1 files changed, 126 insertions, 0 deletions
diff --git a/lib/filenamecat.c b/lib/filenamecat.c
new file mode 100644
index 0000000..f947346
--- /dev/null
+++ b/lib/filenamecat.c
@@ -0,0 +1,126 @@
+/* Concatenate two arbitrary file names.
+
+   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free
+   Software Foundation, Inc.
+
+   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, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Jim Meyering.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Specification.  */
+#include "filenamecat.h"
+
+#include <string.h>
+
+#include "dirname.h"
+#include "xalloc.h"
+
+#if ! HAVE_MEMPCPY && ! defined mempcpy
+# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
+#endif
+
+/* Return the longest suffix of F that is a relative file name.
+   If it has no such suffix, return the empty string.  */
+
+static char const *
+longest_relative_suffix (char const *f)
+{
+  for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
+    continue;
+  return f;
+}
+
+/* Concatenate two file name components, DIR and ABASE, in
+   newly-allocated storage and return the result.
+   The resulting file name F is such that the commands "ls F" and "(cd
+   DIR; ls BASE)" refer to the same file, where BASE is ABASE with any
+   file system prefixes and leading separators removed.
+   Arrange for a directory separator if necessary between DIR and BASE
+   in the result, removing any redundant separators.
+   In any case, if BASE_IN_RESULT is non-NULL, set
+   *BASE_IN_RESULT to point to the copy of ABASE in the returned
+   concatenation.  However, if ABASE begins with more than one slash,
+   set *BASE_IN_RESULT to point to the sole corresponding slash that
+   is copied into the result buffer.
+
+   Report an error if memory is exhausted.  */
+
+char *
+file_name_concat (char const *dir, char const *abase, char **base_in_result)
+{
+  char const *dirbase = base_name (dir);
+  size_t dirbaselen = base_len (dirbase);
+  size_t dirlen = dirbase - dir + dirbaselen;
+  size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
+
+  char const *base = longest_relative_suffix (abase);
+  size_t baselen = strlen (base);
+
+  char *p_concat = xmalloc (dirlen + needs_separator + baselen + 1);
+  char *p;
+
+  p = mempcpy (p_concat, dir, dirlen);
+  *p = DIRECTORY_SEPARATOR;
+  p += needs_separator;
+
+  if (base_in_result)
+    *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
+
+  p = mempcpy (p, base, baselen);
+  *p = '\0';
+
+  return p_concat;
+}
+
+#ifdef TEST_FILE_NAME_CONCAT
+# include <stdlib.h>
+# include <stdio.h>
+int
+main ()
+{
+  static char const *const tests[][3] =
+    {
+      {"a", "b",   "a/b"},
+      {"a/", "b",  "a/b"},
+      {"a/", "/b", "a/b"},
+      {"a", "/b",  "a/b"},
+
+      {"/", "b",  "/b"},
+      {"/", "/b", "/b"},
+      {"/", "/",  "/"},
+      {"a", "/",  "a/"},   /* this might deserve a diagnostic */
+      {"/a", "/", "/a/"},  /* this might deserve a diagnostic */
+      {"a", "//b",  "a/b"},
+    };
+  size_t i;
+  bool fail = false;
+  for (i = 0; i < sizeof tests / sizeof tests[0]; i++)
+    {
+      char *base_in_result;
+      char const *const *t = tests[i];
+      char *res = file_name_concat (t[0], t[1], &base_in_result);
+      if (strcmp (res, t[2]) != 0)
+	{
+	  printf ("got %s, expected %s\n", res, t[2]);
+	  fail = true;
+	}
+    }
+  exit (fail ? EXIT_FAILURE : EXIT_SUCCESS);
+}
+#endif