result from /proc/self/exe is unfriendly in a clearcase view - clang

If I execute a binary in a clearcase view, and look at /proc/self/exe for that on Linux, I see something like the following:
$ cd /proc/19220
$ ls -l exe
lrwxrwxrwx 1 peeterj pdxdb2 0 2012-11-30 13:04 exe -> /home/peeterj/views/peeterj_clang-7.vws/.s/00024/8000028250b8f1d1llvm-config
The clang llvm-config program, not unreasonably, uses this output to try to figure out the absolute fully qualified path that it is located in (I assume in case argv[0] isn't fully qualified).
Is there a way to find the location within the view that this corresponds to. For example, in this case, the llvm-config exe is actually in:
/vbs/bldsupp/linuxamd64/clang/debug/bin
(I'm wondering if it's feasible to modify clang's GetExecutablePath() function to figure this out.)

No trivial solution here (for an old version of ClearCase though):
The technote "PK27447: WITHIN A CLEARCASE DYNAMIC VIEW, THE READLINK() CALL ON LINUX RETURNS THE WRONG PATH FOR THE EXECUTABLE'S /PROC/SELF/EXE VALUE" suggests:
Local fix
Use getcwd(), get_current_dir_name(), getwd() in applications slated for a VOB/View context
Create an interposer library to intercept the readlink() call, and modify to use any of the above calls to return the proper data
The cause:
/proc/self/exe returns the improper path while getcwd succeeds.
Unfortunately, for /proc/self/exe to return the proper value [from within a VOB/View context] would require a change within the Linux kernel to allow MVFS to "override" the present setting.
IBM LTC has been working on having the Linux community adopt this change so that we can then incorporate the new features within MVFS.
Related: Bug Sun 6189256.

Related

Continuous Integration with Blue Ocean, Github and Nuget causes path too long

NUnit.Extension.VSProjectLoader.3.7.0
I try to get a build chain to work with Jenkins Blue Ocean where the sources are in GitHub and additional dependencies are in nuget.
When I restore packages I get the error after the specific package NUnit.Extension.VSProjectLoader.3.7.0:
Errors in packages.config projects
The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.
On the agent machine the path is very short: C:\guinode\ on top of that additional length is added making the packages folder the following size:
MyGitProject is replacing my actual project name, the length is equal.
C:\guinode\workspace\MyGitProject_master-CFRRXMXQEUULVB4YKQOFGB65CQNC4U5VJKTARN2A6TSBK5PBATBA\packages
Checking the package on the agent machine shows that NUnit.Extension.VSProjectLoader.3.7.0 was loaded completely.
Checking a local installation and replacing the first path of the package I can find two files that are 260 characters or longer.
They belong to an internal project, so I have a chance of influencing that.
None of the directories are 248 characters or more.
So the immediate solution for me is to redeploy the internal reference package.
My question for future reference is if I can do something to the packages location or something to workspace\MyGitProject_master-CFRRXMXQEUULVB4YKQOFGB65CQNC4U5VJKTARN2A6TSBK5PBATBA so that I save some characters per default.
According to the microsoft documentation it can be possible to modify the 260 length rule.
If you prefix your file with '\\?\' eg: '\\?\C:\guinode\workspace...' then long path will be in use ( a little bit more than 32000 char). I hope settings JENKINS_HOME to this kind of path make all process use that (I'm not sure)
On recent Windows version (10.1607, 2016?) there is an option in the registry to enable long path. Set 1 to the following key: HKLM\SYSTEM\CurrentControlSet\Control\FileSystem LongPathsEnabled (Type: REG_DWORD) and restart the process.

Get the operating system in maxima

Is it possible to get the operating system in maxima? I have some code that needs the unix / or windows \ for path names. How can I find out which operating system the code is running in?
To give some context, I have the following code:
windows: false$
divider: "/"$
if (windows) then divider: "\\"$
initfile: concat(maxima_userdir, divider, "maxima-init.mac");
load(operatingsystem)$
dir: getcurrentdirectory();
if (substring(dir, slength(dir)) # divider) then dir: concat(dir, divider)$
repo: concat(dir, "$$$.mac")$
live: concat(dir, "live_packages", divider, "$$$.mac")$
with_stdout(initfile, printf(true, ""))$
with_stdout(initfile, printf(true, concat("file_search_maxima: append (file_search_maxima, [
~s,
~s
]);"), repo, live))$
Take a look at the output of build_info, specifically the field host (i.e. foo#host where foo : build_info()). See ? build_info for more information.
On my (Linux) system I get: x86_64-unknown-linux-gnu I think on MS Windows you'll get a string containing windows or at least win or maybe win32.
There may be other ways to figure out the system type so let me know if that doesn't work for you. Also it is possible that there is a global variable floating around which tells the path separator; I would have to look for that.
If you're not adverse to writing a little bit of Lisp code, another approach is to use the file and directory functions in Common Lisp, which are more extensive than in Maxima. See the section on filenames in the Common Lisp Hyperspec. I think maybe MERGE-PATHNAMES and/or MAKE-PATHNAME might be relevant.

