tempfile/lib.rs
1//! This is a library for creating temporary files and directories that are automatically deleted
2//! when no longer referenced (i.e., on drop).
3//!
4//! - Use [`tempfile()`] when you need a real [`std::fs::File`] but don't need to refer to it
5//! by-path.
6//! - Use [`NamedTempFile::new()`] when you need a _named_ temporary file that can be refered to its
7//! path.
8//! - Use [`tempdir()`] when you need a temporary directory that will be recursively deleted on drop.
9//! - Use [`spooled_tempfile()`] when you need an in-memory buffer that will ultimately be backed by
10//! a temporary file if it gets too large.
11//!
12//! # Design
13//!
14//! This crate provides several approaches to creating temporary files and directories.
15//! [`tempfile()`] relies on the OS to remove the temporary file once the last handle is closed.
16//! [`TempDir`] and [`NamedTempFile`] both rely on Rust destructors for cleanup.
17//!
18//! ## Resource Leaking
19//!
20//! `tempfile` will (almost) never fail to cleanup temporary resources. However `TempDir` and
21//! `NamedTempFile` will fail if their destructors don't run. This is because `tempfile` relies on
22//! the OS to cleanup the underlying file, while `TempDir` and `NamedTempFile` rely on rust
23//! destructors to do so. Destructors may fail to run if the process exits through an unhandled
24//! signal interrupt (like `SIGINT`), or if the instance is declared statically (like with
25//! [`lazy_static`]), among other possible reasons.
26//!
27//! ## Unexpected File Deletion
28//!
29//! Most operating systems periodically clean up temporary files that haven't been accessed recently
30//! (often on the order of multiple days). This issue does not affect unnamed temporary files but
31//! can invalidate the paths associated with named temporary files on Unix-like systems because the
32//! temporary file can be unlinked from the filesystem while still open and in-use. See the
33//! [temporary file cleaner](#temporary-file-cleaners) section for more security implications.
34//!
35//! ## Security
36//!
37//! This section discusses security issues relevant to Unix-like operating systems that use shared
38//! temporary directories by default. Importantly, it's not relevant for Windows or macOS as both
39//! operating systems use private per-user temporary directories by default.
40//!
41//! Applications can mitigate the issues described below by using [`env::override_temp_dir`] to
42//! change the default temporary directory but should do so if and only if default the temporary
43//! directory ([`env::temp_dir`]) is unsuitable (is world readable, world writable, managed by a
44//! temporary file cleaner, etc.).
45//!
46//! ### Temporary File Cleaners
47//!
48//! In the presence of pathological temporary file cleaner, relying on file paths is unsafe because
49//! a temporary file cleaner could delete the temporary file which an attacker could then replace.
50//!
51//! This isn't an issue for [`tempfile`] as it doesn't rely on file paths. However, [`NamedTempFile`]
52//! and temporary directories _do_ rely on file paths for _some_ operations. See the security
53//! documentation on the [`NamedTempFile`] and the [`TempDir`] types for more information.
54//!
55//! Mitigation:
56//!
57//! - This is rarely an issue for short-lived files as temporary file cleaners usually only remove
58//! temporary files that haven't been modified or accessed within many (10-30) days.
59//! - Very long lived temporary files should be placed in directories not managed by temporary file
60//! cleaners.
61//!
62//! ### Access Permissions
63//!
64//! Temporary _files_ created with this library are private by default on all operating systems.
65//! However, temporary _directories_ are created with the default permissions and will therefore be
66//! world-readable by default unless the user has changed their umask and/or default temporary
67//! directory.
68//!
69//! ### Denial of Service
70//!
71//! If the file-name randomness ([`Builder::rand_bytes`]) is too small and/or this crate is built
72//! without the `getrandom` feature, it may be possible for an attacker to predict the random file
73//! names chosen by this library, preventing temporary file creation by creating temporary files
74//! with these predicted file names. By default, this library mitigates this denial of service
75//! attack by:
76//!
77//! 1. Defaulting to 6 random characters per temporary file forcing an attacker to create billions
78//! of files before random collisions are expected (at which point you probably have larger
79//! problems).
80//! 2. Re-seeding the random filename generator from system randomness after 3 failed attempts to
81//! create temporary a file (when the `getrandom` feature is enabled as it is by default on all
82//! major platforms).
83//!
84//! ## Early drop pitfall
85//!
86//! Because `TempDir` and `NamedTempFile` rely on their destructors for cleanup, this can lead
87//! to an unexpected early removal of the directory/file, usually when working with APIs which are
88//! generic over `AsRef<Path>`. Consider the following example:
89//!
90//! ```no_run
91//! use tempfile::tempdir;
92//! use std::process::Command;
93//!
94//! // Create a directory inside of `env::temp_dir()`.
95//! let temp_dir = tempdir()?;
96//!
97//! // Spawn the `touch` command inside the temporary directory and collect the exit status
98//! // Note that `temp_dir` is **not** moved into `current_dir`, but passed as a reference
99//! let exit_status = Command::new("touch").arg("tmp").current_dir(&temp_dir).status()?;
100//! assert!(exit_status.success());
101//!
102//! # Ok::<(), std::io::Error>(())
103//! ```
104//!
