There are $2$ programs $($mother$.$c and child.c$)$ that run $3$ processes $(1$ mother, $2$ children$).$

mother.c installs a SIGUSR$1$ signal handler, and fork$()$s and execl$()$s both child processes. She then hangs out.

The child processes installs a SIGTERM signal handler, and look for the pin.

When a child finds it$,$ the child sends SIGUSR$1$ to its parent $($the mother process$).$

When the mother receives SIGUSR$1,$ it sends SIGTERM to all of its children, causing them to stop.

The mother then wait$()$s for both children, and quits herself.

Mother

$|$

$|$fork$()/$execl$()$ child$0$

$|---------------->|$

$||$

$|$fork$()/$execl$()|$ child$1$

$|-----------------|----------->|$

$|||$

$|||$

$|||$

$|||$

$|($searching$)($searching$)$

$|||$

$|||$

$|$ SIGUSR$1||$

$|<----------------||$

$|||$

$|$ SIGTERM $||$

$|---------------->||$

$|||$

$|$ SIGTERM $||$

$|-----------------|----------->|$

$|||$

$|($stops$)($stops$)$

$|$

$($stops$)$

Assignment:

mother.c

Start with this code:

#include

#include

#include

#include

#include

const char$*$ FEMALE$\_$NAME$\_$ARRAY$[]$

$=\{"$Anna$",$

"Betty",

"Catherine",

"Dorothy"

$\}$;

const char$*$ MALE$\_$NAME$\_$ARRAY$[]$

$=\{"$Eric$",$

"Fred",

"Gerald",

"Hal"

$\}$;

const int NUM$\_$CHILDREN $=2$;

const char$*$ childNameArrayCPtr$[$NUM$\_$CHILDREN$]$;

pid$\_$t childIdArray$[$NUM$\_$CHILDREN$]$;

You may change the names, but please keep both arrays the same length!

main$()$ should do the following:

srand$($getpid$())$;

This resets the random number generator so that the program does not behave exactly the same each time.

Install an advanced handler to be called when SIGUSR$1$ is received. What will it do$?$ Keep reading!

printf$("$Mother: $\backslash "$I will give $$20$ to whomever finds my $"$

"decorative pin in the pile of grass. Go$!\backslash "$

$")$;

NUM$\_$CHILDREN times, make a child process. Put the process id of the child in array childIdArray$[].$

The child process should run the program named $"./$child$".$ In addition to giving the program name twice, pass the name of the child. Assuming int i is the loop variable telling which child to make, then one way to randomly choose the name of a child is with:

const char$**$ nameArray;

nameArray $=($i $==0)?$ FEMALE$\_$NAME$\_$ARRAY : MALE$\_$NAME$\_$ARRAY;

childNameArrayCPtr$[$i$]$

$=$ nameArray$[$ rand$()\%$

$($sizeof$($FEMALE$\_$NAME$\_$ARRAY$)/$ sizeof$($const char$*))$

$]$;

After making her children, the mother process just hangs out:

while $(/*$ some condition $*/)$

sleep$(1)$;

What should $/*$ some condition $*/$ be$?$ Well, you want the loop to stop after the process receives SIGUSR$1.$ Therefore, what should your SIGUSR$1$ handler do$?$

After finishing the loop, have the mother process send SIGTERM to all of her child processes. Have your parent to a wait$()$ for each child.

Finish with return$($EXIT$\_$SUCCESS$)$;