| 1 | /* Concatenate two arbitrary file names.
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| 2 |
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| 3 | Copyright (C) 1996-2007, 2009-2021 Free Software Foundation, Inc.
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| 4 |
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| 5 | This file is free software: you can redistribute it and/or modify
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| 6 | it under the terms of the GNU Lesser General Public License as
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| 7 | published by the Free Software Foundation; either version 2.1 of the
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| 8 | License, or (at your option) any later version.
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| 9 |
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| 10 | This file is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU Lesser General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU Lesser General Public License
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| 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 17 |
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| 18 | /* Written by Jim Meyering. */
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| 19 |
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| 20 | #include <config.h>
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| 21 |
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| 22 | /* Specification. */
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| 23 | #include "filenamecat.h"
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| 24 |
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| 25 | #include <stdlib.h>
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| 26 | #include <string.h>
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| 27 |
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| 28 | #include "basename-lgpl.h"
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| 29 | #include "filename.h"
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| 30 |
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| 31 | #if ! HAVE_MEMPCPY && ! defined mempcpy
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| 32 | # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
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| 33 | #endif
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| 34 |
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| 35 | /* Concatenate two file name components, DIR and BASE, in
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| 36 | newly-allocated storage and return the result.
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| 37 | The resulting file name F is such that the commands "ls F" and "(cd
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| 38 | DIR; ls ./BASE)" refer to the same file. If necessary, put
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| 39 | a separator between DIR and BASE in the result. Typically this
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| 40 | separator is "/", but in rare cases it might be ".".
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| 41 | In any case, if BASE_IN_RESULT is non-NULL, set
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| 42 | *BASE_IN_RESULT to point to the copy of BASE at the end of the
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| 43 | returned concatenation.
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| 44 |
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| 45 | If malloc fails, return NULL with errno set. */
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| 46 |
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| 47 | char *
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| 48 | mfile_name_concat (char const *dir, char const *base, char **base_in_result)
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| 49 | {
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| 50 | char const *dirbase = last_component (dir);
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| 51 | size_t dirbaselen = base_len (dirbase);
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| 52 | size_t dirlen = dirbase - dir + dirbaselen;
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| 53 | size_t baselen = strlen (base);
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| 54 | char sep = '\0';
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| 55 | if (dirbaselen)
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| 56 | {
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| 57 | /* DIR is not a file system root, so separate with / if needed. */
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| 58 | if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base))
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| 59 | sep = '/';
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| 60 | }
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| 61 | else if (ISSLASH (*base))
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| 62 | {
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| 63 | /* DIR is a file system root and BASE begins with a slash, so
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| 64 | separate with ".". For example, if DIR is "/" and BASE is
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| 65 | "/foo" then return "/./foo", as "//foo" would be wrong on
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| 66 | some POSIX systems. A fancier algorithm could omit "." in
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| 67 | some cases but is not worth the trouble. */
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| 68 | sep = '.';
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| 69 | }
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| 70 |
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| 71 | char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1);
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| 72 | if (p_concat == NULL)
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| 73 | return NULL;
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| 74 |
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| 75 | {
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| 76 | char *p;
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| 77 |
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| 78 | p = mempcpy (p_concat, dir, dirlen);
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| 79 | *p = sep;
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| 80 | p += sep != '\0';
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| 81 |
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| 82 | if (base_in_result)
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| 83 | *base_in_result = p;
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| 84 |
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| 85 | p = mempcpy (p, base, baselen);
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| 86 | *p = '\0';
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| 87 | }
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| 88 |
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| 89 | return p_concat;
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| 90 | }
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