Magisk/native/src/base/cstr.rs

636 lines
16 KiB
Rust
Raw Normal View History

use std::cmp::min;
use std::ffi::{CStr, FromBytesWithNulError, OsStr};
use std::fmt::{Arguments, Debug, Display, Formatter, Write};
use std::ops::{Deref, DerefMut};
use std::path::Path;
use std::str::{Utf8Chunks, Utf8Error};
use std::{fmt, mem, slice, str};
use crate::slice_from_ptr_mut;
use libc::c_char;
use thiserror::Error;
2023-09-27 15:21:24 -07:00
// Utf8CStr types are UTF-8 validated and null terminated strings.
//
// Several Utf8CStr types:
//
// Utf8CStr: can only exist as reference, similar to &str
// Utf8CString: dynamically sized buffer allocated on the heap
// Utf8CStrBufRef: reference to a fixed sized buffer
// Utf8CStrBufArr<N>: fixed sized buffer allocated on the stack
//
// In most cases, these are the types being used
//
// &Utf8CStr: whenever a printable null terminated string is needed
// &mut dyn Utf8CStrWrite: whenever we need a buffer that only needs to support appending
// strings to the end, and has to be null terminated
// &mut dyn Utf8CStrBuf: whenever we need a pre-allocated buffer that is large enough to fit
// in the result, and has to be null terminated
//
// All types dereferences to &Utf8CStr.
// Utf8CString, Utf8CStrBufRef, and Utf8CStrBufArr<N> implements Utf8CStrWrite.
// Utf8CStrBufRef and Utf8CStrBufArr<N> implements Utf8CStrBuf.
pub fn copy_cstr<T: AsRef<CStr> + ?Sized>(dest: &mut [u8], src: &T) -> usize {
let src = src.as_ref().to_bytes_with_nul();
let len = min(src.len(), dest.len());
dest[..len].copy_from_slice(&src[..len]);
len - 1
}
2023-09-27 15:21:24 -07:00
fn utf8_cstr_buf_append(buf: &mut dyn Utf8CStrBuf, s: &[u8]) -> usize {
let mut used = buf.len();
if used >= buf.capacity() - 1 {
// Truncate
return 0;
}
let dest = unsafe { &mut buf.mut_buf()[used..] };
let len = min(s.len(), dest.len() - 1);
dest[..len].copy_from_slice(&s[..len]);
dest[len] = b'\0';
used += len;
unsafe { buf.set_len(used) };
len
}
2023-09-27 15:21:24 -07:00
fn utf8_cstr_append_lossy(buf: &mut dyn Utf8CStrWrite, s: &[u8]) -> usize {
let chunks = Utf8Chunks::new(s);
let mut len = 0_usize;
for chunk in chunks {
2023-09-27 15:21:24 -07:00
len += buf.push_str(chunk.valid());
if !chunk.invalid().is_empty() {
2023-09-27 15:21:24 -07:00
len += buf.push_str(char::REPLACEMENT_CHARACTER.encode_utf8(&mut [0; 4]));
}
}
len
}
2023-09-27 15:21:24 -07:00
// Trait definitions
pub trait Utf8CStrWrite:
Write + AsRef<Utf8CStr> + AsMut<Utf8CStr> + Deref<Target = Utf8CStr> + DerefMut
{
fn len(&self) -> usize;
2023-09-27 15:21:24 -07:00
#[inline(always)]
fn is_empty(&self) -> bool {
self.len() == 0
}
fn push_str(&mut self, s: &str) -> usize;
fn push_lossy(&mut self, s: &[u8]) -> usize;
fn clear(&mut self);
}
pub trait Utf8CStrBuf: Utf8CStrWrite {
fn buf(&self) -> &[u8];
// Modifying the underlying buffer or length is unsafe because it can either:
// 1. Break null termination
// 2. Break UTF-8 validation
