1 files changed, 151 insertions, 0 deletions
diff --git a/gl/lib/chown.c b/gl/lib/chown.c
new file mode 100644
index 0000000..6a8a76c
--- /dev/null
+++ b/gl/lib/chown.c
@@ -0,0 +1,151 @@
+/* provide consistent interface to chown for systems that don't interpret
+   an ID of -1 as meaning "don't change the corresponding ID".
+
+   Copyright (C) 1997, 2004-2007, 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 Jim Meyering */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#if !HAVE_CHOWN
+
+/* Simple stub that always fails with ENOSYS, for mingw.  */
+int
+chown (const char *file _GL_UNUSED, uid_t uid _GL_UNUSED,
+       gid_t gid _GL_UNUSED)
+{
+  errno = ENOSYS;
+  return -1;
+}
+
+#else /* HAVE_CHOWN */
+
+/* Below we refer to the system's chown().  */
+# undef chown
+
+/* Provide a more-closely POSIX-conforming version of chown on
+   systems with one or both of the following problems:
+   - chown doesn't treat an ID of -1 as meaning
+   "don't change the corresponding ID".
+   - chown doesn't dereference symlinks.  */
+
+int
+rpl_chown (const char *file, uid_t uid, gid_t gid)
+{
+  struct stat st;
+  bool stat_valid = false;
+  int result;
+
+# if CHOWN_CHANGE_TIME_BUG
+  if (gid != (gid_t) -1 || uid != (uid_t) -1)
+    {
+      if (stat (file, &st))
+        return -1;
+      stat_valid = true;
+    }
+# endif
+
+# if CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE
+  if (gid == (gid_t) -1 || uid == (uid_t) -1)
+    {
+      /* Stat file to get id(s) that should remain unchanged.  */
+      if (!stat_valid && stat (file, &st))
+        return -1;
+      if (gid == (gid_t) -1)
+        gid = st.st_gid;
+      if (uid == (uid_t) -1)
+        uid = st.st_uid;
+    }
+# endif
+
+# if CHOWN_MODIFIES_SYMLINK
+  {
+    /* Handle the case in which the system-supplied chown function
+       does *not* follow symlinks.  Instead, it changes permissions
+       on the symlink itself.  To work around that, we open the
+       file (but this can fail due to lack of read or write permission) and
+       use fchown on the resulting descriptor.  */
+    int open_flags = O_NONBLOCK | O_NOCTTY | O_CLOEXEC;
+    int fd = open (file, O_RDONLY | open_flags);
+    if (0 <= fd
+        || (errno == EACCES
+            && 0 <= (fd = open (file, O_WRONLY | open_flags))))
+      {
+        int saved_errno;
+        bool fchown_socket_failure;
+
+        result = fchown (fd, uid, gid);
+        saved_errno = errno;
+
+        /* POSIX says fchown can fail with errno == EINVAL on sockets
+           and pipes, so fall back on chown in that case.  */
+        fchown_socket_failure =
+          (result != 0 && saved_errno == EINVAL
+           && fstat (fd, &st) == 0
+           && (S_ISFIFO (st.st_mode) || S_ISSOCK (st.st_mode)));
+
+        close (fd);
+
+        if (! fchown_socket_failure)
+          {
+            errno = saved_errno;
+            return result;
+          }
+      }
+    else if (errno != EACCES)
+      return -1;
+  }
+# endif
+
+# if CHOWN_TRAILING_SLASH_BUG
+  if (!stat_valid)
+    {
+      size_t len = strlen (file);
+      if (len && file[len - 1] == '/' && stat (file, &st))
+        return -1;
+    }
+# endif
+
+  result = chown (file, uid, gid);
+
+# if CHOWN_CHANGE_TIME_BUG
+  if (result == 0 && stat_valid
+      && (uid == st.st_uid || uid == (uid_t) -1)
+      && (gid == st.st_gid || gid == (gid_t) -1))
+    {
+      /* No change in ownership, but at least one argument was not -1,
+         so we are required to update ctime.  Since chown succeeded,
+         we assume that chmod will do likewise.  Fortunately, on all
+         known systems where a 'no-op' chown skips the ctime update, a
+         'no-op' chmod still does the trick.  */
+      result = chmod (file, st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO
+                                          | S_ISUID | S_ISGID | S_ISVTX));
+    }
+# endif
+
+  return result;
+}
+
+#endif /* HAVE_CHOWN */