1//! Inspection and manipulation of the process's environment.
2//!
3//! This module contains functions to inspect various aspects such as
4//! environment variables, process arguments, the current directory, and various
5//! other important directories.
6//!
7//! There are several functions and structs in this module that have a
8//! counterpart ending in `os`. Those ending in `os` will return an [`OsString`]
9//! and those without will return a [`String`].
10
11#![stable(feature = "env", since = "1.0.0")]
12
13#[cfg(test)]
14mod tests;
15
16use crate::error::Error;
17use crate::ffi::{OsStr, OsString};
18use crate::fmt;
19use crate::io;
20use crate::path::{Path, PathBuf};
21use crate::sys;
22use crate::sys::os as os_imp;
23
24/// Returns the current working directory as a [`PathBuf`].
25///
26/// # Platform-specific behavior
27///
28/// This function [currently] corresponds to the `getcwd` function on Unix
29/// and the `GetCurrentDirectoryW` function on Windows.
30///
31/// [currently]: crate::io#platform-specific-behavior
32///
33/// # Errors
34///
35/// Returns an [`Err`] if the current working directory value is invalid.
36/// Possible cases:
37///
38/// * Current directory does not exist.
39/// * There are insufficient permissions to access the current directory.
40///
41/// # Examples
42///
43/// ```
44/// use std::env;
45///
46/// fn main() -> std::io::Result<()> {
47/// let path = env::current_dir()?;
48/// println!("The current directory is {}", path.display());
49/// Ok(())
50/// }
51/// ```
52#[doc(alias = "pwd")]
53#[doc(alias = "getcwd")]
54#[doc(alias = "GetCurrentDirectory")]
55#[stable(feature = "env", since = "1.0.0")]
56pub fn current_dir() -> io::Result<PathBuf> {
57 os_imp::getcwd()
58}
59
60/// Changes the current working directory to the specified path.
61///
62/// # Platform-specific behavior
63///
64/// This function [currently] corresponds to the `chdir` function on Unix
65/// and the `SetCurrentDirectoryW` function on Windows.
66///
67/// Returns an [`Err`] if the operation fails.
68///
69/// [currently]: crate::io#platform-specific-behavior
70///
71/// # Examples
72///
73/// ```
74/// use std::env;
75/// use std::path::Path;
76///
77/// let root = Path::new("/");
78/// assert!(env::set_current_dir(&root).is_ok());
79/// println!("Successfully changed working directory to {}!", root.display());
80/// ```
81#[doc(alias = "chdir", alias = "SetCurrentDirectory", alias = "SetCurrentDirectoryW")]
82#[stable(feature = "env", since = "1.0.0")]
83pub fn set_current_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
84 os_imp::chdir(path.as_ref())
85}
86
87/// An iterator over a snapshot of the environment variables of this process.
88///
89/// This structure is created by [`env::vars()`]. See its documentation for more.
90///
91/// [`env::vars()`]: vars
92#[stable(feature = "env", since = "1.0.0")]
93pub struct Vars {
94 inner: VarsOs,
95}
96
97/// An iterator over a snapshot of the environment variables of this process.
98///
99/// This structure is created by [`env::vars_os()`]. See its documentation for more.
100///
101/// [`env::vars_os()`]: vars_os
102#[stable(feature = "env", since = "1.0.0")]
103pub struct VarsOs {
104 inner: os_imp::Env,
105}
106
107/// Returns an iterator of (variable, value) pairs of strings, for all the
108/// environment variables of the current process.
109///
110/// The returned iterator contains a snapshot of the process's environment
111/// variables at the time of this invocation. Modifications to environment
112/// variables afterwards will not be reflected in the returned iterator.
113///
114/// # Panics
115///
116/// While iterating, the returned iterator will panic if any key or value in the
117/// environment is not valid unicode. If this is not desired, consider using
118/// [`env::vars_os()`].
119///
120/// # Examples
121///
122/// ```
123/// use std::env;
124///
125/// // We will iterate through the references to the element returned by
126/// // env::vars();
127/// for (key, value) in env::vars() {
128/// println!("{key}: {value}");
129/// }
130/// ```
131///
132/// [`env::vars_os()`]: vars_os
133#[must_use]
134#[stable(feature = "env", since = "1.0.0")]
135pub fn vars() -> Vars {
136 Vars { inner: vars_os() }
137}
138
139/// Returns an iterator of (variable, value) pairs of OS strings, for all the
140/// environment variables of the current process.
