Adapt the ext2 create file system progress tracker to used the new
ProgressBar class. Also make it track when the text progress indicator
completes so that the progress bar can be stopped as well as started
when needed.
Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
copy methods
Adapt the ext2 resize progress tracker to the new ProgressBar class.
Also update the progress function to track when text progress bars have
completely passed in the output so that the progress bar can be stopped
as well as started when needed.
Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
copy methods
Change the Applying pending operations dialog so that it takes it source
of progress from the single ProgressBar object, rather than the fraction
value in every OperationDetail object. Also remove ProgressBar
debugging now that it is being used to drive the UI.
NOTE:
This temporarily causes the existing file system specific progress bars
to not be shown because they still update via the fraction member in
each OperationDetail object, rather than the new ProgressBar. This will
be corrected in following commits.
Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
copy methods
1) Multiple progress bars
The OperationDetail class contains member fraction which is used to feed
data to the current operation progress bar shown in the Applying pending
operations dialog. Dialog_Progress::on_signal_update() gets called for
every updated OperationDetail object and depending on whether fraction
is > 0.0 or not, switches between showing a growing or pulsing progress
bar. This leads to the conclusion that every OperationDetail object
currently being updated is effectively driving the single on screen
progress bar with different data.
The Copy_Blocks code is careful to update text and faction in a single
OperationDetail object and everything is good. The on screen progress
bar is switched into growing mode and then grows to 100%.
Since external command output is updated in real time [1] there are two
OperationDetail objects, one for stdout and one for stderr, which are
updated whenever data is read from the relevant stream. Also now that
progress is interpreted from some external command output [2][3][4] a
separate OperationDetail object is getting updated with the progress
fraction. (Actually the grandparent OperationDetail of the ones
receiving stdout and stderr updates as used by the file system specific
*_progress() methods). In the normal case of an external command
which is reporting it's progress two OperationDetails are constantly
being updated together, the OperationDetail object tracking stdout and
it's grandparent receiving progress fraction updates. This causes the
the code in Dialog_Progress::on_signal_update() to constantly switch
between growing and pulsing progress bar mode. The only reason this
doesn't flash the progress bar is because the stdout OperationDetail
object is updated first and before the 100 ms timeout fires to pulse the
bar, it's grandparent is updated with the new fraction to keep growing
the bar instead.
2) Common code
The Copy_Blocks code currently tracks the progress of blocks copied
against target amount, which it has to do anyway. That information is
then used to generate the text and fraction to update into the
OperationDetail object and drive the on screen progress bar. This same
level of tracking is wanted for the XFS and ext2/3/4 file system
specific copy methods.
Conclusion and solution
Having multiple sources of progress bar data is a problem and makes it
clear that there must be only one source of progress data. Also some
code can be shared for tracking the amount of blocks copied and
generating the display.
Therefore have a single ProgressBar object which is used everywhere.
This commit
It just creates a single ProgressBar object which is available via all
OperationDetail objects and Copy_Blocks is updated accordingly. Note
that the ProgressBar still contains debugging and that the GUI progress
bar of the current operation is still driven via the fraction member in
any OperationDetail object.
Referenced commits:
[1] 52a2a9b00a
Reduce threading (#685740)
[2] ae434579e1
Display progress for e2fsck (#467925)
[3] baea186138
Display progress for mke2fs (#467925)
[4] 57b028bb8e
Display progress during resize (#467925)
Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
copy methods
Write a generic progress bar class. Has the following features:
* Has separate progress and target numbers, rather than a single
completion fraction, to enable the the next feature.
* Optionally generates text reporting the amount of data copied using
the progress and target numbers like this:
"1.00 MiB of 16.00 MiB copied"
* After running for 5 seconds, also add estimated remaining time.
(Waits to allow the data copying rate to settle down a little before
estimating the remaining time). Looks like this:
"1.00 MiB of 16.00 MiB copied (00:01:59) remaining)"
The ProgressBar class is not driving the visual progress bar yet. It
has just been added into the internal block copy algorithm and generates
debug messages showing the progress bar is operating correctly.
