| 1 | /* dirname.c -- return all but the last element in a file name |
| 2 | |
| 3 | Copyright (C) 1990, 1998, 2000-2001, 2003-2006, 2009-2020 Free Software |
| 4 | 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 <https://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <config.h> |
| 20 | |
| 21 | #include "dirname.h" |
| 22 | |
| 23 | #include <stdlib.h> |
| 24 | #include <string.h> |
| 25 | |
| 26 | /* Return the length of the prefix of FILE that will be used by |
| 27 | dir_name. If FILE is in the working directory, this returns zero |
| 28 | even though 'dir_name (FILE)' will return ".". Works properly even |
| 29 | if there are trailing slashes (by effectively ignoring them). */ |
| 30 | |
| 31 | size_t |
| 32 | dir_len (char const *file) |
| 33 | { |
| 34 | size_t prefix_length = FILE_SYSTEM_PREFIX_LEN (file); |
| 35 | size_t length; |
| 36 | |
| 37 | /* Advance prefix_length beyond important leading slashes. */ |
| 38 | prefix_length += (prefix_length != 0 |
| 39 | ? (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE |
| 40 | && ISSLASH (file[prefix_length])) |
| 41 | : (ISSLASH (file[0]) |
| 42 | ? ((DOUBLE_SLASH_IS_DISTINCT_ROOT |
| 43 | && ISSLASH (file[1]) && ! ISSLASH (file[2]) |
| 44 | ? 2 : 1)) |
| 45 | : 0)); |
| 46 | |
| 47 | /* Strip the basename and any redundant slashes before it. */ |
| 48 | for (length = last_component (file) - file; |
| 49 | prefix_length < length; length--) |
| 50 | if (! ISSLASH (file[length - 1])) |
| 51 | break; |
| 52 | return length; |
| 53 | } |
| 54 | |
| 55 | |
| 56 | /* In general, we can't use the builtin 'dirname' function if available, |
| 57 | since it has different meanings in different environments. |
| 58 | In some environments the builtin 'dirname' modifies its argument. |
| 59 | |
| 60 | Return the leading directories part of FILE, allocated with malloc. |
| 61 | Works properly even if there are trailing slashes (by effectively |
| 62 | ignoring them). Return NULL on failure. |
| 63 | |
| 64 | If lstat (FILE) would succeed, then { chdir (dir_name (FILE)); |
| 65 | lstat (base_name (FILE)); } will access the same file. Likewise, |
| 66 | if the sequence { chdir (dir_name (FILE)); |
| 67 | rename (base_name (FILE), "foo"); } succeeds, you have renamed FILE |
| 68 | to "foo" in the same directory FILE was in. */ |
| 69 | |
| 70 | char * |
| 71 | mdir_name (char const *file) |
| 72 | { |
| 73 | size_t length = dir_len (file); |
| 74 | bool append_dot = (length == 0 |
| 75 | || (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE |
| 76 | && length == FILE_SYSTEM_PREFIX_LEN (file) |
| 77 | && file[2] != '\0' && ! ISSLASH (file[2]))); |
| 78 | char *dir = malloc (length + append_dot + 1); |
| 79 | if (!dir) |
| 80 | return NULL; |
| 81 | memcpy (dir, file, length); |
| 82 | if (append_dot) |
| 83 | dir[length++] = '.'; |
| 84 | dir[length] = '\0'; |
| 85 | return dir; |
| 86 | } |