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//! Inspection and manipulation of the process's environment.
//!
//! This module contains functions to inspect various aspects such as
//! environment variables, process arguments, the current directory, and various
//! other important directories.
//!
//! There are several functions and structs in this module that have a
//! counterpart ending in `os`. Those ending in `os` will return an [`OsString`]
//! and those without will return a [`String`].
#![stable(feature = "env", since = "1.0.0")]
#[cfg(test)]
mod tests;
use crate::error::Error;
use crate::ffi::{OsStr, OsString};
use crate::fmt;
use crate::io;
use crate::path::{Path, PathBuf};
use crate::sys;
use crate::sys::os as os_imp;
/// Returns the current working directory as a [`PathBuf`].
///
/// # Platform-specific behavior
///
/// This function [currently] corresponds to the `getcwd` function on Unix
/// and the `GetCurrentDirectoryW` function on Windows.
///
/// [currently]: crate::io#platform-specific-behavior
///
/// # Errors
///
/// Returns an [`Err`] if the current working directory value is invalid.
/// Possible cases:
///
/// * Current directory does not exist.
/// * There are insufficient permissions to access the current directory.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// fn main() -> std::io::Result<()> {
/// let path = env::current_dir()?;
/// println!("The current directory is {}", path.display());
/// Ok(())
/// }
/// ```
#[doc(alias = "pwd")]
#[doc(alias = "getcwd")]
#[doc(alias = "GetCurrentDirectory")]
#[stable(feature = "env", since = "1.0.0")]
pub fn current_dir() -> io::Result<PathBuf> {
os_imp::getcwd()
}
/// Changes the current working directory to the specified path.
///
/// # Platform-specific behavior
///
/// This function [currently] corresponds to the `chdir` function on Unix
/// and the `SetCurrentDirectoryW` function on Windows.
///
/// Returns an [`Err`] if the operation fails.
///
/// [currently]: crate::io#platform-specific-behavior
///
/// # Examples
///
/// ```
/// use std::env;
/// use std::path::Path;
///
/// let root = Path::new("/");
/// assert!(env::set_current_dir(&root).is_ok());
/// println!("Successfully changed working directory to {}!", root.display());
/// ```
#[doc(alias = "chdir")]
#[stable(feature = "env", since = "1.0.0")]
pub fn set_current_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
os_imp::chdir(path.as_ref())
}
/// An iterator over a snapshot of the environment variables of this process.
///
/// This structure is created by [`env::vars()`]. See its documentation for more.
///
/// [`env::vars()`]: vars
#[stable(feature = "env", since = "1.0.0")]
pub struct Vars {
inner: VarsOs,
}
/// An iterator over a snapshot of the environment variables of this process.
///
/// This structure is created by [`env::vars_os()`]. See its documentation for more.
///
/// [`env::vars_os()`]: vars_os
#[stable(feature = "env", since = "1.0.0")]
pub struct VarsOs {
inner: os_imp::Env,
}
/// Returns an iterator of (variable, value) pairs of strings, for all the
/// environment variables of the current process.
///
/// The returned iterator contains a snapshot of the process's environment
/// variables at the time of this invocation. Modifications to environment
/// variables afterwards will not be reflected in the returned iterator.
///
/// # Panics
///
/// While iterating, the returned iterator will panic if any key or value in the
/// environment is not valid unicode. If this is not desired, consider using
/// [`env::vars_os()`].
///
/// # Examples
///
/// ```
/// use std::env;
///
/// // We will iterate through the references to the element returned by
/// // env::vars();
/// for (key, value) in env::vars() {
/// println!("{key}: {value}");
/// }
/// ```
///
/// [`env::vars_os()`]: vars_os
#[must_use]
#[stable(feature = "env", since = "1.0.0")]
pub fn vars() -> Vars {
Vars { inner: vars_os() }
}
/// Returns an iterator of (variable, value) pairs of OS strings, for all the
/// environment variables of the current process.
///
/// The returned iterator contains a snapshot of the process's environment
/// variables at the time of this invocation. Modifications to environment
/// variables afterwards will not be reflected in the returned iterator.