// 3. Introduce inner null byte in the string
unsafe fn mut_buf(&mut self) -> &mut [u8];
unsafe fn set_len(&mut self, len: usize);
2023-09-27 15:21:24 -07:00
#[inline(always)]
fn capacity(&self) -> usize {
self.buf().len()
}
}
trait AsUtf8CStr {
fn as_utf8_cstr(&self) -> &Utf8CStr;
fn as_utf8_cstr_mut(&mut self) -> &mut Utf8CStr;
}
// Implementation for Utf8CString
trait StringExt {
fn nul_terminate(&mut self) -> &mut [u8];
}
impl StringExt for String {
fn nul_terminate(&mut self) -> &mut [u8] {
self.reserve(1);
// SAFETY: the string is reserved to have enough capacity to fit in the null byte
// SAFETY: the null byte is explicitly added outside of the string's length
unsafe {
let buf = slice::from_raw_parts_mut(self.as_mut_ptr(), self.len() + 1);
*buf.get_unchecked_mut(self.len()) = b'\0';
buf
}
}
}
#[derive(Default)]
pub struct Utf8CString(String);
2023-09-27 15:21:24 -07:00
impl Utf8CString {
#[inline(always)]
2023-09-27 15:21:24 -07:00
pub fn new() -> Self {
Self::default()
}
2023-09-27 15:21:24 -07:00
}
2023-09-27 15:21:24 -07:00
impl AsUtf8CStr for Utf8CString {
#[inline(always)]
2023-09-27 15:21:24 -07:00
fn as_utf8_cstr(&self) -> &Utf8CStr {
// SAFETY: the internal string is always null terminated
unsafe { mem::transmute(slice::from_raw_parts(self.0.as_ptr(), self.0.len() + 1)) }
}
#[inline(always)]
fn as_utf8_cstr_mut(&mut self) -> &mut Utf8CStr {
Utf8CStr::from_string(&mut self.0)
}
}
impl Utf8CStrWrite for Utf8CString {
#[inline(always)]
fn len(&self) -> usize {
self.0.len()
}
fn push_str(&mut self, s: &str) -> usize {
self.0.push_str(s);
self.0.nul_terminate();
s.len()
}
#[inline(always)]
fn push_lossy(&mut self, s: &[u8]) -> usize {
utf8_cstr_append_lossy(self, s)
}
fn clear(&mut self) {
2023-09-27 15:21:24 -07:00
self.0.clear();
self.0.nul_terminate();
}
}
impl From<String> for Utf8CString {
fn from(mut value: String) -> Self {
value.nul_terminate();
Utf8CString(value)
}
}
2023-09-27 15:21:24 -07:00
// Implementations for Utf8CStrBuf
impl<T: Utf8CStrBuf> AsUtf8CStr for T {
#[inline(always)]
fn as_utf8_cstr(&self) -> &Utf8CStr {
// SAFETY: the internal buffer is always UTF-8 checked
// SAFETY: self.used is guaranteed to always <= SIZE - 1
unsafe { Utf8CStr::from_bytes_unchecked(self.buf().get_unchecked(..(self.len() + 1))) }
}
#[inline(always)]
fn as_utf8_cstr_mut(&mut self) -> &mut Utf8CStr {
// SAFETY: the internal buffer is always UTF-8 checked
// SAFETY: self.used is guaranteed to always <= SIZE - 1
unsafe {
let len = self.len() + 1;
Utf8CStr::from_bytes_unchecked_mut(self.mut_buf().get_unchecked_mut(..len))
}
}
}
// UTF-8 validated + null terminated reference to buffer
2023-09-27 15:21:24 -07:00
pub struct Utf8CStrBufRef<'a> {
used: usize,
buf: &'a mut [u8],
}
2023-09-27 15:21:24 -07:00
impl<'a> Utf8CStrBufRef<'a> {
pub unsafe fn from_ptr(buf: *mut u8, len: usize) -> Utf8CStrBufRef<'a> {
Self::from(slice_from_ptr_mut(buf, len))
}
}
2023-09-27 15:21:24 -07:00
