476 lines
14 KiB
Rust
476 lines
14 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
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use error::{Error, FromError};
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use fmt;
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use io;
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use iter::IteratorExt;
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use libc;
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use mem;
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use old_io;
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use ops::Deref;
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use option::Option::{self, Some, None};
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use result::Result::{self, Ok, Err};
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use slice::{self, SliceExt};
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use str::StrExt;
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use string::String;
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use vec::Vec;
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/// A type representing an owned C-compatible string
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///
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/// This type serves the primary purpose of being able to safely generate a
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/// C-compatible string from a Rust byte slice or vector. An instance of this
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/// type is a static guarantee that the underlying bytes contain no interior 0
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/// bytes and the final byte is 0.
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///
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/// A `CString` is created from either a byte slice or a byte vector. After
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/// being created, a `CString` predominately inherits all of its methods from
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/// the `Deref` implementation to `[libc::c_char]`. Note that the underlying
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/// array is represented as an array of `libc::c_char` as opposed to `u8`. A
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/// `u8` slice can be obtained with the `as_bytes` method. Slices produced from
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/// a `CString` do *not* contain the trailing nul terminator unless otherwise
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/// specified.
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///
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/// # Example
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///
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/// ```no_run
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/// # extern crate libc;
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/// # fn main() {
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/// use std::ffi::CString;
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/// use libc;
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///
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/// extern {
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/// fn my_printer(s: *const libc::c_char);
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/// }
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///
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/// let to_print = b"Hello, world!";
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/// let c_to_print = CString::new(to_print).unwrap();
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/// unsafe {
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/// my_printer(c_to_print.as_ptr());
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/// }
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/// # }
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/// ```
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#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
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pub struct CString {
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inner: Vec<u8>,
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}
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/// Representation of a borrowed C string.
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///
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/// This dynamically sized type is only safely constructed via a borrowed
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/// version of an instance of `CString`. This type can be constructed from a raw
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/// C string as well and represents a C string borrowed from another location.
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///
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/// Note that this structure is **not** `repr(C)` and is not recommended to be
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/// placed in the signatures of FFI functions. Instead safe wrappers of FFI
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/// functions may leverage the unsafe `from_ptr` constructor to provide a safe
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/// interface to other consumers.
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///
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/// # Examples
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///
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/// Inspecting a foreign C string
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///
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/// ```no_run
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/// extern crate libc;
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/// use std::ffi::CStr;
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///
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/// extern { fn my_string() -> *const libc::c_char; }
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///
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/// fn main() {
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/// unsafe {
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/// let slice = CStr::from_ptr(my_string());
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/// println!("string length: {}", slice.to_bytes().len());
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/// }
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/// }
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/// ```
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///
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/// Passing a Rust-originating C string
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///
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/// ```no_run
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/// extern crate libc;
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/// use std::ffi::{CString, CStr};
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///
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/// fn work(data: &CStr) {
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/// extern { fn work_with(data: *const libc::c_char); }
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///
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/// unsafe { work_with(data.as_ptr()) }
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/// }
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///
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/// fn main() {
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/// let s = CString::new("data data data data").unwrap();
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/// work(&s);
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/// }
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/// ```
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#[derive(Hash)]
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pub struct CStr {
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inner: [libc::c_char]
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}
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/// An error returned from `CString::new` to indicate that a nul byte was found
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/// in the vector provided.
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#[derive(Clone, PartialEq, Debug)]
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pub struct NulError(usize, Vec<u8>);
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/// A conversion trait used by the constructor of `CString` for types that can
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/// be converted to a vector of bytes.
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pub trait IntoBytes {
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/// Consumes this container, returning a vector of bytes.
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fn into_bytes(self) -> Vec<u8>;
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}
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impl CString {
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/// Create a new C-compatible string from a container of bytes.
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///
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/// This method will consume the provided data and use the underlying bytes
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/// to construct a new string, ensuring that there is a trailing 0 byte.
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///
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/// # Examples
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///
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/// ```no_run
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/// extern crate libc;
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/// use std::ffi::CString;
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///
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/// extern { fn puts(s: *const libc::c_char); }
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///
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/// fn main() {
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/// let to_print = CString::new("Hello!").unwrap();
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/// unsafe {
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/// puts(to_print.as_ptr());
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/// }
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/// }
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/// ```
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///
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/// # Errors
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///
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/// This function will return an error if the bytes yielded contain an
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/// internal 0 byte. The error returned will contain the bytes as well as
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/// the position of the nul byte.
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pub fn new<T: IntoBytes>(t: T) -> Result<CString, NulError> {
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let bytes = t.into_bytes();
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match bytes.iter().position(|x| *x == 0) {
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Some(i) => Err(NulError(i, bytes)),
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None => Ok(unsafe { CString::from_vec_unchecked(bytes) }),
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}
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}
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/// Create a new C-compatible string from a byte slice.
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///
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/// This method will copy the data of the slice provided into a new
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/// allocation, ensuring that there is a trailing 0 byte.
