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  • ptrace'ing of parent process

    - by osgx
    Hello Can child process use the ptrace system call to trace its parent? Os is linux 2.6 Thanks. upd1: I want to trace process1 from "itself". It is impossible, so I do fork and try to do ptrace(process1_pid, PTRACE_ATTACH) from child process. But I can't, there is a strange error, like kernel prohibits child from tracing their parent processes UPD2: such tracing can be prohibited by security policies. Which polices do this? Where is the checking code in the kernel? UPD3: on my embedded linux I have no errors with PEEKDATA, but not with GETREGS: child: getregs parent: -1 errno is 1, strerror is Operation not permitted errno = EPERM

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  • Java Client .class File Protection

    - by Zac
    I am in the requirements phase of building a JEE application that will most likely run on a GlassFish/JBoss backend (doesn't matter for now). I know I shouldn't be thinking about architecture at requirements time, but one can't help but start to imagine how the components would all snap together :-) Here are some hard, non-flexible requirements on the client-side: (1) The client application will be a Swing box (2) The client is free to download, but will use a subscription model (thus requiring a login mechanism with server-side authentication/authorization, etc.) (3) Yes, Java is the best platform solution for the problem at hand for reasons outside the scope of this post (4) The client-side .class files need safeguarding against decompiling That last (4th) requirement is the basis of this post. I'm not really worried about someone actually decompiling and getting at my source code: in the end, it's just Swing controls driven by some lightweight business logic. I'm worried about a scenario where someone decompiles my code, modifies it to exploit/attack the server, re-compiles, and fires it up. I've envisioned all sorts of nasty solutions, but didn't know if this was a common problem with a common solution for JEE developers. Any thoughts? Not interested in "code obfuscation" techniques! Thanks for any input!

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  • kill -9 and production application

    - by valodzka
    Which problem can cause kill -9 in production application (in linux to be exact)? I have application which do some periodical work, stopping these takes long time, and I don't care if some jobs will be aborted - work can be finished by new processes. So can I use kill -9 just to stop it immediately or this can cause serious OS problems? For example, Unicorn, uses it as normal working procedure: When your application goes awry, a BOFH can just "kill -9" the runaway worker process without worrying about tearing all clients down, just one. But this article claims: The -9 (or KILL) argument to kill(1) should never be used on Unix systems

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  • Should a new language compiler target the JVM?

    - by Pindatjuh
    I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so, it may lead to small changes to the language and it's design. So that's the reason behind this doubt, and thus this question: Is targetting the JVM a good idea, when creating a compiler for a new language? Or should I stick with x86? I have experience in generating JVM bytecode. Are there any workarounds to JVM's GC? The language has deterministic implicit memory management. How to produce JIT-compatible bytecode, such that it will get the highest speedup? Is it similar to compiling for IA-32, such as the 4-1-1 muops pattern on Pentium? I can imagine some advantages (please correct me if I'm wrong): JVM bytecode is easier than x86. Like x86 communicates with Windows, JVM communicates with the Java Foundation Classes. To provide I/O, Threading, GUI, etc. Implementing "lightweight"-threads.I've seen a very clever implementation of this at http://www.malhar.net/sriram/kilim/. Most advantages of the Java Runtime (portability, etc.) The disadvantages, as I imagined, are: Less freedom? On x86 it'll be more easy to create low-level constructs, while JVM has a higher level (more abstract) processor. Most disadvantages of the Java Runtime (no native dynamic typing, etc.)

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  • Getting a nicely formatted timestamp without lots of overhead?

    - by Brad Hein
    In my app I have a textView which contains real-time messages from my app, as things happen, messages get printed to this text box. Each message is time-stamped with HH:MM:SS. Up to now, I had also been chasing what seemed to be a memory leak, but as it turns out, it's just my time-stamp formatting method (see below), It apparently produces thousands of objects that later get gc'd. For 1-10 messages per second, I was seeing 500k-2MB of garbage collected every second by the GC while this method was in place. After removing it, no more garbage problem (its back to a nice interval of about 30 seconds, and only a few k of junk typically) So I'm looking for a new, more lightweight method for producing a HH:MM:SS timestamp string :) Old code: /** * Returns a string containing the current time stamp. * @return - a string. */ public static String currentTimeStamp() { String ret = ""; Date d = new Date(); SimpleDateFormat timeStampFormatter = new SimpleDateFormat("hh:mm:ss"); ret = timeStampFormatter.format(d); return ret; }