impl<'a> From<&'a mut [u8]> for Utf8CStrBufRef<'a> {
fn from(buf: &'a mut [u8]) -> Utf8CStrBufRef<'a> {
buf[0] = b'\0';
2023-09-27 15:21:24 -07:00
Utf8CStrBufRef { used: 0, buf }
}
}
2023-09-27 15:21:24 -07:00
impl Utf8CStrBuf for Utf8CStrBufRef<'_> {
#[inline(always)]
fn buf(&self) -> &[u8] {
self.buf
}
#[inline(always)]
unsafe fn mut_buf(&mut self) -> &mut [u8] {
self.buf
}
#[inline(always)]
unsafe fn set_len(&mut self, len: usize) {
self.used = len;
}
}
// UTF-8 validated + null terminated buffer on the stack
2023-09-27 15:21:24 -07:00
pub struct Utf8CStrBufArr<const N: usize> {
used: usize,
buf: [u8; N],
}
2023-09-27 15:21:24 -07:00
impl<const N: usize> Utf8CStrBufArr<N> {
pub fn new() -> Self {
2023-09-27 15:21:24 -07:00
Utf8CStrBufArr {
used: 0,
buf: [0; N],
}
}
}
2023-09-27 15:21:24 -07:00
impl<const N: usize> Utf8CStrBuf for Utf8CStrBufArr<N> {
#[inline(always)]
fn buf(&self) -> &[u8] {
&self.buf
}
#[inline(always)]
unsafe fn mut_buf(&mut self) -> &mut [u8] {
&mut self.buf
}
#[inline(always)]
unsafe fn set_len(&mut self, len: usize) {
self.used = len;
}
#[inline(always)]
fn capacity(&self) -> usize {
N
}
}
2023-09-27 15:21:24 -07:00
impl Default for Utf8CStrBufArr<4096> {
fn default() -> Self {
2023-09-27 15:21:24 -07:00
Utf8CStrBufArr::<4096>::new()
}
}
#[derive(Debug, Error)]
pub enum StrErr {
#[error(transparent)]
Utf8Error(#[from] Utf8Error),
#[error(transparent)]
CStrError(#[from] FromBytesWithNulError),
#[error("argument is null")]
NullPointerError,
}
// UTF-8 validated + null terminated string slice
pub struct Utf8CStr([u8]);
impl Utf8CStr {
pub fn from_cstr(cstr: &CStr) -> Result<&Utf8CStr, StrErr> {
// Validate the buffer during construction
str::from_utf8(cstr.to_bytes())?;
Ok(unsafe { Self::from_bytes_unchecked(cstr.to_bytes_with_nul()) })
}
pub fn from_bytes(buf: &[u8]) -> Result<&Utf8CStr, StrErr> {
Self::from_cstr(CStr::from_bytes_with_nul(buf)?)
}
pub fn from_bytes_mut(buf: &mut [u8]) -> Result<&mut Utf8CStr, StrErr> {
CStr::from_bytes_with_nul(buf)?;
str::from_utf8(buf)?;
// Both condition checked
unsafe { Ok(mem::transmute(buf)) }
}
pub fn from_string(s: &mut String) -> &mut Utf8CStr {
let buf = s.nul_terminate();
// SAFETY: the null byte is explicitly added to the buffer
unsafe { mem::transmute(buf) }
}
#[inline(always)]
pub unsafe fn from_bytes_unchecked(buf: &[u8]) -> &Utf8CStr {
mem::transmute(buf)
}
#[inline(always)]
pub unsafe fn from_bytes_unchecked_mut(buf: &mut [u8]) -> &mut Utf8CStr {
mem::transmute(buf)
}
pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> Result<&'a Utf8CStr, StrErr> {
if ptr.is_null() {
return Err(StrErr::NullPointerError);
}
Self::from_cstr(unsafe { CStr::from_ptr(ptr) })
}
#[inline(always)]
pub fn as_bytes_with_nul(&self) -> &[u8] {
&self.0
}
#[inline(always)]
pub fn as_ptr(&self) -> *const c_char {
self.0.as_ptr().cast()
}
#[inline(always)]
pub fn as_mut_ptr(&mut self) -> *mut c_char {
self.0.as_mut_ptr().cast()
}
#[inline(always)]
