mkfs.cramfs: add endianness support to cramfs tools

cramfs is an endianness dependent file system.  So far, the cramfs
utilities did not support cramfs images of different endianness than
the host machine.

A separate utility, cramfsswap, was required in order to change the
endianness of the image before and after using cramfs utilities. The
extra utility introduced extra maintenance and an additional step in
the process.

This patch adds endianness support to mkfs.cramfs and fsck.cramfs.
fsck.cramfs now automatically detects the image endianness, and can
work on images of either endianness.  mkfs.cramfs now accepts a new
optional parameter (-N) that allows creating the cramfs image in
either endianness.

Signed-off-by: Roy Peled <the.roy.peled@gmail.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/disk-utils/cramfs_common.c b/disk-utils/cramfs_common.c
new file mode 100644
index 000000000..ffdad9b09
--- /dev/null
+++ b/disk-utils/cramfs_common.c
@@ -0,0 +1,105 @@
+/*
+ * cramfs_common - cramfs common code
+ *
+ * Copyright (c) 2008 Roy Peled, the.roy.peled  -at-  gmail.com
+ * Copyright (c) 2004-2006 by Michael Holzt, kju -at- fqdn.org
+ *
+ * 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 2 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.
+ *
+ */
+
+#include <string.h>
+#include "cramfs_common.h"
+#include "../include/bitops.h"
+
+u32 u32_toggle_endianness(int big_endian, u32 what)
+{
+	return big_endian == HOST_IS_BIG_ENDIAN ? what : swab32(what);
+}
+
+void super_toggle_endianness(int big_endian, struct cramfs_super *super)
+{
+	if (big_endian != HOST_IS_BIG_ENDIAN) {
+		super->magic = swab32(super->magic);
+		super->size = swab32(super->size);
+		super->flags = swab32(super->flags);
+		super->future = swab32(super->future);
+		super->fsid.crc = swab32(super->fsid.crc);
+		super->fsid.edition = swab32(super->fsid.edition);
+		super->fsid.blocks = swab32(super->fsid.blocks);
+		super->fsid.files = swab32(super->fsid.files);	
+	}
+}
+
+void inode_toggle_endianness(int input_big_endian, int output_big_endian, struct cramfs_inode *inode_in, struct cramfs_inode *inode_out)
+{
+	if (input_big_endian == output_big_endian) {
+		memmove(inode_out, inode_in, sizeof(*inode_out));
+	}
+	else {
+		unsigned char inode_out_buf[sizeof(*inode_in)];
+		unsigned char *inode_in_buf = (unsigned char*)inode_in;
+
+		inode_out_buf[0] = inode_in_buf[1]; /* 16 bit: mode */
+		inode_out_buf[1] = inode_in_buf[0];
+
+		inode_out_buf[2] = inode_in_buf[3]; /* 16 bit: uid */
+		inode_out_buf[3] = inode_in_buf[2]; 
+
+		inode_out_buf[4] = inode_in_buf[6]; /* 24 bit: size */
+		inode_out_buf[5] = inode_in_buf[5];
+		inode_out_buf[6] = inode_in_buf[4];
+
+		inode_out_buf[7] = inode_in_buf[7]; /* 8 bit: gid width */
+
+		/* Stop the madness! Outlaw C bitfields! They are unportable and nasty!
+		See for yourself what a mess this is: */
+
+		if (output_big_endian) {
+			inode_out_buf[ 8] = ( (inode_in_buf[ 8]&0x3F) << 2 ) | 
+				( (inode_in_buf[11]&0xC0) >> 6 );
+
+			inode_out_buf[ 9] = ( (inode_in_buf[11]&0x3F) << 2 ) |
+				( (inode_in_buf[10]&0xC0) >> 6 );
+
+			inode_out_buf[10] = ( (inode_in_buf[10]&0x3F) << 2 ) |
+				( (inode_in_buf[ 9]&0xC0) >> 6 );
+
+			inode_out_buf[11] = ( (inode_in_buf[ 9]&0x3F) << 2 ) |
+				( (inode_in_buf[ 8]&0xC0) >> 6 );
+		}
+		else {
+			inode_out_buf[ 8] = ( (inode_in_buf[ 8]&0xFD) >> 2 ) | 
+				( (inode_in_buf[11]&0x03) << 6 );
+
+			inode_out_buf[ 9] = ( (inode_in_buf[11]&0xFD) >> 2 ) | 
+				( (inode_in_buf[10]&0x03) << 6 );
+
+			inode_out_buf[10] = ( (inode_in_buf[10]&0xFD) >> 2 ) | 
+				( (inode_in_buf[ 9]&0x03) << 6 );
+
+			inode_out_buf[11] = ( (inode_in_buf[ 9]&0xFD) >> 2 ) | 
+				( (inode_in_buf[ 8]&0x03) << 6 );
+		}
+
+		memmove(inode_out, inode_out_buf, sizeof(*inode_out));
+	}
+}
+
+void inode_to_host(int from_big_endian, struct cramfs_inode *inode_in, struct cramfs_inode *inode_out)
+{
+	inode_toggle_endianness(from_big_endian, HOST_IS_BIG_ENDIAN, inode_in, inode_out);
+}
+
+void inode_from_host(int to_big_endian, struct cramfs_inode *inode_in, struct cramfs_inode *inode_out)
+{
+	inode_toggle_endianness(HOST_IS_BIG_ENDIAN, to_big_endian, inode_in, inode_out);
+}