//! Temporary files and directories. //! //! - Use the [`tempfile()`] function for temporary files //! - Use the [`tempdir()`] function for temporary directories. //! //! # Design //! //! This crate provides several approaches to creating temporary files and directories. //! [`tempfile()`] relies on the OS to remove the temporary file once the last handle is closed. //! [`TempDir`] and [`NamedTempFile`] both rely on Rust destructors for cleanup. //! //! When choosing between the temporary file variants, prefer `tempfile` //! unless you either need to know the file's path or to be able to persist it. //! //! ## Resource Leaking //! //! `tempfile` will (almost) never fail to cleanup temporary resources. However `TempDir` and //! `NamedTempFile` will fail if their destructors don't run. This is because `tempfile` relies on //! the OS to cleanup the underlying file, while `TempDir` and `NamedTempFile` rely on rust //! destructors to do so. Destructors may fail to run if the process exits through an unhandled //! signal interrupt (like `SIGINT`), or if the instance is declared statically (like with //! [`lazy_static`]), among other possible reasons. //! //! ## Unexpected File Deletion //! //! Most operating systems periodically clean up temporary files that haven't been accessed recently //! (often on the order of multiple days). This issue does not affect unnamed temporary files but //! can invalidate the paths associated with named temporary files on Unix-like systems because the //! temporary file can be unlinked from the filesystem while still open and in-use. See the //! [temporary file cleaner](#temporary-file-cleaners) section for more security implications. //! //! ## Security //! //! This section discusses security issues relevant to Unix-like operating systems that use shared //! temporary directories by default. Importantly, it's not relevant for Windows or macOS as both //! operating systems use private per-user temporary directories by default. //! //! Applications can mitigate the issues described below by using [`env::override_temp_dir`] to //! change the default temporary directory but should do so if and only if default the temporary //! directory ([`env::temp_dir`]) is unsuitable (is world readable, world writable, managed by a //! temporary file cleaner, etc.). //! //! ### Temporary File Cleaners //! //! In the presence of pathological temporary file cleaner, relying on file paths is unsafe because //! a temporary file cleaner could delete the temporary file which an attacker could then replace. //! //! This isn't an issue for [`tempfile`] as it doesn't rely on file paths. However, [`NamedTempFile`] //! and temporary directories _do_ rely on file paths for _some_ operations. See the security //! documentation on the [`NamedTempFile`] and the [`TempDir`] types for more information. //! //! Mitigation: //! //! - This is rarely an issue for short-lived files as temporary file cleaners usually only remove //! temporary files that haven't been modified or accessed within many (10-30) days. //! - Very long lived temporary files should be placed in directories not managed by temporary file //! cleaners. //! //! ### Access Permissions //! //! Temporary _files_ created with this library are private by default on all operating systems. //! However, temporary _directories_ are created with the default permissions and will therefore be //! world-readable by default unless the user has changed their umask and/or default temporary //! directory. //! //! ### Denial of Service //! //! If the file-name randomness ([`Builder::rand_bytes`]) is too small and/or this crate is built //! without the `getrandom` feature, it may be possible for an attacker to predict the random file //! names chosen by this library, preventing temporary file creation by creating temporary files //! with these predicted file names. By default, this library mitigates this denial of service //! attack by: //! //! 1. Defaulting to 6 random characters per temporary file forcing an attacker to create billions //! of files before random collisions are expected (at which point you probably have larger //! problems). //! 