1 /* addext.c -- add an extension to a file name
2 Copyright (C) 1990, 1997-1999, 2001-2003, 2005-2006, 2020 Free Software
3 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 <https://www.gnu.org/licenses/>. */
17
18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu> and Paul Eggert */
19
20 #include <config.h>
21
22 #ifndef HAVE_DOS_FILE_NAMES
23 # define HAVE_DOS_FILE_NAMES 0
24 #endif
25 #ifndef HAVE_LONG_FILE_NAMES
26 # define HAVE_LONG_FILE_NAMES 0
27 #endif
28
29 #include "backupfile.h"
30
31 #include <limits.h>
32 #ifndef _POSIX_NAME_MAX
33 # define _POSIX_NAME_MAX 14
34 #endif
35
36 #include <sys/types.h>
37 #if HAVE_STRING_H
38 # include <string.h>
39 #else
40 # include <strings.h>
41 #endif
42
43 #include <unistd.h>
44
45 #include "basename-lgpl.h"
46
47 /* Append to FILENAME the extension EXT, unless the result would be too long,
48 in which case just append the character E. */
49
50 void
addext(char * filename,char const * ext,char e)51 addext (char *filename, char const *ext, char e)
52 {
53 char *s = last_component (filename);
54 size_t slen = strlen (s), extlen = strlen (ext);
55 long slen_max = -1;
56
57 #if HAVE_PATHCONF && defined _PC_NAME_MAX
58 if (slen + extlen <= _POSIX_NAME_MAX && ! HAVE_DOS_FILE_NAMES)
59 /* The file name is so short there's no need to call pathconf. */
60 slen_max = _POSIX_NAME_MAX;
61 else if (s == filename)
62 slen_max = pathconf (".", _PC_NAME_MAX);
63 else
64 {
65 char c = *s;
66 *s = 0;
67 slen_max = pathconf (filename, _PC_NAME_MAX);
68 *s = c;
69 }
70 #endif
71 if (slen_max < 0)
72 slen_max = HAVE_LONG_FILE_NAMES ? 255 : 14;
73
74 if (HAVE_DOS_FILE_NAMES && slen_max <= 12)
75 {
76 /* Live within DOS's 8.3 limit. */
77 char *dot = strchr (s, '.');
78 if (dot)
79 {
80 slen -= dot + 1 - s;
81 s = dot + 1;
82 slen_max = 3;
83 }
84 else
85 slen_max = 8;
86 extlen = 9; /* Don't use EXT. */
87 }
88
89 if (slen + extlen <= slen_max)
90 strcpy (s + slen, ext);
91 else
92 {
93 if (slen_max <= slen)
94 slen = slen_max - 1;
95 s[slen] = e;
96 s[slen + 1] = 0;
97 }
98 }
99