schedule log wake (win scheduler - system - power-troubleshooter - event id 1)

log_wake.c

#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>

int file_exists(const char *filename){
    struct stat buffer;
    return (stat (filename, &buffer) == 0);
}

int main(){
    time_t current_time;
    const struct tm* struct_current_time;
    FILE  *fp;
    char *c_time_string;
    const char err_msg[] = "Failure to obtain current time.\n";
    const char log_file_name[] = "log_wake.log";
    const char sep[] = "sep=|\n";
    const char time_output_fields[] = "time_str|year|month|day|hour|minute|second|weekday|daylight";
    const char time_output[] = "%i|%i|%i|%i|%i|%i|%i|%i\n";
    char s_out[256];

    // obtain current time
    current_time = time(NULL);

    if(current_time == ((time_t) - 1)){
        fprintf(stderr, err_msg);
    }

    // convert time to local time format

    struct_current_time = localtime(&current_time);
    c_time_string = asctime(struct_current_time);

    if(c_time_string == NULL){
        fprintf(stderr, err_msg);
    }

    // print to stdout

    printf("Current time: %s", c_time_string);
    sprintf(
        s_out, time_output, 
        struct_current_time->tm_year + 1900, // year since 1900
        struct_current_time->tm_mon + 1, // months since Jan [0,11]
        struct_current_time->tm_mday + 0, // day of the month [1,31]
        struct_current_time->tm_hour + 0, // hours since midnight [0,23]
        struct_current_time->tm_min + 0, // min after the hour [0,59]
        struct_current_time->tm_sec + 0, // sec after the minute [0, 60]
        struct_current_time->tm_wday + 0, // days since Sunday [0, 6],
        struct_current_time->tm_isdst // daylight savings bool
        );

    // append date struct to log_wake.log

    if(file_exists(log_file_name)){
        // append mode
        fp = fopen(log_file_name, "a");
    }else{
        //create / write mode
        fp = fopen(log_file_name, "w");
        fprintf(fp, sep);
        fprintf(fp, time_output_fields);
        fputc('\n', fp);
    }

    for(int i=0; c_time_string[i]!='\n' && c_time_string[i]!='\0'; i++){
        fputc(c_time_string[i], fp);
    }
    fputc('|', fp);
    fprintf(fp, s_out);
    fclose(fp);
    return 0;
}