Debugging looks like this:
DEBUG: ProgressBar::start(target=2.0636e+09, text_mode=PROGRESSBAR_TEXT_COPY_BYTES)
DEBUG: ProgressBar::update(progress=1.30023e+08) m_fraction=0.0630081 m_text="124.00 MiB of 1.92 GiB copied"
DEBUG: ProgressBar::update(progress=2.67387e+08) m_fraction=0.129573 m_text="255.00 MiB of 1.92 GiB copied"
DEBUG: ProgressBar::update(progress=4.0475e+08) m_fraction=0.196138 m_text="386.00 MiB of 1.92 GiB copied"
...
DEBUG: ProgressBar::update(progress=1.13351e+09) m_fraction=0.549289 m_text="1.06 GiB of 1.92 GiB copied (00:00:04 remaining)"
DEBUG: ProgressBar::update(progress=1.26249e+09) m_fraction=0.611789 m_text="1.18 GiB of 1.92 GiB copied (00:00:04 remaining)"
DEBUG: ProgressBar::update(progress=1.39041e+09) m_fraction=0.67378 m_text="1.29 GiB of 1.92 GiB copied (00:00:03 remaining)"
...
DEBUG: ProgressBar::update(progress=1.97552e+09) m_fraction=0.957317 m_text="1.84 GiB of 1.92 GiB copied (00:00:00 remaining)"
DEBUG: ProgressBar::update(progress=2.0636e+09) m_fraction=1 m_text="1.92 GiB of 1.92 GiB copied"
DEBUG: ProgressBar::stop()
Bug 760709 - Add progress bars to XFS and EXT2/3/4 file system specific
copy methods
Simplify code in Dialog_Partition_Info::Dialog_Info() which was open
coding concatenating together a vector of strings with a new line
between each. Replace with Glib::build_path(), as used elsewhere in
this method and other code.
Create and open a LUKS mapping but don't create any file system within.
# cryptsetup luksFormat /dev/sdb5
# cryptsetup luksOpen /dev/sdb5 sdb5_crypt
GParted was incorrectly reporting this warning:
Unable to read the contents of this file system!
Because of this some operations may be unavailable.
The cause might be a missing software package.
The following list of software packages is required for luks file
system support: dmsetup.
This is even though the usage figures for the on disk LUKS encryption
are fully known. See luks::set_used_sectors().
This was occurring because derived PartitionLUKS::set_usage_known()
was checking usage figures for the outer LUKS and the inner encrypted
file system, unknown in this case. Correct when displaying figures in
the UI, but not correct in GParted_Core::set_used_sectors() when only
checking the outer LUKS usage figures were set correctly. Fix this.
Bug 760080 - Implement read-only LUKS support
At the moment any messages for an encrypted file system aren't shown,
only messages from the outer PartitionLUKS object are shown. Also in
Win_GParted::activate_paste() the selected Partition object, possibly
a derived PartitionLUKS, is cloned and the messages cleared.
Therefore a set of accessor methods must be provided to query and modify
partition messages. Messages will be stored in the Partition object to
which they are added and retrieved from all. So in the case of a
derived PartitionLUKS they will be retrieved from the messages vector of
the PartitionLUKS object itself and the messages vector for the
encrypted file system it contains.
To replace code like this in GParted_Core:
partition_temp->messages = messages;
We might naturally provide a set_messages() method which assigns the
messages vector and is used like this:
partition_temp->set_messages( messages );
However on a PartitionLUKS object what should set_messages() do? By the
name it will replace any existing messages in the PartitionLUKS object
itself, but what should happen to the messages for the contained
encrypted Partition object? Should they be cleared or left alone?
Rather than implement set_messages() with unclear semantics implement
append_messages(), which in the PartitionLUKS object case will clearly
leave any messages for the contained encrypted Partition object alone.
