* grp.cc (read_etc_group): When emulating nonexisting group file on

	NT systems, read primary group SID from process token.  Use that info
	to create correct group entry.  On error or on 9x systems fallback
	to emulating Administrators group as before.
	(read_etc_passwd): When emulating nonexisting passwd file on NT systems,
	read user and primary group SID from process token.  Use that info to
	create correct passwd entry.  On error or on 9x systems fallback to
	emulating user with Administrator user id and Administrators group
	as before.

1 files changed, 41 insertions, 11 deletions

diff --git a/winsup/cygwin/grp.cc b/winsup/cygwin/grp.cc
index 13f74dd64..25d2ff864 100644
--- a/winsup/cygwin/grp.cc
+++ b/winsup/cygwin/grp.cc
@@ -171,19 +171,49 @@ read_etc_group ()
 	  SID_NAME_USE acType;
 	  static char linebuf [200];
 
-	  debug_printf ("Emulating /etc/group");
-	  strncpy (group_name, "Administrators", sizeof (group_name));
-	  if (! LookupAccountSidA (NULL, well_known_admins_sid, group_name,
-				   &group_name_len, domain_name,
-				   &domain_name_len, &acType))
+	  if (wincap.has_security ())
 	    {
-	      strcpy (group_name, "unknown");
-	      debug_printf ("Failed to get local admins group name. %E");
+	      HANDLE ptok;
+	      cygsid tg;
+	      DWORD siz;
+
+	      if (OpenProcessToken (GetCurrentProcess (), TOKEN_QUERY, &ptok))
+	        {
+		  if (GetTokenInformation (ptok, TokenPrimaryGroup, &tg,
+					   sizeof tg, &siz)
+		      && LookupAccountSidA (NULL, tg, group_name,
+					    &group_name_len, domain_name,
+				            &domain_name_len, &acType))
+		    {
+		      char strbuf[100];
+		      snprintf (linebuf, sizeof (linebuf), "%s:%s:%u:",
+		      		group_name, 
+				tg.string (strbuf),
+				*GetSidSubAuthority(tg,
+				             *GetSidSubAuthorityCount(tg) - 1));
+		      debug_printf ("Emulating /etc/group: %s", linebuf);
+		      add_grp_line (linebuf);
+		      group_state = emulated;
+		    }
+		  CloseHandle (ptok);
+		}
+	    }
+	  if (group_state != emulated)
+	    {
+	      strncpy (group_name, "Administrators", sizeof (group_name));
+	      if (!LookupAccountSidA (NULL, well_known_admins_sid, group_name,
+				      &group_name_len, domain_name,
+				      &domain_name_len, &acType))
+		{
+		  strcpy (group_name, "unknown");
+		  debug_printf ("Failed to get local admins group name. %E");
+		}
+	      snprintf (linebuf, sizeof (linebuf), "%s::%u:", group_name,
+			(unsigned) DEFAULT_GID);
+	      debug_printf ("Emulating /etc/group: %s", linebuf);
+	      add_grp_line (linebuf);
+	      group_state = emulated;
 	    }
-	  snprintf (linebuf, sizeof (linebuf), "%s::%u:\n", group_name,
-		    (unsigned) DEFAULT_GID);
-	  add_grp_line (linebuf);
-	  group_state = emulated;
 	}
     }