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Struct std::ffi::OsString

pub struct OsString { /* fields omitted */ }

A type that can represent owned, mutable platform-native strings, but is cheaply inter-convertible with Rust strings.

The need for this type arises from the fact that:

  • On Unix systems, strings are often arbitrary sequences of non-zero bytes, in many cases interpreted as UTF-8.

  • On Windows, strings are often arbitrary sequences of non-zero 16-bit values, interpreted as UTF-16 when it is valid to do so.

  • In Rust, strings are always valid UTF-8, which may contain zeros.

OsString and OsStr bridge this gap by simultaneously representing Rust and platform-native string values, and in particular allowing a Rust string to be converted into an "OS" string with no cost if possible. A consequence of this is that OsString instances are not NUL terminated; in order to pass to e.g., Unix system call, you should create a CStr.

OsString is to &OsStr as String is to &str: the former in each pair are owned strings; the latter are borrowed references.

Note, OsString and OsStr internally do not necessarily hold strings in the form native to the platform; While on Unix, strings are stored as a sequence of 8-bit values, on Windows, where strings are 16-bit value based as just discussed, strings are also actually stored as a sequence of 8-bit values, encoded in a less-strict variant of UTF-8. This is useful to understand when handling capacity and length values.

Creating an OsString

From a Rust string: OsString implements From<String>, so you can use my_string.from to create an OsString from a normal Rust string.

From slices: Just like you can start with an empty Rust String and then String::push_str &str sub-string slices into it, you can create an empty OsString with the OsString::new method and then push string slices into it with the OsString::push method.

Extracting a borrowed reference to the whole OS string

You can use the OsString::as_os_str method to get an &OsStr from an OsString; this is effectively a borrowed reference to the whole string.

Conversions

See the module's toplevel documentation about conversions for a discussion on the traits which OsString implements for conversions from/to native representations.

Implementations

impl OsString[src]

pub fn new() -> OsString[src]

Constructs a new empty OsString.

Examples

use std::ffi::OsString;

let os_string = OsString::new();

pub fn as_os_str(&self) -> &OsStr[src]

Converts to an OsStr slice.

Examples

use std::ffi::{OsString, OsStr};

let os_string = OsString::from("foo");
let os_str = OsStr::new("foo");
assert_eq!(os_string.as_os_str(), os_str);

pub fn into_string(self) -> Result<String, OsString>[src]

Converts the OsString into a String if it contains valid Unicode data.

On failure, ownership of the original OsString is returned.

Examples

use std::ffi::OsString;

let os_string = OsString::from("foo");
let string = os_string.into_string();
assert_eq!(string, Ok(String::from("foo")));

pub fn push<T: AsRef<OsStr>>(&mut self, s: T)[src]

Extends the string with the given &OsStr slice.

Examples

use std::ffi::OsString;

let mut os_string = OsString::from("foo");
os_string.push("bar");
assert_eq!(&os_string, "foobar");

pub fn with_capacity(capacity: usize) -> OsString[src]1.9.0

Creates a new OsString with the given capacity.

The string will be able to hold exactly capacity length units of other OS strings without reallocating. If capacity is 0, the string will not allocate.

See main OsString documentation information about encoding.

Examples

use std::ffi::OsString;

let mut os_string = OsString::with_capacity(10);
let capacity = os_string.capacity();

// This push is done without reallocating
os_string.push("foo");

assert_eq!(capacity, os_string.capacity());

pub fn clear(&mut self)[src]1.9.0

Truncates the OsString to zero length.

Examples

use std::ffi::OsString;

let mut os_string = OsString::from("foo");
assert_eq!(&os_string, "foo");

os_string.clear();
assert_eq!(&os_string, "");

pub fn capacity(&self) -> usize[src]1.9.0

Returns the capacity this OsString can hold without reallocating.

See OsString introduction for information about encoding.

Examples

use std::ffi::OsString;

let os_string = OsString::with_capacity(10);
assert!(os_string.capacity() >= 10);

pub fn reserve(&mut self, additional: usize)[src]1.9.0

Reserves capacity for at least additional more capacity to be inserted in the given OsString.

The collection may reserve more space to avoid frequent reallocations.

