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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`].
+//!
+//! [`OsString`]: ../../std/ffi/struct.OsString.html
+//! [`String`]: ../string/struct.String.html
+
+#![stable(feature = "env", since = "1.0.0")]
+
+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`].
+///
+/// # 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.
+///
+/// [`PathBuf`]: ../../std/path/struct.PathBuf.html
+/// [`Err`]: ../../std/result/enum.Result.html#method.err
+///
+/// # Examples
+///
+/// ```
+/// use std::env;
+///
+/// fn main() -> std::io::Result<()> {
+/// let path = env::current_dir()?;
+/// println!("The current directory is {}", path.display());
+/// Ok(())
+/// }
+/// ```
+#[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.
+///
+/// Returns an [`Err`] if the operation fails.
+///
+/// [`Err`]: ../../std/result/enum.Result.html#method.err
+///
+/// # 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());
+/// ```
+#[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 the [`std::env::vars`] function. See its
+/// documentation for more.
+///
+/// [`std::env::vars`]: fn.vars.html
+#[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 the [`std::env::vars_os`] function. See
+/// its documentation for more.
+///
+/// [`std::env::vars_os`]: fn.vars_os.html
+#[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 the
+/// [`env::vars_os`] function.
+///
+/// [`env::vars_os`]: fn.vars_os.html
+///
+/// # 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);
+/// }
+/// ```
+#[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.
+///
+/// # 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);
+/// }
+/// ```
+#[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 {
+ f.pad("Vars { .. }")
+ }
+}
+
+#[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 {
+ f.pad("VarsOs { .. }")
+ }
+}
+
+/// Fetches the environment variable `key` from the current process.
+///
+/// # Errors
+///
+/// * Environment variable is not present
+/// * Environment variable is not valid unicode
+///
+/// # 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 = "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.
+///
+/// [`None`]: ../option/enum.Option.html#variant.None
+///
+/// # 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 = "HOME";
+/// match env::var_os(key) {
+/// Some(val) => println!("{}: {:?}", key, val),
+/// None => println!("{} is not defined in the environment.", key)
+/// }
+/// ```
+#[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)
+ .unwrap_or_else(|e| panic!("failed to get environment variable `{:?}`: {}", key, e))
+}
+
+/// The error type for operations interacting with environment variables.
+/// Possibly returned from the [`env::var`] function.
+///
+/// [`env::var`]: fn.var.html
+#[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 `k` to the value `v` for the currently running
+/// process.
+///
+/// Note that while concurrent access to environment variables is safe in Rust,
+/// some platforms only expose inherently unsafe non-threadsafe APIs for
+/// inspecting the environment. As a result, extra care needs to be taken when
+/// auditing calls to unsafe external FFI functions to ensure that any external
+/// environment accesses are properly synchronized with accesses in Rust.
+///
+/// Discussion of this unsafety on Unix may be found in:
+///
+/// - [Austin Group Bugzilla](http://austingroupbugs.net/view.php?id=188)
+/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
+///
+/// # 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()));
+/// ```
+#[stable(feature = "env", since = "1.0.0")]
+pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>(k: K, v: V) {
+ _set_var(k.as_ref(), v.as_ref())
+}
+
+fn _set_var(k: &OsStr, v: &OsStr) {
+ os_imp::setenv(k, v).unwrap_or_else(|e| {
+ panic!("failed to set environment variable `{:?}` to `{:?}`: {}", k, v, e)
+ })
+}
+
+/// Removes an environment variable from the environment of the currently running process.
+///
+/// Note that while concurrent access to environment variables is safe in Rust,
+/// some platforms only expose inherently unsafe non-threadsafe APIs for
+/// inspecting the environment. As a result extra care needs to be taken when
+/// auditing calls to unsafe external FFI functions to ensure that any external
+/// environment accesses are properly synchronized with accesses in Rust.
+///
+/// Discussion of this unsafety on Unix may be found in:
+///
+/// - [Austin Group Bugzilla](http://austingroupbugs.net/view.php?id=188)
+/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
+///
+/// # 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>>(k: K) {
+ _remove_var(k.as_ref())
+}
+
+fn _remove_var(k: &OsStr) {
+ os_imp::unsetenv(k)
+ .unwrap_or_else(|e| panic!("failed to remove environment variable `{:?}`: {}", k, 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 the [`std::env::split_paths`] function. See its
+/// documentation for more.
