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-rw-r--r--gl/lib/unlinkat.c124
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diff --git a/gl/lib/unlinkat.c b/gl/lib/unlinkat.c
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+/* Work around unlinkat bugs on Solaris 9 and Hurd.
+
+ Copyright (C) 2009-2022 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>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include <stdlib.h>
+
+#include "filename.h"
+#include "openat.h"
+
+#if HAVE_UNLINKAT
+
+# undef unlinkat
+
+/* unlinkat without AT_REMOVEDIR does not honor trailing / on Solaris 9.
+ Hurd has the same issue.
+
+ unlinkat without AT_REMOVEDIR erroneously ignores ".." on Darwin 14.
+
+ Solve these in a similar manner to unlink. */
+
+int
+rpl_unlinkat (int fd, char const *name, int flag)
+{
+ size_t len;
+ int result = 0;
+ /* rmdir behavior has no problems with trailing slash. */
+ if (flag & AT_REMOVEDIR)
+ return unlinkat (fd, name, flag);
+
+ len = strlen (name);
+ if (len && ISSLASH (name[len - 1]))
+ {
+ /* See the lengthy comment in unlink.c why we disobey the POSIX
+ rule of letting unlink("link-to-dir/") attempt to unlink a
+ directory. */
+ struct stat st;
+ result = fstatat (fd, name, &st, AT_SYMLINK_NOFOLLOW);
+ if (result == 0 || errno == EOVERFLOW)
+ {
+ /* Trailing NUL will overwrite the trailing slash. */
+ char *short_name = malloc (len);
+ if (!short_name)
+ {
+ errno = EPERM;
+ return -1;
+ }
+ memcpy (short_name, name, len);
+ while (len && ISSLASH (short_name[len - 1]))
+ short_name[--len] = '\0';
+ if (len && (fstatat (fd, short_name, &st, AT_SYMLINK_NOFOLLOW)
+ || S_ISLNK (st.st_mode)))
+ {
+ free (short_name);
+ errno = EPERM;
+ return -1;
+ }
+ free (short_name);
+ result = 0;
+ }
+ }
+ if (!result)
+ {
+# if UNLINK_PARENT_BUG
+ if (len >= 2 && name[len - 1] == '.' && name[len - 2] == '.'
+ && (len == 2 || ISSLASH (name[len - 3])))
+ {
+ errno = EISDIR; /* could also use EPERM */
+ return -1;
+ }
+# endif
+ result = unlinkat (fd, name, flag);
+ }
+ return result;
+}
+
+#else /* !HAVE_UNLINKAT */
+
+/* Replacement for Solaris' function by the same name.
+ <https://www.google.com/search?q=unlinkat+site:docs.oracle.com>
+ First, try to simulate it via (unlink|rmdir) ("/proc/self/fd/FD/FILE").
+ Failing that, simulate it via save_cwd/fchdir/(unlink|rmdir)/restore_cwd.
+ If either the save_cwd or the restore_cwd fails (relatively unlikely),
+ then give a diagnostic and exit nonzero.
+ Otherwise, this function works just like Solaris' unlinkat. */
+
+# define AT_FUNC_NAME unlinkat
+# define AT_FUNC_F1 rmdir
+# define AT_FUNC_F2 unlink
+# define AT_FUNC_USE_F1_COND AT_REMOVEDIR
+# define AT_FUNC_POST_FILE_PARAM_DECLS , int flag
+# define AT_FUNC_POST_FILE_ARGS /* empty */
+# include "at-func.c"
+# undef AT_FUNC_NAME
+# undef AT_FUNC_F1
+# undef AT_FUNC_F2
+# undef AT_FUNC_USE_F1_COND
+# undef AT_FUNC_POST_FILE_PARAM_DECLS
+# undef AT_FUNC_POST_FILE_ARGS
+
+#endif /* !HAVE_UNLINKAT */