1/* basename.c -- return the last element in a file name
2
3   Copyright (C) 1990, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2006 Free
4   Software Foundation, Inc.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2, or (at your option)
9   any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software Foundation,
18   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
19
20#include <config.h>
21
22#include "dirname.h"
23
24#include <string.h>
25#include "xalloc.h"
26#include "xstrndup.h"
27
28/* Return the address of the last file name component of NAME.  If
29   NAME has no relative file name components because it is a file
30   system root, return the empty string.  */
31
32char *
33last_component (char const *name)
34{
35  char const *base = name + FILE_SYSTEM_PREFIX_LEN (name);
36  char const *p;
37  bool saw_slash = false;
38
39  while (ISSLASH (*base))
40    base++;
41
42  for (p = base; *p; p++)
43    {
44      if (ISSLASH (*p))
45	saw_slash = true;
46      else if (saw_slash)
47	{
48	  base = p;
49	  saw_slash = false;
50	}
51    }
52
53  return (char *) base;
54}
55
56
57/* In general, we can't use the builtin `basename' function if available,
58   since it has different meanings in different environments.
59   In some environments the builtin `basename' modifies its argument.
60
61   Return the last file name component of NAME, allocated with
62   xmalloc.  On systems with drive letters, a leading "./"
63   distinguishes relative names that would otherwise look like a drive
64   letter.  Unlike POSIX basename(), NAME cannot be NULL,
65   base_name("") returns "", and the first trailing slash is not
66   stripped.
67
68   If lstat (NAME) would succeed, then { chdir (dir_name (NAME));
69   lstat (base_name (NAME)); } will access the same file.  Likewise,
70   if the sequence { chdir (dir_name (NAME));
71   rename (base_name (NAME), "foo"); } succeeds, you have renamed NAME
72   to "foo" in the same directory NAME was in.  */
73
74char *
75base_name (char const *name)
76{
77  char const *base = last_component (name);
78  size_t length;
79
80  /* If there is no last component, then name is a file system root or the
81     empty string.  */
82  if (! *base)
83    return xstrndup (name, base_len (name));
84
85  /* Collapse a sequence of trailing slashes into one.  */
86  length = base_len (base);
87  if (ISSLASH (base[length]))
88    length++;
89
90  /* On systems with drive letters, `a/b:c' must return `./b:c' rather
91     than `b:c' to avoid confusion with a drive letter.  On systems
92     with pure POSIX semantics, this is not an issue.  */
93  if (FILE_SYSTEM_PREFIX_LEN (base))
94    {
95      char *p = xmalloc (length + 3);
96      p[0] = '.';
97      p[1] = '/';
98      memcpy (p + 2, base, length);
99      p[length + 2] = '\0';
100      return p;
101    }
102
103  /* Finally, copy the basename.  */
104  return xstrndup (base, length);
105}
106
107/* Return the length of the basename NAME.  Typically NAME is the
108   value returned by base_name or last_component.  Act like strlen
109   (NAME), except omit all trailing slashes.  */
110
111size_t
112base_len (char const *name)
113{
114  size_t len;
115  size_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
116
117  for (len = strlen (name);  1 < len && ISSLASH (name[len - 1]);  len--)
118    continue;
119
120  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && len == 1
121      && ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2])
122    return 2;
123
124  if (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE && prefix_len
125      && len == prefix_len && ISSLASH (name[prefix_len]))
126    return prefix_len + 1;
127
128  return len;
129}
130