pub fn as_cstr(&self) -> &CStr {
// SAFETY: Already validated as null terminated during construction
unsafe { CStr::from_bytes_with_nul_unchecked(&self.0) }
}
#[inline(always)]
pub fn as_str(&self) -> &str {
// SAFETY: Already UTF-8 validated during construction
// SAFETY: The length of the slice is at least 1 due to null termination check
unsafe { str::from_utf8_unchecked(self.0.get_unchecked(..self.0.len() - 1)) }
}
#[inline(always)]
pub fn as_str_mut(&mut self) -> &mut str {
// SAFETY: Already UTF-8 validated during construction
// SAFETY: The length of the slice is at least 1 due to null termination check
unsafe { str::from_utf8_unchecked_mut(self.0.get_unchecked_mut(..self.0.len() - 1)) }
}
}
impl Deref for Utf8CStr {
type Target = str;
#[inline(always)]
fn deref(&self) -> &str {
self.as_str()
}
}
impl DerefMut for Utf8CStr {
#[inline(always)]
fn deref_mut(&mut self) -> &mut Self::Target {
self.as_str_mut()
}
}
// File system path extensions types
pub struct FsPath(Utf8CStr);
impl FsPath {
#[inline(always)]
pub fn from<'a, T: AsRef<Utf8CStr>>(value: T) -> &'a FsPath {
unsafe { mem::transmute(value.as_ref()) }
}
#[inline(always)]
pub fn from_mut<'a, T: AsMut<Utf8CStr>>(mut value: T) -> &'a mut FsPath {
unsafe { mem::transmute(value.as_mut()) }
}
}
impl Deref for FsPath {
type Target = Utf8CStr;
#[inline(always)]
fn deref(&self) -> &Utf8CStr {
&self.0
}
}
impl DerefMut for FsPath {
#[inline(always)]
fn deref_mut(&mut self) -> &mut Utf8CStr {
&mut self.0
}
}
2023-09-27 15:21:24 -07:00
pub struct FsPathBuf<'a>(&'a mut dyn Utf8CStrWrite);
impl<'a> FsPathBuf<'a> {
2023-09-27 15:21:24 -07:00
pub fn new(value: &'a mut dyn Utf8CStrWrite) -> Self {
FsPathBuf(value)
}
pub fn join<T: AsRef<str>>(self, path: T) -> Self {
2023-09-27 15:21:24 -07:00
fn inner(buf: &mut dyn Utf8CStrWrite, path: &str) {
if path.starts_with('/') {
buf.clear();
} else {
2023-09-27 15:21:24 -07:00
buf.push_str("/");
}
2023-09-27 15:21:24 -07:00
buf.push_str(path);
}
inner(self.0, path.as_ref());
self
}
pub fn join_fmt<T: Display>(self, name: T) -> Self {
2023-09-27 15:21:24 -07:00
fn inner(buf: &mut dyn Utf8CStrWrite, path: Arguments) {
buf.write_fmt(path).ok();
}
inner(self.0, format_args!("/{}", name));
self
}
}
impl<'a> Deref for FsPathBuf<'a> {
type Target = FsPath;
fn deref(&self) -> &FsPath {
FsPath::from(&self.0)
}
}
impl<'a> DerefMut for FsPathBuf<'a> {
fn deref_mut(&mut self) -> &mut Self::Target {
FsPath::from_mut(&mut self.0)
}
}
// Boilerplate trait implementations
macro_rules! impl_str {
($( ($t:ty, $($g:tt)*) )*) => {$(
impl<$($g)*> AsRef<Utf8CStr> for $t {
#[inline(always)]
fn as_ref(&self) -> &Utf8CStr {
self
}
}
impl<$($g)*> AsRef<str> for $t {
#[inline(always)]
fn as_ref(&self) -> &str {
self.as_str()
}
}
impl<$($g)*> AsRef<CStr> for $t {
#[inline(always)]
fn as_ref(&self) -> &CStr {
self.as_cstr()
}
}
impl<$($g)*> AsRef<OsStr> for $t {
#[inline(always)]
fn as_ref(&self) -> &OsStr {
OsStr::new(self.as_str())