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  • Message queue proxy in Python + Twisted

    - by gasper_k
    Hi, I want to implement a lightweight Message Queue proxy. It's job is to receive messages from a web application (PHP) and send them to the Message Queue server asynchronously. The reason for this proxy is that the MQ isn't always avaliable and is sometimes lagging, or even down, but I want to make sure the messages are delivered, and the web application returns immediately. So, PHP would send the message to the MQ proxy running on the same host. That proxy would save the messages to SQLite for persistence, in case of crashes. At the same time it would send the messages from SQLite to the MQ in batches when the connection is available, and delete them from SQLite. Now, the way I understand, there are these components in this service: message listener (listens to the messages from PHP and writes them to a Incoming Queue) DB flusher (reads messages from the Incoming Queue and saves them to a database; due to SQLite single-threadedness) MQ connection handler (keeps the connection to the MQ server online by reconnecting) message sender (collects messages from SQlite db and sends them to the MQ server, then removes them from db) I was thinking of using Twisted for #1 (TCPServer), but I'm having problem with integrating it with other points, which aren't event-driven. Intuition tells me that each of these points should be running in a separate thread, because all are IO-bound and independent of each other, but I could easily put them in a single thread. Even though, I couldn't find any good and clear (to me) examples on how to implement this worker thread aside of Twisted's main loop. The example I've started with is the chatserver.py, which uses service.Application and internet.TCPServer objects. If I start my own thread prior to creating TCPServer service, it runs a few times, but the it stops and never runs again. I'm not sure, why this is happening, but it's probably because I don't use threads with Twisted correctly. Any suggestions on how to implement a separate worker thread and keep Twisted? Do you have any alternative architectures in mind?

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  • Passing multiple arguments to a UNIX shell script

    - by Waffles
    I have the following (bash) shell script, that I would ideally use to kill multiple processes by name. #!/bin/bash kill `ps -A | grep $* | awk '{ print $1 }'` However, while this script works is one argument is passed: end chrome (the name of the script is end) it does not work if more than one argument is passed: $end chrome firefox grep: firefox: No such file or directory What is going on here? I thought the $* passes multiple arguments to the shell script in sequence. I'm not mistyping anything in my input - and I the programs I want to kill (chrome and firefox) are open. Any help is appreciated.

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  • How does a programmer think?

    - by Gordon Potter
    This may be a hopelessly vague question. But I am interested to hear whatever logical thought processes people go through when learning a new concept or trying to get their brain around code they might not have ever seen before. Basically, what general steps does one take to to break down problems and what does it take to "get it"? If you were to diagram a flowchart of how your mental process works when you look at code or try to solve a problem what might it look like? What common references, tips, and mental assumptions do you find useful in problem solving? How is this different between different domains? For example in what ways is a web programmer's thought process similar or different from a traditional desktop app developer's process?

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  • Artificial Intelligence in online game using Google App Engine

    - by Hortinstein
    I am currently in the planning stages of a game for google app engine, but cannot wrap my head around how I am going to handle AI. I intend to have persistant NPCs that will move about the map, but short of writing a program that generates the same XML requests I use to control player actions, than run it on another server I am stuck on how to do it. I have looked at the Task Queue feature, but due to long running processes not being an option on the App engine, I am a little stuck. I intend to run multiple server instances with 200+ persistant NPC entities that I will need to update. Most action is slowly roaming around based on player movements/concentrations, and attacking close range players...(you can probably guess the type of game im developing)

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  • Rewinding std::cout to go back to the beginning of a line

    - by fbrereto
    I'm writing a command-line tool for Mac OS X that processes a bunch of files. I would like to show the user the current file being processed, but do not want a bazillion files polluting the terminal window. Instead I would like to use a single line to output the file path, then reuse that line for the next file. Is there a character (or some other code) to output to std::cout to accomplish this? Also, if I wanted to re-target this tool for Windows, would the solution be the same for both platforms?

