library/std/src/env.rs

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