/* A rename wrapper to make tools like mv -- that would normally rely
   on the underlying rename syscall -- work more consistently.
   On at least NetBSD 1.6, `rename ("dir", "B/")' fails when B doesn't
   exist, whereas it succeeds on Linux-2.6.x and Solaris 10.  This wrapper
   provides an interface for systems like the former so that the tools
   (namely mv) relying on the rename syscall have more consistent
   semantics.

   Copyright (C) 2006, 2009 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 <http://www.gnu.org/licenses/>.  */

/* written by Jim Meyering */

#include <config.h>
#undef rename

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

#include "dirname.h"
#include "same-inode.h"
#include "xalloc.h"

static bool
has_trailing_slash (char const *file)
{
  /* Don't count "/", "//", etc., as having a trailing slash.  */
  bool has_non_slash = false;
  bool ends_in_slash = false;

  for (file += FILE_SYSTEM_PREFIX_LEN (file); *file; file++)
    {
      ends_in_slash = ISSLASH (*file);
      has_non_slash |= ~ ends_in_slash;
    }

  return has_non_slash & ends_in_slash;
}

/* This is a rename wrapper for systems where the rename syscall
   works differently than desired when SRC is a directory and DST does
   not exist but is specified with a trailing slash.  On NetBSD 6.1,
   rename fails in that case.  On Linux and Solaris systems, it succeeds.
   This wrapper makes it succeed on NetBSD by running the originally
   requested rename, and if it fails due to the above scenario, calling
   it again with DST's trailing slashes removed.  */
int
rpl_rename_dest_slash (char const *src, char const *dst)
{
  struct stat sb;
  struct stat db;
  int ret_val;

  if (lstat (src, &sb))
    return -1;
  if (lstat (dst, &db) == 0 && SAME_INODE (sb, db))
    return 0;

  ret_val = rename (src, dst);

  if (ret_val != 0 && errno == ENOENT && has_trailing_slash (dst))
    {
      int rename_errno = ENOENT;

      /* Fail now, unless SRC is a directory.  */
      if (lstat (src, &sb) == 0 && S_ISDIR (sb.st_mode))
	{
	  char *dst_temp = xstrdup (dst);
	  strip_trailing_slashes (dst_temp);
	  ret_val = rename (src, dst_temp);
	  rename_errno = errno;
	  free (dst_temp);
	}

      errno = rename_errno;
    }

  return ret_val;
}