Examples

use std::ffi::OsString;

let mut s = OsString::new();
s.reserve(10);
assert!(s.capacity() >= 10);

pub fn reserve_exact(&mut self, additional: usize)[src]1.9.0

Reserves the minimum capacity for exactly additional more capacity to be inserted in the given OsString. Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore, capacity can not be relied upon to be precisely minimal. Prefer reserve if future insertions are expected.

Examples

use std::ffi::OsString;

let mut s = OsString::new();
s.reserve_exact(10);
assert!(s.capacity() >= 10);

pub fn shrink_to_fit(&mut self)[src]1.19.0

Shrinks the capacity of the OsString to match its length.

Examples

use std::ffi::OsString;

let mut s = OsString::from("foo");

s.reserve(100);
assert!(s.capacity() >= 100);

s.shrink_to_fit();
assert_eq!(3, s.capacity());

pub fn shrink_to(&mut self, min_capacity: usize)[src]

🔬 This is a nightly-only experimental API. (shrink_to #56431)new API

Shrinks the capacity of the OsString with a lower bound.

The capacity will remain at least as large as both the length and the supplied value.

Panics if the current capacity is smaller than the supplied minimum capacity.

Examples

#![feature(shrink_to)]
use std::ffi::OsString;

let mut s = OsString::from("foo");

s.reserve(100);
assert!(s.capacity() >= 100);

s.shrink_to(10);
assert!(s.capacity() >= 10);
s.shrink_to(0);
assert!(s.capacity() >= 3);

pub fn into_boxed_os_str(self) -> Box<OsStr>ⓘ

Notable traits for Box<F>

impl<F> Future for Box<F> where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]1.20.0

Converts this OsString into a boxed OsStr.

Examples

use std::ffi::{OsString, OsStr};

let s = OsString::from("hello");

let b: Box<OsStr> = s.into_boxed_os_str();

Methods from Deref<Target = OsStr>

pub fn to_str(&self) -> Option<&str>[src]

Yields a &str slice if the OsStr is valid Unicode.

This conversion may entail doing a check for UTF-8 validity.

Examples

use std::ffi::OsStr;

let os_str = OsStr::new("foo");
assert_eq!(os_str.to_str(), Some("foo"));

pub fn to_string_lossy(&self) -> Cow<'_, str>[src]

Converts an OsStr to a Cow<str>.

Any non-Unicode sequences are replaced with U+FFFD REPLACEMENT CHARACTER.

Examples

Calling to_string_lossy on an OsStr with invalid unicode:

// Note, due to differences in how Unix and Windows represent strings,
// we are forced to complicate this example, setting up example `OsStr`s
// with different source data and via different platform extensions.
// Understand that in reality you could end up with such example invalid
// sequences simply through collecting user command line arguments, for
// example.

#[cfg(any(unix, target_os = "redox"))] {
    use std::ffi::OsStr;
    use std::os::unix::ffi::OsStrExt;

    // Here, the values 0x66 and 0x6f correspond to 'f' and 'o'
    // respectively. The value 0x80 is a lone continuation byte, invalid
    // in a UTF-8 sequence.
    let source = [0x66, 0x6f, 0x80, 0x6f];
    let os_str = OsStr::from_bytes(&source[..]);

    assert_eq!(os_str.to_string_lossy(), "fo�o");
}
#[cfg(windows)] {
    use std::ffi::OsString;
    use std::os::windows::prelude::*;

    // Here the values 0x0066 and 0x006f correspond to 'f' and 'o'
    // respectively. The value 0xD800 is a lone surrogate half, invalid
    // in a UTF-16 sequence.
    let source = [0x0066, 0x006f, 0xD800, 0x006f];
    let os_string = OsString::from_wide(&source[..]);
    let os_str = os_string.as_os_str();

    assert_eq!(os_str.to_string_lossy(), "fo�o");
}

pub fn to_os_string(&self) -> OsString[src]

Copies the slice into an owned OsString.

Examples

use std::ffi::{OsStr, OsString};

let os_str = OsStr::new("foo");
let os_string = os_str.to_os_string();
assert_eq!(os_string, OsString::from("foo"));

pub fn is_empty(&self) -> bool[src]1.9.0

Checks whether the OsStr is empty.

