123 lines
3.5 KiB
C
123 lines
3.5 KiB
C
/* Work around unlinkat bugs on Solaris 9 and Hurd.
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Copyright (C) 2009-2020 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Eric Blake. */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include "dosname.h"
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#include "openat.h"
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#if HAVE_UNLINKAT
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# undef unlinkat
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/* unlinkat without AT_REMOVEDIR does not honor trailing / on Solaris 9.
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Hurd has the same issue.
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unlinkat without AT_REMOVEDIR erroneously ignores ".." on Darwin 14.
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Solve these in a similar manner to unlink. */
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int
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rpl_unlinkat (int fd, char const *name, int flag)
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{
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size_t len;
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int result = 0;
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/* rmdir behavior has no problems with trailing slash. */
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if (flag & AT_REMOVEDIR)
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return unlinkat (fd, name, flag);
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len = strlen (name);
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if (len && ISSLASH (name[len - 1]))
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{
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/* See the lengthy comment in unlink.c why we disobey the POSIX
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rule of letting unlink("link-to-dir/") attempt to unlink a
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directory. */
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struct stat st;
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result = lstatat (fd, name, &st);
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if (result == 0)
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{
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/* Trailing NUL will overwrite the trailing slash. */
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char *short_name = malloc (len);
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if (!short_name)
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{
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errno = EPERM;
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return -1;
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}
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memcpy (short_name, name, len);
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while (len && ISSLASH (short_name[len - 1]))
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short_name[--len] = '\0';
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if (len && (lstatat (fd, short_name, &st) || S_ISLNK (st.st_mode)))
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{
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free (short_name);
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errno = EPERM;
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return -1;
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}
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free (short_name);
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}
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}
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if (!result)
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{
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# if UNLINK_PARENT_BUG
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if (len >= 2 && name[len - 1] == '.' && name[len - 2] == '.'
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&& (len == 2 || ISSLASH (name[len - 3])))
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{
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errno = EISDIR; /* could also use EPERM */
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return -1;
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}
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# endif
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result = unlinkat (fd, name, flag);
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}
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return result;
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}
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#else /* !HAVE_UNLINKAT */
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/* Replacement for Solaris' function by the same name.
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<https://www.google.com/search?q=unlinkat+site:docs.oracle.com>
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First, try to simulate it via (unlink|rmdir) ("/proc/self/fd/FD/FILE").
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Failing that, simulate it via save_cwd/fchdir/(unlink|rmdir)/restore_cwd.
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If either the save_cwd or the restore_cwd fails (relatively unlikely),
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then give a diagnostic and exit nonzero.
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Otherwise, this function works just like Solaris' unlinkat. */
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# define AT_FUNC_NAME unlinkat
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# define AT_FUNC_F1 rmdir
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# define AT_FUNC_F2 unlink
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# define AT_FUNC_USE_F1_COND AT_REMOVEDIR
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# define AT_FUNC_POST_FILE_PARAM_DECLS , int flag
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# define AT_FUNC_POST_FILE_ARGS /* empty */
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# include "at-func.c"
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# undef AT_FUNC_NAME
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# undef AT_FUNC_F1
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# undef AT_FUNC_F2
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# undef AT_FUNC_USE_F1_COND
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# undef AT_FUNC_POST_FILE_PARAM_DECLS
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# undef AT_FUNC_POST_FILE_ARGS
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#endif /* !HAVE_UNLINKAT */
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