* modules/extensions (License): Change to LGPL.

[gnulib.git] / lib / path-concat.c

diff --git a/lib/path-concat.c b/lib/path-concat.c
index ce74ed1..6e40922 100644 (file)
--- a/lib/path-concat.c
+++ b/lib/path-concat.c
@@ -1,5 +1,7 @@
 /* path-concat.c -- concatenate two arbitrary pathnames
-   Copyright (C) 1996 Free Software Foundation, Inc.
+
+   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
@@ -17,42 +19,108 @@
 
 /* Written by Jim Meyering.  */
 
-#ifdef HAVE_CONFIG_H
-#include <config.h>
+#if HAVE_CONFIG_H
+# include <config.h>
 #endif
 
-char *malloc ();
-char *stpcpy ();
+/* Specification.  */
+#include "path-concat.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 pathname components, DIR and BASE, in newly-allocated
-   storage and return the result.  Return 0 if out of memory.  Add a slash
-   between DIR and BASE in the result if neither would contribute one.
-   If each would contribute at least one, elide one from the end of DIR.
-   Otherwise, simply concatenate DIR and BASE.  In any case, if
-   BASE_IN_RESULT is non-NULL, set *BASE_IN_RESULT to point to the copy of
-   BASE in the returned concatenation.  */
+/* Concatenate two pathname 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 *
-path_concat (const char *dir, const char *base, char **base_in_result)
+path_concat (char const *dir, char const *abase, char **base_in_result)
 {
-  char *p;
-  char *p_concat;
+  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]));
 
-  p_concat = malloc (strlen (dir) + strlen (base) + 2);
-  if (!p_concat)
-    return 0;
+  char const *base = longest_relative_suffix (abase);
+  size_t baselen = strlen (base);
 
-  p = stpcpy (p_concat, dir);
+  char *p_concat = xmalloc (dirlen + needs_separator + baselen + 1);
+  char *p;
 
-  if (*(p - 1) == '/' && *base == '/')
-    --p;
-  else if (*(p - 1) != '/' && *base != '/')
-    p = stpcpy (p, "/");
+  p = mempcpy (p_concat, dir, dirlen);
+  *p = DIRECTORY_SEPARATOR;
+  p += needs_separator;
 
   if (base_in_result)
-    *base_in_result = p;
+    *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
 
-  stpcpy (p, base);
+  p = mempcpy (p, base, baselen);
+  *p = '\0';
 
   return p_concat;
 }
+
+#ifdef TEST_PATH_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 = path_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