+/*
+ * Empire - A multi-player, client/server Internet based war game.
+ * Copyright (C) 1986-2008, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ * Ken Stevens, Steve McClure
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * ---
+ *
+ * See files README, COPYING and CREDITS in the root of the source
+ * tree for related information and legal notices. It is expected
+ * that future projects/authors will amend these files as needed.
+ *
+ * ---
+ *
+ * fnameat.c: Interpret file names relative to a directory
+ *
+ * Known contributors to this file:
+ * Markus Armbruster, 2008
+ */
+
+#include <config.h>
+
+#include <errno.h>
+#include "prototypes.h"
+
+static int fname_is_abs(const char *);
+
+/*
+ * Interpret FNAME relative to directory DIR.
+ * Return FNAME if it is absolute, or DIR is null or empty.
+ * Else return a malloc'ed string containing DIR/FNAME, or null
+ * pointer when that fails.
+ */
+char *
+fnameat(const char *fname, const char *dir)
+{
+ char *res;
+
+ if (fname_is_abs(fname) || !dir || !*dir)
+ return (char *)fname;
+
+ res = malloc(strlen(dir) + 1 + strlen(fname) + 1);
+ if (!res)
+ return NULL;
+
+ sprintf(res, "%s/%s", dir, fname);
+ return res;
+}
+
+static int
+fname_is_abs(const char *fname)
+{
+#ifdef _WIN32
+ /* Treat as absolute if it starts with '/', '\\' or a drive */
+ return fname[0] == '/' || fname[0] == '\\'
+ || (fname[0] != 0 && fname[1] == ':');
+#else
+ return fname[0] == '/';
+#endif
+}