The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

    20140508-Delphi-2007--Project-Options--Cannot-Edit-Application-Title-HelpFile-Icon-Theming20140430-Fiddler-Filter-Actions-Button-Run-Filterset-now20140424-VMware-Fusion-6.0.3.-no-reclaimable
    More Photos

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,994 other followers

Archive for the ‘PowerShell’ Category

« Previous Entries

When NTFS shrink fails, despite using the default settings from the shrink dialog

Posted by jpluimers on 2020/05/25

Sometimes an NTFS shrink still fails, even though you use the built in Windows defragmentation tools, of SysInternals contig tool.

The best you can do is to follow the steps in:

  1. run diskmgmt.msc to try shrinking the disk, then often it is already in the error message: “You can’t shrink a volume beyond the point where any unremoveable files are located see the defrag event in application log for detailed information about the operation when it has completed.”
  2. use eventvwr.exe and look at the Windows Logs for the most recent Application entries that has Source set to defrag

Those defrag entries usually tell about the last file that could not be moved.

You can use wevtutill to query events on the commandline.

Note that contrary to [WayBack] WEVTUTIL – Windows CMD – SS64.com documentation, the option /rd cannot be expanded to /reversedirection , as you will get an error “invalid option reversedirection” – Google Search.

For querying the above defrag event, use this command line (replace /format:XML with /format:text for more readable but also more verbose output):

wevtutil query-events Application /count:2 /format:XML /rd:true /query:"*[System[(EventID=259)]]"

On Windows 10, this is often caused by “System Protection” which locks files under C:\Recovery, but I have also seen $BITMAP, $MFT and $DATA entries.

System protected drives

To view which drives are currently used for system protection (this opens the “System Properties” dialog focussed on the “System Protection” tab):

SystemPropertiesProtection.exe

To disable it for one drive:

Disable-ComputerRestore -Drive "C:"

To enable it for one drive:

Enable-ComputerRestore -Drive "C:"

There seems to be no easy one-command PowerShell way to view the drives have ComputerRestore enabled, as this does not show drive letters:

PowerShell Get-ComputerRestorePoint ^| Format-List

The above gives more detailed output than a plain PowerShell Get-ComputerRestorePoint

Deleting restore points

PowerShell does not have a built-in option to delete restore points, but vssadmin has, but calls them “shadows”.

First list them:

vssadmin list shadows

Then delete them (but be aware this will not prompt for confirmation because of the /quiet):

vssadmin delete shadows /for=C: /quiet

You can also delete them for all drives (this will not prompt for confirmation either):

vssadmin delete shadows /all /quiet

Stopping the volume shadow copy service:

net stop vss

Managing hibernation and page file

Hibernation:

powercfg.exe /hibernate off

powercfg.exe /hibernate on

Page file:

wmic pagefile list /format:list
AllocatedBaseSize=2944
CurrentUsage=0
Description=C:\pagefile.sys
InstallDate=20181018215808.683376+120
Name=C:\pagefile.sys
PeakUsage=0
Status=
TempPageFile=FALSE

wmic computersystem where name="%computername%" get AutomaticManagedPagefile
AutomaticManagedPagefile
TRUE

wmic computersystem where name="%computername%" set AutomaticManagedPagefile=False
Updating property(s) of '\\MYCOMPUTER\ROOT\CIMV2:Win32_ComputerSystem.Name="LAPTOPUW08"'
Property(s) update successful.

wmic computersystem where name="%computername%" get AutomaticManagedPagefile
AutomaticManagedPagefile
FALSE

wmic.exe pagefileset where name="C:\\pagefile.sys" delete
Deleting instance \\MYCOMPUTER\ROOT\CIMV2:Win32_PageFileSetting.Name="C:\\pagefile.sys"
Instance deletion successful.

Sometimes the deletion does not work (see below for workaround):

wmic pagefile list /format:list

AllocatedBaseSize=2944
CurrentUsage=0
Description=C:\pagefile.sys
InstallDate=20181018215808.683376+120
Name=C:\pagefile.sys
PeakUsage=0
Status=
TempPageFile=FALSE

Do not do this:

wmic pagefile delete
Deleting instance \\MYCOMPUTER\ROOT\CIMV2:Win32_PageFileUsage.Name="C:\\pagefile.sys"
ERROR:
Description = Provider is not capable of the attempted operation

wmic pagefileset set name="c:\\pagefile.sys",InitialSize=0,MaximumSize=0
No Instance(s) Available.

Sometimes it still fails, so then you have to use the UI:

  1. Run SystemPropertiesAdvanced.exe
  2. Under Performance, click on Settings
  3. Click the Advanced tab
  4. Under Virtual memory, click the Change button
  5. Ensure Automatically manage page file size for all drives is disabled
  6. Ensure No paging file is selected
  7. Click the Set button
  8. Confirm you really want no page file
  9. Press on the three OK buttons to fully leave the Advanced System Properties dialog.
  10. Reboot

After resizing the disk, reverse the steps:

  1. Run SystemPropertiesAdvanced.exe
  2. Under Performance, click on Settings
  3. Click the Advanced tab
  4. Under Virtual memory, click the Change button
  5. Ensure Automatically manage page file size for all drives is enabled
  6. Confirm you really want no page file
  7. Press on the three OK buttons to fully leave the Advanced System Properties dialog.
  8. Reboot

Bitmap file

Sometimes the file blocking the resize is the NTFS "\$BitMap::$DATA", which few defragmentation tools can move as it is the MFT Bitmap.