Examples

use std::ffi::OsStr;

let os_str = OsStr::new("");
assert!(os_str.is_empty());

let os_str = OsStr::new("foo");
assert!(!os_str.is_empty());

pub fn len(&self) -> usize[src]1.9.0

Returns the length of this OsStr.

Note that this does not return the number of bytes in the string in OS string form.

The length returned is that of the underlying storage used by OsStr. As discussed in the OsString introduction, OsString and OsStr store strings in a form best suited for cheap inter-conversion between native-platform and Rust string forms, which may differ significantly from both of them, including in storage size and encoding.

This number is simply useful for passing to other methods, like OsString::with_capacity to avoid reallocations.

Examples

use std::ffi::OsStr;

let os_str = OsStr::new("");
assert_eq!(os_str.len(), 0);

let os_str = OsStr::new("foo");
assert_eq!(os_str.len(), 3);

pub fn make_ascii_lowercase(&mut self)[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Converts this string to its ASCII lower case equivalent in-place.

ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use OsStr::to_ascii_lowercase.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;

let mut s = OsString::from("GRÜßE, JÜRGEN ❤");

s.make_ascii_lowercase();

assert_eq!("grÜße, jÜrgen ❤", s);

pub fn make_ascii_uppercase(&mut self)[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Converts this string to its ASCII upper case equivalent in-place.

ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use OsStr::to_ascii_uppercase.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;

let mut s = OsString::from("Grüße, Jürgen ❤");

s.make_ascii_uppercase();

assert_eq!("GRüßE, JüRGEN ❤", s);

pub fn to_ascii_lowercase(&self) -> OsString[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.

ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.

To lowercase the value in-place, use OsStr::make_ascii_lowercase.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;
let s = OsString::from("Grüße, Jürgen ❤");

assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());

pub fn to_ascii_uppercase(&self) -> OsString[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.

ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.

To uppercase the value in-place, use OsStr::make_ascii_uppercase.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;
let s = OsString::from("Grüße, Jürgen ❤");

assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());

pub fn is_ascii(&self) -> bool[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Checks if all characters in this string are within the ASCII range.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;

let ascii = OsString::from("hello!\n");
let non_ascii = OsString::from("Grüße, Jürgen ❤");

assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());

pub fn eq_ignore_ascii_case<S: ?Sized + AsRef<OsStr>>(&self, other: &S) -> bool[src]

🔬 This is a nightly-only experimental API. (osstring_ascii #70516)

Checks that two strings are an ASCII case-insensitive match.

Same as to_ascii_lowercase(a) == to_ascii_lowercase(b), but without allocating and copying temporaries.

Examples

#![feature(osstring_ascii)]
use std::ffi::OsString;

assert!(OsString::from("Ferris").eq_ignore_ascii_case("FERRIS"));
assert!(OsString::from("Ferrös").eq_ignore_ascii_case("FERRöS"));
assert!(!OsString::from("Ferrös").eq_ignore_ascii_case("FERRÖS"));

Trait Implementations

impl AsRef<OsStr> for OsString[src]

impl AsRef<Path> for OsString[src]

impl Borrow<OsStr> for OsString[src]

impl Clone for OsString[src]

impl Debug for OsString[src]

impl Default for OsString[src]1.9.0

fn default() -> OsString[src]

Constructs an empty OsString.

impl Deref for OsString[src]

type Target = OsStr

The resulting type after dereferencing.

impl DerefMut for OsString[src]1.44.0

impl Eq for OsString[src]

impl<T: ?Sized + AsRef<OsStr>, '_> From<&'_ T> for OsString[src]

impl<'a> From<&'a OsString> for Cow<'a, OsStr>[src]1.28.0

impl From<Box<OsStr>> for OsString[src]1.18.0

fn from(boxed: Box<OsStr>) -> OsString[src]

Converts a Box<OsStr> into a OsString without copying or allocating.

impl<'a> From<Cow<'a, OsStr>> for OsString[src]1.28.0

impl From<OsString> for Box<OsStr>[src]1.20.0

fn from(s: OsString) -> Box<OsStr>ⓘ

Notable traits for Box<F>

impl<F> Future for Box<F> where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]

Converts a OsString into a Box<OsStr> without copying or allocating.