141///
142/// The returned iterator contains a snapshot of the process's environment
143/// variables at the time of this invocation. Modifications to environment
144/// variables afterwards will not be reflected in the returned iterator.
145///
146/// Note that the returned iterator will not check if the environment variables
147/// are valid Unicode. If you want to panic on invalid UTF-8,
148/// use the [`vars`] function instead.
149///
150/// # Examples
151///
152/// ```
153/// use std::env;
154///
155/// // We will iterate through the references to the element returned by
156/// // env::vars_os();
157/// for (key, value) in env::vars_os() {
158/// println!("{key:?}: {value:?}");
159/// }
160/// ```
161#[must_use]
162#[stable(feature = "env", since = "1.0.0")]
163pub fn vars_os() -> VarsOs {
164 VarsOs { inner: os_imp::env() }
165}
166
167#[stable(feature = "env", since = "1.0.0")]
168impl Iterator for Vars {
169 type Item = (String, String);
170 fn next(&mut self) -> Option<(String, String)> {
171 self.inner.next().map(|(a: OsString, b: OsString)| (a.into_string().unwrap(), b.into_string().unwrap()))
172 }
173 fn size_hint(&self) -> (usize, Option<usize>) {
174 self.inner.size_hint()
175 }
176}
177
178#[stable(feature = "std_debug", since = "1.16.0")]
179impl fmt::Debug for Vars {
180 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
181 let Self { inner: VarsOs { inner: &Env } } = self;
182 f.debug_struct("Vars").field(name:"inner", &inner.str_debug()).finish()
183 }
184}
185
186#[stable(feature = "env", since = "1.0.0")]
187impl Iterator for VarsOs {
188 type Item = (OsString, OsString);
189 fn next(&mut self) -> Option<(OsString, OsString)> {
190 self.inner.next()
191 }
192 fn size_hint(&self) -> (usize, Option<usize>) {
193 self.inner.size_hint()
194 }
195}
196
197#[stable(feature = "std_debug", since = "1.16.0")]
198impl fmt::Debug for VarsOs {
199 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
200 let Self { inner: &Env } = self;
201 f.debug_struct("VarsOs").field(name:"inner", value:inner).finish()
202 }
203}
204
205/// Fetches the environment variable `key` from the current process.
206///
207/// # Errors
208///
209/// This function will return an error if the environment variable isn't set.
210///
211/// This function may return an error if the environment variable's name contains
212/// the equal sign character (`=`) or the NUL character.
213///
214/// This function will return an error if the environment variable's value is
215/// not valid Unicode. If this is not desired, consider using [`var_os`].
216///
217/// # Examples
218///
219/// ```
220/// use std::env;
221///
222/// let key = "HOME";
223/// match env::var(key) {
224/// Ok(val) => println!("{key}: {val:?}"),
225/// Err(e) => println!("couldn't interpret {key}: {e}"),
226/// }
227/// ```
228#[stable(feature = "env", since = "1.0.0")]
229pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError> {
230 _var(key.as_ref())
231}
232
233fn _var(key: &OsStr) -> Result<String, VarError> {
234 match var_os(key) {
235 Some(s: OsString) => s.into_string().map_err(op:VarError::NotUnicode),
236 None => Err(VarError::NotPresent),
237 }
238}
239
240/// Fetches the environment variable `key` from the current process, returning
241/// [`None`] if the variable isn't set or if there is another error.
242///
243/// It may return `None` if the environment variable's name contains
244/// the equal sign character (`=`) or the NUL character.
245///
246/// Note that this function will not check if the environment variable
247/// is valid Unicode. If you want to have an error on invalid UTF-8,
248/// use the [`var`] function instead.
249///
250/// # Examples
251///
252/// ```
253/// use std::env;
254///
255/// let key = "HOME";
256/// match env::var_os(key) {
257/// Some(val) => println!("{key}: {val:?}"),
258/// None => println!("{key} is not defined in the environment.")
259/// }
260/// ```
261///
262/// If expecting a delimited variable (such as `PATH`), [`split_paths`]
263/// can be used to separate items.
264#[must_use]
265#[stable(feature = "env", since = "1.0.0")]
266pub fn var_os<K: AsRef<OsStr>>(key: K) -> Option<OsString> {
267 _var_os(key.as_ref())
268}
269
270fn _var_os(key: &OsStr) -> Option<OsString> {
271 os_imp::getenv(key)
272}
273
274/// The error type for operations interacting with environment variables.
