/* Concatenate two arbitrary file names. Copyright (C) 1996-2007, 2009-2024 Free Software Foundation, Inc. This file is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This file is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see . */ /* Written by Jim Meyering. */ #include /* Specification. */ #include "filenamecat.h" #include #include #include "basename-lgpl.h" #include "filename.h" #if ! HAVE_MEMPCPY && ! defined mempcpy # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N))) #endif /* Concatenate two file name components, DIR and BASE, in newly-allocated storage and return the result. The resulting file name F is such that the commands "ls F" and "(cd DIR; ls ./BASE)" refer to the same file. If necessary, put a separator between DIR and BASE in the result. Typically this separator is "/", but in rare cases it might be ".". In any case, if BASE_IN_RESULT is non-NULL, set *BASE_IN_RESULT to point to the copy of BASE at the end of the returned concatenation. If malloc fails, return NULL with errno set. */ char * mfile_name_concat (char const *dir, char const *base, char **base_in_result) { char const *dirbase = last_component (dir); size_t dirbaselen = base_len (dirbase); size_t dirlen = dirbase - dir + dirbaselen; size_t baselen = strlen (base); char sep = '\0'; if (dirbaselen) { /* DIR is not a file system root, so separate with / if needed. */ if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base)) sep = '/'; } else if (ISSLASH (*base)) { /* DIR is a file system root and BASE begins with a slash, so separate with ".". For example, if DIR is "/" and BASE is "/foo" then return "/./foo", as "//foo" would be wrong on some POSIX systems. A fancier algorithm could omit "." in some cases but is not worth the trouble. */ sep = '.'; } char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1); if (p_concat == NULL) return NULL; { char *p; p = mempcpy (p_concat, dir, dirlen); *p = sep; p += sep != '\0'; if (base_in_result) *base_in_result = p; p = mempcpy (p, base, baselen); *p = '\0'; } return p_concat; }