///
/// Note that the returned iterator will not check if the environment variables
/// are valid Unicode. If you want to panic on invalid UTF-8,
/// use the [`vars`] function instead.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// // We will iterate through the references to the element returned by
/// // env::vars_os();
/// for (key, value) in env::vars_os() {
/// println!("{key:?}: {value:?}");
/// }
/// ```
#[must_use]
#[stable(feature = "env", since = "1.0.0")]
pub fn vars_os() -> VarsOs {
VarsOs { inner: os_imp::env() }
}
#[stable(feature = "env", since = "1.0.0")]
impl Iterator for Vars {
type Item = (String, String);
fn next(&mut self) -> Option<(String, String)> {
self.inner.next().map(|(a, b)| (a.into_string().unwrap(), b.into_string().unwrap()))
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for Vars {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self { inner: VarsOs { inner } } = self;
f.debug_struct("Vars").field("inner", &inner.str_debug()).finish()
}
}
#[stable(feature = "env", since = "1.0.0")]
impl Iterator for VarsOs {
type Item = (OsString, OsString);
fn next(&mut self) -> Option<(OsString, OsString)> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for VarsOs {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self { inner } = self;
f.debug_struct("VarsOs").field("inner", inner).finish()
}
}
/// Fetches the environment variable `key` from the current process.
///
/// # Errors
///
/// This function will return an error if the environment variable isn't set.
///
/// This function may return an error if the environment variable's name contains
/// the equal sign character (`=`) or the NUL character.
///
/// This function will return an error if the environment variable's value is
/// not valid Unicode. If this is not desired, consider using [`var_os`].
///
/// # Examples
///
/// ```
/// use std::env;
///
/// let key = "HOME";
/// match env::var(key) {
/// Ok(val) => println!("{key}: {val:?}"),
/// Err(e) => println!("couldn't interpret {key}: {e}"),
/// }
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError> {
_var(key.as_ref())
}
fn _var(key: &OsStr) -> Result<String, VarError> {
match var_os(key) {
Some(s) => s.into_string().map_err(VarError::NotUnicode),
None => Err(VarError::NotPresent),
}
}
/// Fetches the environment variable `key` from the current process, returning
/// [`None`] if the variable isn't set or if there is another error.
///
/// It may return `None` if the environment variable's name contains
/// the equal sign character (`=`) or the NUL character.
///
/// Note that this function will not check if the environment variable
/// is valid Unicode. If you want to have an error on invalid UTF-8,
/// use the [`var`] function instead.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// let key = "HOME";
/// match env::var_os(key) {
/// Some(val) => println!("{key}: {val:?}"),
/// None => println!("{key} is not defined in the environment.")
/// }
/// ```
#[must_use]
#[stable(feature = "env", since = "1.0.0")]
pub fn var_os<K: AsRef<OsStr>>(key: K) -> Option<OsString> {
_var_os(key.as_ref())
}
fn _var_os(key: &OsStr) -> Option<OsString> {
os_imp::getenv(key)
}
/// The error type for operations interacting with environment variables.
/// Possibly returned from [`env::var()`].
///
/// [`env::var()`]: var
#[derive(Debug, PartialEq, Eq, Clone)]
#[stable(feature = "env", since = "1.0.0")]
pub enum VarError {
/// The specified environment variable was not present in the current
/// process's environment.
#[stable(feature = "env", since = "1.0.0")]
NotPresent,
/// The specified environment variable was found, but it did not contain
/// valid unicode data. The found data is returned as a payload of this
/// variant.
#[stable(feature = "env", since = "1.0.0")]
NotUnicode(#[stable(feature = "env", since = "1.0.0")] OsString),
}
#[stable(feature = "env", since = "1.0.0")]
impl fmt::Display for VarError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
VarError::NotPresent => write!(f, "environment variable not found"),
VarError::NotUnicode(ref s) => {
write!(f, "environment variable was not valid unicode: {:?}", s)
}
}
}
}
#[stable(feature = "env", since = "1.0.0")]
impl Error for VarError {
#[allow(deprecated)]
fn description(&self) -> &str {
match *self {
VarError::NotPresent => "environment variable not found",
VarError::NotUnicode(..) => "environment variable was not valid unicode",
}
}
}
/// Sets the environment variable `key` to the value `value` for the currently running
/// process.