275/// Possibly returned from [`env::var()`].
276///
277/// [`env::var()`]: var
278#[derive(Debug, PartialEq, Eq, Clone)]
279#[stable(feature = "env", since = "1.0.0")]
280pub enum VarError {
281 /// The specified environment variable was not present in the current
282 /// process's environment.
283 #[stable(feature = "env", since = "1.0.0")]
284 NotPresent,
285
286 /// The specified environment variable was found, but it did not contain
287 /// valid unicode data. The found data is returned as a payload of this
288 /// variant.
289 #[stable(feature = "env", since = "1.0.0")]
290 NotUnicode(#[stable(feature = "env", since = "1.0.0")] OsString),
291}
292
293#[stable(feature = "env", since = "1.0.0")]
294impl fmt::Display for VarError {
295 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
296 match *self {
297 VarError::NotPresent => write!(f, "environment variable not found"),
298 VarError::NotUnicode(ref s: &OsString) => {
299 write!(f, "environment variable was not valid unicode: {:?}", s)
300 }
301 }
302 }
303}
304
305#[stable(feature = "env", since = "1.0.0")]
306impl Error for VarError {
307 #[allow(deprecated)]
308 fn description(&self) -> &str {
309 match *self {
310 VarError::NotPresent => "environment variable not found",
311 VarError::NotUnicode(..) => "environment variable was not valid unicode",
312 }
313 }
314}
315
316/// Sets the environment variable `key` to the value `value` for the currently running
317/// process.
318///
319/// # Safety
320///
321/// Even though this function is currently not marked as `unsafe`, it needs to
322/// be because invoking it can cause undefined behaviour. The function will be
323/// marked `unsafe` in a future version of Rust. This is tracked in
324/// [rust#27970](https://github.com/rust-lang/rust/issues/27970).
325///
326/// This function is safe to call in a single-threaded program.
327///
328/// In multi-threaded programs, you must ensure that are no other threads
329/// concurrently writing or *reading*(!) from the environment through functions
330/// other than the ones in this module. You are responsible for figuring out
331/// how to achieve this, but we strongly suggest not using `set_var` or
332/// `remove_var` in multi-threaded programs at all.
333///
334/// Most C libraries, including libc itself do not advertise which functions
335/// read from the environment. Even functions from the Rust standard library do
336/// that, e.g. for DNS lookups from [`std::net::ToSocketAddrs`].
337///
338/// Discussion of this unsafety on Unix may be found in:
339///
340/// - [Austin Group Bugzilla](https://austingroupbugs.net/view.php?id=188)
341/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
342///
343/// [`std::net::ToSocketAddrs`]: crate::net::ToSocketAddrs
344///
345/// # Panics
346///
347/// This function may panic if `key` is empty, contains an ASCII equals sign `'='`
348/// or the NUL character `'\0'`, or when `value` contains the NUL character.
349///
350/// # Examples
351///
352/// ```
353/// use std::env;
354///
355/// let key = "KEY";
356/// env::set_var(key, "VALUE");
357/// assert_eq!(env::var(key), Ok("VALUE".to_string()));
358/// ```
359#[stable(feature = "env", since = "1.0.0")]
360pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>(key: K, value: V) {
361 _set_var(key.as_ref(), value.as_ref())
362}
363
364fn _set_var(key: &OsStr, value: &OsStr) {
365 os_imp::setenv(key, value).unwrap_or_else(|e: Error| {
366 panic!("failed to set environment variable `{key:?}` to `{value:?}`: {e}")
367 })
368}
369
370/// Removes an environment variable from the environment of the currently running process.
371///
372/// # Safety
373///
374/// Even though this function is currently not marked as `unsafe`, it needs to
375/// be because invoking it can cause undefined behaviour. The function will be
376/// marked `unsafe` in a future version of Rust. This is tracked in
377/// [rust#27970](https://github.com/rust-lang/rust/issues/27970).
378///
379/// This function is safe to call in a single-threaded program.
380///
381/// In multi-threaded programs, you must ensure that are no other threads
382/// concurrently writing or *reading*(!) from the environment through functions
383/// other than the ones in this module. You are responsible for figuring out
384/// how to achieve this, but we strongly suggest not using `set_var` or
385/// `remove_var` in multi-threaded programs at all.
386///
387/// Most C libraries, including libc itself do not advertise which functions
388/// read from the environment. Even functions from the Rust standard library do
389/// that, e.g. for DNS lookups from [`std::net::ToSocketAddrs`].