+///
+/// [`PathBuf`]: ../../std/path/struct.PathBuf.html
+/// [`std::env::split_paths`]: fn.split_paths.html
+#[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!("{} is not defined in the environment.", key)
+/// }
+/// ```
+///
+/// [`PathBuf`]: ../../std/path/struct.PathBuf.html
+#[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.pad("SplitPaths { .. }")
+ }
+}
+
+/// The error type for operations on the `PATH` variable. Possibly returned from
+/// the [`env::join_paths`] function.
+///
+/// [`env::join_paths`]: fn.join_paths.html
+#[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`][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).
+///
+/// [`Path`]: ../../std/path/struct.Path.html
+/// [`OsString`]: ../../std/ffi/struct.OsString.html
+/// [err]: ../../std/result/enum.Result.html#variant.Err
+///
+/// # 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`]: fn.split_paths.html
+#[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
+///
+/// # 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!"),
+/// }
+/// ```
+#[rustc_deprecated(
+ since = "1.29.0",
+ reason = "This function's behavior is unexpected and probably not what you want. \
+ Consider using a crate from crates.io instead."
+)]
+#[stable(feature = "env", since = "1.0.0")]
+pub fn home_dir() -> Option<PathBuf> {
+ os_imp::home_dir()
+}
+
+/// Returns the path of a temporary directory.
+///
+/// # Unix
+///
+/// Returns the value of the `TMPDIR` environment variable if it is
+/// set, otherwise for non-Android it returns `/tmp`. If Android, since there
+/// is no global temporary folder (it is usually allocated per-app), it returns
+/// `/data/local/tmp`.
+///
+/// # Windows
+///
+/// Returns the value of, in order, the `TMP`, `TEMP`,
+/// `USERPROFILE` environment variable if any are set and not the empty
+/// string. Otherwise, `temp_dir` returns the path of the Windows directory.
+/// This behavior is identical to that of [`GetTempPath`][msdn], which this
+/// function uses internally.
+///
+/// [msdn]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppatha
+///
+/// ```no_run
+/// use std::env;
+/// use std::fs::File;
+///
+/// fn main() -> std::io::Result<()> {
+/// let mut dir = env::temp_dir();
+/// dir.push("foo.txt");
+///
+/// let f = File::create(dir)?;
+/// Ok(())
+/// }
+/// ```
+#[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.
+///
+/// # 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 used in anything that might have
+/// security implications. For example:
+///
+/// ```
+/// fn main() {
+/// println!("{:?}", std::env::current_exe());
+/// }
+/// ```
+///
+/// On Linux systems, if this is compiled as `foo`:
+///
+/// ```bash
+/// $ rustc foo.rs
+/// $ ./foo
+/// Ok("/home/alex/foo")
+/// ```
+///
+/// And you make a hard link of the program:
+///
+/// ```bash
+/// $ ln foo bar
+/// ```
+///
+/// When you run it, you won’t get the path of the original executable, you’ll
+/// get the path of the hard link:
+///
+/// ```bash
+/// $ ./bar
+/// Ok("/home/alex/bar")
+/// ```
+///
+/// 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 the [`std::env::args`] function. See its
+/// documentation for more.
+///
+/// The first element is traditionally the path of the executable, but it can be
+/// set to arbitrary text, and may not even exist. This means this property
+/// should not be relied upon for security purposes.
+///
+/// [`String`]: ../string/struct.String.html
+/// [`std::env::args`]: ./fn.args.html
+#[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 the [`std::env::args_os`] function. See its
+/// documentation for more.
+///
+/// The first element is traditionally the path of the executable, but it can be
+/// set to arbitrary text, and may not even exist. This means this property
+/// should not be relied upon for security purposes.
+///
+/// [`OsString`]: ../ffi/struct.OsString.html
+/// [`std::env::args_os`]: ./fn.args_os.html
+#[stable(feature = "env", since = "1.0.0")]
+pub struct ArgsOs {
+ inner: sys::args::Args,
+}
+
+/// Returns the arguments which 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 may not even exist. This means this property should
+/// not be relied upon for security purposes.
+///
+/// On Unix systems 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);
+/// }
+/// ```
+///
+/// [`args_os`]: ./fn.args_os.html
+#[stable(feature = "env", since = "1.0.0")]
+pub fn args() -> Args {
+ Args { inner: args_os() }
+}
+
+/// Returns the arguments which 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 it may not even exist, so this property should
+/// not be relied upon for security purposes.
+///
+/// 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.
