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/* basename.c -- return the last element in a file name
Copyright (C) 1990, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006 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
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. */
#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))
for (p = base; *p; p++)
if (ISSLASH (*p))
saw_slash = true;
else if (saw_slash)
base = p;
saw_slash = false;
return (char *) base;
/* 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.
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
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 (char const *name)
char const *base = last_component (name);
size_t length;
/* 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));
/* Collapse a sequence of trailing slashes into one. */
length = base_len (base);
if (ISSLASH (base[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. */
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. */
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--)
&& ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2])
return 2;
&& len == prefix_len && ISSLASH (name[prefix_len]))
return prefix_len + 1;
return len;