| 1 | /* Concatenate two arbitrary file names. |
| 2 | |
| 3 | Copyright (C) 1996-2007, 2009-2016 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 <http://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 | /* Return the longest suffix of F that is a relative file name. |
| 35 | If it has no such suffix, return the empty string. */ |
| 36 | |
| 37 | static char const * _GL_ATTRIBUTE_PURE |
| 38 | longest_relative_suffix (char const *f) |
| 39 | { |
| 40 | for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++) |
| 41 | continue; |
| 42 | return f; |
| 43 | } |
| 44 | |
| 45 | /* Concatenate two file name components, DIR and ABASE, in |
| 46 | newly-allocated storage and return the result. |
| 47 | The resulting file name F is such that the commands "ls F" and "(cd |
| 48 | DIR; ls BASE)" refer to the same file, where BASE is ABASE with any |
| 49 | file system prefixes and leading separators removed. |
| 50 | Arrange for a directory separator if necessary between DIR and BASE |
| 51 | in the result, removing any redundant separators. |
| 52 | In any case, if BASE_IN_RESULT is non-NULL, set |
| 53 | *BASE_IN_RESULT to point to the copy of ABASE in the returned |
| 54 | concatenation. However, if ABASE begins with more than one slash, |
| 55 | set *BASE_IN_RESULT to point to the sole corresponding slash that |
| 56 | is copied into the result buffer. |
| 57 | |
| 58 | Return NULL if malloc fails. */ |
| 59 | |
| 60 | char * |
| 61 | mfile_name_concat (char const *dir, char const *abase, char **base_in_result) |
| 62 | { |
| 63 | char const *dirbase = last_component (dir); |
| 64 | size_t dirbaselen = base_len (dirbase); |
| 65 | size_t dirlen = dirbase - dir + dirbaselen; |
| 66 | size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1])); |
| 67 | |
| 68 | char const *base = longest_relative_suffix (abase); |
| 69 | size_t baselen = strlen (base); |
| 70 | |
| 71 | char *p_concat = malloc (dirlen + needs_separator + baselen + 1); |
| 72 | char *p; |
| 73 | |
| 74 | if (p_concat == NULL) |
| 75 | return NULL; |
| 76 | |
| 77 | p = mempcpy (p_concat, dir, dirlen); |
| 78 | *p = DIRECTORY_SEPARATOR; |
| 79 | p += needs_separator; |
| 80 | |
| 81 | if (base_in_result) |
| 82 | *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase); |
| 83 | |
| 84 | p = mempcpy (p, base, baselen); |
| 85 | *p = '\0'; |
| 86 | |
| 87 | return p_concat; |
| 88 | } |