Append_messages() is then used to add messages as the Partition or
PartitionLUKS objects when populating the data in GParted_Core.
Bug 760080 - Implement read-only LUKS support
For LUKS formatted partitions add an encryption section into the
Information dialog and display the type of encryption, path, UUID and
status of the encryption.
The file system section continues to display appropriate file system
details, including the partition graphic with the file system specific
border colour and correct usage. The details will either be of a plain
file system, an encrypted file system, or nothing when there is no open
dm-crypt mapping, leaving the encrypted file system inaccessible.
Should there be LUKS encryption directly within LUKS encryption then the
details of the inner encryption will be displayed in the file system
section. However this configuration will not be further supported by
GParted.
Bug 760080 - Implement read-only LUKS support
There is already the set of methods in the Partition class to report the
file system usage. Virtualise them and provide PartitionLUKS specific
implementations to calculate the usage of a file system wrapped in LUKS
encryption.
See the ascii art and comment in PartitionLUKS.cc for the details of
those calculations.
Bug 760080 - Implement read-only LUKS support
LUKS headers don't provide any concept of label. Also there is already
the method Partition::get_filesystem_label() for getting the *file
system* label, so virtualise it and provide an appropriate
implementation to get the label of an encrypted file system represented
within a derived PartitionLUKS object. This causes the label to be
displayed correctly in the main window.
It also happens to display the encrypted file system label in the
Information dialog for a LUKS formatted partition. However the whole
Information dialog will be addressed differently in a following commit.
Bug 760080 - Implement read-only LUKS support
In the main window disk graphic, when there is an open dm-crypt mapping,
display the colour of the encrypted file system.
Bug 760080 - Implement read-only LUKS support
In the File System column in the GUI, when there is an open dm-crypt
mapping, display the colour square for the encrypted file system within
and the text as "[Encrypted] FSTYPE". For closed mappings nothing can
be known about the encrypted file system within so continue to display a
purple square and the text "[Encrypted]".
Looks like:
Partition | File System
...
/dev/sdb3 # ext4
v /dev/sdb4 * # extended
/dev/sdb5 # [Encrypted]
/dev/sdb6 * # [Encrypted] unknown
/dev/sdb7 * # [Encrypted] ext4
Bug 760080 - Implement read-only LUKS support
Partition object represents a region of a disk and the file system
within. GParted always displays the colour base of the type of the file
system. Therefore remove the color member and always look it up from
the type of the file system as needed.
This makes one less member that will need virtual accessor methods with
different handling in the derived PartitionLUKS class.
Bug 760080 - Implement read-only LUKS support
When there exists an open dm-crypt mapping, populate the encrypted
Partition object representing the encrypted file system.
Bug 760080 - Implement read-only LUKS support
Absolute minimum implementation of a PartitionLUKS class which can be
constructed, polymorphically copied and destroyed. Contains an
"encrypted" member of type Partition to represent the encrypted file
system within the LUKS format.
Create PartitionLUKS objects instead of base Partition objects when a
LUKS formatted partition is found. Only the base Partition object
member values have been populated, and the "encrypted" member remains
blank at this point.
Bug 760080 - Implement read-only LUKS support
This is the equivalent change as made to set_mountpoints() in an earlier
commit. Change GParted_Core::set_used_sectors() from being called with
a vector of partitions and processing them all to being called per
partition. This is in preparation for calling set_used_sectors() on a
single Partition object inside a PartitionLUKS object.
Bug 760080 - Implement read-only LUKS support
Populate the canonical device name, /dev/mapper/NAME, used to access the
encrypted file system into the mount points of the Partition object.
This is the equivalent of what is already done for the Volume Group name
and SWRaid Array device.
This does get displayed in the Mount Point column in the main window,
which isn't wanted. However the data will be needed when displaying
details of the encryption mapping in the Information dialog. Both will
be dealt with in following commits.