///
/// # Safety
///
/// Even though this function is currently not marked as `unsafe`, it needs to
/// be because invoking it can cause undefined behaviour. The function will be
/// marked `unsafe` in a future version of Rust. This is tracked in
/// [rust#27970](https://github.com/rust-lang/rust/issues/27970).
///
/// This function is safe to call in a single-threaded program.
///
/// In multi-threaded programs, you must ensure that are no other threads
/// concurrently writing or *reading*(!) from the environment through functions
/// other than the ones in this module. You are responsible for figuring out
/// how to achieve this, but we strongly suggest not using `set_var` or
/// `remove_var` in multi-threaded programs at all.
///
/// Most C libraries, including libc itself do not advertise which functions
/// read from the environment. Even functions from the Rust standard library do
/// that, e.g. for DNS lookups from [`std::net::ToSocketAddrs`].
///
/// Discussion of this unsafety on Unix may be found in:
///
/// - [Austin Group Bugzilla](https://austingroupbugs.net/view.php?id=188)
/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
///
/// [`std::net::ToSocketAddrs`]: crate::net::ToSocketAddrs
///
/// # Panics
///
/// This function may panic if `key` is empty, contains an ASCII equals sign `'='`
/// or the NUL character `'\0'`, or when `value` contains the NUL character.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// let key = "KEY";
/// env::set_var(key, "VALUE");
/// assert_eq!(env::var(key), Ok("VALUE".to_string()));
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>(key: K, value: V) {
_set_var(key.as_ref(), value.as_ref())
}
fn _set_var(key: &OsStr, value: &OsStr) {
os_imp::setenv(key, value).unwrap_or_else(|e| {
panic!("failed to set environment variable `{key:?}` to `{value:?}`: {e}")
})
}
/// Removes an environment variable from the environment of the currently running process.
///
/// # Safety
///
/// Even though this function is currently not marked as `unsafe`, it needs to
/// be because invoking it can cause undefined behaviour. The function will be
/// marked `unsafe` in a future version of Rust. This is tracked in
/// [rust#27970](https://github.com/rust-lang/rust/issues/27970).
///
/// This function is safe to call in a single-threaded program.
///
/// In multi-threaded programs, you must ensure that are no other threads
/// concurrently writing or *reading*(!) from the environment through functions
/// other than the ones in this module. You are responsible for figuring out
/// how to achieve this, but we strongly suggest not using `set_var` or
/// `remove_var` in multi-threaded programs at all.
///
/// Most C libraries, including libc itself do not advertise which functions
/// read from the environment. Even functions from the Rust standard library do
/// that, e.g. for DNS lookups from [`std::net::ToSocketAddrs`].
///
/// Discussion of this unsafety on Unix may be found in:
///
/// - [Austin Group Bugzilla](https://austingroupbugs.net/view.php?id=188)
/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
///
/// [`std::net::ToSocketAddrs`]: crate::net::ToSocketAddrs
///
/// # Panics
///
/// This function may panic if `key` is empty, contains an ASCII equals sign
/// `'='` or the NUL character `'\0'`, or when the value contains the NUL
/// character.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// let key = "KEY";
/// env::set_var(key, "VALUE");
/// assert_eq!(env::var(key), Ok("VALUE".to_string()));
///
/// env::remove_var(key);
/// assert!(env::var(key).is_err());
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn remove_var<K: AsRef<OsStr>>(key: K) {
_remove_var(key.as_ref())
}
fn _remove_var(key: &OsStr) {
os_imp::unsetenv(key)
.unwrap_or_else(|e| panic!("failed to remove environment variable `{key:?}`: {e}"))
}
/// An iterator that splits an environment variable into paths according to
/// platform-specific conventions.
///
/// The iterator element type is [`PathBuf`].
///
/// This structure is created by [`env::split_paths()`]. See its
/// documentation for more.
