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
32 char *
33 last_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
74 char *
75 base_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
111 size_t
112 base_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 }