Is it possible to keep my Nix packages in sync across machines not running NixOS?

I know with NixOS, you can simply copy over the configuration.nix file to sync your OS state including installed packages between machines.
Is it possible then, to do the same using Nix the package manager on a non-NixOS OS to sync only the installed packages?
Please note, that at least since 30.03.2017 (corresponding to 17.03 Nix/NixOS channel/release), as far as I understand the official, modern, supported and suggested solution is to use the so called overlays.
See the chapter titled "Overlays" in the nixpkgs manual for a nice guide on how to use the new approach.
As a short summary: you can put any number of files with .nix extension in $HOME/.config/nixpkgs/overlays/ directory. They will be processed in alphabetical order, and each one can modify the set of available Nix packages. Each of the files must be written as in the following pattern:
self: super:
{
boost = super.boost.override {
python = self.python3;
};
rr = super.callPackage ./pkgs/rr {
stdenv = self.stdenv_32bit;
};
}
The super set corresponds to the "old" set of packages (before the overlay was applied). If you want to refer to the old version of a package (as in boost above), or callPackage, you should reference it via super.
The self set corresponds to the eventual, "future" set of packages, representing the final result after all overlays are applied. (Note: don't be scared when sometimes using them might get rejected by Nix, as it would result in infinite recursion. Probably you should rather just use super in those cases instead.)
Note: with the above changes, the solution I mention below in the original answer seems "deprecated" now — I believe it should still work as of April 2017, but I have no idea for how long. It appears marked as "obsolete" in the nixpkgs repository.
Old answer, before 17.03:
Assuming you want to synchronize apps per-user (as non-NixOS Nix keeps apps visible on per-user basis, not system-wide, as far as I know), it is possible to do it declaratively. It's just not well advertised in the manual — though it seems quite popular among long-time Nixers!
You must create a text file at: $HOME/.nixpkgs/config.nix — e.g.:
$ mkdir -p ~/.nixpkgs
$ $EDITOR ~/.nixpkgs/config.nix
then enter the following contents:
{
packageOverrides = defaultPkgs: with defaultPkgs; {
home = with pkgs; buildEnv {
name = "home";
paths = [
nethack mc pstree #...your favourite pkgs here...
];
};
};
}
Then you should be able to install all listed packages with:
$ nix-env -i home
or:
$ nix-env -iA nixos.home # *much* faster than above
In paths you can put stuff in a similar way like in /etc/nixos/configuration.nix on NixOS. Also, home is actually a "fake package" here. You can add more custom package definitions beside it, and then include them your "paths".
(Side note: I'm hoping to write a blog post with what I learned on how exactly this works, and also showing how to extend it with more customizations. I'll try to remember to link it here if I succeed.)

Starting a Mono Process Programmatically

How can I start a process in mono using the Process.Start API? My best guess would be the following (in F#):
let start (path : string) =
System.Diagnostics.Process.Start("/usr/bin/env", sprintf "mono \"%s\"" path)
This seems to work in linux, but it is obviously not correct in Mono/Windows. Is there any way I could obtain the location of the mono executable programmatically?
It turns out that you can basically just Process.Start with just the target executable path, no need to specify the mono executable.
You can find the location of Mono on windows using the following registry keys
$version = HKLM_LOCAL_MACHINE\Software\Novell\Mono\DefaultCLR
$monoprefix = HKLM_LOCAL_MACHINE\Software\Novell\Mono\$version\SdkInstallRoot
where you use the version you found to find the mono prefix.
Taken from this page
Rather than starting a new instance of the CLR, you can start assemblies from within your existing instance. Microsoft documents the relevant functionality here: http://msdn.microsoft.com/en-us/library/yk22e11a%28v=vs.110%29.aspx. Mono implements this as well.
What you have to do is create a new AppDomain to provide you with an execution environment isolated from your current one, load an assembly in there, and execute it.
Example:
var domain = AppDomain.CreateDomain("Foo");
domain.ExecuteAssembly("Bar.exe");

