2019-SE-01

#include <stdio.h>
#include <unistd.h>
#include <err.h>
#include <time.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/wait.h>
#include <string.h>

int getCode(int);
bool isCondition(time_t, time_t, int, int);
int writeToFile(int, time_t, time_t, int);
int convert(char*);

int getCode(int status) {
        if (WIFEXITED(status)) {
                return WEXITSTATUS(status);
        }
        return 129;
}

bool isCondition(time_t start, time_t end, int code, int limit) {
        return code != 0 && limit < (end - start);
}

int writeToFile(int fd, time_t start, time_t end, int exitCode) {
        return dprintf(fd, "%ld %ld %d\n", start, end, exitCode);
}

int convert(char* str) {
        if (strlen(str) != 1 || str[0] < '1' || str[1] > '9') {
                errx(5, "invalid number");
        }

        return str[0] - '0';
}

int main(int argc, char* argv[]) {
        //argv -> P secs Q args

        if (argc < 3) {
                errx(1, "Invalid number of arguments");
        }

        int limit = convert(argv[1]);

        int conditionInRow = 0;

        int fd = open("run.log", O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);

        if (-1 == fd) {
                err(4, "error opening/creating file");
        }

        while(conditionInRow != 2) {
                pid_t pid = fork();

                if(-1 == pid) {
                        err(2, "error forking");
                }

                if (0 == pid) {
                        execvp(argv[2], argv + 2);
                        err(3, "error executing");
                }

                time_t start = time(NULL);

                int status;
                wait(&status);

                time_t end = time(NULL);

                int code = getCode(status);

                if (writeToFile(fd, start, end, code) < 0) {
                        err(4, "error writing to fd");
                }

                if (isCondition(start, end, code, limit)) {
                        conditionInRow++;
                } else {
                        conditionInRow = 0;
                }
        }

        close(fd);
}