Bug 760080 - Implement read-only LUKS support
Previously GParted_Core::set_mountpoints() was called with a vector of
partitions and processed them all. Now make set_mountpoints() process a
single partition and push the calls to it down one level from
set_devices_thread() into set_device_partitions() and
set_device_one_partition(). This is in preparation for having an
encrypted file system represented as a Partition object inside a
PartitionLUKS object and needing to call set_mountpoints() for the inner
single Partition object.
Bug 760080 - Implement read-only LUKS support
Only load the LUKS_Info cache of active dm-crypt mappings when the first
LUKS partition is encountered. Not needed from a performance point of
view as the longest that I have ever seen "dmsetup table --target crypt"
take to run is 0.05 seconds. Just means that the dmsetup command is
only run when there are LUKS partitions and the information is needed.
Bug 760080 - Implement read-only LUKS support
Populate the used, unused and unallocated figures in the Partition
object for a LUKS formatted partition. See comment in
luks::set_used_sectors() for the rational of what is used, unused and
unallocated.
As that rational mentions, a LUKS header does not store the size of the
encrypted data and is assumed to extend to the end of the partition by
the tools which start the mapping.
An underlying block device of 128 MiB (131072 KiB).
# sfdisk -s /dev/sde
131072
An active LUKS mapping at offset 2 MiB (4096 512-byte sectors) and
length 126 MiB (129024 KiB, 258048 512-byte sectors).
# sfdisk -s /dev/mapper/sde_crypt
129024
# cryptsetup status sde_crypt
/dev/mapper/sde_crypt is active.
type: LUKS1
cipher: aes-cbc-essiv:sha256
keysize: 256 bits
device: /dev/sde
offset: 4096 sectors
size: 258048 sectors
mode: read/write
No size/length reported when dumping the LUKS header, just (payload)
offset.
# cryptsetup luksDump /dev/sde
LUKS header information for /dev/sde
Version: 1
Cipher name: aes
Cipher mode: cbc-essiv:sha256
Hash spec: sha1
Payload offset: 4096
MK bits: 256
MK digest: 7f fb ba 40 7e ba e4 3b 2f c6 d0 93 7b f7 05 49 7b 72 d4 ad
MK salt: 4a 5b 54 f9 7b 67 af 6e ef 16 31 0a fe d9 7e 5f
c3 66 dc 8a ed e0 07 f4 45 c3 7c 1a 8d 7d ac f4
MK iterations: 37750
UUID: 0a337705-434a-4994-a842-5b4351cb3778
...
Shrink the LUKS mapping to 64 MiB (65536 KiB, 131072 512-byte sectors).
# cryptsetup resize --size 131072 sde_crypt
# sfdisk -s /dev/mapper/sde_crypt
65536
# cryptsetup status sde_crypt
/dev/mapper/sde_crypt is active.
type: LUKS1
cipher: aes-cbc-essiv:sha256
keysize: 256 bits
device: /dev/sde
offset: 4096 sectors
size: 131072 sectors
mode: read/write
Stop and start the LUKS mapping.
# cryptsetup luksClose sde_crypt
# cryptsetup luksOpen /dev/sde sde_crypt
The size of the LUKS mapping is back to 126 MiB (129024 KiB, 258048
512-byte sectors), extending to the end of the partition.
# sfdisk -s /dev/mapper/sde_crypt
129024
# cryptsetup status sde_crypt
/dev/mapper/sde_crypt is active.
type: LUKS1
cipher: aes-cbc-essiv:sha256
keysize: 256 bits
device: /dev/sde
offset: 4096 sectors
size: 258048 sectors
mode: read/write
Bug 760080 - Implement read-only LUKS support
Also load the starting offset and length of the active dm-crypt mapping
into the LUKS_Info module from the dmsetup output. This provides the
location and size of the encrypted data within the underlying block
device.
Note that dmsetup reports in units of 512 bytes sectors [1], the GParted
LUKS_Info module uses bytes and GParted Partition objects work in device
sector size units. However the actual sector size of a dm-crypt mapping
[2] is the same as that of the underlying block device [3].