Tomcat6 Service Setup; programatically concatenate JvmOptions using Batch File

This may bit a bit of a basic question, but I can't seem to find an answer on the web. I'm trying to automatically set up tomcat as a service through a batch file.
My batch file currently looks like this:
set memSize=512
set jvmOptions="-XX:MaxPermSize=512M"
ECHO Setting up tomcat as a service.
call service.bat install
ECHO Setting the memory allocation to a maximum of %memSize%
ECHO Using JVM options %jvmOptions%
Tomcat6 //US// --JvmMx=%memSize% --Startup="auto" --JvmOptions=%jvmOptions%
The issue I'm facing is that running the --JvmOptions switch overwrites all the current java options that are set in the tomcat6w.exe.
So my question is, does anyone know how to have the --JvmOptions switch concatenate the passed value to the end of the current value?
Thanks in advance
Could it be as simple as this (if I understand your question correctly)
set memSize=512
REM I removed the quotes and reused the variable in its own definition
set jvmOptions=%jvmOptions%-XX:MaxPermSize=512M
ECHO Setting up tomcat as a service.
call service.bat install
ECHO Setting the memory allocation to a maximum of %memSize%
ECHO Using JVM options %jvmOptions%
REM Added the quotes back here
Tomcat6 //US// --JvmMx=%memSize% --Startup="auto" --JvmOptions="%jvmOptions%"
After a long hard search I did manage to find the answer in a code example. But then to make me feel very foolish I noticed that the answer was also here right under my nose on the Tomcat6 Windows Service How To page. By replacing the -- with ++ the option is concatenated rather than replacing the original.
So the batch file became.
set memSize=512
set jvmOptions="-XX:MaxPermSize=512M"
ECHO Setting up tomcat as a service.
call service.bat install
ECHO Setting the memory allocation to a maximum of %memSize%
ECHO Using JVM options %jvmOptions%
Tomcat6 //US// --JvmMx=%memSize% --Startup="auto" ++JvmOptions=%jvmOptions%
Thanks.
A bit of an old post, but I have to do a bunch of Tomcat uninstalls/installs due another application being upgraded (a term I use loosely) and was trying to figure out how to do something similar to avoid using the UI and ensure consistency.
Some scripting tips (based on my experience so far):
REM -- Use variables for the Tomcat install directory & executable:
set TomcatDir=%ProgramFiles%\Tomcat
set TomcatExe=%TomcatDir%\bin\Tomcat7.exe
REM -- If using multiple instances, turn these in to array
set TomcatInstance[1]=Tomcat7
set TomcatInstance[2]=MyAppInstance1
set TomcatInstance[3]=MyAppInstance2
set TomcatInstance[4]=MyAppInstance3
set TomcatInstance[5]=MyAppInstance4
REM -- When updating/adding Java options and you need to use a ";" between
REM -- values, single-quote the semi-colon, ';' so it isn't intepretted as a CrLf
REM -- For example,
call "%TomcatExe%" //US/%TomcatInstance% ++JvmOptions "-Djava.library.path=%TomcatDir%\bin';'%TomcatDir%\endorsed"
REM -- So to ensure all instances have the same settings...
for /L %I in (1,1,5) do (
call "%TomcatExe%" //US/!TomcatInstance[%I]! ++JvmOptions "-Djava.library.path=%TomcatDir%\bin';'%TomcatDir%\endorsed"
)
REM -- Block scripts sections with setlocal/endlocal
REM -- "EnableDelayedExpansion" allows the above delayed variable expansion to occur
::--==--==--==--==--==--==--==--==--==--==
:Routine_Name
::--==--==--==--==--==--==--==--==--==--==
setlocal EnableDelayedExpansion
echo script commands go here
endlocal
goto :EOF
Note: This would be much easier in an actual scripting language (vbs, js or ps), but I need to leave the script "easy" to modify for whomever takes over for me when I leave my current gig.
FWIW, the how to doc for Tomcat7 is http://tomcat.apache.org/tomcat-7.0-doc/windows-service-howto.html.

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