A few more symlink-related fixes. Fix a bug triggered by cp

--parents and symlinks.  Close some race conditions possible when
the destination replaces a newly-created file with a symlink.
* NEWS: Document that 'cp --parents' no longer mishandles
symlinks in file name components of source.
* src/copy.c (HAVE_LCHOWN): Default to false.
(lchown) [!defined HAVE_LCHOWN]: Define to chown, for convenience.
* src/cp.c (lchown) [!HAVE_LCHOWN]: Likewise.
* src/install.c (lchown [!HAVE_LCHOWN]: Likewise.
* src/copy.c (set_owner): Use lchown instead of chown, for safety
in case the file got replaced by a symlink in the meantime.
* src/cp.c (re_protect): Likewise.
* src/install.c (change_attributes): Likewise.
* src/copy.c (copy_internal): Use ordinary C rather than an #if.
* src/cp.c (lchown) [!HAVE_LCHOWN]: Define to chown, for convenience.
(struct dir_attr): Cache the entire struct stat of the directory,
rather than just its mode, so that we needn't stat the directory
twice (which can lead to races).
(re_protect): Don't use XSTAT as that's not appropriate in
this context (symlinks should be followed here).  Instead, use
the cached stat value.
(make_dir_parents_private): Save dir's entire struct stat, not
just its mode.
* tests/cp/cp-parents: Add test to check against bug with
cp --parents and symlinks.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/install.c b/src/install.c
index dc7ff0141..39d514957 100644
--- a/src/install.c
+++ b/src/install.c
@@ -62,6 +62,10 @@ static bool use_default_selinux_context = true;
 # define endpwent() ((void) 0)
 #endif
 
+#if ! HAVE_LCHOWN
+# define lchown(name, uid, gid) chown (name, uid, gid)
+#endif
+
 /* Initial number of entries in each hash table entry's table of inodes.  */
 #define INITIAL_HASH_MODULE 100
 
@@ -606,7 +610,7 @@ change_attributes (char const *name)
      want to know.  */
 
   if (! (owner_id == (uid_t) -1 && group_id == (gid_t) -1)
-      && chown (name, owner_id, group_id) != 0)
+      && lchown (name, owner_id, group_id) != 0)
     error (0, errno, _("cannot change ownership of %s"), quote (name));
   else if (chmod (name, mode) != 0)
     error (0, errno, _("cannot change permissions of %s"), quote (name));