Book Image

Practical C Programming

By : B. M. Harwani
Book Image

Practical C Programming

By: B. M. Harwani

Overview of this book

Used in everything from microcontrollers to operating systems, C is a popular programming language among developers because of its flexibility and versatility. This book helps you get hands-on with various tasks, covering the fundamental as well as complex C programming concepts that are essential for making real-life applications. You’ll start with recipes for arrays, strings, user-defined functions, and pre-processing directives. Once you’re familiar with the basic features, you’ll gradually move on to learning pointers, file handling, concurrency, networking, and inter-process communication (IPC). The book then illustrates how to carry out searching and arrange data using different sorting techniques, before demonstrating the implementation of data structures such as stacks and queues. Later, you’ll learn interesting programming features such as using graphics for drawing and animation, and the application of general-purpose utilities. Finally, the book will take you through advanced concepts such as low-level programming, embedded software, IoT, and security in coding, as well as techniques for improving code performance. By the end of this book, you'll have a clear understanding of C programming, and have the skills you need to develop robust apps.
Table of Contents (20 chapters)

Learning how to avoid vulnerabilities while writing a file in C

The special care we will take in this recipe is that we will unlink all the links (if any) to the file that we are going to create. We will also ensure that our program does not overwrite any file if it already exists. 

How to do it...

Here are the steps to write a program to avoid vulnerabilities while creating a file in C:

  1. A file pointer is defined.
  2. The hacker might create a soft link and attach a sensitive file to the file that we want to create.
  3. Remove the links from the file that you want to write in.
  4. Open the file using the flags that check whether the file already exists or not. If the file exists, it should be overwritten.
  5. Associate the file descriptor...