390///
391/// Discussion of this unsafety on Unix may be found in:
392///
393/// - [Austin Group Bugzilla](https://austingroupbugs.net/view.php?id=188)
394/// - [GNU C library Bugzilla](https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2)
395///
396/// [`std::net::ToSocketAddrs`]: crate::net::ToSocketAddrs
397///
398/// # Panics
399///
400/// This function may panic if `key` is empty, contains an ASCII equals sign
401/// `'='` or the NUL character `'\0'`, or when the value contains the NUL
402/// character.
403///
404/// # Examples
405///
406/// ```
407/// use std::env;
408///
409/// let key = "KEY";
410/// env::set_var(key, "VALUE");
411/// assert_eq!(env::var(key), Ok("VALUE".to_string()));
412///
413/// env::remove_var(key);
414/// assert!(env::var(key).is_err());
415/// ```
416#[stable(feature = "env", since = "1.0.0")]
417pub fn remove_var<K: AsRef<OsStr>>(key: K) {
418 _remove_var(key.as_ref())
419}
420
421fn _remove_var(key: &OsStr) {
422 os_imp::unsetenv(key)
423 .unwrap_or_else(|e: Error| panic!("failed to remove environment variable `{key:?}`: {e}"))
424}
425
426/// An iterator that splits an environment variable into paths according to
427/// platform-specific conventions.
428///
429/// The iterator element type is [`PathBuf`].
430///
431/// This structure is created by [`env::split_paths()`]. See its
432/// documentation for more.
433///
434/// [`env::split_paths()`]: split_paths
435#[must_use = "iterators are lazy and do nothing unless consumed"]
436#[stable(feature = "env", since = "1.0.0")]
437pub struct SplitPaths<'a> {
438 inner: os_imp::SplitPaths<'a>,
439}
440
441/// Parses input according to platform conventions for the `PATH`
442/// environment variable.
443///
444/// Returns an iterator over the paths contained in `unparsed`. The iterator
445/// element type is [`PathBuf`].
446///
447/// On most Unix platforms, the separator is `:` and on Windows it is `;`. This
448/// also performs unquoting on Windows.
449///
450/// [`join_paths`] can be used to recombine elements.
451///
452/// # Panics
453///
454/// This will panic on systems where there is no delimited `PATH` variable,
455/// such as UEFI.
456///
457/// # Examples
458///
459/// ```
460/// use std::env;
461///
462/// let key = "PATH";
463/// match env::var_os(key) {
464/// Some(paths) => {
465/// for path in env::split_paths(&paths) {
466/// println!("'{}'", path.display());
467/// }
468/// }
469/// None => println!("{key} is not defined in the environment.")
470/// }
471/// ```
472#[stable(feature = "env", since = "1.0.0")]
473pub fn split_paths<T: AsRef<OsStr> + ?Sized>(unparsed: &T) -> SplitPaths<'_> {
474 SplitPaths { inner: os_imp::split_paths(unparsed.as_ref()) }
475}
476
477#[stable(feature = "env", since = "1.0.0")]
478impl<'a> Iterator for SplitPaths<'a> {
479 type Item = PathBuf;
480 fn next(&mut self) -> Option<PathBuf> {
481 self.inner.next()
482 }
483 fn size_hint(&self) -> (usize, Option<usize>) {
484 self.inner.size_hint()
485 }
486}
487
488#[stable(feature = "std_debug", since = "1.16.0")]
489impl fmt::Debug for SplitPaths<'_> {
490 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
491 f.debug_struct(name:"SplitPaths").finish_non_exhaustive()
492 }
493}
494
495/// The error type for operations on the `PATH` variable. Possibly returned from
496/// [`env::join_paths()`].
497///
498/// [`env::join_paths()`]: join_paths
499#[derive(Debug)]
500#[stable(feature = "env", since = "1.0.0")]
501pub struct JoinPathsError {
502 inner: os_imp::JoinPathsError,
503}
504
505/// Joins a collection of [`Path`]s appropriately for the `PATH`
506/// environment variable.
507///
508/// # Errors
509///
510/// Returns an [`Err`] (containing an error message) if one of the input
511/// [`Path`]s contains an invalid character for constructing the `PATH`
512/// variable (a double quote on Windows or a colon on Unix), or if the system
513/// does not have a `PATH`-like variable (e.g. UEFI or WASI).