Background reading

–jeroen

Posted in CommandLine, Console (command prompt window), Development, Power User, PowerShell, PowerShell, Scripting, Software Development, Windows | Leave a Comment »

Cool hacking stuff…

Posted by jpluimers on 2020/05/06

Boy, it is indeed a game of walls and ladders:

–jeroen

Posted in CommandLine, Development, Power User, PowerShell, PowerShell, Scripting, Software Development, Windows | Leave a Comment »

Mad With PowerShell

Posted by jpluimers on 2020/02/19

This is such a cool blog: Mad With PowerShell (Tim Curwick’s PowerShell blog, tips and tricks, tools and techniques, explanations and explorations).

I bumped into it by finding these two:

What I like most is that it gives great insight on how and why the internals of PowerShell work the way they do, and how to use that to your advantage.

–jeroen

Posted in CommandLine, Development, PowerShell, PowerShell, Scripting, Software Development | Leave a Comment »

ρσℓα¢ķ͌͌͌͌͌͌͌͌͌͌͌͌͌͌ on Twitter : “The PowerShell console history file isn’t just useful for DFIR peeps, red team-ers should check it too! 4096 entries by default, here’s the path…”

Posted by jpluimers on 2020/01/15

Not sure why, but I checked a few of my systems and no  file at %userprofile%\AppData\Roaming\Microsoft\Windows\PowerShell\PSReadline\ConsoleHost_history.txt

Heck: no ConsoleHost_history.txt files on those systems anywhere.

[WayBack] ρσℓα¢ķ͌͌͌͌͌͌͌͌͌͌͌͌͌͌ on Twitter : “The PowerShell console history file isn’t just useful for DFIR peeps, red team-ers should check it too! 4096 entries by default, here’s the path: %userprofile%\AppData\Roaming\Microsoft\Windows\PowerShell\PSReadline\ConsoleHost_history.txt”

–jeroen

Read the rest of this entry »

Posted in CommandLine, Power User, PowerShell, PowerShell | Leave a Comment »

Delphi, decoding files to strings and finding line endings: some links, some history on Windows NT and UTF/UCS encodings

Posted by jpluimers on 2019/12/31

A while back there were a few G+ threads sprouted by David Heffernan on decoding big files into line-ending splitted strings:

Code comparison:

Python:

with open(filename, 'r', encoding='utf-16-le') as f:
  for line in f:
    pass

Delphi:

for Line in TLineReader.FromFile(filename, TEncoding.Unicode) do
  ;

This spurred some nice observations and unfounded statements on which encodings should be used, so I posted a bit of history that is included below.

Some tips and observations from the links:

  • Good old text files are not “good” with Unicode support, neither are TextFile Device Drivers; nobody has written a driver supporting a wide range of encodings as of yet.
  • Good old text files are slow as well, even with a changed SetTextBuffer
  • When using the TStreamReader, the decoding takes much more time than the actual reading, which means that [WayBack] Faster FileStream with TBufferedFileStream • DelphiABall does not help much
  • TStringList.LoadFromFile, though fast, is a memory allocation dork and has limits on string size
  • Delphi RTL code is not what it used to be: pre-Delphi Unicode RTL code is of far better quality than Delphi 2009 and up RTL code
  • Supporting various encodings is important
  • EBCDIC days: three kinds of spaces, two kinds of hyphens, multiple codepages
  • Strings are just that: strings. It’s about the encoding from/to the file that needs to be optimal.
  • When processing large files, caching only makes sense when the file fits in memory. Otherwise caching just adds overhead.
  • On Windows, if you read a big text file into memory, open the file in “sequential read” mode, to disable caching. Use the FILE_FLAG_SEQUENTIAL_SCAN flag under Windows, as stated at [WayBack] How do FILE_FLAG_SEQUENTIAL_SCAN and FILE_FLAG_RANDOM_ACCESS affect how the operating system treats my file? – The Old New Thing
  • Python string reading depends on the way you read files (ASCII or Unicode); see [WayBack] unicode – Python codecs line ending – Stack Overflow

Though TLineReader is not part of the RTL, I think it is from [WayBack] For-in Enumeration – ADUG.

Encodings in use

It doesn’t help that on the Windows Console, various encodings are used:

Good reading here is [WayBack] c++ – What unicode encoding (UTF-8, UTF-16, other) does Windows use for its Unicode data types? – Stack Overflow

Encoding history

+A. Bouchez I’m with +David Heffernan here:

At its release in 1993, Windows NT was very early in supporting Unicode. Development of Windows NT started in 1990 where they opted for UCS-2 having 2 bytes per character and had a non-required annex on UTF-1.

UTF-1 – that later evolved into UTF-8 – did not even exist at that time. Even UCS-2 was still young: it got designed in 1989. UTF-8 was outlined late 1992 and became a standard in 1993

Some references:

–jeroen

Read the rest of this entry »

Posted in Delphi, Development, Encoding, PowerShell, PowerShell, Python, Scripting, Software Development, The Old New Thing, Unicode, UTF-16, UTF-8, Windows Development | Leave a Comment »

« Previous Entries
 
%d bloggers like this: