1  /*
       2   * cramfs_common - cramfs common code
       3   *
       4   * Copyright (c) 2008 Roy Peled, the.roy.peled  -at-  gmail.com
       5   * Copyright (c) 2004-2006 by Juliane Holzt, kju -at- fqdn.org
       6   *
       7   * This program is free software; you can redistribute it and/or modify
       8   * it under the terms of the GNU General Public License as published by
       9   * the Free Software Foundation; either version 2 of the License, or
      10   * (at your option) any later version.
      11   *
      12   * This program is distributed in the hope that it will be useful,
      13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15   * GNU General Public License for more details.
      16   *
      17   */
      18  
      19  #include <string.h>
      20  #include "cramfs.h"
      21  #include "../include/bitops.h"
      22  
      23  uint32_t u32_toggle_endianness(int big_endian, uint32_t what)
      24  {
      25  	return big_endian == HOST_IS_BIG_ENDIAN ? what : swab32(what);
      26  }
      27  
      28  void super_toggle_endianness(int big_endian, struct cramfs_super *super)
      29  {
      30  	if (big_endian != HOST_IS_BIG_ENDIAN) {
      31  		super->magic = swab32(super->magic);
      32  		super->size = swab32(super->size);
      33  		super->flags = swab32(super->flags);
      34  		super->future = swab32(super->future);
      35  		super->fsid.crc = swab32(super->fsid.crc);
      36  		super->fsid.edition = swab32(super->fsid.edition);
      37  		super->fsid.blocks = swab32(super->fsid.blocks);
      38  		super->fsid.files = swab32(super->fsid.files);
      39  	}
      40  }
      41  
      42  static void inode_toggle_endianness(int input_big_endian, int output_big_endian,
      43  			     struct cramfs_inode *inode_in,
      44  			     struct cramfs_inode *inode_out)
      45  {
      46  	if (input_big_endian == output_big_endian) {
      47  		memmove(inode_out, inode_in, sizeof(*inode_out));
      48  	} else {
      49  		unsigned char inode_out_buf[sizeof(*inode_in)];
      50  		unsigned char *inode_in_buf = (unsigned char*)inode_in;
      51  
      52  		inode_out_buf[0] = inode_in_buf[1]; /* 16 bit: mode */
      53  		inode_out_buf[1] = inode_in_buf[0];
      54  
      55  		inode_out_buf[2] = inode_in_buf[3]; /* 16 bit: uid */
      56  		inode_out_buf[3] = inode_in_buf[2];
      57  
      58  		inode_out_buf[4] = inode_in_buf[6]; /* 24 bit: size */
      59  		inode_out_buf[5] = inode_in_buf[5];
      60  		inode_out_buf[6] = inode_in_buf[4];
      61  
      62  		inode_out_buf[7] = inode_in_buf[7]; /* 8 bit: gid width */
      63  
      64  		/*
      65  		 * Stop the madness! Outlaw C bitfields! They are unportable
      66  		 * and nasty! See for yourself what a mess this is:
      67  		 */
      68  		if (output_big_endian) {
      69  			inode_out_buf[ 8] = ( (inode_in_buf[ 8]&0x3F) << 2 ) |
      70  				( (inode_in_buf[11]&0xC0) >> 6 );
      71  
      72  			inode_out_buf[ 9] = ( (inode_in_buf[11]&0x3F) << 2 ) |
      73  				( (inode_in_buf[10]&0xC0) >> 6 );
      74  
      75  			inode_out_buf[10] = ( (inode_in_buf[10]&0x3F) << 2 ) |
      76  				( (inode_in_buf[ 9]&0xC0) >> 6 );
      77  
      78  			inode_out_buf[11] = ( (inode_in_buf[ 9]&0x3F) << 2 ) |
      79  				( (inode_in_buf[ 8]&0xC0) >> 6 );
      80  		} else {
      81  			inode_out_buf[ 8] = ( (inode_in_buf[ 8]&0xFD) >> 2 ) |
      82  				( (inode_in_buf[11]&0x03) << 6 );
      83  
      84  			inode_out_buf[ 9] = ( (inode_in_buf[11]&0xFD) >> 2 ) |
      85  				( (inode_in_buf[10]&0x03) << 6 );
      86  
      87  			inode_out_buf[10] = ( (inode_in_buf[10]&0xFD) >> 2 ) |
      88  				( (inode_in_buf[ 9]&0x03) << 6 );
      89  
      90  			inode_out_buf[11] = ( (inode_in_buf[ 9]&0xFD) >> 2 ) |
      91  				( (inode_in_buf[ 8]&0x03) << 6 );
      92  		}
      93  		memmove(inode_out, inode_out_buf, sizeof(*inode_out));
      94  	}
      95  }
      96  
      97  void inode_to_host(int from_big_endian, struct cramfs_inode *inode_in,
      98  		   struct cramfs_inode *inode_out)
      99  {
     100  	inode_toggle_endianness(from_big_endian, HOST_IS_BIG_ENDIAN, inode_in,
     101  				inode_out);
     102  }
     103  
     104  void inode_from_host(int to_big_endian, struct cramfs_inode *inode_in,
     105  		     struct cramfs_inode *inode_out)
     106  {
     107  	inode_toggle_endianness(HOST_IS_BIG_ENDIAN, to_big_endian, inode_in,
     108  				inode_out);
     109  }