///
/// [`env::split_paths()`]: split_paths
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "env", since = "1.0.0")]
pub struct SplitPaths<'a> {
inner: os_imp::SplitPaths<'a>,
}
/// Parses input according to platform conventions for the `PATH`
/// environment variable.
///
/// Returns an iterator over the paths contained in `unparsed`. The iterator
/// element type is [`PathBuf`].
///
/// # Examples
///
/// ```
/// use std::env;
///
/// let key = "PATH";
/// match env::var_os(key) {
/// Some(paths) => {
/// for path in env::split_paths(&paths) {
/// println!("'{}'", path.display());
/// }
/// }
/// None => println!("{key} is not defined in the environment.")
/// }
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn split_paths<T: AsRef<OsStr> + ?Sized>(unparsed: &T) -> SplitPaths<'_> {
SplitPaths { inner: os_imp::split_paths(unparsed.as_ref()) }
}
#[stable(feature = "env", since = "1.0.0")]
impl<'a> Iterator for SplitPaths<'a> {
type Item = PathBuf;
fn next(&mut self) -> Option<PathBuf> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for SplitPaths<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SplitPaths").finish_non_exhaustive()
}
}
/// The error type for operations on the `PATH` variable. Possibly returned from
/// [`env::join_paths()`].
///
/// [`env::join_paths()`]: join_paths
#[derive(Debug)]
#[stable(feature = "env", since = "1.0.0")]
pub struct JoinPathsError {
inner: os_imp::JoinPathsError,
}
/// Joins a collection of [`Path`]s appropriately for the `PATH`
/// environment variable.
///
/// # Errors
///
/// Returns an [`Err`] (containing an error message) if one of the input
/// [`Path`]s contains an invalid character for constructing the `PATH`
/// variable (a double quote on Windows or a colon on Unix).
///
/// # Examples
///
/// Joining paths on a Unix-like platform:
///
/// ```
/// use std::env;
/// use std::ffi::OsString;
/// use std::path::Path;
///
/// fn main() -> Result<(), env::JoinPathsError> {
/// # if cfg!(unix) {
/// let paths = [Path::new("/bin"), Path::new("/usr/bin")];
/// let path_os_string = env::join_paths(paths.iter())?;
/// assert_eq!(path_os_string, OsString::from("/bin:/usr/bin"));
/// # }
/// Ok(())
/// }
/// ```
///
/// Joining a path containing a colon on a Unix-like platform results in an
/// error:
///
/// ```
/// # if cfg!(unix) {
/// use std::env;
/// use std::path::Path;
///
/// let paths = [Path::new("/bin"), Path::new("/usr/bi:n")];
/// assert!(env::join_paths(paths.iter()).is_err());
/// # }
/// ```
///
/// Using `env::join_paths()` with [`env::split_paths()`] to append an item to
/// the `PATH` environment variable:
///
/// ```
/// use std::env;
/// use std::path::PathBuf;
///
/// fn main() -> Result<(), env::JoinPathsError> {
/// if let Some(path) = env::var_os("PATH") {
/// let mut paths = env::split_paths(&path).collect::<Vec<_>>();
/// paths.push(PathBuf::from("/home/xyz/bin"));
/// let new_path = env::join_paths(paths)?;
/// env::set_var("PATH", &new_path);
/// }
///
/// Ok(())
/// }
/// ```
///
/// [`env::split_paths()`]: split_paths
#[stable(feature = "env", since = "1.0.0")]
pub fn join_paths<I, T>(paths: I) -> Result<OsString, JoinPathsError>
where
I: IntoIterator<Item = T>,
T: AsRef<OsStr>,
{
os_imp::join_paths(paths.into_iter()).map_err(|e| JoinPathsError { inner: e })
}
#[stable(feature = "env", since = "1.0.0")]
impl fmt::Display for JoinPathsError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.inner.fmt(f)
}
}
#[stable(feature = "env", since = "1.0.0")]
impl Error for JoinPathsError {
#[allow(deprecated, deprecated_in_future)]
fn description(&self) -> &str {
self.inner.description()
}
}
/// Returns the path of the current user's home directory if known.
///
/// # Unix
///
/// - Returns the value of the 'HOME' environment variable if it is set
/// (including to an empty string).