impl From<OsString> for Arc<OsStr>[src]1.24.0

fn from(s: OsString) -> Arc<OsStr>[src]

Converts a OsString into a Arc<OsStr> without copying or allocating.

impl From<OsString> for Rc<OsStr>[src]1.24.0

fn from(s: OsString) -> Rc<OsStr>[src]

Converts a OsString into a Rc<OsStr> without copying or allocating.

impl<'a> From<OsString> for Cow<'a, OsStr>[src]1.28.0

impl From<OsString> for PathBuf[src]

fn from(s: OsString) -> PathBuf[src]

Converts a OsString into a PathBuf

This conversion does not allocate or copy memory.

impl From<PathBuf> for OsString[src]1.14.0

fn from(path_buf: PathBuf) -> OsString[src]

Converts a PathBuf into a OsString

This conversion does not allocate or copy memory.

impl From<String> for OsString[src]

fn from(s: String) -> OsString[src]

Converts a String into a OsString.

The conversion copies the data, and includes an allocation on the heap.

impl FromStr for OsString[src]1.45.0

type Err = Infallible

The associated error which can be returned from parsing.

impl Hash for OsString[src]

impl Index<RangeFull> for OsString[src]

type Output = OsStr

The returned type after indexing.

impl IndexMut<RangeFull> for OsString[src]1.44.0

impl Ord for OsString[src]

impl OsStringExt for OsString[src]

impl OsStringExt for OsString[src]

impl<'_> PartialEq<&'_ str> for OsString[src]1.29.0

impl<'a, 'b> PartialEq<&'a OsStr> for OsString[src]1.8.0

impl<'a, 'b> PartialEq<&'a Path> for OsString[src]1.8.0

impl<'a, 'b> PartialEq<Cow<'a, OsStr>> for OsString[src]1.8.0

impl<'a, 'b> PartialEq<Cow<'a, Path>> for OsString[src]1.8.0

impl<'a, 'b> PartialEq<OsStr> for OsString[src]1.8.0

impl PartialEq<OsString> for OsString[src]

impl PartialEq<OsString> for str[src]

impl<'a> PartialEq<OsString> for &'a str[src]1.29.0

impl<'a, 'b> PartialEq<OsString> for OsStr[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for &'a OsStr[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for Cow<'a, OsStr>[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for PathBuf[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for Path[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for &'a Path[src]1.8.0

impl<'a, 'b> PartialEq<OsString> for Cow<'a, Path>[src]1.8.0

impl<'a, 'b> PartialEq<Path> for OsString[src]1.8.0

impl<'a, 'b> PartialEq<PathBuf> for OsString[src]1.8.0

impl PartialEq<str> for OsString[src]

impl<'a, 'b> PartialOrd<&'a OsStr> for OsString[src]1.8.0

impl<'a, 'b> PartialOrd<&'a Path> for OsString[src]1.8.0

impl<'a, 'b> PartialOrd<Cow<'a, OsStr>> for OsString[src]1.8.0

impl<'a, 'b> PartialOrd<Cow<'a, Path>> for OsString[src]1.8.0

impl<'a, 'b> PartialOrd<OsStr> for OsString[src]1.8.0

impl PartialOrd<OsString> for OsString[src]

impl<'a, 'b> PartialOrd<OsString> for OsStr[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for &'a OsStr[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for Cow<'a, OsStr>[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for PathBuf[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for Path[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for &'a Path[src]1.8.0

impl<'a, 'b> PartialOrd<OsString> for Cow<'a, Path>[src]1.8.0

impl<'a, 'b> PartialOrd<Path> for OsString[src]1.8.0

impl<'a, 'b> PartialOrd<PathBuf> for OsString[src]1.8.0

impl PartialOrd<str> for OsString[src]

Auto Trait Implementations

impl RefUnwindSafe for OsString

impl Send for OsString

impl Sync for OsString

impl Unpin for OsString

impl UnwindSafe for OsString

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized, [src]

impl<T> Borrow<T> for T where
    T: ?Sized, [src]

impl<T> BorrowMut<T> for T where
    T: ?Sized, [src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, [src]

impl<T> ToOwned for T where
    T: Clone, [src]

type Owned = T

The resulting type after obtaining ownership.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, [src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, [src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/ffi/struct.OsString.html