1/* Concatenate two arbitrary file names. 2 3 Copyright (C) 1996-2007 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#include "xalloc.h" 30 31#if ! HAVE_MEMPCPY && ! defined mempcpy 32# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N))) 33#endif 34 35/* Return the longest suffix of F that is a relative file name. 36 If it has no such suffix, return the empty string. */ 37 38static char const * 39longest_relative_suffix (char const *f) 40{ 41 for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++) 42 continue; 43 return f; 44} 45 46/* Concatenate two file name components, DIR and ABASE, in 47 newly-allocated storage and return the result. 48 The resulting file name F is such that the commands "ls F" and "(cd 49 DIR; ls BASE)" refer to the same file, where BASE is ABASE with any 50 file system prefixes and leading separators removed. 51 Arrange for a directory separator if necessary between DIR and BASE 52 in the result, removing any redundant separators. 53 In any case, if BASE_IN_RESULT is non-NULL, set 54 *BASE_IN_RESULT to point to the copy of ABASE in the returned 55 concatenation. However, if ABASE begins with more than one slash, 56 set *BASE_IN_RESULT to point to the sole corresponding slash that 57 is copied into the result buffer. 58 59 Return NULL if malloc fails. */ 60 61char * 62mfile_name_concat (char const *dir, char const *abase, char **base_in_result) 63{ 64 char const *dirbase = last_component (dir); 65 size_t dirbaselen = base_len (dirbase); 66 size_t dirlen = dirbase - dir + dirbaselen; 67 size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1])); 68 69 char const *base = longest_relative_suffix (abase); 70 size_t baselen = strlen (base); 71 72 char *p_concat = malloc (dirlen + needs_separator + baselen + 1); 73 char *p; 74 75 if (p_concat == NULL) 76 return NULL; 77 78 p = mempcpy (p_concat, dir, dirlen); 79 *p = DIRECTORY_SEPARATOR; 80 p += needs_separator; 81 82 if (base_in_result) 83 *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase); 84 85 p = mempcpy (p, base, baselen); 86 *p = '\0'; 87 88 return p_concat; 89} 90 91/* Just like mfile_name_concat, above, except, rather than 92 returning NULL upon malloc failure, here, we report the 93 "memory exhausted" condition and exit. */ 94 95char * 96file_name_concat (char const *dir, char const *abase, char **base_in_result) 97{ 98 char *p = mfile_name_concat (dir, abase, base_in_result); 99 if (p == NULL) 100 xalloc_die (); 101 return p; 102} 103