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  • killall httpd for sleep process

    - by user172697
    Hello guys this shell explain the issue , after executing the .sh file halt and nothing happen , any clue where is my mistake its kill httpd if there is more than 10 sleep process and start the httpd with zero sleep process #!/bin/bash #this means loop forever while [ 1 ]; do HTTP=`ps auwxf | grep httpd | grep -v grep | wc -l`; #the above line counts the number of httpd processes found running #and the following line says if there were less then 10 found running if [ $[HTTP] -lt 10 ]; then killall -9 httpd; #inside the if now, so there are less then 10, kill them all and wait 1 second sleep 1; #start apache /etc/init.d/httpd start; fi; #all done, sleep for ten seconds before we loop again sleep 10;done

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  • Different Scala Actor Implementations Overview

    - by Stefan K.
    I'm trying to find the 'right' actor implementation for my thesis. I realized there is a bunch of them and it's a bit confusing to pick one. Personally I'm especially interested in remote actors, but I guess a complete overview would be helpful to many others. This is a pretty general question, so feel free to answer just for the implementation you know about. I know about the following Scala Actor implementations (SAI). Please add the missing ones. Scala 2.7 (difference to) Scala 2.8 Akka (http://www.akkasource.org/) Lift (http://liftweb.net/) Scalaz (http://code.google.com/p/scalaz/) What are the target use-cases for these SAIs (lightweight vs. "heavy" enterprise framework)? do they support remote actors? What shortcomings do remote actors have in the SAIs? How is their performace? How active is there community? How easy are they to get started? How good is the documentation? How easy are they to extend? How stable are they? Which projects are using them? What are their shortcomings? What are their design principles? Are they thread based or event based (receive/ react) or both? Nested receiveS hotswapping the Actor’s message loop

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  • Delphi DateTimeFormat returning wrong year

    - by Leslie
    I have a form that allows users to enter a date of birth: ie: 4/16/40 Then when the user processes the form there's a function that checks it's length, adds leading zeros, parses the date and then uses FormatDateTime to just return the year of birth: strTemp := strPostedByDOB; If Length(strTemp) = 5 then strTemp = '0' + strTemp; if Length(strTemp) = 6 then begin strTemp := Copy(strTemp, 1 ,2) + '/' + copy(strTemp, 3, 2) + '/' + Copy(strTemp, 5, 2); strTemp := FormatDateTime('YYYY', StrToDate(strTemp)); end else strTemp := EmptyStr; using this code the strTemp is calculated as 2040 instead of 1940. Can anyone help me figure out how to make it show 1940 in strTemp? Do I have to change the form to accept a 4 digit year? Thanks, Leslie

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  • What do you do when you feel you need a variatic list comprehension?

    - by cspyr0
    I would like to make a method where I could give it a list of lengths and it would return all combinations of cartesian coordinates up to those lengths. Easier to explain with an example: cart [2,5] Prelude> [ [0,0],[0,1],[0,2],[0,3],[0,4],[1,0],[1,1],[1,2],[1,3],[1,4] ] cart [2,2,2] Prelude> [ [0,0,0],[0,0,1],[0,1,0],[0,1,1],[1,0,0],[1,0,1],[1,1,0],[1,1,1] ] A simple list comprehension won't work because I don't know how long the lists are going to be. While I love Haskell's simplicity for many problems, this is one that I could write procedurally (in C or something) in 5 minutes whereas Haskell gives me an aneurysm! A solution to this specific problem would help me out a lot; I'd also love to hear about your thought processes when tackling stuff like this.

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  • Tutorials/Books on using Mono to develop RESTful webservices?

    - by max
    Hi, anyone out there got any pointers to good links/tutorials/books on developing webservices with Mono? In more detail, I am interested in using Mono from project start on a Linux host developing in C# using Visual Studio for development, ideally with remote debugging if that is realistic developing web-services in MONO accessible in a RESTful manner, returning JSON hiding the services processes behind an Apache access the services either via javascript/AJAX or from a thin script layer written in PHP scalability is important for me unit-testing of webservices Any recommendations for material I could sift through to get a good head-start? I might add that I'm C#/.NET savvy, but not in the context of web development. I've been using it since it came out, but mainly for internal server-client applications where the clients were Windows desktop apps and the communication layer was remoting or, sometimes, more low-level socket-based. Thanks, max