/// - Otherwise, it tries to determine the home directory by invoking the `getpwuid_r` function
/// using the UID of the current user. An empty home directory field returned from the
/// `getpwuid_r` function is considered to be a valid value.
/// - Returns `None` if the current user has no entry in the /etc/passwd file.
///
/// # Windows
///
/// - Returns the value of the 'HOME' environment variable if it is set
/// (including to an empty string).
/// - Otherwise, returns the value of the 'USERPROFILE' environment variable if it is set
/// (including to an empty string).
/// - If both do not exist, [`GetUserProfileDirectory`][msdn] is used to return the path.
///
/// [msdn]: https://docs.microsoft.com/en-us/windows/win32/api/userenv/nf-userenv-getuserprofiledirectorya
///
/// # Deprecation
///
/// This function is deprecated because the behaviour on Windows is not correct.
/// The 'HOME' environment variable is not standard on Windows, and may not produce
/// desired results; for instance, under Cygwin or Mingw it will return `/home/you`
/// when it should return `C:\Users\you`.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// match env::home_dir() {
/// Some(path) => println!("Your home directory, probably: {}", path.display()),
/// None => println!("Impossible to get your home dir!"),
/// }
/// ```
#[deprecated(
since = "1.29.0",
note = "This function's behavior may be unexpected on Windows. \
Consider using a crate from crates.io instead."
)]
#[must_use]
#[stable(feature = "env", since = "1.0.0")]
pub fn home_dir() -> Option<PathBuf> {
os_imp::home_dir()
}
/// Returns the path of a temporary directory.
///
/// The temporary directory may be shared among users, or between processes
/// with different privileges; thus, the creation of any files or directories
/// in the temporary directory must use a secure method to create a uniquely
/// named file. Creating a file or directory with a fixed or predictable name
/// may result in "insecure temporary file" security vulnerabilities. Consider
/// using a crate that securely creates temporary files or directories.
///
/// # Platform-specific behavior
///
/// On Unix, returns the value of the `TMPDIR` environment variable if it is
/// set, otherwise for non-Android it returns `/tmp`. On Android, since there
/// is no global temporary folder (it is usually allocated per-app), it returns
/// `/data/local/tmp`.
/// On Windows, the behavior is equivalent to that of [`GetTempPath2`][GetTempPath2] /
/// [`GetTempPath`][GetTempPath], which this function uses internally.
/// Note that, this [may change in the future][changes].
///
/// [changes]: io#platform-specific-behavior
/// [GetTempPath2]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppath2a
/// [GetTempPath]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppatha
///
/// ```no_run
/// use std::env;
///
/// fn main() {
/// let dir = env::temp_dir();
/// println!("Temporary directory: {}", dir.display());
/// }
/// ```
#[must_use]
#[stable(feature = "env", since = "1.0.0")]
pub fn temp_dir() -> PathBuf {
os_imp::temp_dir()
}
/// Returns the full filesystem path of the current running executable.
///
/// # Platform-specific behavior
///
/// If the executable was invoked through a symbolic link, some platforms will
/// return the path of the symbolic link and other platforms will return the
/// path of the symbolic link’s target.
///
/// If the executable is renamed while it is running, platforms may return the
/// path at the time it was loaded instead of the new path.
///
/// # Errors
///
/// Acquiring the path of the current executable is a platform-specific operation
/// that can fail for a good number of reasons. Some errors can include, but not
/// be limited to, filesystem operations failing or general syscall failures.
///
/// # Security
///
/// The output of this function should not be trusted for anything
/// that might have security implications. Basically, if users can run
/// the executable, they can change the output arbitrarily.
///
/// As an example, you can easily introduce a race condition. It goes
/// like this:
///
/// 1. You get the path to the current executable using `current_exe()`, and
/// store it in a variable.
/// 2. Time passes. A malicious actor removes the current executable, and
/// replaces it with a malicious one.
/// 3. You then use the stored path to re-execute the current
/// executable.
///
/// You expected to safely execute the current executable, but you're
/// instead executing something completely different. The code you
/// just executed run with your privileges.
