/* 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 Free Software Foundation, Inc.
+ Copyright (C) 1997, 2004 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
/* written by Jim Meyering */
#include <config.h>
+
+/* Disable the definition of chown to rpl_chown (from config.h) in this
+ file. Otherwise, we'd get conflicting prototypes for rpl_chown on
+ most systems. */
+#undef chown
+
#include <sys/types.h>
-#ifdef HAVE_UNISTD_H
+#include <sys/stat.h>
+#if HAVE_UNISTD_H
# include <unistd.h>
#endif
+#if HAVE_FCNTL_H
+# include <fcntl.h>
+#else
+# include <sys/file.h>
+#endif
+#include <errno.h>
-/* FIXME: describe. */
+/* 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
-chown (file, gid, uid)
- const char *file;
- gid_t git;
- uid_t uit;
+rpl_chown (const char *file, uid_t uid, gid_t gid)
{
+#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 will remain unchanged. */
- FIXME
- }
+ struct stat file_stats;
-#undef chown
+ /* Stat file to get id(s) that should remain unchanged. */
+ if (stat (file, &file_stats))
+ return 1;
- return chown (file, gid, uid);
+ if (gid == (gid_t) -1)
+ gid = file_stats.st_gid;
+
+ if (uid == (uid_t) -1)
+ uid = file_stats.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 fd = open (file, O_RDONLY | O_NONBLOCK | O_NOCTTY);
+ if (fd < 0
+ && (fd = open (file, O_WRONLY | O_NONBLOCK | O_NOCTTY)) < 0)
+ return -1;
+ if (fchown (fd, uid, gid))
+ {
+ int saved_errno = errno;
+ close (fd);
+ errno = saved_errno;
+ return -1;
+ }
+ return close (fd);
+ }
+#else
+ return chown (file, uid, gid);
+#endif
}