---
 unix/init.c  |   16 ++++++++++++++--
 unix/spawn.c |   18 +++++++++++++++---
 unix/uid.c   |   11 +++++++++++
 3 files changed, 40 insertions(+), 5 deletions(-)

--- unix/init.c
+++ unix/init.c	2017-04-01 08:29:41.877900913 +0000
@@ -30,6 +30,7 @@
 #include "sysdep.h"
 
 #include <errno.h>
+#include <grp.h>
 #include <pwd.h>
 
 #if HAVE_FCNTL_H
@@ -272,7 +273,11 @@ usysdep_initialize (puuconf,iflags)
     {
       q = getpwnam (OWNER);
       if (q != NULL)
-	setuid (q->pw_uid);
+	{
+	  if (q->pw_name)
+	    initgroups (q->pw_name, q->pw_gid);
+	  setuid (q->pw_uid);
+	}
     }
 
   if ((iflags & INIT_GETCWD) != 0)
@@ -370,7 +375,14 @@ usysdep_exit (fsuccess)
 boolean fsysdep_other_config (z)
      const char *z ATTRIBUTE_UNUSED;
 {
-  (void) setuid (getuid ());
+  struct passwd *q;
+  uid_t uid = getuid ();
+
+  q = getpwuid (uid);
+  if (q && q->pw_name)
+    initgroups (q->pw_name, q->pw_gid);
+
+  (void) setuid (uid);
   (void) setgid (getgid ());
   return TRUE;
 }
--- unix/spawn.c
+++ unix/spawn.c	2017-04-01 08:11:14.802602723 +0000
@@ -28,6 +28,8 @@
 #include "sysdep.h"
 
 #include <errno.h>
+#include <grp.h>
+#include <pwd.h>
 
 #if HAVE_FCNTL_H
 #include <fcntl.h>
@@ -113,6 +115,8 @@ ixsspawn (pazargs, aidescs, fkeepuid, fk
   int aichild_close[3];
   pid_t iret = 0;
   const char *zcmd;
+  uid_t uid;
+  struct passwd *pw;
 
   /* If we might have to use the shell, allocate enough space for the
      quoted command before forking.  Otherwise the allocation would
@@ -352,7 +356,11 @@ ixsspawn (pazargs, aidescs, fkeepuid, fk
   if (! fkeepuid)
     {
       /* Return to the uid of the invoking user.  */
-      (void) setuid (getuid ());
+      uid = getuid ();
+      pw = getpwuid (uid);
+      if (pw && pw->pw_name)
+	initgroups (pw->pw_name, pw->pw_gid);
+      (void) setuid (uid);
       (void) setgid (getgid ());
     }
   else
@@ -368,11 +376,15 @@ ixsspawn (pazargs, aidescs, fkeepuid, fk
 	 Fixing this problem would seem to require a special setuid
 	 root program; I have not used this approach because
 	 modern systems should not suffer from it.  */
+      uid = geteuid ();
+      pw = getpwuid (uid);
+      if (pw && pw->pw_name)
+	initgroups (pw->pw_name, pw->pw_gid);
 #if HAVE_SETREUID
-      (void) setreuid (geteuid (), -1);
+      (void) setreuid (uid, -1);
       (void) setregid (getegid (), -1);
 #else
-      (void) setuid (geteuid ());
+      (void) setuid (uid);
       (void) setgid (getegid ());
 #endif
     }
--- unix/uid.c
+++ unix/uid.c	2017-04-01 08:31:20.292059493 +0000
@@ -28,6 +28,8 @@
 #include "sysdep.h"
 
 #include <errno.h>
+#include <grp.h>
+#include <pwd.h>
 
 /* NetBSD apparently does not support setuid as required by POSIX when
    using saved setuid, so use seteuid instead.  */
@@ -45,6 +47,7 @@ fsuser_perms (pieuid, piegid)
 {
   uid_t ieuid, iuid;
   gid_t iegid, igid;
+  struct passwd *pw;
 
   ieuid = geteuid ();
   iuid = getuid ();
@@ -57,6 +60,14 @@ fsuser_perms (pieuid, piegid)
     *piegid = iegid;
 
 #if HAVE_SETREUID
+  pw = getpwuid (ieuid);
+#else
+  pw = getpwuid (iuid);
+#endif
+  if (pw && pw->pw_name)
+    initgroups (pw->pw_name, pw->pw_gid);
+
+#if HAVE_SETREUID
   /* Swap the effective user id and the real user id.  We can then
      swap them back again when we want to return to the uucp user's
      permissions.  */