2. Re-seeding the random filename generator from system randomness after 3 failed attempts to //! create temporary a file (when the `getrandom` feature is enabled as it is by default on all //! major platforms). //! //! ## Early drop pitfall //! //! Because `TempDir` and `NamedTempFile` rely on their destructors for cleanup, this can lead //! to an unexpected early removal of the directory/file, usually when working with APIs which are //! generic over `AsRef`. Consider the following example: //! //! ```no_run //! use tempfile::tempdir; //! use std::process::Command; //! //! // Create a directory inside of `env::temp_dir()`. //! let temp_dir = tempdir()?; //! //! // Spawn the `touch` command inside the temporary directory and collect the exit status //! // Note that `temp_dir` is **not** moved into `current_dir`, but passed as a reference //! let exit_status = Command::new("touch").arg("tmp").current_dir(&temp_dir).status()?; //! assert!(exit_status.success()); //! //! # Ok::<(), std::io::Error>(()) //! ``` //! //! This works because a reference to `temp_dir` is passed to `current_dir`, resulting in the //! destructor of `temp_dir` being run after the `Command` has finished execution. Moving the //! `TempDir` into the `current_dir` call would result in the `TempDir` being converted into //! an internal representation, with the original value being dropped and the directory thus //! being deleted, before the command can be executed. //! //! The `touch` command would fail with an `No such file or directory` error. //! //! ## Examples //! //! Create a temporary file and write some data into it: //! //! ``` //! use tempfile::tempfile; //! use std::io::Write; //! //! // Create a file inside of `env::temp_dir()`. //! let mut file = tempfile()?; //! //! writeln!(file, "Brian was here. Briefly.")?; //! # Ok::<(), std::io::Error>(()) //! ``` //! //! Create a named temporary file and open an independent file handle: //! //! ``` //! use tempfile::NamedTempFile; //! use std::io::{Write, Read}; //! //! let text = "Brian was here. Briefly."; //! //! // Create a file inside of `env::temp_dir()`. //! let mut file1 = NamedTempFile::new()?; //! //! // Re-open it. //! let mut file2 = file1.reopen()?; //! //! // Write some test data to the first handle. //! file1.write_all(text.as_bytes())?; //! //! // Read the test data using the second handle. //! let mut buf = String::new(); //! file2.read_to_string(&mut buf)?; //! assert_eq!(buf, text); //! # Ok::<(), std::io::Error>(()) //! ``` //! //! Create a temporary directory and add a file to it: //! //! ``` //! use tempfile::tempdir; //! use std::fs::File; //! use std::io::Write; //! //! // Create a directory inside of `env::temp_dir()`. //! let dir = tempdir()?; //! //! let file_path = dir.path().join("my-temporary-note.txt"); //! let mut file = File::create(file_path)?; //! writeln!(file, "Brian was here. Briefly.")?; //! //! // By closing the `TempDir` explicitly, we can check that it has //! // been deleted successfully. If we don't close it explicitly, //! // the directory will still be deleted when `dir` goes out //! // of scope, but we won't know whether deleting the directory //! // succeeded. //! drop(file); //! dir.close()?; //! # Ok::<(), std::io::Error>(()) //! ``` //! //! [`tempfile()`]: fn.tempfile.html //! [`tempdir()`]: fn.tempdir.html //! [`TempDir`]: struct.TempDir.html //! [`NamedTempFile`]: struct.NamedTempFile.html //! [`lazy_static`]: https://github.com/rust-lang-nursery/lazy-static.rs/issues/62 #![doc( html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png", html_favicon_url = "https://www.rust-lang.org/favicon.ico", html_root_url = "https://docs.rs/tempfile/latest" )] #![cfg_attr(test, deny(warnings))] #![deny(rust_2018_idioms)] #![allow(clippy::redundant_field_names)] // wasip2 conditionally gates stdlib APIs. // https://github.com/rust-lang/rust/issues/130323 #![cfg_attr( all(feature = "nightly", target_os = "wasi", target_env = "p2"), feature(wasip2) )] #![cfg_attr(all(feature = "nightly", target_os = "wasi"), feature(wasi_ext))] #[cfg(doctest)] doc_comment::doctest!