1 files changed, 141 insertions, 0 deletions
diff --git a/lib/dirchownmod.c b/lib/dirchownmod.c
new file mode 100644
index 0000000..64a1202
--- /dev/null
+++ b/lib/dirchownmod.c
@@ -0,0 +1,141 @@
+/* Change the ownership and mode bits of a directory.
+
+   Copyright (C) 2006-2020 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 Paul Eggert.  */
+
+#include <config.h>
+
+#include "dirchownmod.h"
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "stat-macros.h"
+
+#ifndef HAVE_FCHMOD
+# define HAVE_FCHMOD 0
+# undef fchmod
+# define fchmod(fd, mode) (-1)
+#endif
+
+/* Change the ownership and mode bits of a directory.  If FD is
+   nonnegative, it should be a file descriptor associated with the
+   directory; close it before returning.  DIR is the name of the
+   directory.
+
+   If MKDIR_MODE is not (mode_t) -1, mkdir (DIR, MKDIR_MODE) has just
+   been executed successfully with umask zero, so DIR should be a
+   directory (not a symbolic link).
+
+   First, set the file's owner to OWNER and group to GROUP, but leave
+   the owner alone if OWNER is (uid_t) -1, and similarly for GROUP.
+
+   Then, set the file's mode bits to MODE, except preserve any of the
+   bits that correspond to zero bits in MODE_BITS.  In other words,
+   MODE_BITS is a mask that specifies which of the file's mode bits
+   should be set or cleared.  MODE should be a subset of MODE_BITS,
+   which in turn should be a subset of CHMOD_MODE_BITS.
+
+   This implementation assumes the current umask is zero.
+
+   Return 0 if successful, -1 (setting errno) otherwise.  Unsuccessful
+   calls may do the chown but not the chmod.  */
+
+int
+dirchownmod (int fd, char const *dir, mode_t mkdir_mode,
+             uid_t owner, gid_t group,
+             mode_t mode, mode_t mode_bits)
+{
+  struct stat st;
+  int result = (fd < 0 ? stat (dir, &st) : fstat (fd, &st));
+
+  if (result == 0)
+    {
+      mode_t dir_mode = st.st_mode;
+
+      /* Check whether DIR is a directory.  If FD is nonnegative, this
+         check avoids changing the ownership and mode bits of the
+         wrong file in many cases.  This doesn't fix all the race
+         conditions, but it is better than nothing.  */
+      if (! S_ISDIR (dir_mode))
+        {
+          errno = ENOTDIR;
+          result = -1;
+        }
+      else
+        {
+          /* If at least one of the S_IXUGO bits are set, chown might
+             clear the S_ISUID and S_SGID bits.  Keep track of any
+             file mode bits whose values are indeterminate due to this
+             issue.  */
+          mode_t indeterminate = 0;
+
+          /* On some systems, chown clears S_ISUID and S_ISGID, so do
+             chown before chmod.  On older System V hosts, ordinary
+             users can give their files away via chown; don't worry
+             about that here, since users shouldn't do that.  */
+
+          if ((owner != (uid_t) -1 && owner != st.st_uid)
+              || (group != (gid_t) -1 && group != st.st_gid))
+            {
+              result = (0 <= fd
+                        ? fchown (fd, owner, group)
+                        : mkdir_mode != (mode_t) -1
+                        ? lchown (dir, owner, group)
+                        : chown (dir, owner, group));
+
+              /* Either the user cares about an indeterminate bit and
+                 it'll be set properly by chmod below, or the user
+                 doesn't care and it's OK to use the bit's pre-chown
+                 value.  So there's no need to re-stat DIR here.  */
+
+              if (result == 0 && (dir_mode & S_IXUGO))
+                indeterminate = dir_mode & (S_ISUID | S_ISGID);
+            }
+
+          /* If the file mode bits might not be right, use chmod to
+             change them.  Don't change bits the user doesn't care
+             about.  */
+          if (result == 0 && (((dir_mode ^ mode) | indeterminate) & mode_bits))
+            {
+              mode_t chmod_mode =
+                mode | (dir_mode & CHMOD_MODE_BITS & ~mode_bits);
+              result = (HAVE_FCHMOD && 0 <= fd
+                        ? fchmod (fd, chmod_mode)
+                        : mkdir_mode != (mode_t) -1
+                        ? lchmod (dir, chmod_mode)
+                        : chmod (dir, chmod_mode));
+            }
+        }
+    }
+
+  if (0 <= fd)
+    {
+      if (result == 0)
+        result = close (fd);
+      else
+        {
+          int e = errno;
+          close (fd);
+          errno = e;
+        }
+    }
+
+  return result;
+}