| /* Create a symlink relative to an open directory. |
| Copyright (C) 2009-2020 Free Software Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program 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 General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| /* written by Eric Blake */ |
| |
| #include <config.h> |
| |
| /* Specification. */ |
| #include <unistd.h> |
| |
| #include <errno.h> |
| #include <stdlib.h> |
| |
| #if HAVE_SYMLINKAT |
| # undef symlinkat |
| |
| #include <sys/stat.h> |
| #include <string.h> |
| |
| /* Create a symlink, but reject trailing slash. */ |
| int |
| rpl_symlinkat (char const *contents, int fd, char const *name) |
| { |
| size_t len = strlen (name); |
| if (len && name[len - 1] == '/') |
| { |
| struct stat st; |
| if (fstatat (fd, name, &st, 0) == 0) |
| errno = EEXIST; |
| return -1; |
| } |
| return symlinkat (contents, fd, name); |
| } |
| |
| #elif !HAVE_SYMLINK |
| /* Mingw lacks symlink, and it is more efficient to provide a trivial |
| wrapper than to go through at-func.c to call rpl_symlink. */ |
| |
| int |
| symlinkat (char const *path1 _GL_UNUSED, int fd _GL_UNUSED, |
| char const *path2 _GL_UNUSED) |
| { |
| errno = ENOSYS; |
| return -1; |
| } |
| |
| #else /* HAVE_SYMLINK */ |
| |
| /* Our openat helper functions expect the directory parameter first, |
| not second. These shims make life easier. */ |
| |
| /* Like symlink, but with arguments reversed. */ |
| static int |
| symlink_reversed (char const *file, char const *contents) |
| { |
| return symlink (contents, file); |
| } |
| |
| /* Like symlinkat, but with arguments reversed. */ |
| |
| static int |
| symlinkat_reversed (int fd, char const *file, char const *contents); |
| |
| # define AT_FUNC_NAME symlinkat_reversed |
| # define AT_FUNC_F1 symlink_reversed |
| # define AT_FUNC_POST_FILE_PARAM_DECLS , char const *contents |
| # define AT_FUNC_POST_FILE_ARGS , contents |
| # include "at-func.c" |
| # undef AT_FUNC_NAME |
| # undef AT_FUNC_F1 |
| # undef AT_FUNC_POST_FILE_PARAM_DECLS |
| # undef AT_FUNC_POST_FILE_ARGS |
| |
| /* Create a symlink FILE, in the directory open on descriptor FD, |
| holding CONTENTS. If possible, do it without changing the |
| working directory. Otherwise, resort to using save_cwd/fchdir, |
| then symlink/restore_cwd. If either the save_cwd or the restore_cwd |
| fails, then give a diagnostic and exit nonzero. */ |
| |
| int |
| symlinkat (char const *contents, int fd, char const *file) |
| { |
| return symlinkat_reversed (fd, file, contents); |
| } |
| |
| #endif /* HAVE_SYMLINK */ |