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Refactor UDF label manipulation code (#784533) 

Make especially the Volume Identifier length limit code simpler to
understand and therefore easier to maintain.

Bug 784533 - Add support for UDF file system
This commit is contained in:
Mike Fleetwood 2017-07-27 16:23:11 +01:00
parent 861bc8df5d
commit a0c44d766d
2 changed files with 59 additions and 43 deletions
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6
include/udf.h
View File

@ -21,6 +21,9 @@
#include "FileSystem.h"
#include "Partition.h"
#include <stddef.h>
#include <glibmm/ustring.h>
namespace GParted
{
@ -33,6 +36,9 @@ public:
bool create( const Partition & new_partition, OperationDetail & operationdetail );
private:
static bool contains_only_ascii( const Glib::ustring & str );
static size_t find_first_non_latin1( const Glib::ustring & str );
bool old_mkudffs; // Pre 1.1 version of mkudffs
};

96
src/udf.cc
View File

@ -18,6 +18,9 @@
#include "Partition.h"
#include "Utils.h"
#include <stddef.h>
#include <glibmm/ustring.h>
namespace GParted
{
@ -74,46 +77,22 @@ bool udf::create( const Partition & new_partition, OperationDetail & operationde
return false;
}
// NOTE: UDF Logical Volume Identifier (--lvid) represents the label but blkid
// (from util-linux) prior to version v2.26 used the Volume Identifier (--vid).
// Therefore for compatibility reasons store label in both locations.
Glib::ustring label_args;
if ( ! new_partition.get_filesystem_label().empty() )
{
const Glib::ustring label = new_partition.get_filesystem_label();
int non_ascii_pos_label = -1;
int non_latin1_pos_label = -1;
int pos = 0;
for ( Glib::ustring::const_iterator it = label.begin(); it != label.end(); ++it )
{
if ( *it > 0x7F && non_ascii_pos_label == -1 )
non_ascii_pos_label = pos;
if ( *it > 0xFF && non_latin1_pos_label == -1 )
non_latin1_pos_label = pos;
if ( non_ascii_pos_label != -1 && non_latin1_pos_label != -1 )
break;
++pos;
}
// NOTE: mkudffs from udftools prior to version 1.1 damage label if contains
// non-ASCII characters. So do not allow non-ASCII characters in old mkudffs.
if ( old_mkudffs && non_ascii_pos_label != -1 )
// Mkudffs from udftools prior to version 1.1 damages the label if it
// contains non-ASCII characters. Therefore do not allow a label with
// such characters with old versions of mkudffs.
if ( old_mkudffs && ! contains_only_ascii( label ) )
{
operationdetail.add_child( OperationDetail(
_("mkudffs prior to version 1.1 does not support non-ASCII characters in the label."),
STATUS_ERROR ) );
_("mkudffs prior to version 1.1 does not support non-ASCII characters in the label."),
STATUS_ERROR ) );
return false;
}
// NOTE: UDF Volume Identifier (--vid) can contain maximally 30 Unicode code
// points. And if one is above U+FF then only 15. UDF Logical Volume Identifier
// (--lvid) can contain maximally 126 resp. 63 Unicode code points. To allow
// long 126 characters in label, UDF Volume Identifier would be truncated.
// When UDF Volume Identifier or UDF Logical Volume Identifier is too long
// mkuddfs fail with error.
// NOTE: According to the OSTA specification, UDF supports only strings
// encoded in 8-bit or 16-bit OSTA Compressed Unicode format. They are
// equivalent to ISO-8859-1 (Latin 1) and UCS-2BE respectively.
@ -122,20 +101,25 @@ bool udf::create( const Partition & new_partition, OperationDetail & operationde
// specification was created before the introduction of UTF-16, but lots
// of UDF tools are able to decode UTF-16 including UTF-16 Surrogate pairs
// outside the BMP (Basic Multilingual Plane).
//
// The Volume Identifier (--vid) can only contain 30 bytes, either 30
// ISO-8859-1 (Latin 1) characters or 15 UCS-2BE characters. Store the
// most characters possible in the Volume Identifier. Either up to 15
// UCS-2BE characters when a character needing 16-bit encoding is found in
// the first 15 characters, or up to 30 characters when a character
// needing 16-bit encoding is found in the second 15 characters.
Glib::ustring vid = label.substr( 0, 30 );
size_t first_non_latin1_pos = find_first_non_latin1( label );
if ( first_non_latin1_pos < 15 )
vid = label.substr( 0, 15 );
else if ( first_non_latin1_pos < 30 )
vid = label.substr( 0, first_non_latin1_pos );
Glib::ustring vid_arg;
if ( non_latin1_pos_label > 30 )
vid_arg = new_partition.get_filesystem_label().substr(0, 30);
else if ( non_latin1_pos_label > 15 )
vid_arg = new_partition.get_filesystem_label().substr(0, non_latin1_pos_label-1);
else if ( non_latin1_pos_label == -1 && label.length() > 30 )
vid_arg = new_partition.get_filesystem_label().substr(0, 30);
else if ( label.length() > 15 )
vid_arg = new_partition.get_filesystem_label().substr(0, 15);
else
vid_arg = new_partition.get_filesystem_label();
label_args = "--lvid=\"" + label + "\" " + "--vid=\"" + vid_arg + "\" ";
// UDF Logical Volume Identifier (--lvid) represents the label, but blkid
// (from util-linux) prior to version v2.26 reads the Volume Identifier
// (--vid). Therefore for compatibility reasons store the label in both
// locations.
label_args = "--lvid=\"" + label + "\" " + "--vid=\"" + vid + "\" ";
}
// NOTE: UDF block size must match logical sector size of underlying media.
@ -149,4 +133,30 @@ bool udf::create( const Partition & new_partition, OperationDetail & operationde
EXEC_CHECK_STATUS|EXEC_CANCEL_SAFE );
}
// Private methods
// Return true only if all the characters in the string are ASCII (<= 0x7F), otherwise false.
bool udf::contains_only_ascii( const Glib::ustring & str )
{
for ( Glib::ustring::const_iterator it = str.begin() ; it != str.end() ; ++it )
{
if ( *it > 0x7F )
return false;
}
return true;
}
// Return the offset of the first non-Latin1 character (> 0xFF), or npos when none found.
size_t udf::find_first_non_latin1( const Glib::ustring & str )
{
size_t pos = 0;
for ( Glib::ustring::const_iterator it = str.begin() ; it != str.end() ; ++it )
{
if ( *it > 0xFF )
return pos;
++pos;
}
return Glib::ustring::npos;
}
} //GParted