z-shell/pipes_redirection.c at master · chainsaw95/z-shell · GitHub

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//pipes_redirection.c
#include "headers.h"

int pipes_(char *a[], char *b[])
{

	int fd_A[2];
	int status;
	int i;

	pipe(fd_A);
	pid_t pid_a, pid_b;

	if (!(pid_a = fork()))
	{
		close(1);
		dup(fd_A[WRITE_END]);

		close(fd_A[0]);
		close(fd_A[1]);

		execvp(a[0], a);
	}
	else
	{

		//wait for the first command to end
		wait(&status);
		if (!(pid_b = fork()))
		{
			close(0);
			dup(fd_A[READ_END]);
			//the second process
			close(fd_A[0]);
			close(fd_A[1]);
			execvp(b[0], b);
		}

		close(fd_A[WRITE_END]);
		close(fd_A[READ_END]);
	}

	wait(&status);
	//wait for 2nd process to end
	return 0;
}

int redirection_(char *a[], char type_red[], char *b[])
{

	int err = -1;
	int fileDescriptor;
	int option = 0;

	pid_t pid;

	if (strcmp(type_red, ">") == 0)
		option = 0;
	if (strcmp(type_red, "<") == 0)
		option = 1;
	if (strcmp(type_red, ">>") == 0)
		option = 2;

	if ((pid = fork()) == -1)
	{
		printf("Child process could not be created\n");
		return;
	}
	if (pid == 0)
	{

		if (option == 0)
		{

			fileDescriptor = open(b[0], O_CREAT | O_TRUNC | O_WRONLY, 0600);
			dup2(fileDescriptor, STDOUT_FILENO);
			close(fileDescriptor);
		}
		else if (option == 1)
		{

			fileDescriptor = open(b[0], O_RDONLY, 0600);
			dup2(fileDescriptor, STDIN_FILENO);
			close(fileDescriptor);
		}
		else if (option == 2)
		{

			fileDescriptor = open(b[0], O_CREAT | O_WRONLY | O_APPEND, 0600);
			dup2(fileDescriptor, STDOUT_FILENO);
			close(fileDescriptor);
		}

		if (execvp(a[0], a) == err)
		{
			printf("err");
			kill(getpid(), SIGTERM);
		}
	}
	waitpid(pid, NULL, 0);

	return 0;
}

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

	char *command1[10];
	char *command2[10];
	int pipe_count = 0;
	int i;
	int temp_count1, temp_count2;
	int flag_pipe, flag_redirection;
	temp_count1 = 0;
	temp_count2 = 0;
	char type_red[3];
	memset(command1, 0, sizeof(command1));
	memset(command2, 0, sizeof(command2));

	for (i = 0; i < argc; i++)
	{

		if (strchr(argv[i], '<') != NULL || strchr(argv[i], '|') != NULL || strchr(argv[i], '>') != NULL)
		{
			pipe_count = pipe_count + 1;
			if (strchr(argv[i], '<') != NULL || strchr(argv[i], '>') != NULL)
			{
				flag_redirection = 1;
				strcpy(type_red, argv[i]);
			}
			if (strcmp(argv[i], "|") == 0)
				flag_pipe = 1;

			continue;
		}

		if (pipe_count == 0)
		{

			command1[temp_count1] = (char *)malloc(sizeof(char) * (strlen(argv[i]) + 1));
			command1[temp_count1] = argv[i];
			temp_count1++;
		}
		if (pipe_count == 1)
		{

			command2[temp_count2] = (char *)malloc(sizeof(char) * (strlen(argv[i]) + 1));
			command2[temp_count2] = argv[i];
			temp_count2++;
		}
	}

	if (flag_pipe == 1 && flag_redirection == 1)
	{
		printf("This is a basic shell nesting of pipes and redirection not allowed\n");
		return -1;
	}

	if (flag_pipe == 1)
		pipes_(command1, command2);

	if (flag_redirection == 1)
		redirection_(command1, type_red, command2);

	return 0;
}