This is in C

$,$

$$please don't use chatgpt, Write a simple program and show that it runs correctly

$($

example code available on Canvas; can be used as

starting point

$)$

$$where processes synchronize via polling. Consider THREE

processes: A

$,$

$$B and C

$.$

$$Process A is the master process and will print out the

strings from shared memory written by two other writing processes

$($

B first

and then C second

$)$

$.$

$$Process A needs to 'wait' by polling until B and C finish

writing their strings to memory. Each of processes A

$,$

$$B and C should be in

different code files. Create THREE different shared memory locations:

$($

i

$)$

$$one

for storing the pid,

$($

ii

$)$

$$for storing the process identifier

$($

A

$,$

$$B or C

$)$

$$and

$($

iii

$)$

$$for

storing the string. Here is the sequence of events that needs to be

implemented:

$1$

$.$

$$Process A writes

$$

$$

$$to the first shared memory location and

$$

A

$$

$$to

the second location. It also writes the string

$$

I am Process A

$$

$$into the

string shared memory location. It then prints out the shared memory

location in the following format:

$$

I am Process A

$-$

$$

$.$

$$Process A

then waits until B and C completes.

$2$

$.$

$$Process B first checks if the second shared memory location has a

$$

A

$$

in it

$.$

$$When true, it writes its into the first shared memory location

and the string "I am Process B

$"$

$$into the third shared memory location

and then signals A & C that it is complete by writing

$$

B

$$

$$into the second

shared memory location

$($

note: B must wait to write into the process

identifier shared memory location until after process A writes

$$

A

$$

$$there

$)$

$.$

Then process B quits. At this point, process

$-$

A prints out the shared

memory location in the following format:

$$

I am Process B

$-$

$$

$.$

$3$

$.$

$$Process C writes the string "I am Process C

$"$

$$into the string shared

memory and its pid into the first shared memory location. It then signals

A that it is complete by writing

$$

C

$$

$$into the second shared memory

location

$($

note: C must wait until process B

writes

$$

B

$$

$$into the process identifier shared memory

$)$

$.$

$$Then process C

quits. At this point, process

$-$

A prints out the shared memory location in

the following format:

$$

I am Process C

$-$

$$

$.$

$4$

$.$

$$Process A needs to keep polling the process identifier shared memory

location continuously. After process B writes

$$

I am Process B

$$

$,$

$$process

A should be able to print it out. Similarly, after process C writes

$$

I am

Process C

$$

$,$

$$process A needs to be able to print it out. Here some ad

$-$

hoc

synchronization is needed. Specifically, consider using the usleep

$($

$)$

function to delay processes B and C between writing the pid, string and

the process identifier to give process A a chance to poll and print. Adjust

the delay such that prints happen properly.

$5$

$.$

$$Process A is the last one to quit and prints out a

$$

GoodBye

$$

message at the very end before quitting

#include

#include

#include

#include

#include

#define SHMSZ

$2$

$7$

int

main

$($

$)$

$\{$

$$ int shmid;

$$ key

$\_$

t key;

$$ char

$*$

shm

$,$

$*$

s;

$$

$/$

$*$

$$

$*$

$$We need to get the segment named

$$

$*$

$"$

$5$

$6$

$7$

$8$

$"$

$,$

$$created by the server.

$$

$*$

$/$

$$ key

$=$

$5$

$6$

$7$

$8$

;

$$

$/$

$*$

$$

$*$

$$Locate the segment.

$$

$*$

$/$

$$ if

$($

$($

shmid

$=$

$$shmget

$($

key

$,$

$$SHMSZ

$,$

$0$

$6$

$6$

$6$

$)$

$)$

$<$

$0$

$)$

$$

$\{$

$$ perror

$($

$"$

shmget

$"$

$)$

;

$$ exit

$($

$1$

$)$

;

$$

$\}$

$$

$/$

$*$

$$

$*$

$$Now we attach the segment to our data space.

$$

$*$

$/$

$$ if

$($

$($

shm

$=$

$$shmat

$($

shmid

$,$

$$NULL$,$

$0$

$)$

$)$

$=$

$=$

$($

char

$*$

$)$

$-$

$1$

$)$

$$

$\{$

$$ perror

$($

$"$

shmat

$"$

$)$

;

$$ exit

$($

$1$

$)$

;

$$

$\}$

$$

$/$

$*$

$$

$*$

$$Now read what the server put in the memory.

$$

$*$

$/$

$$ for

$($

$$s

$=$

$$shm;

$*$

s

$!$

$=$

$($

char

$)$

$$NULL; s

$+$

$+$

$)$

$$ putchar

$($

$*$

s

$)$

;

$$ putchar

$($

$\text{'}$

$\text{'}$

$)$

;

$$

$/$

$*$

$$

$*$

$$Finally$,$ change the first character of the

$$

$*$

$$segment to

$\text{'}$

$*$

$\text{'}$

$,$

$$indicating we have read

$$

$*$

$$the segment.

$$

$*$

$/$

$$

$*$

shm

$=$

$\text{'}$

$*$

$\text{'}$

;

$$ return

$0$

;

$\}$

#include

#include

#include

#include

#include

$/$

$*$

$$for exit

$*$

$/$

#define SHMSZ

$2$

$7$

int

main

$($

$)$

$\{$

$$ char c;

$$ int shmid;

$$ key

$\_$

t key;

$$ char

$*$

shm

$,$

$*$

s;

$$

$/$

$*$

$$

$*$

$$We$\text{'}$ll name our shared memory segment

$$

$*$

$"$

$5$

$6$

$7$

$8$

$"$

$.$

$$

$*$

$/$

$$ key

$=$

$5$

$6$

$7$

$8$

;

$$

$/$

$*$

$$

$*$

$$Create the segment.

$$

$*$

$/$

$$ if

$($

$($

shmid

$=$

$$shmget

$($

key

$,$

$$SHMSZ

$,$

$$IPC

$\_$

CREAT

$|$

$0$

$6$

$6$

$6$

$)$

$)$

$<$

$0$

$)$

$$

$\{$

$$ perror

$($

$"$

shmget

$"$

$)$

;

$$ exit

$($

$1$

$)$

;

$$

$\}$

$$

$/$

$*$

$$

$*$

$$Now we attach the segment to our data space.

$$

$*$

$/$

$$ if

$($

$($

shm

$=$

$$shmat

$($

shmid

$,$

$$NULL$,$

$0$

$)$

$)$

$=$

$=$

$($

char

$*$

$)$

$-$

$1$

$)$

$$ per