# modprobe scsi_debug dev_size_mb=128 sector_size=4096
# fgrep scsi_debug /sys/block/*/device/model
/sys/block/sdd/device/model:scsi_debug
# parted /dev/sde print
Error: /dev/sde: unrecognised disk label
Model: Linux scsi_debug (scsi)
Disk /dev/sde: 134MB
[3] Sector size (logical/physical): 4096B/4096B
Partition Table: unknown
# cryptsetup luksFormat /dev/sde
# cryptsetup luksOpen /dev/sde sde_crypt
# parted /dev/mapper/sde_crypt print
Error: /dev/mapper/sde_crypt: unrecognised disk label
Model: Linux device-mapper (crypt) (dm)
Disk /dev/mapper/sde_crypt: 132MB
[2] Sector size (logical/physical): 4096B/4096B
Partition Table: unknown
# cryptsetup status sde_crypt
/dev/mapper/sde_crypt is active.
type: LUKS1
cipher: aes-cbc-essiv:sha256
keysize: 256 bits
device: /dev/sde
offset: 4096 sectors
size: 258048 sectors
mode: read/write
# dmsetup table --target crypt
...
sde_crypt: 0 258048 crypt aes-cbc-essiv:sha256 0000000000000000000000000000000000000000000000000000000000000000 0 8:64 4096
[1] Both cryptsetup and dmsetup report the offset as 4096 and the size/
length as 258048. 128 MiB / (4096+258048) = 512 byte units, even on a
4096 byte sector size device.
Update debugging of LUKS to this:
# ./gpartedbin
======================
libparted : 2.4
======================
DEBUG: /dev/sdb5: LUKS closed
DEBUG: /dev/sdb6: LUKS open mapping /dev/mapper/sdb6_crypt, offset=2097152, length=534773760
/dev/sde: unrecognised disk label
DEBUG: /dev/sde: LUKS open mapping /dev/mapper/sde_crypt, offset=2097152, length=132120576
Bug 760080 - Implement read-only LUKS support
The code currently allows attempting to mount and unmount a LUKS
partition. It is nonsense to directly try to mount and unmount a LUKS
partition and obviously doesn't work. For read-only LUKS support there
is no need to attempt to apply this to the encrypted file system within.
Therefore prevent these operations for LUKS partitions.
Bug 760080 - Implement read-only LUKS support
This patchset is adding read-only LUKS support. Creation of LUKS is
planned to be a tick box adding encryption in the Create New Partition
dialog. Therefore remove the greyed out crypt-luks entry in the Create
New Partition dialog and the Format menu.
Bug 760080 - Implement read-only LUKS support
Provide a minimal implementation of a luks file system class which only
does busy detection.
NOTE:
For now, read-only LUKS support, a LUKS partition will be busy when a
dm-crypt mapping exists. Later when read-write LUKS support is added
GParted will need to look at the busy status of the encrypted file
system within the open LUKS partition and map LUKS partition busy status
to encryption being open or closed.
Bug 760080 - Implement read-only LUKS support
Load basic details of active Device-mapper encryption mappings from the
kernel. Use dmsetup active targets.
# cryptsetup luksFormat /dev/sdb5
# cryptsetup luksFormat /dev/sdb6
# cryptsetup luksOpen /dev/sdb6 sdb6_crypt
# ls -l /dev/mapper/sdb6_crypt /dev/dm-0
lrwxrwxrwx. 1 root root 7 Nov 15 09:03 /dev/mapper/sdb6_crypt -> ../dm-0
brw-rw----. 1 root disk 253, 0 Nov 15 09:03 /dev/dm-0
# ls -l /dev/sdb6
brw-rw----. 1 root disk 8, 22 Nov 15 09:02 /dev/sdb6
# dmsetup table --target crypt
sdb6_crypt: 0 1044480 crypt aes-cbc-essiv:sha256 0000000000000000000000000000000000000000000000000000000000000000 0 8:22 4096
So far just load the mapping name and underlying block device reference
(path or major, minor pair).