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///
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/// # Examples
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///
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/// ```no_run
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/// extern crate libc;
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/// use std::ffi::CString;
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///
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/// extern { fn puts(s: *const libc::c_char); }
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///
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/// fn main() {
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/// let to_print = CString::new("Hello!").unwrap();
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/// unsafe {
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/// puts(to_print.as_ptr());
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/// }
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/// }
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/// ```
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///
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/// # Panics
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///
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/// This function will panic if the provided slice contains any
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/// interior nul bytes.
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#[unstable(feature = "std_misc")]
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#[deprecated(since = "1.0.0", reason = "use CString::new instead")]
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#[allow(deprecated)]
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pub fn from_slice(v: &[u8]) -> CString {
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CString::from_vec(v.to_vec())
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}
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/// Create a C-compatible string from a byte vector.
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///
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/// This method will consume ownership of the provided vector, appending a 0
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/// byte to the end after verifying that there are no interior 0 bytes.
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///
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/// # Panics
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///
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/// This function will panic if the provided slice contains any
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/// interior nul bytes.
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#[unstable(feature = "std_misc")]
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#[deprecated(since = "1.0.0", reason = "use CString::new instead")]
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pub fn from_vec(v: Vec<u8>) -> CString {
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match v.iter().position(|x| *x == 0) {
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Some(i) => panic!("null byte found in slice at: {}", i),
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None => unsafe { CString::from_vec_unchecked(v) },
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}
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}
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/// Create a C-compatible string from a byte vector without checking for
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/// interior 0 bytes.
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///
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/// This method is equivalent to `from_vec` except that no runtime assertion
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/// is made that `v` contains no 0 bytes.
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pub unsafe fn from_vec_unchecked(mut v: Vec<u8>) -> CString {
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v.push(0);
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CString { inner: v }
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}
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/// Returns the contents of this `CString` as a slice of bytes.
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///
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/// The returned slice does **not** contain the trailing nul separator and
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/// it is guaranteed to not have any interior nul bytes.
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pub fn as_bytes(&self) -> &[u8] {
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&self.inner[..self.inner.len() - 1]
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}
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/// Equivalent to the `as_bytes` function except that the returned slice
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/// includes the trailing nul byte.
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pub fn as_bytes_with_nul(&self) -> &[u8] {
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&self.inner
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}
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}
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impl Deref for CString {
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type Target = CStr;
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fn deref(&self) -> &CStr {
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unsafe { mem::transmute(self.as_bytes_with_nul()) }
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl fmt::Debug for CString {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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fmt::Debug::fmt(&String::from_utf8_lossy(self.as_bytes()), f)
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}
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}
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impl NulError {
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/// Returns the position of the nul byte in the slice that was provided to
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/// `CString::from_vec`.
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pub fn nul_position(&self) -> usize { self.0 }
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/// Consumes this error, returning the underlying vector of bytes which
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/// generated the error in the first place.
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pub fn into_vec(self) -> Vec<u8> { self.1 }
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}
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impl Error for NulError {
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fn description(&self) -> &str { "nul byte found in data" }
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}
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impl fmt::Display for NulError {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "nul byte found in provided data at position: {}", self.0)
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}
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}
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impl FromError<NulError> for io::Error {
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fn from_error(_: NulError) -> io::Error {
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io::Error::new(io::ErrorKind::InvalidInput,
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"data provided contains a nul byte", None)
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}
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}
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impl FromError<NulError> for old_io::IoError {
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fn from_error(_: NulError) -> old_io::IoError {
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old_io::IoError {
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kind: old_io::IoErrorKind::InvalidInput,
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desc: "data provided contains a nul byte",
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detail: None
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}
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}
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}
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impl CStr {
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/// Cast a raw C string to a safe C string wrapper.
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///
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/// This function will cast the provided `ptr` to the `CStr` wrapper which
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/// allows inspection and interoperation of non-owned C strings. This method
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/// is unsafe for a number of reasons:
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///
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/// * There is no guarantee to the validity of `ptr`
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/// * The returned lifetime is not guaranteed to be the actual lifetime of
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/// `ptr`
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/// * There is no guarantee that the memory pointed to by `ptr` contains a
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/// valid nul terminator byte at the end of the string.
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///
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/// > **Note**: This operation is intended to be a 0-cost cast but it is
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/// > currently implemented with an up-front calculation of the length of
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/// > the string. This is not guaranteed to always be the case.
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///
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/// # Example
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///
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/// ```no_run
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/// # extern crate libc;
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/// # fn main() {
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/// use std::ffi::CStr;
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/// use std::str;
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/// use libc;
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///
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/// extern {
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/// fn my_string() -> *const libc::c_char;
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/// }
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///
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/// unsafe {
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/// let slice = CStr::from_ptr(my_string());
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/// println!("string returned: {}",
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/// str::from_utf8(slice.to_bytes()).unwrap());
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/// }
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/// # }
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/// ```
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pub unsafe fn from_ptr<'a>(ptr: *const libc::c_char) -> &'a CStr {
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let len = libc::strlen(ptr);
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mem::transmute(slice::from_raw_parts(ptr, len as usize + 1))
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}
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/// Return the inner pointer to this C string.