///
/// This sort of behavior has been known to [lead to privilege escalation] when
/// used incorrectly.
///
/// [lead to privilege escalation]: https://securityvulns.com/Wdocument183.html
///
/// # Examples
///
/// ```
/// use std::env;
///
/// match env::current_exe() {
/// Ok(exe_path) => println!("Path of this executable is: {}",
/// exe_path.display()),
/// Err(e) => println!("failed to get current exe path: {e}"),
/// };
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn current_exe() -> io::Result<PathBuf> {
os_imp::current_exe()
}
/// An iterator over the arguments of a process, yielding a [`String`] value for
/// each argument.
///
/// This struct is created by [`env::args()`]. See its documentation
/// for more.
///
/// The first element is traditionally the path of the executable, but it can be
/// set to arbitrary text, and might not even exist. This means this property
/// should not be relied upon for security purposes.
///
/// [`env::args()`]: args
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "env", since = "1.0.0")]
pub struct Args {
inner: ArgsOs,
}
/// An iterator over the arguments of a process, yielding an [`OsString`] value
/// for each argument.
///
/// This struct is created by [`env::args_os()`]. See its documentation
/// for more.
///
/// The first element is traditionally the path of the executable, but it can be
/// set to arbitrary text, and might not even exist. This means this property
/// should not be relied upon for security purposes.
///
/// [`env::args_os()`]: args_os
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "env", since = "1.0.0")]
pub struct ArgsOs {
inner: sys::args::Args,
}
/// Returns the arguments that this program was started with (normally passed
/// via the command line).
///
/// The first element is traditionally the path of the executable, but it can be
/// set to arbitrary text, and might not even exist. This means this property should
/// not be relied upon for security purposes.
///
/// On Unix systems the shell usually expands unquoted arguments with glob patterns
/// (such as `*` and `?`). On Windows this is not done, and such arguments are
/// passed as-is.
///
/// On glibc Linux systems, arguments are retrieved by placing a function in `.init_array`.
/// glibc passes `argc`, `argv`, and `envp` to functions in `.init_array`, as a non-standard
/// extension. This allows `std::env::args` to work even in a `cdylib` or `staticlib`, as it
/// does on macOS and Windows.
///
/// # Panics
///
/// The returned iterator will panic during iteration if any argument to the
/// process is not valid Unicode. If this is not desired,
/// use the [`args_os`] function instead.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// // Prints each argument on a separate line
/// for argument in env::args() {
/// println!("{argument}");
/// }
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn args() -> Args {
Args { inner: args_os() }
}
/// Returns the arguments that this program was started with (normally passed
/// via the command line).
///
/// The first element is traditionally the path of the executable, but it can be
/// set to arbitrary text, and might not even exist. This means this property should
/// not be relied upon for security purposes.
///
/// On Unix systems the shell usually expands unquoted arguments with glob patterns
/// (such as `*` and `?`). On Windows this is not done, and such arguments are
/// passed as-is.
///
/// On glibc Linux systems, arguments are retrieved by placing a function in `.init_array`.
/// glibc passes `argc`, `argv`, and `envp` to functions in `.init_array`, as a non-standard
/// extension. This allows `std::env::args_os` to work even in a `cdylib` or `staticlib`, as it
/// does on macOS and Windows.
///
/// Note that the returned iterator will not check if the arguments to the
/// process are valid Unicode. If you want to panic on invalid UTF-8,
/// use the [`args`] function instead.