Note that all supported kernels appear to report the underlying block
device as major, minor pair in the dmsetup output. Underlying block
device paths are added to the cache when found during a search to avoid
stat(2) call on subsequent searches for the same path.
Prints debugging to show results, like this:
# ./gpartedbin
======================
libparted : 2.4
======================
DEBUG: /dev/sdb5: LUKS closed
DEBUG: /dev/sdb6: LUKS open mapping /dev/mapper/sdb6_crypt
Bug 760080 - Implement read-only LUKS support
Renamed from DEV_MAP_PATH to DEV_MAPPER_PATH. Moved so that the
constant is logically intended for use outside of the DMRaid class.
Also specifically make the string constant have external linkage, rather
than the default internal (static) linkage for constants, so that there
is only one copy of the variable in the program, rather than one copy in
each compilation unit which included DMRaid.h. Namely DMRaid.cc and
GParted_Core.cc.
References:
[1] Proper way to do const std::string in a header file?
http://stackoverflow.com/questions/10201880/proper-way-to-do-const-stdstring-in-a-header-file
[2] What is external linkage and internal linkage in C++
http://stackoverflow.com/questions/1358400/what-is-external-linkage-and-internal-linkage-in-c/1358796#1358796
Bug 760080 - Implement read-only LUKS support
History:
1) The constructor was added by commit:
6d8b169e73
2006-03-14 21:37:47
changed the way devices and partitions store their devicepaths. Instead of
2) Removed from most of the file system specific ::Copy() methods by
commit:
ad9f2126e7
2006-03-19 15:30:20
fixed issues with copying (see also #335004) cleanups + added FIXME added
3) Removed from GParted_Core::copy() method by commit:
7bb7e8a84f
2006-05-23 22:17:34
Use ped_device_read and ped_device_write instead of 'dd' to copy
4) Finally removed from the last place in xfs::Copy() method by commit:
e414b71b73
2012-01-11 19:49:13
Update xfs resize and copy to use new helper functions
The Partition(path) constructor is no longer used. Remove.
When a base class destructor is virtual, derived class destructors are
also virtual [1] even if they don't have the virtual qualifier.
As the Operation destructor is virtual, derived Operation* classes
destructors are virtual too. Add virtual qualifier just to reflect what
the C++ language mandates the compiler implement.
[1] Derived class with non-virtual destructor
http://stackoverflow.com/questions/7403883/derived-class-with-non-virtual-destructor
The sector_size parameter is unnecessary as the value can be retrieved
from the sector size of the selected Partition object on which the
create new, copy & paste or resize/move operation is being performed.
For the create new and resize/move operations it is trivial as the
existing unallocated or in use Partition object on which the operation
is being perform already contains the correct sector size. For the copy
& paste operation, which can copy across disk devices of different
sector sizes, we merely have to use the sector size of the existing
selected (destination) Partition object rather than copied (source)
Partition object. Hence these relevant lines in the new code:
Dialog_Partition_Copy::set_data(selected_partition, copied_partition)
new_partition = copied_partition.clone();
...
new_partition->sector_size = selected_partition.sector_size;
The expressions used in the call to Set() were comparing
lp_partition->type to 0 for the type parameter and passing it as a bool
for the inside_extended parameter. Libparted lp_partition->type is
actually an enumeration. The code was only working because of the
specific values assigned to the symbolic names, PED_PARTITION_NORMAL = 0
and PED_PARTITION_EXTENDED is non-zero (true).
Make the code use the symbolic names and not depend on the actual
enumeration values, which should be considered changeable and private to
libparted.
When displaying an unallocated partition
Win_GParted::set_valid_operations() calls GParted_Core::get_fs() with
parameter FS_UNALLOCATED.
Before this change, get_fs() would fail to find file system capabilities
set for FS_UNALLOCATED and construct a not supported capabilities set
and return that.