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///
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/// The returned pointer will be valid for as long as `self` is and points
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/// to a contiguous region of memory terminated with a 0 byte to represent
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/// the end of the string.
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pub fn as_ptr(&self) -> *const libc::c_char {
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self.inner.as_ptr()
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}
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/// Convert this C string to a byte slice.
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///
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/// This function will calculate the length of this string (which normally
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/// requires a linear amount of work to be done) and then return the
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/// resulting slice of `u8` elements.
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///
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/// The returned slice will **not** contain the trailing nul that this C
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/// string has.
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///
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/// > **Note**: This method is currently implemented as a 0-cost cast, but
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/// > it is planned to alter its definition in the future to perform the
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/// > length calculation whenever this method is called.
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pub fn to_bytes(&self) -> &[u8] {
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let bytes = self.to_bytes_with_nul();
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&bytes[..bytes.len() - 1]
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}
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/// Convert this C string to a byte slice containing the trailing 0 byte.
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///
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/// This function is the equivalent of `to_bytes` except that it will retain
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/// the trailing nul instead of chopping it off.
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///
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/// > **Note**: This method is currently implemented as a 0-cost cast, but
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/// > it is planned to alter its definition in the future to perform the
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/// > length calculation whenever this method is called.
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pub fn to_bytes_with_nul(&self) -> &[u8] {
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unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&self.inner) }
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}
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}
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impl PartialEq for CStr {
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fn eq(&self, other: &CStr) -> bool {
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self.to_bytes().eq(other.to_bytes())
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}
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}
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impl Eq for CStr {}
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impl PartialOrd for CStr {
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fn partial_cmp(&self, other: &CStr) -> Option<Ordering> {
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self.to_bytes().partial_cmp(&other.to_bytes())
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}
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}
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impl Ord for CStr {
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fn cmp(&self, other: &CStr) -> Ordering {
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self.to_bytes().cmp(&other.to_bytes())
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}
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}
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/// Deprecated in favor of `CStr`
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#[unstable(feature = "std_misc")]
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#[deprecated(since = "1.0.0", reason = "use CStr::from_ptr(p).to_bytes() instead")]
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pub unsafe fn c_str_to_bytes<'a>(raw: &'a *const libc::c_char) -> &'a [u8] {
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let len = libc::strlen(*raw);
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slice::from_raw_parts(*(raw as *const _ as *const *const u8), len as usize)
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}
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/// Deprecated in favor of `CStr`
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#[unstable(feature = "std_misc")]
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#[deprecated(since = "1.0.0",
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reason = "use CStr::from_ptr(p).to_bytes_with_nul() instead")]
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pub unsafe fn c_str_to_bytes_with_nul<'a>(raw: &'a *const libc::c_char)
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-> &'a [u8] {
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let len = libc::strlen(*raw) + 1;
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slice::from_raw_parts(*(raw as *const _ as *const *const u8), len as usize)
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}
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impl<'a> IntoBytes for &'a str {
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fn into_bytes(self) -> Vec<u8> { self.as_bytes().to_vec() }
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}
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impl<'a> IntoBytes for &'a [u8] {
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fn into_bytes(self) -> Vec<u8> { self.to_vec() }
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}
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impl IntoBytes for String {
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fn into_bytes(self) -> Vec<u8> { self.into_bytes() }
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}
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impl IntoBytes for Vec<u8> {
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fn into_bytes(self) -> Vec<u8> { self }
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}
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#[cfg(test)]
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mod tests {
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use prelude::v1::*;
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use super::*;
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use libc;
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use mem;
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#[test]
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fn c_to_rust() {
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let data = b"123\0";
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let ptr = data.as_ptr() as *const libc::c_char;
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unsafe {
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assert_eq!(c_str_to_bytes(&ptr), b"123");
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assert_eq!(c_str_to_bytes_with_nul(&ptr), b"123\0");
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}
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}
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#[test]
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fn simple() {
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let s = CString::new(b"1234").unwrap();
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assert_eq!(s.as_bytes(), b"1234");
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assert_eq!(s.as_bytes_with_nul(), b"1234\0");
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}
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#[test]
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fn build_with_zero1() {
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assert!(CString::new(b"\0").is_err());
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}
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#[test]
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fn build_with_zero2() {
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assert!(CString::new(vec![0]).is_err());
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}
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#[test]
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fn build_with_zero3() {
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unsafe {
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let s = CString::from_vec_unchecked(vec![0]);
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assert_eq!(s.as_bytes(), b"\0");
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}
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}
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#[test]
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fn formatted() {
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let s = CString::new(b"12").unwrap();
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assert_eq!(format!("{:?}", s), "\"12\"");
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}
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#[test]
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fn borrowed() {
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unsafe {
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let s = CStr::from_ptr(b"12\0".as_ptr() as *const _);
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assert_eq!(s.to_bytes(), b"12");
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assert_eq!(s.to_bytes_with_nul(), b"12\0");
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}
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}
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}
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