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[gnulib.git] / lib / basename.c

diff --git a/lib/basename.c b/lib/basename.c
index 8d18a8f..426ed40 100644 (file)
--- a/lib/basename.c
+++ b/lib/basename.c
@@ -1,32 +1,128 @@
-/* basename.c -- return the last element in a path */
+/* basename.c -- return the last element in a file name
 
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+   Copyright (C) 1990, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006 Free
+   Software Foundation, Inc.
 
-#include <backupfile.h>
+   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 3 of the License, or
+   (at your option) any later version.
 
-#ifndef FILESYSTEM_PREFIX_LEN
-#define FILESYSTEM_PREFIX_LEN(f) 0
-#endif
+   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, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "dirname.h"
+
+#include <string.h>
+#include "xalloc.h"
+#include "xstrndup.h"
+
+/* Return the address of the last file name component of NAME.  If
+   NAME has no relative file name components because it is a file
+   system root, return the empty string.  */
+
+char *
+last_component (char const *name)
+{
+  char const *base = name + FILE_SYSTEM_PREFIX_LEN (name);
+  char const *p;
+  bool saw_slash = false;
+
+  while (ISSLASH (*base))
+    base++;
+
+  for (p = base; *p; p++)
+    {
+      if (ISSLASH (*p))
+       saw_slash = true;
+      else if (saw_slash)
+       {
+         base = p;
+         saw_slash = false;
+       }
+    }
+
+  return (char *) base;
+}
 
-#ifndef ISSLASH
-#define ISSLASH(c) ((c) == '/')
-#endif
 
 /* In general, we can't use the builtin `basename' function if available,
    since it has different meanings in different environments.
-   In some environments the builtin `basename' modifies its argument.  */
+   In some environments the builtin `basename' modifies its argument.
+
+   Return the last file name component of NAME, allocated with
+   xmalloc.  On systems with drive letters, a leading "./"
+   distinguishes relative names that would otherwise look like a drive
+   letter.  Unlike POSIX basename(), NAME cannot be NULL,
+   base_name("") returns "", and the first trailing slash is not
+   stripped.
+
+   If lstat (NAME) would succeed, then { chdir (dir_name (NAME));
+   lstat (base_name (NAME)); } will access the same file.  Likewise,
+   if the sequence { chdir (dir_name (NAME));
+   rename (base_name (NAME), "foo"); } succeeds, you have renamed NAME
+   to "foo" in the same directory NAME was in.  */
 
 char *
-base_name (name)
-     char const *name;
+base_name (char const *name)
 {
-  char const *base = name += FILESYSTEM_PREFIX_LEN (name);
+  char const *base = last_component (name);
+  size_t length;
 
-  for (; *name; name++)
-    if (ISSLASH (*name))
-      base = name + 1;
+  /* If there is no last component, then name is a file system root or the
+     empty string.  */
+  if (! *base)
+    return xstrndup (name, base_len (name));
 
-  return (char *) base;
+  /* Collapse a sequence of trailing slashes into one.  */
+  length = base_len (base);
+  if (ISSLASH (base[length]))
+    length++;
+
+  /* On systems with drive letters, `a/b:c' must return `./b:c' rather
+     than `b:c' to avoid confusion with a drive letter.  On systems
+     with pure POSIX semantics, this is not an issue.  */
+  if (FILE_SYSTEM_PREFIX_LEN (base))
+    {
+      char *p = xmalloc (length + 3);
+      p[0] = '.';
+      p[1] = '/';
+      memcpy (p + 2, base, length);
+      p[length + 2] = '\0';
+      return p;
+    }
+
+  /* Finally, copy the basename.  */
+  return xstrndup (base, length);
+}
+
+/* Return the length of the basename NAME.  Typically NAME is the
+   value returned by base_name or last_component.  Act like strlen
+   (NAME), except omit all trailing slashes.  */
+
+size_t
+base_len (char const *name)
+{
+  size_t len;
+  size_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
+
+  for (len = strlen (name);  1 < len && ISSLASH (name[len - 1]);  len--)
+    continue;
+
+  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && len == 1
+      && ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2])
+    return 2;
+
+  if (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE && prefix_len
+      && len == prefix_len && ISSLASH (name[prefix_len]))
+    return prefix_len + 1;
+
+  return len;
 }