Afterwards, find_supported_filesystems() creates a not supported
capabilities set from the NULL pointer for FS_UNALLOCATED and adds this
entry into the FILESYSTEMS vector. Then get_fs() finds that not
supported capabilities set for FS_UNALLOCATED in the FILESYSTEMS vector
and returns that.
This makes no functional difference. It just seems right as other
unsupported but used file system types have entries in FILESYSTEM_MAP.
The struct FS constructor initialised every member *except* filesystem
and busy. Then in *most* cases after declaring struct FS, assignments
followed like this:
FS fs;
fs.filesystem = FS_BTRFS;
fs.busy = FS::GPARTED;
But member busy wasn't always initialised.
Add initialisation of members filesystem and busy to the struct FS
constructor. Specify optional parameter to the constructor to set the
filesystem member, or when left off filesystem is initialised to
FS_UNKNOWN.
get_fs() used to work by (1) returning the supported capabilities of the
requested file system found in the FILESYSTEMS vector; (2) if not found
return the supported capabilities for file system FS_UNKNOWN; and (3)
if that wasn't found either, create a not supported capabilities set for
FS_UNKNOWN and return that.
This is more complicated that required. Also the not supported
capabilities set, as created by struct FS() constructor, is the same as
that created in file_supported_filesystems() local variable fs_notsupp.
Simplify get_fs() just using a single not found code path returning a
not supported capabilities set.
Final step for full polymorphic handling of Partition objects is to
implement a virtual copy constructor. C++ doesn't directly support
virtual copy constructors, so instead use the virtual copy constructor
idiom [1]. (Just a virtual method called clone() which is implemented
in every polymorphic class and creates a clone of the current object and
returns a pointer to it).
Then replace all calls to the (monomorphic) Partition object copy
constructor throughout the code, except in the clone() implementation
itself, with calls to the new virtual clone() method "virtual copy
constructor".
Also have to make the Partition destructor virtual too [2][3] so that
the derived class destructor is called when deleting using a base class
pointer. C++ supports this directly.
[1] Wikibooks: More C++ Idioms / Virtual Constructor
https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Virtual_Constructor
[2] When to use virtual destructors?
http://stackoverflow.com/questions/461203/when-to-use-virtual-destructors
[3] Virtuality
Guideline #4: A base class destructor should be either public and
virtual, or protected and nonvirtual
http://www.gotw.ca/publications/mill18.htm
Bug 759726 - Implement Partition object polymorphism
SQUASH: When first using pointers to Partition and calling delete
Copy assignment of Partition objects is now only performed in a few
places in the Operation and OperationResizeMove classes when updating
the displayed PartitionVector. (From Refresh_Visual() when each
operation is visually applied to the display_partitions vector; the
new_partition from the operation is copy assigned over the top of the
relevant existing partition in the display_partitions vector).
In general polymorphic copy assignment is complicated [1], and is now
unnecessary given the above limited use. All that is needed is a way to
polymorphically replace one Partition object with another in a
PartitionVector.
First, prevent further use of Partition object copy assignment by
providing a private declaration and no implementation, so the compiler
enforces this. Second implement and use PartitionVector method
replace_at() which replaces a pointer to one Partition object with
another at the specified index in the PartitionVector.
[1] The Assignment Operator Revisited
[Section:] Virtual assignment
http://icu-project.org/docs/papers/cpp_report/the_assignment_operator_revisited.html
Bug 759726 - Implement Partition object polymorphism
Now use a pointer to the Partition object in Dialog_Base_Partition class
and derived classes, Dialog_Partition_{Copy,New,Resize_Move}. This is
equivalent to how the Partition objects are managed in the Operation and
derived classes.
The Partition object is allocated and copy constructed in each derived
classes' set_data() method, called from each constructor and deallocated
in the destructors. Considering the remaining Big 3, these classes are
never copy constructed or copy assigned so provide private definitions
and no implementations so the compiler enforces this.
