| 1 | /* Concatenate two arbitrary file names. |
| 2 | |
| 3 | Copyright (C) 1996-2007, 2009-2020 Free Software Foundation, Inc. |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | /* Written by Jim Meyering. */ |
| 19 | |
| 20 | #include <config.h> |
| 21 | |
| 22 | /* Specification. */ |
| 23 | #include "filenamecat.h" |
| 24 | |
| 25 | #include <stdlib.h> |
| 26 | #include <string.h> |
| 27 | |
| 28 | #include "dirname.h" |
| 29 | |
| 30 | #if ! HAVE_MEMPCPY && ! defined mempcpy |
| 31 | # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N))) |
| 32 | #endif |
| 33 | |
| 34 | /* Concatenate two file name components, DIR and BASE, in |
| 35 | newly-allocated storage and return the result. |
| 36 | The resulting file name F is such that the commands "ls F" and "(cd |
| 37 | DIR; ls ./BASE)" refer to the same file. If necessary, put |
| 38 | a separator between DIR and BASE in the result. Typically this |
| 39 | separator is "/", but in rare cases it might be ".". |
| 40 | In any case, if BASE_IN_RESULT is non-NULL, set |
| 41 | *BASE_IN_RESULT to point to the copy of BASE at the end of the |
| 42 | returned concatenation. |
| 43 | |
| 44 | Return NULL if malloc fails. */ |
| 45 | |
| 46 | char * |
| 47 | mfile_name_concat (char const *dir, char const *base, char **base_in_result) |
| 48 | { |
| 49 | char const *dirbase = last_component (dir); |
| 50 | size_t dirbaselen = base_len (dirbase); |
| 51 | size_t dirlen = dirbase - dir + dirbaselen; |
| 52 | size_t baselen = strlen (base); |
| 53 | char sep = '\0'; |
| 54 | if (dirbaselen) |
| 55 | { |
| 56 | /* DIR is not a file system root, so separate with / if needed. */ |
| 57 | if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base)) |
| 58 | sep = '/'; |
| 59 | } |
| 60 | else if (ISSLASH (*base)) |
| 61 | { |
| 62 | /* DIR is a file system root and BASE begins with a slash, so |
| 63 | separate with ".". For example, if DIR is "/" and BASE is |
| 64 | "/foo" then return "/./foo", as "//foo" would be wrong on |
| 65 | some POSIX systems. A fancier algorithm could omit "." in |
| 66 | some cases but is not worth the trouble. */ |
| 67 | sep = '.'; |
| 68 | } |
| 69 | |
| 70 | char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1); |
| 71 | char *p; |
| 72 | |
| 73 | if (p_concat == NULL) |
| 74 | return NULL; |
| 75 | |
| 76 | p = mempcpy (p_concat, dir, dirlen); |
| 77 | *p = sep; |
| 78 | p += sep != '\0'; |
| 79 | |
| 80 | if (base_in_result) |
| 81 | *base_in_result = p; |
| 82 | |
| 83 | p = mempcpy (p, base, baselen); |
| 84 | *p = '\0'; |
| 85 | |
| 86 | return p_concat; |
| 87 | } |