libc/stdio/popen.c


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#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>


FILE *popen(command, rw)
char *command;
char *rw;
{
	int pipe_fd[2];
	int pid, reading;

	if (pipe(pipe_fd) < 0)
		return NULL;
	reading = (rw[0] == 'r');

	pid = vfork();
	if (pid < 0) {
		close(pipe_fd[0]);
		close(pipe_fd[1]);
		return NULL;
	}
	if (pid == 0) {
		close(pipe_fd[!reading]);
		close(reading);
		if (pipe_fd[reading] != reading) {
			dup2(pipe_fd[reading], reading);
			close(pipe_fd[reading]);
		}

		execl("/bin/sh", "sh", "-c", command, (char *) 0);
		_exit(255);
	}

	close(pipe_fd[reading]);
	return fdopen(pipe_fd[!reading], rw);
}

int pclose(fd)
FILE *fd;
{
	int waitstat;

	if (fclose(fd) != 0)
		return EOF;
	wait(&waitstat);
	return waitstat;
}