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use clap::{crate_version, App, Arg};
use rand::prelude::SliceRandom;
use rand::Rng;
use std::cell::{Cell, RefCell};
use std::fs;
use std::fs::{File, OpenOptions};
use std::io;
use std::io::prelude::*;
use std::io::SeekFrom;
use std::path::{Path, PathBuf};
use uucore::display::Quotable;
use uucore::error::{FromIo, UResult, USimpleError, UUsageError};
use uucore::{util_name, InvalidEncodingHandling};
#[macro_use]
extern crate uucore;
const BLOCK_SIZE: usize = 512;
const NAME_CHARSET: &[u8] = b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_.";
const PATTERNS: [&[u8]; 22] = [
b"\x00",
b"\xFF",
b"\x55",
b"\xAA",
b"\x24\x92\x49",
b"\x49\x24\x92",
b"\x6D\xB6\xDB",
b"\x92\x49\x24",
b"\xB6\xDB\x6D",
b"\xDB\x6D\xB6",
b"\x11",
b"\x22",
b"\x33",
b"\x44",
b"\x66",
b"\x77",
b"\x88",
b"\x99",
b"\xBB",
b"\xCC",
b"\xDD",
b"\xEE",
];
#[derive(Clone, Copy)]
enum PassType<'a> {
Pattern(&'a [u8]),
Random,
}
struct FilenameGenerator {
name_len: usize,
name_charset_indices: RefCell<Vec<usize>>,
exhausted: Cell<bool>,
}
impl FilenameGenerator {
fn new(name_len: usize) -> FilenameGenerator {
let indices: Vec<usize> = vec![0; name_len];
FilenameGenerator {
name_len,
name_charset_indices: RefCell::new(indices),
exhausted: Cell::new(false),
}
}
}
impl Iterator for FilenameGenerator {
type Item = String;
fn next(&mut self) -> Option<String> {
if self.exhausted.get() {
return None;
}
let mut name_charset_indices = self.name_charset_indices.borrow_mut();
let mut ret = String::new();
for i in name_charset_indices.iter() {
let c = char::from(NAME_CHARSET[*i]);
ret.push(c);
}
if name_charset_indices[0] == NAME_CHARSET.len() - 1 {
self.exhausted.set(true)
}
for i in (0..self.name_len).rev() {
if name_charset_indices[i] == NAME_CHARSET.len() - 1 {
name_charset_indices[i] = 0;
continue;
} else {
name_charset_indices[i] += 1;
break;
}
}
Some(ret)
}
}
struct BytesGenerator<'a> {
total_bytes: u64,
bytes_generated: Cell<u64>,
block_size: usize,
exact: bool,
gen_type: PassType<'a>,
rng: Option<RefCell<rand::rngs::ThreadRng>>,
bytes: [u8; BLOCK_SIZE],
}
impl<'a> BytesGenerator<'a> {
fn new(total_bytes: u64, gen_type: PassType<'a>, exact: bool) -> BytesGenerator {
let rng = match gen_type {
PassType::Random => Some(RefCell::new(rand::thread_rng())),
_ => None,
};
let bytes = [0; BLOCK_SIZE];
BytesGenerator {
total_bytes,
bytes_generated: Cell::new(0u64),
block_size: BLOCK_SIZE,
exact,
gen_type,
rng,
bytes,
}
}
pub fn reset(&mut self, total_bytes: u64, gen_type: PassType<'a>) {
if let PassType::Random = gen_type {
if self.rng.is_none() {
self.rng = Some(RefCell::new(rand::thread_rng()));
}
}
self.total_bytes = total_bytes;
self.gen_type = gen_type;
self.bytes_generated.set(0);
}
pub fn next(&mut self) -> Option<&[u8]> {
if self.bytes_generated.get() >= self.total_bytes {
return None;
}
let this_block_size = if !self.exact {
self.block_size
} else {
let bytes_left = self.total_bytes - self.bytes_generated.get();
if bytes_left >= self.block_size as u64 {
self.block_size
} else {
(bytes_left % self.block_size as u64) as usize
}
};
let bytes = &mut self.bytes[..this_block_size];
match self.gen_type {
PassType::Random => {
let mut rng = self.rng.as_ref().unwrap().borrow_mut();
rng.fill(bytes);
}
PassType::Pattern(pattern) => {
let skip = if self.bytes_generated.get() == 0 {
0
} else {
(pattern.len() as u64 % self.bytes_generated.get()) as usize
};
let mut i = 0;
while i < this_block_size {
let start = (i + skip) % pattern.len();
let end = (this_block_size - i).min(pattern.len());
let len = end - start;
bytes[i..i + len].copy_from_slice(&pattern[start..end]);
i += len;
}
}
};
let new_bytes_generated = self.bytes_generated.get() + this_block_size as u64;
self.bytes_generated.set(new_bytes_generated);
Some(bytes)
}
}
static ABOUT: &str = "Overwrite the specified FILE(s) repeatedly, in order to make it harder\n\
for even very expensive hardware probing to recover the data.
