Linux System Programming Techniques & Concepts

There are already innumerable courses/tutorials on internet/Udemy which teaches almost every aspect of C programming language. All those courses sound same, talk same and deliver more or less same knowledge. How is this course different from others ?

The intention of this course is to make you ready for System programming Technical interviews, interview level - from Beginner to Intermediate. This course is for (future) Developers, not for testers or System Administrators.

I choose to create this course to fill the gap between novice/beginner and intermediate/Advanced Programmers. This course assumes that you are at-least above average in programming (in any programming language, but preferable in C/C++) - know memory allocations, all kinds of loops, function calls, pointers etc.  In this course, I won't teach C/C++ (there are already many courses on it online), but would teach programming techniques and low-level details regarding how C program works behind the scenes - All topics very important from interview point of view. My Target is to grow this course into Linux/C Bible.

Yet, I always feel, you need to outsmart your fellow colleagues in this era of stiff competition, and therefore, I tried this attempt to present you the wisdom and knowledge which is of utmost importance for a programmer. I have seen though students could write good C/C++ programs, yet they lack the clarity on how one should write better organized, Manageable, extensible and programmable codes in the form of libraries. For example, Students too good in competitive programming, yet do not know how to write a simple Makefile, reason being, Academics do not teach and students do not care to learn.

In this course, I will cover the topics related to creating Linux System Libraries (release 1) with Advanced language-agnostic Programming Concepts (release 2) which can be well applied if you happen to become a programmer in other languages tomorrow. 

The Concepts like MultiThreading, Thread-Synchronization, Socket Programming, IPCs etc demands a separate course on each topic altogether. Currently, I have a course on IPC, pls check it out. These topics are out of scope for this course.

The Course shall be delivered into two Releases :

     Release 1 Building and Managing a Library:  This covers basics regarding how one should create and organize his code as a Library.

     Release 2 Memory Management Concepts:  This covers Advance concepts on Linux Memory Management specifically. Please check Table of Contents for more info.

Why you should *NOT* do this course?

1. Please Excuse this course if you are the ultimate beginner in C programming !!

2. There is no point of doing this course if you don't like hitting the keyboard, and lazy enough to watch lecture VDOs only

3. If you want everything cooked and served on your plate.

Course Pre-requisite :

• Above Beginners Level in C/C++ programming

• Good to have basic OS knowledge

• Zeal to excel and Code

No Third Party libraries

Whatever logic you implement, you need to implement it from scratch. Like all my other courses, this course do not suggest taking help of any third party library to get the jobs done. Use of external libraries completely defeats the purpose of the course.

Warning: This course has auto system-generated subtitles which may not be perfect. Please disable subtitles as per your convenience.

Curriculum :

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Release 1 Building and Managing a Library

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Section 1 : Introduction to Libraries

• What is Library

• Relationship between Library and Application

• Ex : Doubly linked list as a Library

• Quick Compilation Steps

• Summary

Section 2 : Header Files

• Relationship between Source and header files

• Text Substitution Method

• Text Substitution Method - Example and Demo

Section 3 : Preprocessing Directives

• Problem of Duplicate inclusion of Hdr files

• Pre-processing Directives

• Solution to Duplicate inclusion of Hdr files

Section 4 : Correct way of Using Structures and Functions

• Structures - Define and Use thumb Rule

• Functions - Declare and Use thumb rule

• The problem of Recursive Dependency

• A solution to Recursive Dependency

Section 5 : Creation of Static and Dynamic Libraries

• Resuming with Doubly Linked List Library

• Quick Creation of Static and Dynamic Libraries

• Linking with Static Library

• Linking with Dynamic Library

Section 7: Understanding four stages of Compilation

• Four stages of C/C++ Compilation

• How Dynamic Library works ?

• Dynamic Linking : Linking with Dynamic Library

• Comparison - Static Vs Dynamic Linking

Section 8 : Building using a Makefile

• What are Makefiles and why do we need it

• Functions of Makefile

• Makefile Dependency tree

• Steps of Writing a Makefile

• Assignment on Makefile

Section 9 : Run-time Programmable libraries

• What are Programmable Libraries?

