1 files changed, 73 insertions, 0 deletions
diff --git a/lib/concat-filename.c b/lib/concat-filename.c
new file mode 100644
index 000000000..f05484904
--- /dev/null
+++ b/lib/concat-filename.c
@@ -0,0 +1,73 @@
+/* Construct a full filename from a directory and a relative filename.
+   Copyright (C) 2001-2004, 2006-2022 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <haible@clisp.cons.org>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "concat-filename.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "filename.h"
+
+/* Concatenate a directory filename, a relative filename and an optional
+   suffix.  The directory may end with the directory separator.  The second
+   argument may not start with the directory separator (it is relative).
+   Return a freshly allocated filename.  Return NULL and set errno
+   upon memory allocation failure.  */
+char *
+concatenated_filename (const char *directory, const char *filename,
+                       const char *suffix)
+{
+  char *result;
+  char *p;
+
+  if (strcmp (directory, ".") == 0)
+    {
+      /* No need to prepend the directory.  */
+      result = (char *) malloc (strlen (filename)
+                                + (suffix != NULL ? strlen (suffix) : 0)
+                                + 1);
+      if (result == NULL)
+        return NULL; /* errno is set here */
+      p = result;
+    }
+  else
+    {
+      size_t directory_len = strlen (directory);
+      int need_slash =
+        (directory_len > FILE_SYSTEM_PREFIX_LEN (directory)
+         && !ISSLASH (directory[directory_len - 1]));
+      result = (char *) malloc (directory_len + need_slash
+                                + strlen (filename)
+                                + (suffix != NULL ? strlen (suffix) : 0)
+                                + 1);
+      if (result == NULL)
+        return NULL; /* errno is set here */
+      memcpy (result, directory, directory_len);
+      p = result + directory_len;
+      if (need_slash)
+        *p++ = '/';
+    }
+  p = stpcpy (p, filename);
+  if (suffix != NULL)
+    stpcpy (p, suffix);
+  return result;
+}