";
fn usage() -> String {
format!("{} [OPTION]... FILE...", uucore::execution_phrase())
}
static AFTER_HELP: &str =
"Delete FILE(s) if --remove (-u) is specified. The default is not to remove\n\
the files because it is common to operate on device files like /dev/hda,\n\
and those files usually should not be removed.\n\
\n\
CAUTION: Note that shred relies on a very important assumption:\n\
that the file system overwrites data in place. This is the traditional\n\
way to do things, but many modern file system designs do not satisfy this\n\
assumption. The following are examples of file systems on which shred is\n\
not effective, or is not guaranteed to be effective in all file system modes:\n\
\n\
* log-structured or journal file systems, such as those supplied with\n\
AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)\n\
\n\
* file systems that write redundant data and carry on even if some writes\n\
fail, such as RAID-based file systems\n\
\n\
* file systems that make snapshots, such as Network Appliance's NFS server\n\
\n\
* file systems that cache in temporary locations, such as NFS\n\
version 3 clients\n\
\n\
* compressed file systems\n\
\n\
In the case of ext3 file systems, the above disclaimer applies\n\
and shred is thus of limited effectiveness) only in data=journal mode,\n\
which journals file data in addition to just metadata. In both the\n\
data=ordered (default) and data=writeback modes, shred works as usual.\n\
Ext3 journal modes can be changed by adding the data=something option\n\
to the mount options for a particular file system in the /etc/fstab file,\n\
as documented in the mount man page (man mount).\n\
\n\
In addition, file system backups and remote mirrors may contain copies\n\
of the file that cannot be removed, and that will allow a shredded file\n\
to be recovered later.\n\
";
pub mod options {
pub const FORCE: &str = "force";
pub const FILE: &str = "file";
pub const ITERATIONS: &str = "iterations";
pub const SIZE: &str = "size";
pub const REMOVE: &str = "remove";
pub const VERBOSE: &str = "verbose";
pub const EXACT: &str = "exact";
pub const ZERO: &str = "zero";
}
#[uucore_procs::gen_uumain]
pub fn uumain(args: impl uucore::Args) -> UResult<()> {
let args = args
.collect_str(InvalidEncodingHandling::Ignore)
.accept_any();
let usage = usage();
let app = uu_app().usage(&usage[..]);
let matches = app.get_matches_from(args);
if !matches.is_present(options::FILE) {
return Err(UUsageError::new(1, "missing file operand"));
}
let iterations = match matches.value_of(options::ITERATIONS) {
Some(s) => match s.parse::<usize>() {
Ok(u) => u,
Err(_) => {
return Err(USimpleError::new(
1,
format!("invalid number of passes: {}", s.quote()),
))
}
},
None => unreachable!(),
};
let force = matches.is_present(options::FORCE);
let remove = matches.is_present(options::REMOVE);
let size_arg = matches.value_of(options::SIZE).map(|s| s.to_string());
let size = get_size(size_arg);
let exact = matches.is_present(options::EXACT) && size.is_none();
let zero = matches.is_present(options::ZERO);
let verbose = matches.is_present(options::VERBOSE);
for path_str in matches.values_of(options::FILE).unwrap() {