514///
515/// # Examples
516///
517/// Joining paths on a Unix-like platform:
518///
519/// ```
520/// use std::env;
521/// use std::ffi::OsString;
522/// use std::path::Path;
523///
524/// fn main() -> Result<(), env::JoinPathsError> {
525/// # if cfg!(unix) {
526/// let paths = [Path::new("/bin"), Path::new("/usr/bin")];
527/// let path_os_string = env::join_paths(paths.iter())?;
528/// assert_eq!(path_os_string, OsString::from("/bin:/usr/bin"));
529/// # }
530/// Ok(())
531/// }
532/// ```
533///
534/// Joining a path containing a colon on a Unix-like platform results in an
535/// error:
536///
537/// ```
538/// # if cfg!(unix) {
539/// use std::env;
540/// use std::path::Path;
541///
542/// let paths = [Path::new("/bin"), Path::new("/usr/bi:n")];
543/// assert!(env::join_paths(paths.iter()).is_err());
544/// # }
545/// ```
546///
547/// Using `env::join_paths()` with [`env::split_paths()`] to append an item to
548/// the `PATH` environment variable:
549///
550/// ```
551/// use std::env;
552/// use std::path::PathBuf;
553///
554/// fn main() -> Result<(), env::JoinPathsError> {
555/// if let Some(path) = env::var_os("PATH") {
556/// let mut paths = env::split_paths(&path).collect::<Vec<_>>();
557/// paths.push(PathBuf::from("/home/xyz/bin"));
558/// let new_path = env::join_paths(paths)?;
559/// env::set_var("PATH", &new_path);
560/// }
561///
562/// Ok(())
563/// }
564/// ```
565///
566/// [`env::split_paths()`]: split_paths
567#[stable(feature = "env", since = "1.0.0")]
568pub fn join_paths<I, T>(paths: I) -> Result<OsString, JoinPathsError>
569where
570 I: IntoIterator<Item = T>,
571 T: AsRef<OsStr>,
572{
573 os_imp::join_paths(paths.into_iter()).map_err(|e: JoinPathsError| JoinPathsError { inner: e })
574}
575
576#[stable(feature = "env", since = "1.0.0")]
577impl fmt::Display for JoinPathsError {
578 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
579 self.inner.fmt(f)
580 }
581}
582
583#[stable(feature = "env", since = "1.0.0")]
584impl Error for JoinPathsError {
585 #[allow(deprecated, deprecated_in_future)]
586 fn description(&self) -> &str {
587 self.inner.description()
588 }
589}
590
591/// Returns the path of the current user's home directory if known.
592///
593/// # Unix
594///
595/// - Returns the value of the 'HOME' environment variable if it is set
596/// (including to an empty string).
597/// - Otherwise, it tries to determine the home directory by invoking the `getpwuid_r` function
598/// using the UID of the current user. An empty home directory field returned from the
599/// `getpwuid_r` function is considered to be a valid value.
600/// - Returns `None` if the current user has no entry in the /etc/passwd file.
601///
602/// # Windows
603///
604/// - Returns the value of the 'HOME' environment variable if it is set
605/// (including to an empty string).
606/// - Otherwise, returns the value of the 'USERPROFILE' environment variable if it is set
607/// (including to an empty string).
608/// - If both do not exist, [`GetUserProfileDirectory`][msdn] is used to return the path.
609///
610/// [msdn]: https://docs.microsoft.com/en-us/windows/win32/api/userenv/nf-userenv-getuserprofiledirectorya
611///
612/// # Deprecation
613///
614/// This function is deprecated because the behaviour on Windows is not correct.
615/// The 'HOME' environment variable is not standard on Windows, and may not produce
616/// desired results; for instance, under Cygwin or Mingw it will return `/home/you`
617/// when it should return `C:\Users\you`.
618///
619/// # Examples
620///
621/// ```
622/// use std::env;
623///
624/// match env::home_dir() {
625/// Some(path) => println!("Your home directory, probably: {}", path.display()),
626/// None => println!("Impossible to get your home dir!"),
627/// }
628/// ```
629#[deprecated(
630 since = "1.29.0",
631 note = "This function's behavior may be unexpected on Windows. \
632 Consider using a crate from crates.io instead."
633)]
634#[must_use]
635#[stable(feature = "env", since = "1.0.0")]
636pub fn home_dir() -> Option<PathBuf> {
637 os_imp::home_dir()
638}
639
640/// Returns the path of a temporary directory.
