path)) return "path too long";
     memset(&local, 0, sizeof(local));
     strcpy(local.sun_path, path);
     local.sun_family = AF_UNIX;
+    addrlen = sizeof(local) - sizeof(local.sun_path) + len;
 #ifdef UNIX_HAS_SUN_LEN
-    local.sun_len = sizeof(local.sun_family) + sizeof(local.sun_len) 
-        + len + 1;
-    err = socket_bind(&un->sock, (SA *) &local, local.sun_len);
-
-#else 
-    err = socket_bind(&un->sock, (SA *) &local, 
-            sizeof(local.sun_family) + len);
+    local.sun_len = addrlen + 1;
 #endif
+    err = socket_bind(&un->sock, (SA *) &local, addrlen);
     if (err != IO_DONE) socket_destroy(&un->sock);
     return socket_strerror(err); 
 }
@@ -229,20 +226,18 @@ static const char *unix_tryconnect(p_unix un, const char *path)
 {
     struct sockaddr_un remote;
     int err;
+    size_t addrlen;
     size_t len = strlen(path);
     if (len >= sizeof(remote.sun_path)) return "path too long";
     memset(&remote, 0, sizeof(remote));
     strcpy(remote.sun_path, path);
     remote.sun_family = AF_UNIX;
     timeout_markstart(&un->tm);
+    addrlen = sizeof(remote) - sizeof(remote.sun_path) + len;
 #ifdef UNIX_HAS_SUN_LEN
-    remote.sun_len = sizeof(remote.sun_family) + sizeof(remote.sun_len) 
-        + len + 1;
-    err = socket_connect(&un->sock, (SA *) &remote, remote.sun_len, &un->tm);
-#else
-    err = socket_connect(&un->sock, (SA *) &remote, 
-            sizeof(remote.sun_family) + len, &un->tm);
+    remote.sun_len = addrlen + 1;
 #endif
+    err = socket_connect(&un->sock, (SA *) &remote, addrlen, &un->tm);
     if (err != IO_DONE) socket_destroy(&un->sock);
     return socket_strerror(err);
 }