Solving Problem 1 Using Windows Batch files

Posted in Project Euler, Software

As crazy a it sounds, it turns out it is possible to solve Project Euler problem 1 using Windows Batch files! It is possible because modern versions for cmd support delayed expansion of variables, and arithmetic expressions using “SET /A”.

Delayed expansion means that variables are expanded at runtime, rather than parse time. Normally %VARIABLE% will be expanded once with whatever value it contains before the script is run, however with delayed expansion we can use !VARIABLE!. This variable is expanded whenever that line is executed, which with a for loop could be multiple times.

@echo off
setlocal enabledelayedexpansion

set /a sum = 0
FOR /L %%L IN (1, 1, 999) DO (
    set /a mod = %%L %% 3
    IF NOT !mod! EQU 0 set /a mod = %%L %% 5
    IF !mod! EQU 0 set /a sum = sum + %%L
)

echo %sum%
endlocal
       

Enabling Case Sensitivity in Windows

Posted in Software

I recently needed to download a large number of files from a Linux server using SCP, which would take nearly 12 hours. When i checked the next day this transfer had stopped to ask if I wanted to overwrite a file. This was because two files had the same name, differing only in case.

I remembered there was a registry setting that could set the NTFS filesystem to be case sensitive[0], but I’d rather not do that on this workstation. I did a Google search anyway, but then I found there is a newer way to do this which is on a per-folder basis instead of globally[1].

There is a command called “fsutil.exe” that can adjust a lot of filesystem settings, one of them is “SetCaseSensitiveInfo”, which controls if the folder is case sensitive or not.

fsutil.exe file SetCaseSensitiveInfo C:\folder enable

When I restarted the download, it still didn’t work, because that command only applies it to the specified folder, and any new folders created after. It does not apply to existing sub-folders. The following PowerShell command will apply the setting to any existing folder.

Get-ChildItem C:\folder -Recurse | 
	? {$_.PSIsContainer} |
	% { fsutil.exe file SetCaseSensitiveInfo $_.FullName enable }

References

[0] https://superuser.com/questions/266110/how-do-you-make-windows-7-fully-case-sensitive-with-respect-to-the-filesystem

[1] https://docs.microsoft.com/en-us/windows/wsl/case-sensitivity

     

Managing Multiple Versions of Visual Studio

Posted in Retro Computers, Software

In my previous post, I described how to build an old version of GNU Make for Windows. While working on that I wanted to be able to test out different versions of Visual Studio to see if it builds successfully. Quickly switching between versions of Visual Studio was difficult so I created a batch file to help make it a lot easier.

This script takes a single argument that specifies which version of visual studio you want to set up and it then calls the appropriate vsvars32.bat file for that version of Visual Studio.

@echo off

if "%1" == "vs4" goto vs4
if "%1" == "vs6" goto vs6
if "%1" == "vs2003" goto vs2003

goto argerror

:vs4
pushd C:\msdev\bin
call vcvars32 x86
popd
goto done


:vs6
pushd C:\Program Files\Microsoft Visual Studio\VC98\Bin
call vcvars32
popd
goto done


:vs2003
pushd "C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\"
call vsvars32.bat
popd
goto done

:argerror
echo no Visual Studio version specified!
echo usage: setupenv [version]
echo    where version is one of the following: vs4, vs6, vs2003

:done

             

Compiling Old Versions of GNU Make for Windows

Posted in Retro Computers, Software

I needed to build GNU Make v3.8 for Windows, turns out that this is not straightforward and I needed to patch the build script to get it to correctly build. GNU Make 3.8 is a very old version of make, the release note dates back to 2002.

The first issue is it needs an old version of Visual C++, trying to build using VS 2019 you will get a lot of warnings about deprecated flags. Reading the README.W32 file it mentions MSVC 5.x and MSVC 6.x. I opted for MSVC 6 which I happened to have a copy of in a Windows 2000 VM.

The first issue we need to resolve is a linking error caused by a missing library.

Looking through the build output we can see that it cannot find "config.h", which prevents the "subproc.lib" library from compiling which subsequently causes the error we just saw.

C:\BUILD\xxx\make-3.80\w32\subproc>cl.exe /nologo /MT /W3 /GX /Z7 /YX /Od /I .. /I . /I ../include /I ../.. /D WIN32 /D
WINDOWS32 /D _DEBUG /D _WINDOWS /FR.\WinDebug/ /Fp.\WinDebug/subproc.pch /Fo.\WinDebug/ /c sub_proc.c
sub_proc.c
sub_proc.c(9) : fatal error C1083: Cannot open include file: 'config.h': No such file or directory

The reason that "config.h" does not exist is that the file is not created by the build script. The line in the build script that creates it doesn’t get run, this is because there is a “+” at the beginning of the line which stops this line from running.

set make=gnumake
+if not exist config.h copy config.h.W32 config.h
cd w32\subproc

Removing the plus at the beginning of the line allows "subproc.lib" to be compiled and linked, but we still get linker errors. 