///
/// # Examples
///
/// ```
/// use std::env;
///
/// // Prints each argument on a separate line
/// for argument in env::args_os() {
/// println!("{argument:?}");
/// }
/// ```
#[stable(feature = "env", since = "1.0.0")]
pub fn args_os() -> ArgsOs {
ArgsOs { inner: sys::args::args() }
}
#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
impl !Send for Args {}
#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
impl !Sync for Args {}
#[stable(feature = "env", since = "1.0.0")]
impl Iterator for Args {
type Item = String;
fn next(&mut self) -> Option<String> {
self.inner.next().map(|s| s.into_string().unwrap())
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "env", since = "1.0.0")]
impl ExactSizeIterator for Args {
fn len(&self) -> usize {
self.inner.len()
}
fn is_empty(&self) -> bool {
self.inner.is_empty()
}
}
#[stable(feature = "env_iterators", since = "1.12.0")]
impl DoubleEndedIterator for Args {
fn next_back(&mut self) -> Option<String> {
self.inner.next_back().map(|s| s.into_string().unwrap())
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for Args {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self { inner: ArgsOs { inner } } = self;
f.debug_struct("Args").field("inner", inner).finish()
}
}
#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
impl !Send for ArgsOs {}
#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
impl !Sync for ArgsOs {}
#[stable(feature = "env", since = "1.0.0")]
impl Iterator for ArgsOs {
type Item = OsString;
fn next(&mut self) -> Option<OsString> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "env", since = "1.0.0")]
impl ExactSizeIterator for ArgsOs {
fn len(&self) -> usize {
self.inner.len()
}
fn is_empty(&self) -> bool {
self.inner.is_empty()
}
}
#[stable(feature = "env_iterators", since = "1.12.0")]
impl DoubleEndedIterator for ArgsOs {
fn next_back(&mut self) -> Option<OsString> {
self.inner.next_back()
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for ArgsOs {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self { inner } = self;
f.debug_struct("ArgsOs").field("inner", inner).finish()
}
}
/// Constants associated with the current target
#[stable(feature = "env", since = "1.0.0")]
pub mod consts {
use crate::sys::env::os;
/// A string describing the architecture of the CPU that is currently
/// in use.
///
/// Some possible values:
///
/// - x86
/// - x86_64
/// - arm
/// - aarch64
/// - loongarch64
/// - m68k
/// - csky
/// - mips
/// - mips64
/// - powerpc
/// - powerpc64
/// - riscv64
/// - s390x
/// - sparc64
#[stable(feature = "env", since = "1.0.0")]
pub const ARCH: &str = env!("STD_ENV_ARCH");
/// The family of the operating system. Example value is `unix`.
///
/// Some possible values:
///
/// - unix
/// - windows
#[stable(feature = "env", since = "1.0.0")]
pub const FAMILY: &str = os::FAMILY;
/// A string describing the specific operating system in use.
/// Example value is `linux`.
///
/// Some possible values:
///
/// - linux
/// - macos
/// - ios
/// - freebsd
/// - dragonfly
/// - netbsd
/// - openbsd
/// - solaris
/// - android
/// - windows
#[stable(feature = "env", since = "1.0.0")]
pub const OS: &str = os::OS;
/// Specifies the filename prefix used for shared libraries on this
/// platform. Example value is `lib`.
///
/// Some possible values:
///
/// - lib
/// - `""` (an empty string)
#[stable(feature = "env", since = "1.0.0")]
pub const DLL_PREFIX: &str = os::DLL_PREFIX;
/// Specifies the filename suffix used for shared libraries on this
/// platform. Example value is `.so`.
///
/// Some possible values:
///
/// - .so
/// - .dylib
/// - .dll
#[stable(feature = "env", since = "1.0.0")]
pub const DLL_SUFFIX: &str = os::DLL_SUFFIX;
/// Specifies the file extension used for shared libraries on this
/// platform that goes after the dot. Example value is `so`.
///
/// Some possible values:
///
/// - so
/// - dylib
/// - dll
#[stable(feature = "env", since = "1.0.0")]
pub const DLL_EXTENSION: &str = os::DLL_EXTENSION;
/// Specifies the filename suffix used for executable binaries on this
/// platform. Example value is `.exe`.
///
/// Some possible values:
///
/// - .exe
/// - .nexe
/// - .pexe
/// - `""` (an empty string)
#[stable(feature = "env", since = "1.0.0")]
pub const EXE_SUFFIX: &str = os::EXE_SUFFIX;
/// Specifies the file extension, if any, used for executable binaries
/// on this platform. Example value is `exe`.
///
/// Some possible values:
///
/// - exe
/// - `""` (an empty string)
#[stable(feature = "env", since = "1.0.0")]
pub const EXE_EXTENSION: &str = os::EXE_EXTENSION;
}