#include "process.h"
#include "debug.h"

int child_count = 0;

int do_fork(void)
{
	int child, error;
	child = fork();
	if (child < 0) {
		error = errno;
		pr_err("fork() failed: %s\n", strerror(error));
		return -1;
	}

	if (child) {
		pr_info("Forked child %d\n", child);
		child_count++;
		return child;
	}

	/* reset child's child count */
	child_count = 0;
	return 0;
}

int run(const char *cmd, char *const argv[])
{
	int child, error;
	if ((child = do_fork()))
	    return child;

	execvp(cmd, argv);
	error = errno;
	pr_err("Failed to execv command %s: %s\n", cmd, strerror(error));
	exit(1);
	return 0;
}

int harvest_zombies(int pid)
{
	int status, error;

	if (child_count == 0)
		return 0;

	pid = waitpid(pid, &status, 0);
	if (pid < 0) {
		error = errno;
		pr_err("Error on wait(): %s\n", strerror(error));
	}
	else
		pr_info("pid %d: exit code %d. Children left: %d\n", pid,
			status, --child_count);

	return 1;
}

/*
 * Runs a command cmd with params argv, connects stdin and stdout to
 * readfd and writefd
 *
 * Returns the pid of the executed process
 */
int run_piped(const char *cmd, char *const argv[], int *readfd, int *writefd)
{
	int rfd[2], wfd[2], error, pid;

	if (pipe(rfd)) {
		error = errno;
		pr_err("pipe() failed: %s\n", strerror(error));
		return -1;
	}

	if (pipe(wfd)) {
		error = errno;
		pr_err("pipe() failed: %s\n", strerror(error));
		return -1;
	}

	pid = do_fork();
	if (pid) {
		close(rfd[1]);
		close(wfd[0]);
		*readfd = rfd[0];
		*writefd = wfd[1];
		child_count++;
		return pid;
	}

	close(rfd[0]);
	close(wfd[1]);
	dup2(wfd[0], STDIN_FILENO);
	dup2(rfd[1], STDOUT_FILENO);

	/* Now we have redirected both stdin and stdout to parent process */
	execvp(cmd, argv);
	error = errno;
	pr_err("Failed to execv command %s: %s\n", cmd, strerror(error));
	exit(1);
	return 0;
}

/*
 * Runs a command cmd with params argv, connects stdin and stdout to
 * readfd and writefd
 *
 * Returns the pid of the executed process
 */
int run_piped_stream(const char *cmd, char *const argv[],
		     FILE **readf, FILE **writef)
{
	int rfd, wfd, pid, error;

	pid = run_piped(cmd, argv, &rfd, &wfd);

	if (readf) {
		*readf = fdopen(rfd, "r");
		if (*readf == NULL) {
			error = errno;
			pr_err("Error opening file stream for fd %d: %s\n",
			       rfd, strerror(error));
			return -1;
		}
	}

	if (writef) {
		*writef = fdopen(wfd, "w");
		if (*writef == NULL) {
			error = errno;
			pr_err("Error opening file stream for fd %d: %s\n",
			       wfd, strerror(error));
			return -1;
		}
	}

	return pid;
}