show_if_err!(wipe_file(
path_str, iterations, remove, size, exact, zero, verbose, force,
));
}
Ok(())
}
pub fn uu_app() -> App<'static, 'static> {
App::new(uucore::util_name())
.version(crate_version!())
.about(ABOUT)
.after_help(AFTER_HELP)
.arg(
Arg::with_name(options::FORCE)
.long(options::FORCE)
.short("f")
.help("change permissions to allow writing if necessary"),
)
.arg(
Arg::with_name(options::ITERATIONS)
.long(options::ITERATIONS)
.short("n")
.help("overwrite N times instead of the default (3)")
.value_name("NUMBER")
.default_value("3"),
)
.arg(
Arg::with_name(options::SIZE)
.long(options::SIZE)
.short("s")
.takes_value(true)
.value_name("N")
.help("shred this many bytes (suffixes like K, M, G accepted)"),
)
.arg(
Arg::with_name(options::REMOVE)
.short("u")
.long(options::REMOVE)
.help("truncate and remove file after overwriting; See below"),
)
.arg(
Arg::with_name(options::VERBOSE)
.long(options::VERBOSE)
.short("v")
.help("show progress"),
)
.arg(
Arg::with_name(options::EXACT)
.long(options::EXACT)
.short("x")
.help(
"do not round file sizes up to the next full block;\n\
this is the default for non-regular files",
),
)
.arg(
Arg::with_name(options::ZERO)
.long(options::ZERO)
.short("z")
.help("add a final overwrite with zeros to hide shredding"),
)
.arg(Arg::with_name(options::FILE).hidden(true).multiple(true))
}
fn get_size(size_str_opt: Option<String>) -> Option<u64> {
size_str_opt.as_ref()?;
let mut size_str = size_str_opt.as_ref().unwrap().clone();
let unit = match size_str.chars().last().unwrap() {
'K' => {
size_str.pop();
1024u64
}
'M' => {
size_str.pop();
(1024 * 1024) as u64
}
'G' => {
size_str.pop();
(1024 * 1024 * 1024) as u64
}
_ => 1u64,
};
let coefficient = match size_str.parse::<u64>() {
Ok(u) => u,
Err(_) => {
println!(
"{}: {}: Invalid file size",
util_name(),
size_str_opt.unwrap().maybe_quote()
);
std::process::exit(1);
}
};
Some(coefficient * unit)
}
fn pass_name(pass_type: PassType) -> String {
match pass_type {
PassType::Random => String::from("random"),
PassType::Pattern(bytes) => {
let mut s: String = String::new();
while s.len() < 6 {
for b in bytes {
let readable: String = format!("{:x}", b);
s.push_str(&readable);
}
}
s
}
}
}
#[allow(clippy::too_many_arguments)]
fn wipe_file(
path_str: &str,
n_passes: usize,
remove: bool,
size: Option<u64>,
exact: bool,
zero: bool,
verbose: bool,
force: bool,
) -> UResult<()> {
let path: &Path = Path::new(path_str);
if !path.exists() {
return Err(USimpleError::new(
1,
format!("{}: No such file or directory", path.maybe_quote()),
));
}
if !path.is_file() {
return Err(USimpleError::new(
1,
format!("{}: Not a file", path.maybe_quote()),
));
}
if force {
let metadata = fs::metadata(path).map_err_context(String::new)?;
let mut perms = metadata.permissions();
perms.set_readonly(false);
fs::set_permissions(path, perms).map_err_context(String::new)?;
}
let mut pass_sequence: Vec<PassType> = Vec::new();
if n_passes <= 3 {
for _ in 0..n_passes {
pass_sequence.push(PassType::Random)
}
}
else {
let n_full_arrays = n_passes / PATTERNS.len();
let remainder = n_passes % PATTERNS.len();
for _ in 0..n_full_arrays {
for p in &PATTERNS {
pass_sequence.push(PassType::Pattern(*p));
