1 /* Create a symlink relative to an open directory.
2 Copyright (C) 2009-2010 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* written by Eric Blake */
24 /* Mingw lacks symlink, and it is more efficient to provide a trivial
25 wrapper than to go through at-func.c to call rpl_symlink. */
30 symlinkat (char const *path1 _GL_UNUSED, int fd _GL_UNUSED,
31 char const *path2 _GL_UNUSED)
37 #else /* HAVE_SYMLINK */
39 /* Our openat helper functions expect the directory parameter first,
40 not second. These shims make life easier. */
42 /* Like symlink, but with arguments reversed. */
44 symlink_reversed (char const *file, char const *contents)
46 return symlink (contents, file);
49 /* Like symlinkat, but with arguments reversed. */
52 symlinkat_reversed (int fd, char const *file, char const *contents);
54 # define AT_FUNC_NAME symlinkat_reversed
55 # define AT_FUNC_F1 symlink_reversed
56 # define AT_FUNC_POST_FILE_PARAM_DECLS , char const *contents
57 # define AT_FUNC_POST_FILE_ARGS , contents
61 # undef AT_FUNC_POST_FILE_PARAM_DECLS
62 # undef AT_FUNC_POST_FILE_ARGS
64 /* Create a symlink FILE, in the directory open on descriptor FD,
65 holding CONTENTS. If possible, do it without changing the
66 working directory. Otherwise, resort to using save_cwd/fchdir,
67 then symlink/restore_cwd. If either the save_cwd or the restore_cwd
68 fails, then give a diagnostic and exit nonzero. */
71 symlinkat (char const *contents, int fd, char const *file)
73 return symlinkat_reversed (fd, file, contents);
76 #endif /* HAVE_SYMLINK */
78 /* Gnulib provides a readlink stub for mingw; use it for distinction
79 between EINVAL and ENOENT, rather than always failing with ENOSYS. */
81 /* POSIX 2008 says that unlike readlink, readlinkat returns 0 for
82 success instead of the buffer length. But this would render
83 readlinkat worthless since readlink does not guarantee a
84 NUL-terminated buffer. Assume this was a bug in POSIX. */
86 /* Read the contents of symlink FILE into buffer BUF of size LEN, in the
87 directory open on descriptor FD. If possible, do it without changing
88 the working directory. Otherwise, resort to using save_cwd/fchdir,
89 then readlink/restore_cwd. If either the save_cwd or the restore_cwd
90 fails, then give a diagnostic and exit nonzero. */
92 #define AT_FUNC_NAME readlinkat
93 #define AT_FUNC_F1 readlink
94 #define AT_FUNC_POST_FILE_PARAM_DECLS , char *buf, size_t len
95 #define AT_FUNC_POST_FILE_ARGS , buf, len
96 #define AT_FUNC_RESULT ssize_t
100 #undef AT_FUNC_POST_FILE_PARAM_DECLS
101 #undef AT_FUNC_POST_FILE_ARGS
102 #undef AT_FUNC_RESULT