• Steps to Program the libraries

• Registering of the callbacks with Libraries

  • key_match callback

  • comparison_fn callback

• Delegation of Application-specific operations to Libraries

Section 10 : Writing Iterators using Macros

• What are Iterative Macros ?

• Why we need Iterative Macros ?

• How to Write Iterative Macros - For Trees and Linked Lists

• Exercises

Section 11 : Glue Based Libraries and Data structures

• What are the Glue Based Libraries?

• Introducing Glthreads - A Glued LinkedList

• Glthreads Vs Traditional Linked List

• Structure field offset

• GLThread Operations

• Code Walk

• GLThread Benefits 

  
  

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Release 2 Memory Management Concepts

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Section 12 : Memory Layout of Linux Process

• Virtual Memory Basics 

• Memory Layout of Linux Process 

• Example: Memory Layout of Linux Process 

• Exercise on size command 

Section 13 : Stack Memory Management

• Stack Memory Basics and Contents 

• Stack-Overflow and Prevention 

• Stack Memory Corruption 

• Common Cpu Registers

• Procedure Call Mechanism - Step by Step

• Purpose of Base Pointer register (ebp) 

• Procedure Return Mechanism - Step by Step

• Lab session 

Section 14 : Heap Memory Management

• Introduction and Goals

• How Malloc Works

• Top of Heap Memory region - break pointer

• Heap Memory Mgmt Sys Calls - brk and sbrk

• Meta and Data Blocks

• How free() works

• Block Splitting

• Block Merging

• Memory Illness - Problem of Fragmentation

Section 15 : Concept of Paging

• Introduction to Paging

• Byte Addressable Memory

• 32 bit and 64 bit Machine Architecture

• Address Bus and Data bus         

• Physical Vs Virtual Address

• Physical Memory Frames        

• Virtual Address Composition

• Page Table

• Paging In Action

• Shared Physical Memory

Section 16 : Multilevel Paging

Section 17 : Demand Paging

Section 18 : Memory Management for Multi-threaded Process

The intention of this course is to make you ready for System programming Technical interviews from beginners to upto 8-9 yrs of experience.

Q. What are the frequently asked questions by interviewers in a technical round when someone writes C/C++/System Programming language on their resume?

Answer : If i am interviewer, what questions i would ask depends on his no of years of experience in C.

1–3 yrs of experience — I would have asked:

1. Double pointers

2. design a Macro to return the size of the structure

3. Two Dimensional Arrays, passing and returning arrays from a fn

4. Different stages of C program compilation

5. how fork() works

6. What are various ways to debug memory corruptions.

7. various IPCs

8. Heap and Stack memory-based Question

4–6 yrs of experience - I would have asked:

1. How memory is allocated by the OS

2. Internal and external fragmentation, what can be done to avoid it

3. System calls, strace()

4. Trade-of of one IPC over other

5. various ways to communicate with kernel and comparison

6. Data (De)Serialization in C

7. RPC in C

8. callbacks advanced application

9. typedef Vs #define

10. Generic programming in C using macros

11. Thread Synchronization

12. Heap and Stack memory based Question

7+ yrs of experience - I would have asked

1. Have you designed any system module to solve any problem

2. Design thread library 0 what functionalities would you incorporate in and how ?

3. What are Dos and Dont’s for writing a robust and flexible library

4. How to write generic code in C

5. Various ways to implement timers in C, and comparison of approaches

6. How Interrupts work ?

7. IPCs and comparison

8. How would you convert a C code to C++ and vice versa

9. How to write a tool to detect memory leaks, Or garbage collection

10. Design your own memory allocation tool. Why would you write your own memory allocation scheme ?

11. When to go for Multi-process design over Multi-threaded design and vice versa

12. How ValGrind tool works

13. In production code, would you favor recursive but simple logic, Or Non recursive but complex logic, and why ?

If you analyze the pattern,

Candidate with 1–3 yrs of experience, I would chose to ask more of a direct and straightforward Questions.

Candidate with 4–6 yrs of experience, I would chose to ask more advanced technical C Question plus some comparison of approaches based Questions

Candidate with 7+ yrs of experience, I would chose to ask more of a design and Analysis based Question.

Note that, since Question pertains to C and System Programming, so i have not mentioned Data structures and Algorithms.