Bug 759726 - Implement Partition object polymorphism
The code in on_view_clicked() copy constructed a Partition object and
then in the following 3 lines only read a couple of public member
variables from the new copy.
Making a copy of the partition is unnecessary. Change to just creating
a constant reference to the Partition instead.
(It would also be an impediment to polymorphically using Partition
objects, except for the fact that gpart doesn't recognise LUKS
signatures so will never have to create a PartitionLUKS object).
Bug 759726 - Implement Partition object polymorphism
A number of methods in GParted_Core and Win_GParted were using local
Partition objects. Change them into pointers so that Partition object
polymorphism can be implemented.
Bug 759726 - Implement Partition object polymorphism
Change Win_GParted::copied_partition from Partition object which is
copied by value into a pointer to a Partition object object which is
allocated, copy constructed and deleted. Required as part of the
polymorphic implementation of Partitions.
As before when managing the lifetime of pointers to objects in a class
the Big 3 of destructor, copy constructor and copy assignment operator
need to be considered. A destructor is added to finally delete
copied_partition. A single Win_GParted object is only ever created and
destroyed in main(). The class is never copy constructed or copy
assigned. Make the compiler enforce this with private declarations and
no implementations.
Bug 759726 - Implement Partition object polymorphism
Operation classes now internally use pointers to Partition objects and
take on management of their lifetimes. As before, with the
PartitionVector class, when storing pointers in a class the Big 3 of
destructor, copy constructor and copy assignment operator also have to
be considered.
First, all the Partition objects are allocated in the derived Operation*
class parameterised constructors and freed in the associated
destructors. However the Operation classes are never copy constructed
or copy assigned; they are only ever created and destroyed. Only
pointers to the derived Operations are copied into the vector of pending
operations. Therefore the copy construtor and copy assignment operator
aren't needed. To enforce this provide inaccessible private
declarations without any implementation so that the compiler will
enforce this [1][2].
This example code fragment:
1 OperationCheck o1( device, partition );
2 OperationCheck o2 = o1;
3 o2 = o1;
Does these OperationCheck calls:
1 Implemented parameterised construtor,
2 Disallowed copy constructor,
3 Disallowed copy assignment
Trying to compile the above code would fail with errors like these:
../include/OperationCheck.h: In member function 'void GParted::Win_GParted::activate_check()':
../include/OperationCheck.h:36:2: error: 'GParted::OperationCheck::OperationCheck(const GParted::OperationCheck&)' is private
OperationCheck( const OperationCheck & src ); // Not implemented copy constructor
^
test.cc:2:21: error: within this context
OperationCheck o2 = o1;
^
../include/OperationCheck.h:37:19: error: 'GParted::OperationCheck& GParted::OperationCheck::operator=(const GParted::OperationCheck&)' is private
OperationCheck & operator=( const OperationCheck & rhs ); // Not implemented copy assignment operator
^
test.cc:3:4: error: within this context
o2 = o1;
^
[1] Disable copy constructor
http://stackoverflow.com/questions/6077143/disable-copy-constructor
[2] Disable compiler-generated copy-assignment operator [duplicate]
http://stackoverflow.com/questions/7823845/disable-compiler-generated-copy-assignment-operator
Bug 759726 - Implement Partition object polymorphism
The Operation classes contain partition objects which are copied by
value. Need to replace these with pointers to Partition objects instead
and manage their lifetimes so that they can be used polymorphically.
First step is to protect the partition members partition_new,
partition_original, and for OperationCopy class only, partition_copied
within the Operation classes and provide accessor methods.
get_partition_new() and get_partition_original() accessors are
implemented in the Operation base class so all derived classes get an
implementation. get_partition_new() is also virtual so that
OperationCheck and OperationDelete can override the implementation and
assert that they don't use partition_new. get_partition_copied() is
provided for the OperationCopy class only so can only be accessed via an
OperationCopy type variable.
Bug 759726 - Implement Partition object polymorphism
Mike Fleetwood