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  • Spring 3.0 vs J2EE 6.0

    - by StudiousJoseph
    Hi everybody, I'm confronted with a situation... I've been asked to give an advise regarding which approach to take, in terms of J2EE development between Spring 3.0 and J2EE 6.0. I was, and still am, a promoter of Spring 2.5 over classic J2EE 5 development, specially with JBoss, I even migrated old apps to Spring and influenced the re-definition of the development policy here to include Spring specific APIs, and helped the development of a strategic plan to foster more lightweight solutions like Spring + Tomcat, instead of the heavier ones of JBoss, right now, we're using JBoss merely as a Web container, having what i call the "container inside the container paradox", that is, having Spring apps, with most of its APIs, running inside JBoss, So we're in the process of migrating to tomcat. However, with the coming of J2EE 6.0 many features, that made Spring attractive at that time, easy deployment, less-coupling, even some sort of D.I, etc, seems to have been mimicked, in one way or the other. JSF 2.0, JPA 2.0, WebBeans, WebProfiles, etc. So, the question goes... From your point of view, how save, and logical, it is to continue to invest in a non-standard J2EE development framework like Spring given the new perspectives offered by J2EE 6.0? Can we talk about maybe 3 or 4 more years of Spring development, or do you recommend early adoption of J2EE 6.0 APIs and it's practices? I'll appreciate any insights with this...

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  • Linux Kernel - Slab Allocator Question

    - by Drex
    I am playing around with the kernel and am looking at the kmem_cache files_cachep belonging to fork.c. It detects the sizeof(files_struct). My question is this: I have altered files_struct and added a rb_root (red/black tree root) using the built-in functionality in linux/rbtree.h. I can properly insert values into this tree. However, at some point, a segfault occurs and GDB backtraces the following information: (gdb) backtrace 0 0x08066ad7 in page_ok (page=) at arch/um/os-Linux/sys-i386/task_size.c:31 1 0x08066bdf in os_get_top_address () at arch/um/os-Linux/sys-i386/task_size.c:100 2 0x0804a216 in linux_main (argc=1, argv=0xbfb05f14) at arch/um/kernel/um_arch.c:277 3 0x0804acdc in main (argc=1, argv=0xbfb05f14, envp=0xbfb05f1c) at arch/um/os-Linux/main.c:150 I have spent many hours trying to figure out why there is a segfault given that the red/black tree inserts properly. I'm thinking it's a memory allocation issue with new processes made by fork() of a parent process. Could this be the case and could it have something to do with kmem_cache files_cachep?

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  • SSIS Handling Extenal Issues

    - by durilai
    I have an SSIS package that works fine. The package runs every night and takes about 4 hours to complete. I have am a newb to SSIS, so I want to see what my options are. I am not finding anything on the web about these two issues, so any advice is greatly appreciated. What to do when I have an external issue such as a power failure/accidental restart. Is there a way to alert someone or have the package begin again on restart. A couple weeks ago there was a process that got hung and locked table, making the process not execute. How is the best way to handle ensuring I have the proper access before starting and if not, get the access. I am ok with killing the processes etc. Looking for best practice info. Thanks

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  • Plupload - how to stop uploads individualy

    - by Manny Calavera
    Hello. I'm using plupload script with PHP and I am uploading using HTML5. I would like to stop uploads separately, from the list, not the whole process. Is this possible with plupload ? I think it would be useful to stop individual files. Thanks. EDIT: Let's just say that a user tries to upload 2 files and they are added to queue. After that, he clicks the upload button and the upload starts. At some point during the upload he realize that he doesn't really want to upload the second file, he needs to stop the 2nd upload and the 1st upload should continue. I can send an uploader.start(); on the plupload but it will stop all upload processes...and I need to stop just one. Thanks.

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  • WPF Validation of clipboard Data

    - by Peter
    Hello normal validation is always related to some control, but in my case there is no control to fire validation when its content changes and to show errortemplate to the user. because the data to be validated is in the cipboard. when the user presses "PASTE" button viewmodel processes the data and finds it to be invalid. but what is the best way to invoke WPF validation in this case? as far as i understand using IDataErrorInfo is the way to go, but what is the best way to start validation. and whst is the best way of displaying the error? errortemplate of the button element? Thanks a lot for help. Peter

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  • How to terminate process using VBScript

    - by Mark
    Hi, I have this VBScript code to terminate one process Const strComputer = "." Dim objWMIService, colProcessList Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2") Set colProcessList = objWMIService.ExecQuery("SELECT * FROM Win32_Process WHERE Name = 'Process.exe'") For Each objProcess in colProcessList objProcess.Terminate() Next it works fine with some processes, but when it comes to any process runs under SYSTEM, it can't stop it. Is there is anything I need to add to kill the process under SYSTEM? Thanks

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  • ASP MVC - Routing Required?

