#include "usg_common.h"
#include "usg_typedef.h"
#include <iostream> // not needed for many systems
#include <fstream>
#include <string>

using namespace std;
 

// void write_to_file_with_no_lock(int fd, int start, int end) {
// 	int i;
// 	char buf[1024];
// 	for(i = start;  i< end; i++) {
// 		sprintf(buf, "%d\n", i);
// 		if (write(fd,  buf,  strlen(buf)) == -1) {
// 			 err_exit(errno, "write_to_file");
// 		}

// 	}

// }

// void write_to_file_with_lock(int fd, int start, int end) {
// 	int i;
// 	char buf[1024];
// 	for(i = start; i< end; i++) {
// 		sprintf(buf, "%d\n", i);

// 		if (flock(fd , LOCK_EX) == -1) {
// 			err_exit(errno, "LOCK_EX");
// 		}
// 		if (write(fd,  buf,  strlen(buf)) == -1) {
// 			 err_exit(errno, "write_to_file");
// 		}
// 		if (flock(fd, LOCK_UN) == -1)
// 			err_exit(errno, "LOCK_UN");

// 	}

// }


void write_to_file(ofstream &fout, int start, int end) {
	int i;
	for(i = start;  i< end; i++) {
		 fout << i << endl;

	}
	//write_to_file_with_lock(fd, start, end);
}

void read_from_file(ifstream &fin) {
	fin.seekg(0);
	char buf[1024];
	while(fin.getline(buf, 1024)) {
		printf("%s\n", buf);
	}

}

int main() {
	ofstream fout;
	ifstream fin("stand.txt");



	 
	int status, i = 0, processors = 4, scale = 100000;
	pid_t productors[processors], consumers[processors];
	pid_t pid;
	ofstream fouts[processors];

	fout.open("stand.txt", ios_base::app);
	
	write_to_file(fout, 0,  processors * scale);

	fout.close();
	//read_from_file(fin);

	

	for ( i = 0; i < processors; i++) {
		if ((productors[i] = fork()) == 0)     /* Child runs user job */
		{
		   fouts[i].open("test.txt", ios_base::out | ios_base::app);
		   int start = i * scale, end = i * scale + scale;
		   printf("======start=%d, end=%d\n", start, end);
		   write_to_file(fouts[i], start, end);
		   exit(0);
		}
	}


	while ((pid = waitpid(-1, &status, 0)) > 0) {
		if(WIFEXITED(status)) {
			//fprintf(stderr, "child %d terminated normally with exit status=%d\n", pid, WEXITSTATUS(status));
		}else
			fprintf(stderr, "child %d terminated abnormally\n", pid);
	}

	if (errno != ECHILD)
		perror("waitpid error");
	fout.close();
	fin.close();
}