The following program is designed to echo a message from one child process to another, with upper and lowercase letter reversed. The program reliably outputs just the message “h” and then quits. Explain in a very clearly why this is the output.Suggest how the program could be corrected to produce the expected output. #include #include #include #include #include #include int main() { int fd1[2]; int fd2[2]; char message[] = "Hello, world!\n"; char buffer[100]; pid_t pid1; pid_t pid2; if (pipe(fd1) == -1) { return 1; } if (pipe(fd2) == -1) { return 1; } pid1 = fork(); pid2 = fork(); if (pid1 < 0) { return 1; } if (pid2 < 0) { return 1; } if (pid1 > 0) { close(fd2[0]); write(fd2[1], message, strlen(message)+1); close(fd2[1]); close(fd1[1]); read(fd1[0], buffer, 100); close(fd1[0]); printf("%s", buffer); } else if (pid2 > 0) { close(fd2[1]); read(fd2[0], buffer, 100); close(fd2[0]); close(fd1[0]); for (int i=0; i

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
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The following program is designed to echo a message from one child process to another, with upper and lowercase letter reversed. The program reliably outputs just the message “h” and then quits. Explain in a very clearly why this is the output.Suggest how the program could be corrected to produce the expected output.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<sys/types.h>

#include<string.h>

#include<sys/wait.h>

int main()

{

int fd1[2];

int fd2[2];

char message[] = "Hello, world!\n";

char buffer[100];

pid_t pid1;

pid_t pid2;

if (pipe(fd1) == -1)

{ return 1;

}

if (pipe(fd2) == -1)

{ return 1;

}

pid1 = fork();

pid2 = fork();

if (pid1 < 0)

{ return 1;

}

if (pid2 < 0)

{ return 1;

}

if (pid1 > 0)

{

close(fd2[0]);

write(fd2[1], message, strlen(message)+1);

close(fd2[1]);

close(fd1[1]);

read(fd1[0], buffer, 100);

close(fd1[0]);

printf("%s", buffer);

}

else if (pid2 > 0) {

close(fd2[1]);

read(fd2[0], buffer, 100);

close(fd2[0]);

close(fd1[0]);

for (int i=0; i<strlen(buffer)+1; i++) {

if(islower(buffer[i])) {

buffer[i] = toupper(buffer[i]);

}

else {

buffer[i] = tolower(buffer[i]);

}

sleep(1);

write(fd1[1], &buffer[i], 1);

}

close(fd1[1]);

}

return 0;

}

 

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