("../README.md"); const NUM_RETRIES: u32 = 65536; const NUM_RAND_CHARS: usize = 6; use std::ffi::OsStr; use std::fs::OpenOptions; use std::io; use std::path::Path; mod dir; mod error; mod file; mod spooled; mod util; pub mod env; pub use crate::dir::{tempdir, tempdir_in, TempDir}; pub use crate::file::{ tempfile, tempfile_in, NamedTempFile, PathPersistError, PersistError, TempPath, }; pub use crate::spooled::{spooled_tempfile, SpooledData, SpooledTempFile}; /// Create a new temporary file or directory with custom options. #[derive(Debug, Clone, Eq, PartialEq)] pub struct Builder<'a, 'b> { random_len: usize, prefix: &'a OsStr, suffix: &'b OsStr, append: bool, permissions: Option, keep: bool, } impl Default for Builder<'_, '_> { fn default() -> Self { Builder { random_len: crate::NUM_RAND_CHARS, prefix: OsStr::new(".tmp"), suffix: OsStr::new(""), append: false, permissions: None, keep: false, } } } impl<'a, 'b> Builder<'a, 'b> { /// Create a new `Builder`. /// /// # Examples /// /// Create a named temporary file and write some data into it: /// /// ``` /// use std::ffi::OsStr; /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .prefix("my-temporary-note") /// .suffix(".txt") /// .rand_bytes(5) /// .tempfile()?; /// /// let name = named_tempfile /// .path() /// .file_name().and_then(OsStr::to_str); /// /// if let Some(name) = name { /// assert!(name.starts_with("my-temporary-note")); /// assert!(name.ends_with(".txt")); /// assert_eq!(name.len(), "my-temporary-note.txt".len() + 5); /// } /// # Ok::<(), std::io::Error>(()) /// ``` /// /// Create a temporary directory and add a file to it: /// /// ``` /// use std::io::Write; /// use std::fs::File; /// use std::ffi::OsStr; /// use tempfile::Builder; /// /// let dir = Builder::new() /// .prefix("my-temporary-dir") /// .rand_bytes(5) /// .tempdir()?; /// /// let file_path = dir.path().join("my-temporary-note.txt"); /// let mut file = File::create(file_path)?; /// writeln!(file, "Brian was here. Briefly.")?; /// /// // By closing the `TempDir` explicitly, we can check that it has /// // been deleted successfully. If we don't close it explicitly, /// // the directory will still be deleted when `dir` goes out /// // of scope, but we won't know whether deleting the directory /// // succeeded. /// drop(file); /// dir.close()?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// Create a temporary directory with a chosen prefix under a chosen folder: /// /// ```no_run /// use tempfile::Builder; /// /// let dir = Builder::new() /// .prefix("my-temporary-dir") /// .tempdir_in("folder-with-tempdirs")?; /// # Ok::<(), std::io::Error>(()) /// ``` #[must_use] pub fn new() -> Self { Self::default() } /// Set a custom filename prefix. /// /// Path separators are legal but not advisable. /// Default: `.tmp`. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .prefix("my-temporary-note") /// .tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` pub fn prefix + ?Sized>(&mut self, prefix: &'a S) -> &mut Self { self.prefix = prefix.as_ref(); self } /// Set a custom filename suffix. /// /// Path separators are legal but not advisable. /// Default: empty. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .suffix(".txt") /// .tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` pub fn suffix + ?Sized>(&mut self, suffix: &'b S) -> &mut Self { self.suffix = suffix.as_ref(); self } /// Set the number of random bytes. /// /// Default: `6`. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .rand_bytes(5) /// .tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` pub fn rand_bytes(&mut self, rand: usize) -> &mut Self { self.random_len = rand; self } /// Set the file to be opened in append mode. /// /// Default: `false`. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .append(true) /// .tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` pub fn append(&mut self, append: bool) -> &mut Self { self.append = append; self } /// The permissions to create the tempfile or [tempdir](Self::tempdir) with. /// /// # Security /// /// By default, the permissions of tempfiles on Unix are set for it to be /// readable and writable by the owner only, yielding the greatest amount /// of security. /// As this method allows to widen the permissions, security would be /// reduced in such cases. /// /// # Platform Notes /// ## Unix /// /// The actual permission bits set on the tempfile or tempdir will be affected by the `umask` /// applied by the underlying syscall. The actual permission bits are calculated via /// `permissions & !umask`. /// /// Permissions default to `0o600` for tempfiles and `0o777` for tempdirs. Note, this doesn't /// include effects of the current `umask`. For example, combined with the standard umask /// `0o022`, the defaults yield `0o600` for tempfiles and `0o755` for tempdirs. /// /// ## Windows and others /// /// This setting is unsupported and trying to set a file or directory read-only /// will return an error. /// /// # Examples /// /// Create a named temporary file that is world-readable. /// /// ``` /// # #[cfg(unix)] /// # { /// use tempfile::Builder; /// use std::os::unix::fs::PermissionsExt; /// /// let all_read_write = std::fs::Permissions::from_mode(0o666); /// let tempfile = Builder::new().permissions(all_read_write).tempfile()?; /// let actual_permissions = tempfile.path().metadata()?.permissions(); /// assert_ne!