Extracting File Attributes to a Text File

A program that reads all non-hidden files in a specified directory, extracts their permissions and last access times, and writes this information to file.txt.

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>

int main() {
    FILE *output_file = fopen("file.txt", "w");
    if (output_file == NULL) {
        perror("fopen");
        return -1;
    }
    
    char base_path[256] = "/home/gec/gec6818/temp/";
    char user_path[256] = {0};
    
    printf("Enter directory path (format: name/.../.../):\n");
    printf("Default base path is /home/gec/gec6818/temp/\n");
    scanf("%s", user_path);
    getchar();
    
    strcat(base_path, user_path);
    chdir(base_path);
    
    DIR *directory = opendir(base_path);
    if (directory == NULL) {
        perror("opendir");
        return -1;
    }
    
    struct dirent *entry;
    struct stat file_info;
    struct tm *time_info;
    int line_number = 1;
    
    fprintf(output_file, "%2d   %20s  %6s  %s\n", line_number, "Filename", "Mode", "Last Access Time");
    line_number++;
    
    while ((entry = readdir(directory)) != NULL) {
        if (entry->d_name[0] == '.') {
            continue;
        }
        
        if (stat(entry->d_name, &file_info) == -1) {
            perror("stat");
            continue;
        }
        
        time_info = localtime(&file_info.st_atime);
        fprintf(output_file, "%2d %20s  %o  %d-%02d-%02d %02d:%02d:%02d\n",
                line_number,
                entry->d_name,
                file_info.st_mode,
                time_info->tm_year + 1900,
                time_info->tm_mon + 1,
                time_info->tm_mday,
                time_info->tm_hour,
                time_info->tm_min,
                time_info->tm_sec);
        line_number++;
    }
    
    if (errno != 0) {
        perror("readdir");
    }
    
    closedir(directory);
    fclose(output_file);
    return 0;
}

Half-Copy Image File Using Parent-Child Processes

A program that splits an image file copy oepration betwean parent and child proecsses, with the parent copying the first half and the child copying the second half.

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>

int main(int argc, char* argv[]) {
    pid_t process_id = fork();
    
    int source_file = open("/home/gec/Downloads/629e6b7c99237e335dd98f06a6cd51ab.jpeg", O_RDONLY);
    if (source_file < 0) {
        perror("open source");
        return -1;
    }
    
    off_t file_size = lseek(source_file, 0, SEEK_END);
    int odd_size_adjustment = (file_size % 2 == 0) ? 0 : 1;
    lseek(source_file, 0, SEEK_SET);
    
    int destination_file = open("copy.jpeg", O_WRONLY | O_CREAT | O_TRUNC, 0777);
    if (destination_file < 0) {
        perror("open destination");
        return -1;
    }
    
    char buffer[1];
    
    if (process_id > 0) {
        for (off_t i = 0; i < file_size / 2 + odd_size_adjustment; i++) {
            if (read(source_file, buffer, 1) < 0) {
                perror("parent read");
                break;
            }
            write(destination_file, buffer, 1);
        }
    }
    
    if (process_id == 0) {
        sleep(1);
        lseek(source_file, file_size / 2, SEEK_SET);
        lseek(destination_file, file_size / 2, SEEK_SET);
        
        for (off_t i = 0; i < file_size / 2 + odd_size_adjustment; i++) {
            if (read(source_file, buffer, 1) < 0) {
                perror("child read");
                break;
            }
            write(destination_file, buffer, 1);
        }
    }
    
    close(source_file);
    close(destination_file);
    return 0;
}

File comparision with diff shows identical content, and visual inspection confirms the copied image matches the original.