641///
642/// The temporary directory may be shared among users, or between processes
643/// with different privileges; thus, the creation of any files or directories
644/// in the temporary directory must use a secure method to create a uniquely
645/// named file. Creating a file or directory with a fixed or predictable name
646/// may result in "insecure temporary file" security vulnerabilities. Consider
647/// using a crate that securely creates temporary files or directories.
648///
649/// # Platform-specific behavior
650///
651/// On Unix, returns the value of the `TMPDIR` environment variable if it is
652/// set, otherwise for non-Android it returns `/tmp`. On Android, since there
653/// is no global temporary folder (it is usually allocated per-app), it returns
654/// `/data/local/tmp`.
655/// On Windows, the behavior is equivalent to that of [`GetTempPath2`][GetTempPath2] /
656/// [`GetTempPath`][GetTempPath], which this function uses internally.
657/// Note that, this [may change in the future][changes].
658///
659/// [changes]: io#platform-specific-behavior
660/// [GetTempPath2]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppath2a
661/// [GetTempPath]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppatha
662///
663/// ```no_run
664/// use std::env;
665///
666/// fn main() {
667/// let dir = env::temp_dir();
668/// println!("Temporary directory: {}", dir.display());
669/// }
670/// ```
671#[must_use]
672#[doc(alias = "GetTempPath", alias = "GetTempPath2")]
673#[stable(feature = "env", since = "1.0.0")]
674pub fn temp_dir() -> PathBuf {
675 os_imp::temp_dir()
676}
677
678/// Returns the full filesystem path of the current running executable.
679///
680/// # Platform-specific behavior
681///
682/// If the executable was invoked through a symbolic link, some platforms will
683/// return the path of the symbolic link and other platforms will return the
684/// path of the symbolic link’s target.
685///
686/// If the executable is renamed while it is running, platforms may return the
687/// path at the time it was loaded instead of the new path.
688///
689/// # Errors
690///
691/// Acquiring the path of the current executable is a platform-specific operation
692/// that can fail for a good number of reasons. Some errors can include, but not
693/// be limited to, filesystem operations failing or general syscall failures.
694///
695/// # Security
696///
697/// The output of this function should not be trusted for anything
698/// that might have security implications. Basically, if users can run
699/// the executable, they can change the output arbitrarily.
700///
701/// As an example, you can easily introduce a race condition. It goes
702/// like this:
703///
704/// 1. You get the path to the current executable using `current_exe()`, and
705/// store it in a variable.
706/// 2. Time passes. A malicious actor removes the current executable, and
707/// replaces it with a malicious one.
708/// 3. You then use the stored path to re-execute the current
709/// executable.
710///
711/// You expected to safely execute the current executable, but you're
712/// instead executing something completely different. The code you
713/// just executed run with your privileges.
714///
715/// This sort of behavior has been known to [lead to privilege escalation] when
716/// used incorrectly.
717///
718/// [lead to privilege escalation]: https://securityvulns.com/Wdocument183.html
719///
720/// # Examples
721///
722/// ```
723/// use std::env;
724///
725/// match env::current_exe() {
726/// Ok(exe_path) => println!("Path of this executable is: {}",
727/// exe_path.display()),
728/// Err(e) => println!("failed to get current exe path: {e}"),
729/// };
730/// ```
731#[stable(feature = "env", since = "1.0.0")]
732pub fn current_exe() -> io::Result<PathBuf> {
733 os_imp::current_exe()
734}
735
736/// An iterator over the arguments of a process, yielding a [`String`] value for
737/// each argument.
738///
739/// This struct is created by [`env::args()`]. See its documentation
740/// for more.
741///
742/// The first element is traditionally the path of the executable, but it can be
743/// set to arbitrary text, and might not even exist. This means this property
744/// should not be relied upon for security purposes.
745///
746/// [`env::args()`]: args
747#[must_use = "iterators are lazy and do nothing unless consumed"]
748#[stable(feature = "env", since = "1.0.0")]
749pub struct Args {
750 inner: ArgsOs,
751}
752
753/// An iterator over the arguments of a process, yielding an [`OsString`] value
754/// for each argument.
755///
756/// This struct is created by [`env::args_os()`]. See its documentation
757/// for more.
758///
759/// The first element is traditionally the path of the executable, but it can be
760/// set to arbitrary text, and might not even exist. This means this property
761/// should not be relied upon for security purposes.
