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 3 of the License, or 9 (at your option) 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, see <http://www.gnu.org/licenses/>. */ 18 19 #include <config.h> 20 21 #include "dirname.h" 22 23 #include <string.h> 24 #include "xalloc.h" 25 #include "xstrndup.h" 26 27 /* Return the address of the last file name component of NAME. If 28 NAME has no relative file name components because it is a file 29 system root, return the empty string. */ 30 31 char * 32 last_component (char const *name) 33 { 34 char const *base = name + FILE_SYSTEM_PREFIX_LEN (name); 35 char const *p; 36 bool saw_slash = false; 37 38 while (ISSLASH (*base)) 39 base++; 40 41 for (p = base; *p; p++) 42 { 43 if (ISSLASH (*p)) 44 saw_slash = true; 45 else if (saw_slash) 46 { 47 base = p; 48 saw_slash = false; 49 } 50 } 51 52 return (char *) base; 53 } 54 55 56 /* In general, we can't use the builtin `basename' function if available, 57 since it has different meanings in different environments. 58 In some environments the builtin `basename' modifies its argument. 59 60 Return the last file name component of NAME, allocated with 61 xmalloc. On systems with drive letters, a leading "./" 62 distinguishes relative names that would otherwise look like a drive 63 letter. Unlike POSIX basename(), NAME cannot be NULL, 64 base_name("") returns "", and the first trailing slash is not 65 stripped. 66 67 If lstat (NAME) would succeed, then { chdir (dir_name (NAME)); 68 lstat (base_name (NAME)); } will access the same file. Likewise, 69 if the sequence { chdir (dir_name (NAME)); 70 rename (base_name (NAME), "foo"); } succeeds, you have renamed NAME 71 to "foo" in the same directory NAME was in. */ 72 73 char * 74 base_name (char const *name) 75 { 76 char const *base = last_component (name); 77 size_t length; 78 79 /* If there is no last component, then name is a file system root or the 80 empty string. */ 81 if (! *base) 82 return xstrndup (name, base_len (name)); 83 84 /* Collapse a sequence of trailing slashes into one. */ 85 length = base_len (base); 86 if (ISSLASH (base[length])) 87 length++; 88 89 /* On systems with drive letters, `a/b:c' must return `./b:c' rather 90 than `b:c' to avoid confusion with a drive letter. On systems 91 with pure POSIX semantics, this is not an issue. */ 92 if (FILE_SYSTEM_PREFIX_LEN (base)) 93 { 94 char *p = xmalloc (length + 3); 95 p[0] = '.'; 96 p[1] = '/'; 97 memcpy (p + 2, base, length); 98 p[length + 2] = '\0'; 99 return p; 100 } 101 102 /* Finally, copy the basename. */ 103 return xstrndup (base, length); 104 } 105 106 /* Return the length of the basename NAME. Typically NAME is the 107 value returned by base_name or last_component. Act like strlen 108 (NAME), except omit all trailing slashes. */ 109 110 size_t 111 base_len (char const *name) 112 { 113 size_t len; 114 size_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name); 115 116 for (len = strlen (name); 1 < len && ISSLASH (name[len - 1]); len--) 117 continue; 118 119 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && len == 1 120 && ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2]) 121 return 2; 122 123 if (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE && prefix_len 124 && len == prefix_len && ISSLASH (name[prefix_len])) 125 return prefix_len + 1; 126 127 return len; 128 } 129
