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  Smuggling data in pointers

While reading up on The ABA Problem I came across a fantastic hack.  The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page).  One fun, but very hackish solution is to "smuggle" data in a pointer.  Example:#include "stdio.h"void * smuggle(void * ptr, int value){  return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){  return (long long)ptr &...

   C,Pointer,Bit,Data,Atomic,Smuggle     2011-11-14 08:15:59

  A Tiny MySQL++ Tutorial; C++ and MySQL; MySQL++ Example

I wrote a post about how to install MySQL++ and I thought I will write a quick tutorial on how to use it too. This is a very basic MySQL++ program and it’s very self explanatory: #include <mysql++.h> #include <stdlib.h>   using namespace std; using namespace mysqlpp;   int main() { try { Connection conn(false); conn.connect("DB NAME", "DB HOST probably localhost", "DB USER", "DB PASS"); Query query = conn.query(); } catch (BadQuery er...

   C++,Example,MySQL++,Insert,API     2011-09-05 02:12:40

  Generate certificate with cRLDistributionPoints extension using OpenSSL

In an X509 certificate, the cRLDistributionPoints extension provides a mechanism for the certificate validator to retrieve a CRL(Certificate Revocation List) which can be used to verify whether the given certificate is revoked.   A cRLDistributionPoints extension can contain one or more DistributionPoints where the CRL can be retrieved from. Each DistributionPoint consists of three fields,each of which is optional: distributionPoint : it contains either a SEQUENCE of general...

   X509,OPENSSL,CERTIFICATE,CRLDISTRIBUTIONPOINT,EXTENSION     2015-10-22 03:41:11

  Which one cost more in development : Android vs iOS

As for which platform has more development cost, there are many different views. Using Android we no need to spend money on an expensive Mac computer, iOS test machine and $99 year fee for each developer account. While developing iOS apps does not require much testing, screen adaption, debug and script compatibility considerations. Let's see a few views shared by some developers. Nan Li, ERP/SAP/Mobile network/Japan/Apple/KKK@ifanr Because of the performance of iOS, it actually has domina...

   Android,iOS,Development cost,Comparison     2012-03-23 13:39:48

  How to prevent next HeartBleed bug?

How to ensure the security of open source projects is a concern for many open source users including individual users and companies. But it's not an easy task to ensure the security of open source projects. Because everyone can see the source code, there is much higher possibility that a bug may be found by someone. Once a bug is disclosed, people may exploit it and do evil things, this may cause loss of money either for individuals or companies, some of the bugs may even have big impact to the...

   Open source,HeartBleed,Security     2014-04-24 09:07:05

  40+ Techniques to enhance your php code

1. Do not use relative paths , instead define a ROOT path Its quite common to see such lines : 1require_once('../../lib/some_class.php'); This approach has many drawbacks : It first searches for directories specified in the include paths of php , then looks from the current directory. So many directories are checked. When a script is included by another script in a different directory , its base directory changes to that of the including script. Another issue , is that when a script is being ru...

   PHP,Quirk,Trick,Efficiency,Techniques     2012-04-10 13:06:55

  System programming is still there

System programming is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. But nowadays more...

   System programming     2014-02-27 05:46:48

  Fix issue docker-credential-desktop not installed or not available in PATH on Mac

Sometimes you may encounter below issue while running docker-compose on MacOS. Traceback (most recent call last): File "docker-compose", line 6, in <module> File "compose/cli/main.py", line 71, in main File "compose/cli/main.py", line 127, in perform_command File "compose/cli/main.py", line 1085, in up File "compose/cli/main.py", line 1081, in up File "compose/project.py", line 527, in up File "compose/service.py", line 354, in ensure_image_exists File "compose/service.py",...

   MACOS,DOCKER,DOCKER-COMPOSE     2020-06-23 03:25:16

  Android Tutorial: Creating and Using an SD Card in the Emulator

In a previous post, I mentioned how user-friendly Android is for developers. There’s extensive documentation and information on the architecture, the different components and best practices. However, the documentation has a few blind spots. Many of the tools have little documentation and no usage examples. The information is there, it’s just hidden behind a few layers of Android theory.So I’m going to try and document a few of the basic things that you’ll probabl...

   Android,Emulator,SDCard,Load,Create     2011-04-13 12:08:41

  IDC lists top 6 myths, realities about open source

Summary: What are the top 6 myths? That open source software will enter every market, is inherently innovative, it improves faster than commercial software, that it has less lock-in, that it’s free and that it has little benefit if one is not involved in the community. IDC calls these ideas “myths” but acknowledges there’s more than a grain of truth to all of them At its Directions 2012 conference in Boston today, IDC rev...

   IDC,Open source,Reality,Free,Contribution     2012-03-16 08:47:53