[gparted] Remove requirement for xxd and dd for NTFS move or paste action

[Curtis Gedak <gedakc src gnome org>]

commit dd8a57a8fec3abfa8b1b5399a73aa6a5845aed23
Author: Curtis Gedak <gedakc gmail com>
Date:   Sat May 16 12:15:14 2009 -0600

    Remove requirement for xxd and dd for NTFS move or paste action
    
    Perform direct update of Number of Hidden Sectors in NTFS boot record.
    This change removes the need for /usr/bin/xxd and /bin/dd.
    Related to GParted bug #574389
---
 README              |    2 +-
 src/GParted_Core.cc |   57 ++++++++++++++++++++++++++++++++++++++------------
 src/Utils.cc        |    2 +-
 src/ntfs.cc         |   11 +--------
 4 files changed, 47 insertions(+), 25 deletions(-)

diff --git a/README b/README
index 82e0ccb..1be5a29 100644
--- a/README
+++ b/README
@@ -112,7 +112,7 @@ Optional packages include:
    hfsutils
    hfsprogs
    jfsutils
-   ntfsprogs       - dd command, and xxd command from vim-common also required
+   ntfsprogs
    reiser4progs
    reiserfsprogs
    xfsprogs
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index dd714f3..c76deb6 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -2565,37 +2565,66 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition )
 bool GParted_Core::update_bootsector( const Partition & partition, OperationDetail & operationdetail ) 
 {
 	//only for ntfs atm...
-	//FIXME: 1) this should be done without relying on external commands
-	//	 2) this should probably be done in the fsclasses...
+	//FIXME: this should probably be done in the fs classes...
 	if ( partition .filesystem == FS_NTFS )
 	{
+		//The NTFS file system stores a value in the boot record called the
+		//  Number of Hidden Sectors.  This value must match the partition start
+		//  sector number in order for Windows to boot from the file system.
+		//  For more details, refer to the NTFS Volume Boot Record at:
+		//  http://www.geocities.com/thestarman3/asm/mbr/NTFSBR.htm
+
 		operationdetail .add_child( OperationDetail( 
-			String::ucompose( _("updating boot sector of %1 file system on %2"),
+			String::ucompose( _("update boot sector of %1 file system on %2"),
 					  Utils::get_filesystem_string( partition .filesystem ),
 					  partition .get_path() ) ) ) ;
 
+		//convert start sector to hex string
 		std::stringstream ss ;
 		ss << std::hex << partition .sector_start ;
 		Glib::ustring hex = ss .str() ;
-	
+
 		//fill with zeros and reverse...
 		hex .insert( 0, 8 - hex .length(), '0' ) ;
 		Glib::ustring reversed_hex ;
 		for ( int t = 6 ; t >= 0 ; t -=2 )
 			reversed_hex .append( hex .substr( t, 2 ) ) ;
 
-		Glib::ustring output, error, command ;
-		command = 
-			"echo " + reversed_hex + " | xxd -r -p | dd conv=notrunc of=" + partition .get_path() + " bs=1 seek=28" ;
+		//convert reversed hex codes into ascii characters
+		char buf[4] ;
+		for ( unsigned int k = 0; (k < 4 && k < (reversed_hex .length() / 2)); k++ )
+		{
+			Glib::ustring tmp_hex = "0x" + reversed_hex .substr( k * 2, 2 ) ;
+			buf[k] = (char)( std::strtol( tmp_hex .c_str(), NULL, 16 ) ) ;
+		}
 
-		operationdetail .get_last_child() .add_child( OperationDetail( command, STATUS_NONE, FONT_BOLD_ITALIC ) ) ;
-		bool succes = ! Utils::execute_command( command, output, error ) ;
+		//write new Number of Hidden Sectors value into NTFS boot sector at offset 0x1C
+		Glib::ustring error_message = "" ;
+		std::ofstream dev_file ;
+		dev_file .open( partition .get_path() .c_str(), std::ios::out | std::ios::binary ) ;
+		if ( dev_file .is_open() )
+		{
+			dev_file .seekp( 0x1C ) ;
+			if ( dev_file .good() )
+			{
+				dev_file .write( buf, 4 ) ;
+				if ( dev_file .bad() )
+					error_message = String::ucompose( _("Error trying to write to boot sector in %1"), partition .get_path() ) ;;
+			}
+			else
+				error_message = String::ucompose( _("Error trying to seek to position 0x1c in %1"), partition .get_path() ) ;;
+			dev_file .close( ) ;
+		}
+		else
+			error_message = String::ucompose( _("Error trying to open %1"), partition .get_path() ) ;
 
-		if ( ! output .empty() )
-			operationdetail .get_last_child() .get_last_child() .add_child( OperationDetail( output, STATUS_NONE, FONT_ITALIC ) ) ;
-		
-		if ( ! error .empty() )
-			operationdetail .get_last_child() .get_last_child() .add_child( OperationDetail( error, STATUS_NONE, FONT_ITALIC ) ) ;
+		//append error messages if any
+		bool succes = true ;
+		if ( ! error_message .empty() )
+		{
+			succes = false ;
+			operationdetail .get_last_child() .add_child( OperationDetail( error_message, STATUS_NONE, FONT_ITALIC ) ) ;
+		}
 
 		operationdetail .get_last_child() .set_status( succes ? STATUS_SUCCES : STATUS_ERROR ) ;
 		return succes ;
diff --git a/src/Utils.cc b/src/Utils.cc
index 750d3ec..35d4a7f 100644
--- a/src/Utils.cc
+++ b/src/Utils.cc
@@ -157,7 +157,7 @@ Glib::ustring Utils::get_filesystem_software( FILESYSTEM filesystem )
 		case FS_HFSPLUS     : return "hfsprogs" ;
 		case FS_JFS         : return "jfsutils" ;
 		case FS_LINUX_SWAP  : return "util-linux" ;
-		case FS_NTFS        : return "ntfsprogs, xxd, dd" ;
+		case FS_NTFS        : return "ntfsprogs" ;
 		case FS_REISER4     : return "reiser4progs" ;
 		case FS_REISERFS    : return "reiserfsprogs" ;
 		case FS_UFS         : return "" ;
diff --git a/src/ntfs.cc b/src/ntfs.cc
index 4503744..72fbace 100644
--- a/src/ntfs.cc
+++ b/src/ntfs.cc
@@ -49,18 +49,11 @@ FS ntfs::get_filesystem_support()
 			fs .shrink = GParted::FS::EXTERNAL ;
 	}
 
-	//Command xxd used with dd to update NTFS boot sector after move or paste.
-	//  See GParted_Core::update_bootsector().
-
 	//we need ntfsresize to set correct used/unused after cloning
-	if ( ! Glib::find_program_in_path( "ntfsclone" ) .empty() &&
-	     ! Glib::find_program_in_path( "xxd" ) .empty() &&
-	     ! Glib::find_program_in_path( "dd" ) .empty() )
+	if ( ! Glib::find_program_in_path( "ntfsclone" ) .empty() )
 		fs .copy = GParted::FS::EXTERNAL ;
 
-	if ( fs .check && 
-	     ! Glib::find_program_in_path( "xxd" ) .empty() &&
-	     ! Glib::find_program_in_path( "dd" ) .empty() )
+	if ( fs .check )
 		fs .move = GParted::FS::GPARTED ;
 	
 	return fs ;