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secure_delete.c
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secure_delete.c
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#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#define FILE_TYPE 1
#define DIRECTORY_TYPE 2
#define PATH_MAX 4096
static void take_action(char *filepath);
static int overwrite_file(char *filepath);
static int delete_file(char *filepath);
static int delete_directory(char *filepath);
static int get_file_type(char *filepath);
static void handle_error(const char *message, const char *filepath);
int main(int argc, char **argv)
{
if (argc != 2)
{
handle_error("This command only accepts one arguments.", NULL);
exit(1);
}
take_action(argv[1]);
exit(0);
}
static void handle_error(const char *message, const char *filepath)
{
if (filepath)
{
fprintf(stderr, "%s: %s\n", message, filepath);
}
else
{
fprintf(stderr, "%s\n", message);
}
exit(1);
}
static void take_action(char *filepath)
{
switch (get_file_type(filepath))
{
case FILE_TYPE:
delete_file(filepath);
break;
case DIRECTORY_TYPE:
delete_directory(filepath);
break;
default:
handle_error("Invalid file type", filepath);
exit(1);
}
}
// Returns 0 on success
static int overwrite_file(char *filepath)
{
FILE *file;
long file_size;
char *overwrite_value;
// Check if file exists
if (!(file = fopen(filepath, "rb+")))
{
handle_error("File does not exist", filepath);
return 1;
}
// Get size of file
fseek(file, 0, SEEK_END);
if ((file_size = ftell(file)) == -1L)
{
handle_error("Error determining file size", filepath);
fclose(file);
return 1;
}
else if (!file_size)
{
handle_error("Invalid file size", filepath);
fclose(file);
return 1;
}
fseek(file, 0, SEEK_SET);
// Replace file contents
if (!(overwrite_value = malloc(file_size)))
{
handle_error("Failed to allocate memory for overwrite", filepath);
free(overwrite_value);
fclose(file);
return 1;
}
// Pass 1: Overwrite with zeros
memset(overwrite_value, 0, file_size);
if (!fwrite(overwrite_value, file_size, 1, file))
{
handle_error("Error overwriting file", filepath);
free(overwrite_value);
fclose(file);
return 1;
}
// Pass 2: Overwrite with binary ones
memset(overwrite_value, 0xFF, file_size);
if (!fwrite(overwrite_value, file_size, 1, file))
{
handle_error("Error overwriting file", filepath);
free(overwrite_value);
fclose(file);
return 1;
}
// Pass 3: Overwrite with random data
for (long i = 0; i < file_size; i++)
{
overwrite_value[i] = (char)rand();
}
if (!fwrite(overwrite_value, file_size, 1, file))
{
handle_error("Error overwriting file", filepath);
free(overwrite_value);
fclose(file);
return 1;
}
// Clear resources
free(overwrite_value);
fclose(file);
return 0;
}
static int delete_file(char *filepath)
{
if (overwrite_file(filepath))
{
handle_error("Terminating program, unable to overwrite", filepath);
exit(1);
}
if (remove(filepath))
{
handle_error("Error deleting file", filepath);
return 1;
}
printf("File deleted successfully: %s\n", filepath);
return 0;
}
static int delete_directory(char *filepath)
{
DIR *directory;
struct dirent *directory_obj;
char fullpath[PATH_MAX];
// Check if directory exists
if (!(directory = opendir(filepath)))
{
handle_error("Invalid directory", filepath);
return 1;
}
while ((directory_obj = readdir(directory)))
{
if (strcmp(directory_obj->d_name, ".") == 0 || strcmp(directory_obj->d_name, "..") == 0)
{
continue;
}
snprintf(fullpath, sizeof(fullpath), "%s/%s", filepath, directory_obj->d_name);
take_action(fullpath);
}
closedir(directory);
// Remove directory now
if (rmdir(filepath))
{
handle_error("Error deleting directory", filepath);
return 1;
}
fprintf(stdout, "Directory deleted successfully: %s\n", filepath);
return 0;
}
static int get_file_type(char *filepath)
{
struct stat file_info;
if (!stat(filepath, &file_info))
{
if (S_ISREG(file_info.st_mode))
{
return FILE_TYPE;
}
else if (S_ISDIR(file_info.st_mode))
{
return DIRECTORY_TYPE;
}
}
return -1;
}