Design a file-copying program named pipe_filecopy.c using ordinary pipes.

Question

Design a file-copying program named pipe_filecopy.c using ordinary pipes. This program will be passed with two parameters: the name of the file to be copied from and the name of the destination file to be written into.

The program will then create an ordinary pipe and write the contents of the file to be copied to the pipe. The child process will read this file from the pipe and write it to the destination file. For example, if we invoke the program as follows:

./pipe_filecopy input.txt copy.txt

the file input.txt will be copied to the pipe first, and then the child process will read the content from the pipe and write it to the destination file copy.txt.

Answer 1

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <string.h>

#define BUFFER_SIZE 4096 // Define buffer size for reading/writing

void error_exit(const char *msg) {

perror(msg);

exit(EXIT_FAILURE);

}

int main(int argc, char *argv[]) {

if (argc != 3) {

fprintf(stderr, "Usage: %s <source_file> <destination_file>\n", argv[0]);

exit(EXIT_FAILURE);

}

int pipefd[2];

pid_t pid;

// Create a pipe

if (pipe(pipefd) == -1) {

error_exit("pipe");

}

// Fork a new process

pid = fork();

if (pid == -1) {

error_exit("fork");

}

if (pid > 0) {

// Parent process: reads from source file and writes to pipe

// Close the reading end of the pipe

close(pipefd[0]);

// Open source file for reading

int src_fd = open(argv[1], O_RDONLY);

if (src_fd == -1) {

error_exit("open source file");

}

// Read from source file and write to pipe

char buffer[BUFFER_SIZE];

ssize_t bytes_read, bytes_written;

while ((bytes_read = read(src_fd, buffer, sizeof(buffer))) > 0) {

bytes_written = write(pipefd[1], buffer, bytes_read);

if (bytes_written == -1) {

error_exit("write to pipe");

}

}

if (bytes_read == -1) {

error_exit("read from source file");

}

// Close the source file and the writing end of the pipe

close(src_fd);

close(pipefd[1]);

// Wait for child to finish

wait(NULL);

} else {

// Child process: reads from pipe and writes to destination file

// Close the writing end of the pipe

close(pipefd[1]);

// Open destination file for writing (create if it doesn't exist, truncate if it does)

int dest_fd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);

if (dest_fd == -1) {

error_exit("open destination file");

}

// Read from pipe and write to destination file

char buffer[BUFFER_SIZE];

ssize_t bytes_read, bytes_written;

while ((bytes_read = read(pipefd[0], buffer, sizeof(buffer))) > 0) {

bytes_written = write(dest_fd, buffer, bytes_read);

if (bytes_written == -1) {

error_exit("write to destination file");

}

}

if (bytes_read == -1) {

error_exit("read from pipe");

}

// Close the destination file and the reading end of the pipe

close(dest_fd);

close(pipefd[0]);

exit(EXIT_SUCCESS);

}

return 0;

}