}
}
for pattern in PATTERNS.iter().take(remainder) {
pass_sequence.push(PassType::Pattern(pattern));
}
let mut rng = rand::thread_rng();
pass_sequence.shuffle(&mut rng);
let n_random = 3 + n_passes / 10;
for i in 0..n_random {
pass_sequence[i * (n_passes - 1) / (n_random - 1)] = PassType::Random;
}
}
if zero {
pass_sequence.push(PassType::Pattern(b"\x00"));
}
{
let total_passes: usize = pass_sequence.len();
let mut file: File = OpenOptions::new()
.write(true)
.truncate(false)
.open(path)
.map_err_context(|| format!("{}: failed to open for writing", path.maybe_quote()))?;
let mut generator = BytesGenerator::new(0, PassType::Pattern(&[]), exact);
for (i, pass_type) in pass_sequence.iter().enumerate() {
if verbose {
let pass_name: String = pass_name(*pass_type);
if total_passes.to_string().len() == 1 {
println!(
"{}: {}: pass {}/{} ({})... ",
util_name(),
path.maybe_quote(),
i + 1,
total_passes,
pass_name
);
} else {
println!(
"{}: {}: pass {:2.0}/{:2.0} ({})... ",
util_name(),
path.maybe_quote(),
i + 1,
total_passes,
pass_name
);
}
}
show_if_err!(do_pass(&mut file, path, &mut generator, *pass_type, size)
.map_err_context(|| format!("{}: File write pass failed", path.maybe_quote())));
}
}
if remove {
do_remove(path, path_str, verbose)
.map_err_context(|| format!("{}: failed to remove file", path.maybe_quote()))?;
}
Ok(())
}
fn do_pass<'a>(
file: &mut File,
path: &Path,
generator: &mut BytesGenerator<'a>,
generator_type: PassType<'a>,
given_file_size: Option<u64>,
) -> Result<(), io::Error> {
file.seek(SeekFrom::Start(0))?;
let size: u64 = given_file_size.unwrap_or(get_file_size(path)?);
generator.reset(size, generator_type);
while let Some(block) = generator.next() {
file.write_all(block)?;
}
file.sync_data()?;
Ok(())
}
fn get_file_size(path: &Path) -> Result<u64, io::Error> {
let size: u64 = fs::metadata(path)?.len();
Ok(size)
}
fn wipe_name(orig_path: &Path, verbose: bool) -> Option<PathBuf> {
let file_name_len: usize = orig_path.file_name().unwrap().to_str().unwrap().len();
let mut last_path: PathBuf = PathBuf::from(orig_path);
for length in (1..=file_name_len).rev() {
for name in FilenameGenerator::new(length) {
let new_path: PathBuf = orig_path.with_file_name(name);
if new_path.exists() {
continue;
}
match fs::rename(&last_path, &new_path) {
Ok(()) => {
if verbose {
println!(
"{}: {}: renamed to {}",
util_name(),
last_path.maybe_quote(),
new_path.quote()
);
}
{
let new_file: File = File::open(new_path.clone())
.expect("Failed to open renamed file for syncing");
new_file.sync_all().expect("Failed to sync renamed file");
}
last_path = new_path;
break;
}
Err(e) => {
println!(
"{}: {}: Couldn't rename to {}: {}",
util_name(),
last_path.maybe_quote(),
new_path.quote(),
e
);
return None;
}
}
}
}
Some(last_path)
}
fn do_remove(path: &Path, orig_filename: &str, verbose: bool) -> Result<(), io::Error> {
if verbose {
println!("{}: {}: removing", util_name(), orig_filename.maybe_quote());
}
let renamed_path: Option<PathBuf> = wipe_name(path, verbose);
if let Some(rp) = renamed_path {
fs::remove_file(rp)?;
}
if verbose {
println!("{}: {}: removed", util_name(), orig_filename.maybe_quote());
}
Ok(())
}