    - by evo_9
    I've been reading up on MVC2 which came in VS2010 and it sounds pretty interesting. I'm actually in the middle of a large multi-tenant application project, and have just started coding the UI. I'm considering changing to MVC as I'm not that far along at this point. I have some questions about the Routing capabilities, namely are they required to use MVC or can I more or less ignore Routing? Or do I have to setup a default routing record that will make things work like standard ASPX (as far as routing alone is concerned)? The reason why I don't want to use Routing is because I've already defined a custom URL 'rewrite' mechanism of my own (which fires on session_start). In addition, I'm using jquery and opens-standards for the entire UI, and MVC's aspx overhead-free approach seems like a better fit based on how I've already started to build the application (I am not using viewstate at all, for example). I guess my big concern is whether the routing can be ignored, of if I will have to re-implement my custom URL rewriting to work with MVC, and if that's the case, how would I do that? As a new Routing routine, or stick with the session_start (if that's even possible?). Lastly, I don't want to use anything even remotely 'intelligent/readable' for the url - for a site like StackOverflow, the readability of the URL is a positive, but the opposite is true if it's not a public website like this one. In fact, it would seem to me that the more friendly MVC routing URL (which indirectly show method names) could pose a security risk on a private, non-public website app like I'm developing. For all these reasons I would love to use the lightweight aspects of MVC but skip the Routing entirely - is this possible?

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  • Disable Ctrl-Alt-Del and shutdown for kiosk

    - by acidzombie24
    I finished an app for a client. After talking for a bit he would like me to do an additional app or recommend one for their kiosk. The client would like a way to prevent the computer from shutting down. They like to disable Ctrl+Alt+Delete (also so processes cant be killed), Alt+F4 to close their browser and no windows button to make the start menu pop up for the user to click or use keyboard to shutdown. Obviously there should be a way to unlock it I told them i'll look into it but they really don't need it. They are using Windows 7. Is there a WinAPI call I can use or an already existing app or a lib to do this?

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  • Measuring daemon CPU utilization over a portion of it's wall clock run time

    - by WhirlWind
    I am dealing with a network-related daemon: it takes data in, processes it, and spits it out. I would like to increase the performance of this daemon by profiling it and reducing it's CPU utilization. I can do this easily on Linux with gprof. However, I would also like to use something like "time" to measure it's total CPU utilization over a period of time. If possible, I would like to time it over a period that is less than its total run time: thus, I would like to start the daemon, wait awhile, generate CPU statistics, stop generating them, then stop the daemon at some later time. The "time" command would work well for me, but it seems to require that I start and stop the daemon as a child of time. Is there a way to measure CPU utilization for only a portion of the daemon's wall clock time?

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  • What's the most efficient way to setup a multi-lingual website

    - by Jasper De Bruijn
    Hi, I'm developing a website that will be available in different languages. It is a LAMP (Linux, Apache, MySQL, PHP) setup, and it makes use of Smarty, mostly for the template engine. The way we currently translate is by a self-written smarty plugin, which will recognize certain tags in the HTML files, and will find the corresponding tag in an earlier defined language file. The HTML could look as follows: <p>Hi, welcome to $#gamedesc;!</p> And the language file could look like this: gamedesc:Poing 2009$; welcome:this is another tag$; Which would then output <p>Hi, welcome to Poing 2009!</p> This system is very basic, but it is pretty hard to control, if I f.e. would like to keep track of what has been translated so far, or give certain users the rights to translate only certain tags. I've been looking at some alternative ways to approach this, by either replacing the text-file with XML files which could store some extra meta-data, or by perhaps storing all the texts in the database, and retrieving it there. My question is, what would be the best way to make this system both maintainable and perform well with high user-traffic? Are there perhaps any (lightweight) plugins I could take a look at?

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