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-rw-r--r--gl/lib/lchown.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/gl/lib/lchown.c b/gl/lib/lchown.c
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+/* Provide a stub lchown function for systems that lack it.
+
+ Copyright (C) 1998-1999, 2002, 2004, 2006-2007, 2009-2022 Free Software
+ Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file 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 Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* written by Jim Meyering */
+
+#include <config.h>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#if !HAVE_LCHOWN
+
+/* If the system chown does not follow symlinks, we don't want it
+ replaced by gnulib's chown, which does follow symlinks. */
+# if CHOWN_MODIFIES_SYMLINK
+# undef chown
+# endif
+
+/* Work just like chown, except when FILE is a symbolic link.
+ In that case, set errno to EOPNOTSUPP and return -1.
+ But if autoconf tests determined that chown modifies
+ symlinks, then just call chown. */
+
+int
+lchown (const char *file, uid_t uid, gid_t gid)
+{
+# if HAVE_CHOWN
+# if ! CHOWN_MODIFIES_SYMLINK
+ char readlink_buf[1];
+
+ if (0 <= readlink (file, readlink_buf, sizeof readlink_buf))
+ {
+ errno = EOPNOTSUPP;
+ return -1;
+ }
+# endif
+
+ return chown (file, uid, gid);
+
+# else /* !HAVE_CHOWN */
+ errno = ENOSYS;
+ return -1;
+# endif
+}
+
+#else /* HAVE_LCHOWN */
+
+# undef lchown
+
+/* Work around trailing slash bugs in lchown. */
+int
+rpl_lchown (const char *file, uid_t uid, gid_t gid)
+{
+ bool stat_valid = false;
+ int result;
+
+# if CHOWN_CHANGE_TIME_BUG
+ struct stat st;
+
+ if (gid != (gid_t) -1 || uid != (uid_t) -1)
+ {
+ if (lstat (file, &st))
+ return -1;
+ stat_valid = true;
+ if (!S_ISLNK (st.st_mode))
+ return chown (file, uid, gid);
+ }
+# endif
+
+# if CHOWN_TRAILING_SLASH_BUG
+ if (!stat_valid)
+ {
+ size_t len = strlen (file);
+ if (len && file[len - 1] == '/')
+ return chown (file, uid, gid);
+ }
+# endif
+
+ result = lchown (file, uid, gid);
+
+# if CHOWN_CHANGE_TIME_BUG && HAVE_LCHMOD
+ 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 lchown succeeded,
+ we assume that lchmod will do likewise. But if the system
+ lacks lchmod and lutimes, we are out of luck. Oh well. */
+ result = lchmod (file, st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO
+ | S_ISUID | S_ISGID | S_ISVTX));
+ }
+# endif
+
+ return result;
+}
+
+#endif /* HAVE_LCHOWN */