( /// actual_permissions.mode() & !0o170000, /// 0o600, /// "we get broader permissions than the default despite umask" /// ); /// # } /// # Ok::<(), std::io::Error>(()) /// ``` /// /// Create a named temporary directory that is restricted to the owner. /// /// ``` /// # #[cfg(unix)] /// # { /// use tempfile::Builder; /// use std::os::unix::fs::PermissionsExt; /// /// let owner_rwx = std::fs::Permissions::from_mode(0o700); /// let tempdir = Builder::new().permissions(owner_rwx).tempdir()?; /// let actual_permissions = tempdir.path().metadata()?.permissions(); /// assert_eq!( /// actual_permissions.mode() & !0o170000, /// 0o700, /// "we get the narrow permissions we asked for" /// ); /// # } /// # Ok::<(), std::io::Error>(()) /// ``` pub fn permissions(&mut self, permissions: std::fs::Permissions) -> &mut Self { self.permissions = Some(permissions); self } /// Set the file/folder to be kept even when the [`NamedTempFile`]/[`TempDir`] goes out of /// scope. /// /// By default, the file/folder is automatically cleaned up in the destructor of /// [`NamedTempFile`]/[`TempDir`]. When `keep` is set to `true`, this behavior is supressed. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let named_tempfile = Builder::new() /// .keep(true) /// .tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` pub fn keep(&mut self, keep: bool) -> &mut Self { self.keep = keep; self } /// Create the named temporary file. /// /// # Security /// /// See [the security][security] docs on `NamedTempFile`. /// /// # Resource leaking /// /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`. /// /// # Errors /// /// If the file cannot be created, `Err` is returned. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let tempfile = Builder::new().tempfile()?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// [security]: struct.NamedTempFile.html#security /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking pub fn tempfile(&self) -> io::Result { self.tempfile_in(env::temp_dir()) } /// Create the named temporary file in the specified directory. /// /// # Security /// /// See [the security][security] docs on `NamedTempFile`. /// /// # Resource leaking /// /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`. /// /// # Errors /// /// If the file cannot be created, `Err` is returned. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let tempfile = Builder::new().tempfile_in("./")?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// [security]: struct.NamedTempFile.html#security /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking pub fn tempfile_in>(&self, dir: P) -> io::Result { util::create_helper( dir.as_ref(), self.prefix, self.suffix, self.random_len, |path| { file::create_named( path, OpenOptions::new().append(self.append), self.permissions.as_ref(), self.keep, ) }, ) } /// Attempts to make a temporary directory inside of [`env::temp_dir()`] whose /// name will have the prefix, `prefix`. The directory and /// everything inside it will be automatically deleted once the /// returned `TempDir` is destroyed. /// /// # Resource leaking /// /// See [the resource leaking][resource-leaking] docs on `TempDir`. /// /// # Errors /// /// If the directory can not be created, `Err` is returned. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let tmp_dir = Builder::new().tempdir()?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// [resource-leaking]: struct.TempDir.html#resource-leaking pub fn tempdir(&self) -> io::Result { self.tempdir_in(env::temp_dir()) } /// Attempts to make a temporary directory inside of `dir`. /// The directory and everything inside it will be automatically /// deleted once the returned `TempDir` is destroyed. /// /// # Resource leaking /// /// See [the resource leaking][resource-leaking] docs on `TempDir`. /// /// # Errors /// /// If the directory can not be created, `Err` is returned. /// /// # Examples /// /// ``` /// use tempfile::Builder; /// /// let tmp_dir = Builder::new().tempdir_in("./")?