762///
763/// [`env::args_os()`]: args_os
764#[must_use = "iterators are lazy and do nothing unless consumed"]
765#[stable(feature = "env", since = "1.0.0")]
766pub struct ArgsOs {
767 inner: sys::args::Args,
768}
769
770/// Returns the arguments that this program was started with (normally passed
771/// via the command line).
772///
773/// The first element is traditionally the path of the executable, but it can be
774/// set to arbitrary text, and might not even exist. This means this property should
775/// not be relied upon for security purposes.
776///
777/// On Unix systems the shell usually expands unquoted arguments with glob patterns
778/// (such as `*` and `?`). On Windows this is not done, and such arguments are
779/// passed as-is.
780///
781/// On glibc Linux systems, arguments are retrieved by placing a function in `.init_array`.
782/// glibc passes `argc`, `argv`, and `envp` to functions in `.init_array`, as a non-standard
783/// extension. This allows `std::env::args` to work even in a `cdylib` or `staticlib`, as it
784/// does on macOS and Windows.
785///
786/// # Panics
787///
788/// The returned iterator will panic during iteration if any argument to the
789/// process is not valid Unicode. If this is not desired,
790/// use the [`args_os`] function instead.
791///
792/// # Examples
793///
794/// ```
795/// use std::env;
796///
797/// // Prints each argument on a separate line
798/// for argument in env::args() {
799/// println!("{argument}");
800/// }
801/// ```
802#[stable(feature = "env", since = "1.0.0")]
803pub fn args() -> Args {
804 Args { inner: args_os() }
805}
806
807/// Returns the arguments that this program was started with (normally passed
808/// via the command line).
809///
810/// The first element is traditionally the path of the executable, but it can be
811/// set to arbitrary text, and might not even exist. This means this property should
812/// not be relied upon for security purposes.
813///
814/// On Unix systems the shell usually expands unquoted arguments with glob patterns
815/// (such as `*` and `?`). On Windows this is not done, and such arguments are
816/// passed as-is.
817///
818/// On glibc Linux systems, arguments are retrieved by placing a function in `.init_array`.
819/// glibc passes `argc`, `argv`, and `envp` to functions in `.init_array`, as a non-standard
820/// extension. This allows `std::env::args_os` to work even in a `cdylib` or `staticlib`, as it
821/// does on macOS and Windows.
822///
823/// Note that the returned iterator will not check if the arguments to the
824/// process are valid Unicode. If you want to panic on invalid UTF-8,
825/// use the [`args`] function instead.
826///
827/// # Examples
828///
829/// ```
830/// use std::env;
831///
832/// // Prints each argument on a separate line
833/// for argument in env::args_os() {
834/// println!("{argument:?}");
835/// }
836/// ```
837#[stable(feature = "env", since = "1.0.0")]
838pub fn args_os() -> ArgsOs {
839 ArgsOs { inner: sys::args::args() }
840}
841
842#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
843impl !Send for Args {}
844
845#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
846impl !Sync for Args {}
847
848#[stable(feature = "env", since = "1.0.0")]
849impl Iterator for Args {
850 type Item = String;
851 fn next(&mut self) -> Option<String> {
852 self.inner.next().map(|s: OsString| s.into_string().unwrap())
853 }
854 fn size_hint(&self) -> (usize, Option<usize>) {
855 self.inner.size_hint()
856 }
857}
858
859#[stable(feature = "env", since = "1.0.0")]
860impl ExactSizeIterator for Args {
861 fn len(&self) -> usize {
862 self.inner.len()
863 }
864 fn is_empty(&self) -> bool {
865 self.inner.is_empty()
866 }
867}
868
869#[stable(feature = "env_iterators", since = "1.12.0")]
870impl DoubleEndedIterator for Args {
871 fn next_back(&mut self) -> Option<String> {
872 self.inner.next_back().map(|s: OsString| s.into_string().unwrap())
873 }
874}
875
876#[stable(feature = "std_debug", since = "1.16.0")]
877impl fmt::Debug for Args {
878 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
879 let Self { inner: ArgsOs { inner: &Args } } = self;
880 f.debug_struct("Args").field(name:"inner", value:inner).finish()
881 }
882}
883
884#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
885impl !Send for ArgsOs {}
886
887#[stable(feature = "env_unimpl_send_sync", since = "1.26.0")]
888impl !Sync for ArgsOs {}
889
890#[stable(feature = "env", since = "1.0.0")]
891impl Iterator for ArgsOs {
892 type Item = OsString;
893 fn next(&mut self) -> Option<OsString> {
894 self.inner.next()
895 }
896 fn size_hint(&self) -> (usize, Option<usize>) {
897 self.inner.size_hint()
898 }
899}
900
901#[stable(feature = "env", since = "1.0.0")]
902impl ExactSizeIterator for ArgsOs {
903 fn len(&self) -> usize {
904 self.inner.len()
905 }
906 fn is_empty(&self) -> bool {
907 self.inner.is_empty()
908 }
909}
910
911#[stable(feature = "env_iterators", since = "1.12.0")]
912impl DoubleEndedIterator for ArgsOs {
913 fn next_back(&mut self) -> Option<OsString> {
914 self.inner.next_back()
915 }
916}
917
918#[stable(feature = "std_debug", since = "1.16.0")]
919impl fmt::Debug for ArgsOs {
920 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
921 let Self { inner: &Args } = self;
922 f.debug_struct("ArgsOs").field(name:"inner", value:inner).finish()
923 }
924}
925
926/// Constants associated with the current target
927#[stable(feature = "env", since = "1.0.0")]
928pub mod consts {
929 use crate::sys::env::os;
930
931 /// A string describing the architecture of the CPU that is currently
932 /// in use.