+///
+/// # 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 {
+ f.debug_struct("Args").field("inner", &self.inner.inner.inner_debug()).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 {
+ f.debug_struct("ArgsOs").field("inner", &self.inner.inner_debug()).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
+ /// - 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;
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ use crate::path::Path;
+
+ #[test]
+ #[cfg_attr(any(target_os = "emscripten", target_env = "sgx"), ignore)]
+ fn test_self_exe_path() {
+ let path = current_exe();
+ assert!(path.is_ok());
+ let path = path.unwrap();
+
+ // Hard to test this function
+ assert!(path.is_absolute());
+ }
+
+ #[test]
+ fn test() {
+ assert!((!Path::new("test-path").is_absolute()));
+
+ #[cfg(not(target_env = "sgx"))]
+ current_dir().unwrap();
+ }
+
+ #[test]
+ #[cfg(windows)]
+ fn split_paths_windows() {
+ use crate::path::PathBuf;
+
+ fn check_parse(unparsed: &str, parsed: &[&str]) -> bool {
+ split_paths(unparsed).collect::<Vec<_>>()
+ == parsed.iter().map(|s| PathBuf::from(*s)).collect::<Vec<_>>()
+ }
+
+ assert!(check_parse("", &mut [""]));
+ assert!(check_parse(r#""""#, &mut [""]));
+ assert!(check_parse(";;", &mut ["", "", ""]));
+ assert!(check_parse(r"c:\", &mut [r"c:\"]));
+ assert!(check_parse(r"c:\;", &mut [r"c:\", ""]));
+ assert!(check_parse(r"c:\;c:\Program Files\", &mut [r"c:\", r"c:\Program Files\"]));
+ assert!(check_parse(r#"c:\;c:\"foo"\"#, &mut [r"c:\", r"c:\foo\"]));
+ assert!(check_parse(
+ r#"c:\;c:\"foo;bar"\;c:\baz"#,
+ &mut [r"c:\", r"c:\foo;bar\", r"c:\baz"]
+ ));
+ }
+
+ #[test]
+ #[cfg(unix)]
+ fn split_paths_unix() {
+ use crate::path::PathBuf;
+
+ fn check_parse(unparsed: &str, parsed: &[&str]) -> bool {
+ split_paths(unparsed).collect::<Vec<_>>()
+ == parsed.iter().map(|s| PathBuf::from(*s)).collect::<Vec<_>>()
+ }
+
+ assert!(check_parse("", &mut [""]));
+ assert!(check_parse("::", &mut ["", "", ""]));
+ assert!(check_parse("/", &mut ["/"]));
+ assert!(check_parse("/:", &mut ["/", ""]));
+ assert!(check_parse("/:/usr/local", &mut ["/", "/usr/local"]));
+ }
+
+ #[test]
+ #[cfg(unix)]
+ fn join_paths_unix() {
+ use crate::ffi::OsStr;
+
+ fn test_eq(input: &[&str], output: &str) -> bool {
+ &*join_paths(input.iter().cloned()).unwrap() == OsStr::new(output)
+ }
+
+ assert!(test_eq(&[], ""));
+ assert!(test_eq(&["/bin", "/usr/bin", "/usr/local/bin"], "/bin:/usr/bin:/usr/local/bin"));
+ assert!(test_eq(&["", "/bin", "", "", "/usr/bin", ""], ":/bin:::/usr/bin:"));
+ assert!(join_paths(["/te:st"].iter().cloned()).is_err());
+ }
+
+ #[test]
+ #[cfg(windows)]
+ fn join_paths_windows() {
+ use crate::ffi::OsStr;
+
+ fn test_eq(input: &[&str], output: &str) -> bool {
+ &*join_paths(input.iter().cloned()).unwrap() == OsStr::new(output)
+ }
+
+ assert!(test_eq(&[], ""));
+ assert!(test_eq(&[r"c:\windows", r"c:\"], r"c:\windows;c:\"));
+ assert!(test_eq(&["", r"c:\windows", "", "", r"c:\", ""], r";c:\windows;;;c:\;"));
+ assert!(test_eq(&[r"c:\te;st", r"c:\"], r#""c:\te;st";c:\"#));
+ assert!(join_paths([r#"c:\te"st"#].iter().cloned()).is_err());
+ }
+
+ #[test]
+ fn args_debug() {
+ assert_eq!(
+ format!("Args {{ inner: {:?} }}", args().collect::<Vec<_>>()),
+ format!("{:?}", args())
+ );
+ assert_eq!(
+ format!("ArgsOs {{ inner: {:?} }}", args_os().collect::<Vec<_>>()),
+ format!("{:?}", args_os())
+ );
+ }
+}