1 /* Concatenate two arbitrary file names. 2 3 Copyright (C) 1996-2007, 2009-2015 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 } 89