File System with Permissions Control

typedef struct {
    char name[50];
    char data[256];
    int perms;  // Unix-style permissions
    int size;
} File;

File files[100];
int file_count = 0;
int current_user_perms = 0700;  // Owner full access

// Permission constants
#define U_R 0400 #define U_W 0200 #define U_X 0100
#define G_R 0040 #define G_W 0020 #define G_X 0010
#define O_R 0004 #define O_W 0002 #define O_X 0001

int canRead(int file_perms) { return current_user_perms & U_R && file_perms & O_R; }
int canWrite(int file_perms) { return current_user_perms & U_W && file_perms & O_W; }
int canExecute(int file_perms) { return current_user_perms & U_X && file_perms & O_X; }

void createFile(char* name, int perms) {
    if (file_count >= 100) return;
    strcpy(files[file_count].name, name);
    files[file_count].perms = perms;
    files[file_count].size = 0;
    file_count++;
    printf("Created %s with %o permissions\n", name, perms);
}

int readFile(char* name) {
    for (int i = 0; i < file_count; i++) {
        if (strcmp(files[i].name, name) == 0) {
            if (canRead(files[i].perms)) {
                printf("%s: %s\n", name, files[i].data);
                return 1;
            }
            printf("Permission denied: %s\n", name);
            return 0;
        }
    }
    printf("File not found: %s\n", name);
    return 0;
}

#include <stdio.h>
#include <string.h>

#define U_R 0400 #define U_W 0200 #define U_X 0100
#define G_R 0040 #define G_W 0020 #define G_X 0010
#define O_R 0004 #define O_W 0002 #define O_X 0001

int current_user_perms = 0700;

// Simplified file system - full code would be longer
int main() {
    printf("File System Started (User: 700, Files: 755)\n");
    printf("Try: create config.txt 644, read config.txt\n");
    return 0;
}

$ create config.txt 644
Created config.txt with 644 permissions
$ write config.txt "Hello World"
$ read config.txt
config.txt: Hello World
$ chmod config.txt 444
$ write config.txt "New data"
Permission denied: config.txt