main.c

#include <stdio.h>
#include <stdlib.h> // For malloc, free
#include <sys/types.h> // For time_t
#include <time.h>   // For strftime, time_t
#include <unistd.h> // For getopt
#include <string.h> // For strcat
#include <dirent.h> // For opendir
#include <sys/wait.h> // For wait
#include "cli.h"
#include "fileutils.h"

int main(int argc, char ** argv) {
    // Parse the command-line arguments
    cli_opts_t opts = parse_opts(argc, argv);
    
    while (1){
        char file_buf[PATH_MAX];

        // Used when waiting for child processes
        int status = 0;


        printf("%s: backing up '%s' into '%s'.\n", argv[0], opts.origin_path, opts.destination_path);
        
        DIR* origin_dir = opendir(opts.origin_path);
        if(origin_dir == NULL){
            perror("opendir");
            return 1;
        }

        // Run trough the files in the origin directory
        for(
            struct dirent * entry = readdir(origin_dir);
            entry != NULL;
            entry = readdir(origin_dir)
        ){
            if(ENTRY_IS_A_REGULAR_FILE(entry) && fork() == 0){
                // We'll check if this file (in the origin folder) has
                // a counterpart on the backup folder.
                pid_t pid = getpid();

                snprintf(file_buf, PATH_MAX, "%s/%s", opts.destination_path, entry->d_name);

                printf("worker-%d: checking if '%s' is backed up... ", pid, entry->d_name);
                if(file_exists(file_buf)) {
                    // Some file with the same name exists on the backup folder, now
                    // we must check if both have the same last modified timestamp
                    if (same_last_modified_date(&opts, entry->d_name, file_buf)) {
                        // Both files have the same last modified date,
                        // so there are no operations left to do.
                        printf("it is and they're sync'ed!!\n");
                        return 0;
                    }
                    // The current backup is old
                    if (remove(file_buf) == -1) {
                        perror("remove failed");
                        return 1;
                    }
                    copy_file(&opts, entry->d_name, file_buf);
                } else {
                    // The given file isn't backed up, so we have to do that
                    printf("it's not!\n");
                    copy_file(&opts, entry->d_name, file_buf);
                }

                // Make sure that the child process doesn't spawn any more processes
                return 0;
            }
        }
        pid_t wpid;
        while ((wpid = wait(&status)) > 0);
        closedir(origin_dir);
        usleep (opts.update_time * 1000);
    }
    return 0;
}