}
}
impl<$($g)*> AsRef<Path> for $t {
#[inline(always)]
fn as_ref(&self) -> &Path {
Path::new(self.as_str())
}
}
impl<$($g)*> Display for $t {
#[inline(always)]
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Display::fmt(self.as_str(), f)
}
}
impl<$($g)*> Debug for $t {
#[inline(always)]
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
Debug::fmt(self.as_str(), f)
}
}
impl<$($g)*> PartialEq<str> for $t {
#[inline(always)]
fn eq(&self, other: &str) -> bool {
self.as_str() == other
}
}
impl<$($g)*> PartialEq<$t> for str {
#[inline(always)]
fn eq(&self, other: &$t) -> bool {
self == other.as_str()
}
}
impl<$($g)*> PartialEq<CStr> for $t {
#[inline(always)]
fn eq(&self, other: &CStr) -> bool {
self.as_cstr() == other
}
}
impl<$($g)*> PartialEq<$t> for CStr {
#[inline(always)]
fn eq(&self, other: &$t) -> bool {
self == other.as_cstr()
}
}
impl<T: AsRef<Utf8CStr>, $($g)*> PartialEq<T> for $t {
#[inline(always)]
fn eq(&self, other: &T) -> bool {
self.as_bytes_with_nul() == other.as_ref().as_bytes_with_nul()
}
}
)*}
}
impl_str!(
(Utf8CStr,)
(FsPath,)
(FsPathBuf<'_>,)
2023-09-27 15:21:24 -07:00
(Utf8CStrBufRef<'_>,)
(Utf8CStrBufArr<N>, const N: usize)
(Utf8CString,)
);
2023-09-27 15:21:24 -07:00
macro_rules! impl_str_write {
($( ($t:ty, $($g:tt)*) )*) => {$(
impl<$($g)*> Write for $t {
#[inline(always)]
fn write_str(&mut self, s: &str) -> fmt::Result {
2023-09-27 15:21:24 -07:00
self.push_str(s);
Ok(())
}
}
impl<$($g)*> Deref for $t {
type Target = Utf8CStr;
#[inline(always)]
fn deref(&self) -> &Utf8CStr {
self.as_utf8_cstr()
}
}
impl<$($g)*> DerefMut for $t {
#[inline(always)]
fn deref_mut(&mut self) -> &mut Utf8CStr {
self.as_utf8_cstr_mut()
}
}
impl<$($g)*> AsMut<Utf8CStr> for $t {
#[inline(always)]
fn as_mut(&mut self) -> &mut Utf8CStr {
self
}
}
)*}
}
2023-09-27 15:21:24 -07:00
impl_str_write!(
(Utf8CStrBufRef<'_>,)
(Utf8CStrBufArr<N>, const N: usize)
(Utf8CString,)
);
macro_rules! impl_str_buf {
($( ($t:ty, $($g:tt)*) )*) => {$(
impl<$($g)*> Utf8CStrWrite for $t {
#[inline(always)]
fn len(&self) -> usize {
self.used
}
#[inline(always)]
fn push_str(&mut self, s: &str) -> usize {
utf8_cstr_buf_append(self, s.as_bytes())
}
#[inline(always)]
fn push_lossy(&mut self, s: &[u8]) -> usize {
utf8_cstr_append_lossy(self, s)
}
#[inline(always)]
fn clear(&mut self) {
unsafe {
self.mut_buf()[0] = b'\0';
self.set_len(0);
}
}
}
)*}
}
impl_str_buf!(
2023-09-27 15:21:24 -07:00
(Utf8CStrBufRef<'_>,)
(Utf8CStrBufArr<N>, const N: usize)
);
// The cstr! macro is copied from https://github.com/bytecodealliance/rustix/blob/main/src/cstr.rs
#[macro_export]
macro_rules! cstr {
($($str:tt)*) => {{
assert!(
!($($str)*).bytes().any(|b| b == b'\0'),
"cstr argument contains embedded NUL bytes",
);
#[allow(unused_unsafe)]
unsafe {
$crate::Utf8CStr::from_bytes_unchecked(concat!($($str)*, "\0").as_bytes())
}
}};
}
#[macro_export]
macro_rules! raw_cstr {
($($str:tt)*) => {{
cstr!($($str)*).as_ptr()
}};
}