In C$,$ implement a readline$()$ function using only read$(2),$ open$(2),$ close$(2),$ free$(3),$ and malloc$(3).$

Two global variables may be used, READLINE$\_$READ$\_$SIZE and another for a buffer.

The function should accept a file stream or stdin, and read each line until

or EOF. An additional function, void init$\_$my$\_$readline$()$ should reinitialise the global variable and free allocated resources to allow for the next file to be read.

It should not use lseek, fread, or fopen.

Example usage:

int main $()$

$\{$

char $*$str $=$ NULL;

int fd $=$ open$("./$file$.$txt$",$ O$\_$RDONLY$)$;

while $(($str $=$ my$\_$readline$($fd$))!=$ NULL$)$

$\{$

printf$("\%$s

$",$ str$)$;

free$($str$)$;

$\}$

close$($fd$)$;

$//$

$//$ Yes it's also working with stdin :$-)$

$//$ printf$("\%$s$",$ my$\_$readline$(0))$;

$//$

return $0$;

$\}$

int main $()$

$\{$

char $*$str $=$ NULL;

int fd $=$ open$("./$file$.$txt$",$ O$\_$RDONLY$)$;

while $(($str $=$ my$\_$readline$($fd$))!=$ NULL$)$

$\{$

printf$("\%$s

$",$ str$)$;

free$($str$)$;

$\}$

close$($fd$)$;

$//$

$//$ Yes it's also working with stdin $$

$//$ printf$("\%$s$",$ my$\_$readline$(0))$;

$//$

return $0$;

$\}$

The function my$\_$readline reads a line from the strean represented by fd and returns it into an allocated string $($heap or stack $?).$ It stops when either the.

newline character is read or when the end$-$of$-$file is reached, whichever comes first. The newline character is not copied to the string.

On success, a pointer to the string is returned. On error, a null pointer is returned. If the end$-$of$-$file occurs before any characters have been read, the string remains unchanged.

Number of characters read will be set by the global variable READLINE$\_$READ$\_$SIZE You are allowed to maximum two global variables $($one for your

"storage" and one for READLINE$\_$READ$\_$SIZE$).$ Be ready, we will change the value of READLINE$\_$READ$\_$SIZE.

Requirements

Your code must be compiled with the flags $-$Wall $-$Wextra $-$Werror.

Technical description

In order to start reading another file you will also produce a function: void init$\_$my$\_$readline$()$ which will init $($or reinitialize$)$ your global variable.

In the case of reinitialize, you will, obviously, free allocated resources. $$

Hints

Your function should work with any of streams, whether it be a file, standard input or a redirection...

Your function should be able to be used in a loop to read an entire file $($see example$)$

Watch out for memory leaks $!$

You can test your code against memory errors by compiling with the debugging flags $-$g$3-$fsanitize$=$address

Static variables are strictly FORBIDDEN

Authorized function$($s$)$

malloc$(3)$

free

read

open

close

Unauthorized function$($s$)$

Iseek

fread

fopen

Any other functions or system calls

Multiline macros are forbidden

Include another $.$c is forbidden

Macros with logic $($while$/$if$/$variables$/...)$ are forbidden