Memory management of BSTR objects in COM

When working with BSTR with COM objects, the following questions have to be answered:
1. When passing BSTR to a COM object, who is responsible to free the memory allocated to BSTR?
2. When a COM object returns BSTR, who is responsible to free the memory allocated to BSTR?

Answer to both these questions is: caller of the COM object is responsible for freeing memory allocated to BSTR.

Examples:
1. When passing BSTR to COM object
Solution:
    {
            CComPtr<IComDog> dog;
            dog.CoCreateInstance(Animals::CLSID_Dog);
            BSTR nameOfDog = SysAllocString(L"Tiger");
            dog->put_NameOfDog(nameOfDog);
            .....
            // other code for dogs
            .....
            SysFreeString(nameOfDog);
            nameOfDog = NULL;
    }

Instead of using BSTR directly, use CComBSTR which takes care of memory management.
    {
            CComPtr<IComDog> dog;
            dog.CoCreateInstance(Animals::CLSID_Dog);
            CComBSTR nameOfDog = L"Tiger";
            dog->put_Name(nameOfDog);
            .....
            // other code for dogs
            // free'ing memory allocated to nameOfDog is taken care of by CComPtr
     }

2. When COM return a BSTR
     TBD

PowerShell Script to find Process IDs of an Executable

To find the priority of Threads of a process, copy the following script and execute in PowerShell

$timeoutInSeconds = 100;
$processName = "myExecutable.exe"

$processList = Get-WmiObject win32_process | where { $_.ProcessName -eq "$processName" } | select Handle
foreach ($processIds in $processList)
{
    $processId = $processIds.Handle
    Write-Host "process id = $processId"
}


Disclaimer: Use at your own risk. The author does not take any responsibility for the behavior of this script.

Lock Windows Desktop during Remote Session

In order to lock a Windows desktop during remote session, execute the following command

rundll32.exe user32.dll,LockWorkStation

Common WinDbg commands

How to set Symbol path
srv*c:\symbols*http://msdl.microsoft.com/download/symbols;
srv*c:\symbols*c:\temp\localsymbols;
srv*c:\symbols*\\network_share\symbols;

or
set environment variable name: _NT_SYMBOL_PATH
set environment variable value: srv*c:\symbols*http://msdl.microsoft.com/download/symbols;
                     srv*c:\symbols*c:\temp\localsymbols; srv*c:\symbols*\\network_share\symbols;

How to load Wow64 on x64 debugger
.load wow64exts

Other commands
lml
.ecxr
!analyze -v

How to verify if the module and pdb are a match
!itoldyouso <ModuleName> <ModulePDB>

Setup WinDbg as Postmortem Debugger
windbg -I

Setup ProcMon as Postmortem Debugger
procmon -i -ma

Redirect output to a log file
000> .logopen c:\temp\hello.txt
000> <do what ever commands> - all output is shown in windbg window and redirected to log file
000> .logclose

Find machine name (.NET dmp)
kd> x srv!SrvComputerName
fffff880`06ec4540 srv!SrvComputerName = <no type information>
kd> dq fffff880`06ec4540
fffff880`06ec4540  00000000`001a001a fffff8a0`02441df0
fffff880`06ec4550  00000000`00000000 00000000`00000000
fffff880`06ec4560  00000000`00000000 00000000`000c000a
...
kd> du fffff8a0`02441df0
fffff8a0`02441df0  "ABC"

Read GUID from a PDB using WinDbg

Here are the steps for reading GUID of a PDB

1. Install WinDbg
2. Set symbol path to the location of PDB
3. Load any executable into WinDbg
4. Execute in WinDbg 'ld <ModuleName>'
5. Execute in WinDbg '!chksym <ModuleName>
    c:\temp\<name_of_module>.dll
    Timestamp: 53FEA125
    SizeOfImage: DE000
    pdb: c:\temp\sample.pdb
    pdb sig: aaaaaaaa-bbbb-bbbb-bbbb-aaaaaaaaaaaa
    age: 1

Kill Remote Process using PowerShell

Here are the steps to kill a process running on remote machine

1. Start PowerShell
2. $processes = Get-WmiObject -class win32_process -ComputerName <name_of_computer> -Filter "Name='notepad.exe'"
3. $x = $processes.terminate()
4. echo $x

Return value should be 0

Renew IP Address

When computers are moved from one network to another network, its IP address changes. This change is not reflected immediately in network adapters. In order to force a reset of these adapters, the following commands are used.

Renew IP Address

Windows
1. Open a cmd prompt in elevated mode
2. Execute the command
    c:\windows\system32> ipconfig /renew


Linux
1. Open a Terminal as root
2. Execute the command
    $ ifconfig eth0 down
    $ ifconfig eth0 up

Programs for Windows Administration

This is a list of programs, that you can use for Windows administration.

1. Computer Management: compmgmt.msc
2. Component Services: comexp.msc 
3. Event Viewer: eventvwr.exe 
4. Local Security Policy: secpol.msc 
5. ODBC Data Sources: odbcad32.exe
6. Performance Monitor: perfmon.msc
7. Print Management: printmanagement.msc
8. Services: services.msc
9. System Configuration: msconfig.exe 
10. Task Scheduler:taskschd.msc
11. Windows Firewall with Advanced Security: WF.msc 

Common Tools for Regular Use

I use a variety of tools during development. Here is a list of some of them. This list keeps growing as I use additional software.

1. Beyond Compare: for file, folder comparison and file merge
2. gVim: for file editing, comparison and merge
3. WinMerge: file comparison and merge
4. Application Verifier: runtime verification of c, c++ code on Windows
5. Driver Verifier: Windows kernel mode driver runtime verifier
6. WinDbg: debugging C and C++ code on Windows
7. WireShark: network packet analysis and sniffing
8. Maven: build, package
9. Gradle: build, package, deploy
10. Selenium: web site testing
11. JUnit: framework for unit testing of Java code
12. Fortify SCA: source code analysis
13. Clover: code coverage for Java and Groovy code
14. SonarQube: for trend analysis of various aspects in a project
15. BlackDuck: open source software management
16. VMWare Player: free virtual machine software
17. psftp: sftp client
18. putty: telnet client
19. pscp: scp client
20. tomcat: web server
21. process explorer: Windows processes, open files, handles etc
22. dependency finder: for finding dependencies in java code
23. lattix: for finding dependencies in java/c/c++/.net/database code

Disclaimer: This is just a list of software that I used. I do not make any recommendations regarding the software that I listed here.

Windows - Auto Logon

In order to perform auto-logon in Windows
1. Create a batch file with the following content

set autologon_username=
set autologon_password=
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /f /v AutoAdminLogon /t REG_SZ /d 1
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /f /v DefaultUserName /t REG_SZ /d %autologon_username%
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /f /v DefaultUserName /t REG_SZ /d %autologon_password%

2. Execute the batch file in an elevated mode
On rebooting the machine, you should be able to logon automatically to the user account specified with .
Note:Revealing password in plain text is a bad idea. Use this feature cautiously because you are exposing the plain text password.

Windows - Reboot from cmd

In order to reboot from the cmd prompt in Windows, execute the following command. Make sure you saved all open files before executing this command.

shutdown -r