Added core.sys.posix.grp (from Posix <grp.h>).

No Solaris declarations for now.

src/core/sys/posix/grp.d

@@ -0,0 +1,86 @@
+/**
+ * D header file for POSIX.
+ *
+ * Copyright: Copyright Sean Kelly 2005 - 2009, Sönke Ludwig 2013.
+ * License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
+ * Authors:   Sean Kelly, Alex Rønne Petersen, Sönke Ludwig
+ * Standards: The Open Group Base Specifications Issue 6, IEEE Std 1003.1, 2004 Edition
+ */
+
+/*          Copyright Sean Kelly 2005 - 2009.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE or copy at
+ *          http://www.boost.org/LICENSE_1_0.txt)
+ */
+module core.sys.posix.grp;
+
+private import core.sys.posix.config;
+public import core.sys.posix.sys.types; // for gid_t, uid_t
+
+version (Posix):
+extern (C):
+
+//
+// Required
+//
+/*
+struct group
+{
+    char*   gr_name;
+    char*   gr_passwd;
+    gid_t   gr_gid;
+    char**  gr_mem;
+}
+
+group* getgrnam(in char*);
+group* getgrgid(gid_t);
+*/
+
+version( linux )
+{
+    struct group
+    {
+        char*   gr_name;
+        char*   gr_passwd;
+        gid_t   gr_gid;
+        char**  gr_mem;
+    }
+}
+else version( OSX )
+{
+    struct group
+    {
+        char*   gr_name;
+        char*   gr_passwd;
+        gid_t   gr_gid;
+        char**  gr_mem;
+    }
+}
+else version( FreeBSD )
+{
+    struct group
+    {
+        char*   gr_name;
+        char*   gr_passwd;
+        gid_t   gr_gid;
+        char**  gr_mem;
+    }
+}
+else
+{
+    static assert(false, "Unsupported platform");
+}
+
+group* getgrnam(in char*);
+group* getgruid(uid_t);
+
+//
+// Thread-Safe Functions (TSF)
+//
+/*
+int getgrnam_r(in char*, group*, char*, size_t, group**);
+int getgruid_r(gid_t, group*, char*, size_t, group**);
+*/
+
+int getgrnam_r(in char*, group*, char*, size_t, group**);
+int getgruid_r(gid_t, group*, char*, size_t, group**);