📖 get_next_line

💡 About the project

This project is about programming a function that returns a line read from a file descriptor.
It will not only allow you to add a very convenient function to your collection, but it will also make you learn a highly interesting new concept in C programming: static variables.

📝 Requirements

Mandatory part:

• Repeated calls (e.g., using a loop) to your get_next_line() function should let you read the text file pointed to by the file descriptor, one line at a time.
• Your function should return the line that was read. If there is nothing else to read or if an error occurred, it should return NULL.
• Make sure that your function works as expected both when reading a file and when reading from the standard input.
• Please note that the returned line should include the terminating \n character, except if the end of file was reached and does not end with a \n character.
• Your header file get_next_line.h must at least contain the prototype of the get_next_line() function.
• Add all the helper functions you need in the get_next_line_utils.c file
• Because you will have to read files in get_next_line(), add this option to your compiler call: -D BUFFER_SIZE=n. It will define the buffer size for read(). The buffer size value will be modified by your peer-evaluators and the Moulinette in order to test your code.
• You will compile your code as follows (a buffer size of 42 is used as an example): cc -Wall -Wextra -Werror -D BUFFER_SIZE=42 .c
• We consider that get_next_line() has an undefined behavior if the file pointed to by the file descriptor changed since the last call whereas read() didn’t reach the end of file.
• We also consider that get_next_line() has an undefined behavior when reading a binary file. However, you can implement a logical way to handle this behavior if you want to.
• lseek() is forbidden.

Bonus part:

• Develop get_next_line() using only one static variable.
• Your get_next_line() can manage multiple file descriptors at the same time. For example, if you can read from the file descriptors 3, 4 and 5, you should be able to read from a different fd per call without losing the reading thread of each file descriptor or returning a line from another fd. It means that you should be able to call get_next_line() to read from fd 3, then fd 4, then 5, then once again 3, once again 4, and so forth.

📋 Testing

To compile, navigate to the project directory and run:

gcc -Wall -Werror -Wextra -D BUFFER_SIZE=n main.c get_next_line.c get_next_line_utils.c

// n is the BUFFER_SIZE you want to test