C:\BUILD\xxx\make-3.80>echo WinRel\pathstuff.obj  1>>link.rel

C:\BUILD\xxx\make-3.80>echo off
"Linking WinRel/gnumake.exe"
function.obj : error LNK2001: unresolved external symbol _hash_init
variable.obj : error LNK2001: unresolved external symbol _hash_init
file.obj : error LNK2001: unresolved external symbol _hash_init
dir.obj : error LNK2001: unresolved external symbol _hash_init
read.obj : error LNK2001: unresolved external symbol _hash_init
variable.obj : error LNK2001: unresolved external symbol _hash_insert_at
file.obj : error LNK2001: unresolved external symbol _hash_insert_at
dir.obj : error LNK2001: unresolved external symbol _hash_insert_at
read.obj : error LNK2001: unresolved external symbol _hash_insert_at
variable.obj : error LNK2001: unresolved external symbol _hash_deleted_item
file.obj : error LNK2001: unresolved external symbol _hash_deleted_item
dir.obj : error LNK2001: unresolved external symbol _hash_deleted_item
read.obj : error LNK2001: unresolved external symbol _hash_deleted_item
variable.obj : error LNK2001: unresolved external symbol _hash_find_slot
file.obj : error LNK2001: unresolved external symbol _hash_find_slot
dir.obj : error LNK2001: unresolved external symbol _hash_find_slot
read.obj : error LNK2001: unresolved external symbol _hash_find_slot
variable.obj : error LNK2001: unresolved external symbol _hash_find_item
file.obj : error LNK2001: unresolved external symbol _hash_find_item
dir.obj : error LNK2001: unresolved external symbol _hash_find_item
function.obj : error LNK2001: unresolved external symbol _hash_find_item
variable.obj : error LNK2001: unresolved external symbol _hash_free
read.obj : error LNK2001: unresolved external symbol _hash_free
function.obj : error LNK2001: unresolved external symbol _hash_free
variable.obj : error LNK2001: unresolved external symbol _hash_map
file.obj : error LNK2001: unresolved external symbol _hash_map
variable.obj : error LNK2001: unresolved external symbol _hash_delete
file.obj : error LNK2001: unresolved external symbol _hash_delete
variable.obj : error LNK2001: unresolved external symbol _hash_print_stats
file.obj : error LNK2001: unresolved external symbol _hash_print_stats
variable.obj : error LNK2001: unresolved external symbol _hash_map_arg
file.obj : error LNK2001: unresolved external symbol _hash_dump
dir.obj : error LNK2001: unresolved external symbol _hash_insert
function.obj : error LNK2001: unresolved external symbol _hash_insert
function.obj : error LNK2001: unresolved external symbol _hash_load
.\WinRel/gnumake.exe : fatal error LNK1120: 13 unresolved externals
"WinRel build failed"

C:\BUILD\xxx\make-3.80>

There’s a lot of unresolved symbols, I searched for "hash_insert_at" and found the definition for it in "hash.c". Looking through the build script it turns out that this file is not included in the build. I added the following two lines to "build_w32.bat" just after "implicit.c" is compiled.

cl.exe /nologo /MT /W3 /GX /YX /O2 /I . /I glob /I w32/include /D NDEBUG /D WINDOWS32 /D WIN32 /D _CONSOLE /D HAVE_CONFIG_H /FR.\WinRel/ /Fp.\WinRel/%make%.pch /Fo.\WinRel/ /c hash.c
echo WinRel\hash.obj >>link.rel

Running the build script again, and voilà…..

C:\BUILD\build\make-3.80>echo off
"Linking WinRel/gnumake.exe"
LINK : warning LNK4089: all references to "ADVAPI32.dll" discarded by /OPT:REF
"WinRel build succeeded!"

C:\BUILD\build\make-3.80>

YAY!!! It now compiles, and we have gnumake.exe.

         

Stopping “No Disk” Error Pop-up In Windows

Posted in Software

While working on a project that used the Microchip C18 compiler I got this error message:-

If I clicked “Continue” it would appear again instantly, and this kept going dozens of times, the compile worked fine but the error message was very annoying. The drive in question was a partition on my main hard disk, it was not a removable drive!

After a bit of research I found out how to suppress the error message by modifying the system registry. Below is an example of the .reg file I created.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows]
"ErrorMode"=dword:00000002

This will disable all application and system error pop-ups, which may not be what you want so what I did is create two reg files, on disables the errors, the other enables the errors. This means I can temporarily disable the errors when I want.

For more information on this see this Microsoft support page.

WARNING! Modifying your system registry could be dangerous, proceed with caution. I am not responsible for any damage you cause to your system!

I recommend creating a system restore point before making any modifications to the system registry.

   

Changing File Permissions in Cygwin (Windows 8)

Posted in Software

I tried to change the permissions of my ssh private/public keys in the .ssh directory under Cygwin on Windows 8 and it didn’t work. This seems to be a bug in Cygwin but there is a work around that I found through SuperUser.

chgrp -R Users ~/.ssh

Now all you need to do is run the chmod commands as usual and all should work.

 chmod 644 id_rsa.pub
 chmod 600 id_rsa