#include <fcntl.h> /* open(2), O_RDONLY */
#include <stdio.h> /* fprintf(3), perror(3) */
#if !defined EX_OK || !defined EX_OSERR || !defined EX_USAGE
#	include <sysexits.h>
#endif
#include <unistd.h> /* dup(2), dup2(2), fork(2), STDIN_FILENO */
#include <sys/types.h> /* <sys/wait.h> */
#include <sys/wait.h> /* wait(2), WIFEXITED, WEXITSTATUS */
#include "libpsargs.h"

int main(int argc, char *argv[]){
	int child;
	char **corr;
	char **curr;
	int fd;
	int i;
	int r;

	if(argc < 2 || check_arg(curr = &argv[1]) != 2){
		fprintf(stderr,
			"Usage: %s \"[\" [command (arguments...)] \"]\""
			" \"[\" [command (arguments...)] \"]\"\n",
			argc == 0 ? "<no argv[0]>" : argv[0]);
		return EX_USAGE;
	}

	/* substitute standard input for /dev/null */
	if((fd = dup(STDIN_FILENO)) < 0
			|| dup2(open("/dev/null", O_RDONLY), STDIN_FILENO)
				< 0){
		perror(argv[0]);
		return EX_OSERR;
	}

	for(i = 0; ; ++i){
		*(corr = corresponding_arg(curr++)) = NULL;

		if(i == 1 || (r = fork()) == 0)
			execvp(*curr, curr);

		if(		r == -1 /* fork(2) failed */
				|| i == 1 || r == 0 /* exec(3) failed */
				|| dup2(fd, STDIN_FILENO) != STDIN_FILENO){
			perror(argv[0]);
			return EX_OSERR;
		}

		wait(&child);
		if(!WIFEXITED(child) || WEXITSTATUS(child) != 0)
			return 1;

		curr = corr + 1;
	}

	/* UNREACHABLE */
}