933 ///
934 /// Some possible values:
935 ///
936 /// - x86
937 /// - x86_64
938 /// - arm
939 /// - aarch64
940 /// - loongarch64
941 /// - m68k
942 /// - csky
943 /// - mips
944 /// - mips64
945 /// - powerpc
946 /// - powerpc64
947 /// - riscv64
948 /// - s390x
949 /// - sparc64
950 #[stable(feature = "env", since = "1.0.0")]
951 pub const ARCH: &str = env!("STD_ENV_ARCH");
952
953 /// The family of the operating system. Example value is `unix`.
954 ///
955 /// Some possible values:
956 ///
957 /// - unix
958 /// - windows
959 #[stable(feature = "env", since = "1.0.0")]
960 pub const FAMILY: &str = os::FAMILY;
961
962 /// A string describing the specific operating system in use.
963 /// Example value is `linux`.
964 ///
965 /// Some possible values:
966 ///
967 /// - linux
968 /// - macos
969 /// - ios
970 /// - freebsd
971 /// - dragonfly
972 /// - netbsd
973 /// - openbsd
974 /// - solaris
975 /// - android
976 /// - windows
977 #[stable(feature = "env", since = "1.0.0")]
978 pub const OS: &str = os::OS;
979
980 /// Specifies the filename prefix used for shared libraries on this
981 /// platform. Example value is `lib`.
982 ///
983 /// Some possible values:
984 ///
985 /// - lib
986 /// - `""` (an empty string)
987 #[stable(feature = "env", since = "1.0.0")]
988 pub const DLL_PREFIX: &str = os::DLL_PREFIX;
989
990 /// Specifies the filename suffix used for shared libraries on this
991 /// platform. Example value is `.so`.
992 ///
993 /// Some possible values:
994 ///
995 /// - .so
996 /// - .dylib
997 /// - .dll
998 #[stable(feature = "env", since = "1.0.0")]
999 pub const DLL_SUFFIX: &str = os::DLL_SUFFIX;
1000
1001 /// Specifies the file extension used for shared libraries on this
1002 /// platform that goes after the dot. Example value is `so`.
1003 ///
1004 /// Some possible values:
1005 ///
1006 /// - so
1007 /// - dylib
1008 /// - dll
1009 #[stable(feature = "env", since = "1.0.0")]
1010 pub const DLL_EXTENSION: &str = os::DLL_EXTENSION;
1011
1012 /// Specifies the filename suffix used for executable binaries on this
1013 /// platform. Example value is `.exe`.
1014 ///
1015 /// Some possible values:
1016 ///
1017 /// - .exe
1018 /// - .nexe
1019 /// - .pexe
1020 /// - `""` (an empty string)
1021 #[stable(feature = "env", since = "1.0.0")]
1022 pub const EXE_SUFFIX: &str = os::EXE_SUFFIX;
1023
1024 /// Specifies the file extension, if any, used for executable binaries
1025 /// on this platform. Example value is `exe`.
1026 ///
1027 /// Some possible values:
1028 ///
1029 /// - exe
1030 /// - `""` (an empty string)
1031 #[stable(feature = "env", since = "1.0.0")]
1032 pub const EXE_EXTENSION: &str = os::EXE_EXTENSION;
1033}
1034