passfd: Fix test failure on FreeBSD >= 12 and NetBSD in 64-bit mode.

* lib/passfd.c (recvfd): Use the CMSG_SPACE macro to compute the value
for msg_controllen.

2 files changed, 15 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 000690dd55..44d5dd70d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2021-02-16  Bruno Haible  <bruno@clisp.org>
+
+	passfd: Fix test failure on FreeBSD >= 12 and NetBSD in 64-bit mode.
+	* lib/passfd.c (recvfd): Use the CMSG_SPACE macro to compute the value
+	for msg_controllen.
+
 2021-02-16  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Port better to macOS Mojave
diff --git a/lib/passfd.c b/lib/passfd.c
index ca10ba584b..a993f39537 100644
--- a/lib/passfd.c
+++ b/lib/passfd.c
@@ -142,19 +142,23 @@ recvfd (int sock, int flags)
   cmsg->cmsg_len = CMSG_LEN (sizeof fd);
   /* Initialize the payload: */
   memcpy (CMSG_DATA (cmsg), &fd, sizeof fd);
-  msg.msg_controllen = cmsg->cmsg_len;
+  msg.msg_controllen = CMSG_SPACE (sizeof fd);
 
   len = recvmsg (sock, &msg, flags_recvmsg);
   if (len < 0)
     return -1;
-
+  if (len == 0)
+    {
+      /* fake errno: at end the file is not available */
+      errno = ENOTCONN;
+      return -1;
+    }
   cmsg = CMSG_FIRSTHDR (&msg);
   /* be paranoiac */
-  if (len == 0 || cmsg == NULL || cmsg->cmsg_len != CMSG_LEN (sizeof fd)
+  if (cmsg == NULL || cmsg->cmsg_len != CMSG_LEN (sizeof fd)
       || cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
     {
-      /* fake errno: at end the file is not available */
-      errno = len ? EACCES : ENOTCONN;
+      errno = EACCES;
       return -1;
     }