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// [resource-leaking]: struct.TempDir.html#resource-leaking pub fn tempdir_in>(&self, dir: P) -> io::Result { let storage; let mut dir = dir.as_ref(); if !dir.is_absolute() { let cur_dir = std::env::current_dir()?; storage = cur_dir.join(dir); dir = &storage; } util::create_helper(dir, self.prefix, self.suffix, self.random_len, |path| { dir::create(path, self.permissions.as_ref(), self.keep) }) } /// Attempts to create a temporary file (or file-like object) using the /// provided closure. The closure is passed a temporary file path and /// returns an [`std::io::Result`]. The path provided to the closure will be /// inside of [`env::temp_dir()`]. Use [`Builder::make_in`] to provide /// a custom temporary directory. If the closure returns one of the /// following errors, then another randomized file path is tried: /// - [`std::io::ErrorKind::AlreadyExists`] /// - [`std::io::ErrorKind::AddrInUse`] /// /// This can be helpful for taking full control over the file creation, but /// leaving the temporary file path construction up to the library. This /// also enables creating a temporary UNIX domain socket, since it is not /// possible to bind to a socket that already exists. /// /// Note that [`Builder::append`] is ignored when using [`Builder::make`]. /// /// # Security /// /// This has the same [security implications][security] as /// [`NamedTempFile`], but with additional caveats. Specifically, it is up /// to the closure to ensure that the file does not exist and that such a /// check is *atomic*. Otherwise, a [time-of-check to time-of-use /// bug][TOCTOU] could be introduced. /// /// For example, the following is **not** secure: /// /// ``` /// use std::fs::File; /// use tempfile::Builder; /// /// // This is NOT secure! /// let tempfile = Builder::new().make(|path| { /// if path.is_file() { /// return Err(std::io::ErrorKind::AlreadyExists.into()); /// } /// /// // Between the check above and the usage below, an attacker could /// // have replaced `path` with another file, which would get truncated /// // by `File::create`. /// /// File::create(path) /// })?; /// # Ok::<(), std::io::Error>(()) /// ``` /// /// Note that simply using [`std::fs::File::create`] alone is not correct /// because it does not fail if the file already exists: /// /// ``` /// use tempfile::Builder; /// use std::fs::File; /// /// // This could overwrite an existing file! /// let tempfile = Builder::new().make(|path| File::create(path))?; /// # Ok::<(), std::io::Error>(()) /// ``` /// For creating regular temporary files, use [`Builder::tempfile`] instead /// to avoid these problems. This function is meant to enable more exotic /// use-cases. /// /// # Resource leaking /// /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`. /// /// # Errors /// /// If the closure returns any error besides /// [`std::io::ErrorKind::AlreadyExists`] or /// [`std::io::ErrorKind::AddrInUse`], then `Err` is returned. /// /// # Examples /// ``` /// # #[cfg(unix)] /// # { /// use std::os::unix::net::UnixListener; /// use tempfile::Builder; /// /// let tempsock = Builder::new().make(|path| UnixListener::bind(path))?; /// # } /// # Ok::<(), std::io::Error>(()) /// ``` /// /// [TOCTOU]: https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use /// [security]: struct.NamedTempFile.html#security /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking pub fn make(&self, f: F) -> io::Result> where F: FnMut(&Path) -> io::Result, { self.make_in(env::temp_dir(), f) } /// This is the same as [`Builder::make`], except `dir` is used as the base /// directory for the temporary file path. /// /// See [`Builder::make`] for more details and security implications. /// /// # Examples /// ``` /// # #[cfg(unix)] /// # { /// use tempfile::Builder; /// use std::os::unix::net::UnixListener; /// /// let tempsock = Builder::new().make_in("./", |path| UnixListener::bind(path))?; /// # } /// # Ok::<(), std::io::Error>(()) /// ``` pub fn make_in(&self, dir: P, mut f: F) -> io::Result> where F: FnMut(&Path) -> io::Result, P: AsRef, { util::create_helper( dir.as_ref(), self.prefix, self.suffix, self.random_len, move |path| { Ok(NamedTempFile::from_parts( f(&path)?, TempPath::new(path, self.keep), )) }, ) } }