105//! This works because a reference to `temp_dir` is passed to `current_dir`, resulting in the
106//! destructor of `temp_dir` being run after the `Command` has finished execution. Moving the
107//! `TempDir` into the `current_dir` call would result in the `TempDir` being converted into
108//! an internal representation, with the original value being dropped and the directory thus
109//! being deleted, before the command can be executed.
110//!
111//! The `touch` command would fail with an `No such file or directory` error.
112//!
113//! ## Examples
114//!
115//! Create a temporary file and write some data into it:
116//!
117//! ```
118//! use tempfile::tempfile;
119//! use std::io::Write;
120//!
121//! // Create a file inside of `env::temp_dir()`.
122//! let mut file = tempfile()?;
123//!
124//! writeln!(file, "Brian was here. Briefly.")?;
125//! # Ok::<(), std::io::Error>(())
126//! ```
127//!
128//! Create a named temporary file and open an independent file handle:
129//!
130//! ```
131//! use tempfile::NamedTempFile;
132//! use std::io::{Write, Read};
133//!
134//! let text = "Brian was here. Briefly.";
135//!
136//! // Create a file inside of `env::temp_dir()`.
137//! let mut file1 = NamedTempFile::new()?;
138//!
139//! // Re-open it.
140//! let mut file2 = file1.reopen()?;
141//!
142//! // Write some test data to the first handle.
143//! file1.write_all(text.as_bytes())?;
144//!
145//! // Read the test data using the second handle.
146//! let mut buf = String::new();
147//! file2.read_to_string(&mut buf)?;
148//! assert_eq!(buf, text);
149//! # Ok::<(), std::io::Error>(())
150//! ```
151//!
152//! Create a temporary directory and add a file to it:
153//!
154//! ```
155//! use tempfile::tempdir;
156//! use std::fs::File;
157//! use std::io::Write;
158//!
159//! // Create a directory inside of `env::temp_dir()`.
160//! let dir = tempdir()?;
161//!
162//! let file_path = dir.path().join("my-temporary-note.txt");
163//! let mut file = File::create(file_path)?;
164//! writeln!(file, "Brian was here. Briefly.")?;
165//!
166//! // By closing the `TempDir` explicitly, we can check that it has
167//! // been deleted successfully. If we don't close it explicitly,
168//! // the directory will still be deleted when `dir` goes out
169//! // of scope, but we won't know whether deleting the directory
170//! // succeeded.
171//! drop(file);
172//! dir.close()?;
173//! # Ok::<(), std::io::Error>(())
174//! ```
175//!
176//! [`tempfile()`]: fn.tempfile.html
177//! [`tempdir()`]: fn.tempdir.html
178//! [`TempDir`]: struct.TempDir.html
179//! [`NamedTempFile`]: struct.NamedTempFile.html
180//! [`lazy_static`]: https://github.com/rust-lang-nursery/lazy-static.rs/issues/62
181
182#![doc(
183 html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
184 html_favicon_url = "https://www.rust-lang.org/favicon.ico",
185 html_root_url = "https://docs.rs/tempfile/latest"
186)]
187#![cfg_attr(test, deny(warnings))]
188#![deny(rust_2018_idioms)]
189#![allow(clippy::redundant_field_names)]
190// wasip2 conditionally gates stdlib APIs.
191// https://github.com/rust-lang/rust/issues/130323
192#![cfg_attr(
193 all(feature = "nightly", target_os = "wasi", target_env = "p2"),
194 feature(wasip2)
195)]
196#![cfg_attr(all(feature = "nightly", target_os = "wasi"), feature(wasi_ext))]
197
198#[cfg(doctest)]
199doc_comment::doctest!("../README.md");
200
201const NUM_RETRIES: u32 = 65536;
202const NUM_RAND_CHARS: usize = 6;
203
204use std::ffi::OsStr;
205use std::fs::OpenOptions;
206use std::io;
207use std::path::Path;
208
209mod dir;
210mod error;
211mod file;
212mod spooled;
213mod util;
214
215pub mod env;
216
217pub use crate::dir::{tempdir, tempdir_in, TempDir};
218pub use crate::file::{
219 tempfile, tempfile_in, NamedTempFile, PathPersistError, PersistError, TempPath,
220};
221pub use crate::spooled::{spooled_tempfile, spooled_tempfile_in, SpooledData, SpooledTempFile};
222
223/// Create a new temporary file or directory with custom options.
224#[derive(Debug, Clone, Eq, PartialEq)]
225pub struct Builder<'a, 'b> {
226 random_len: usize,
227 prefix: &'a OsStr,
228 suffix: &'b OsStr,
229 append: bool,
230 permissions: Option<std::fs::Permissions>,
231 disable_cleanup: bool,
232}
233
234impl Default for Builder<'_, '_> {
235 fn default() -> Self {
236 Builder {
237 random_len: crate::NUM_RAND_CHARS,
238 prefix: OsStr::new(".tmp"),
239 suffix: OsStr::new(""),
240 append: false,
241 permissions: None,
242 disable_cleanup: false,
243 }
244 }
245}
246
247impl<'a, 'b> Builder<'a, 'b> {
248 /// Create a new `Builder`.
249 ///
250 /// # Examples
251 ///
252 /// Create a named temporary file and write some data into it:
253 ///
254 /// ```
255 /// use std::ffi::OsStr;
256 /// use tempfile::Builder;
257 ///
258 /// let named_tempfile = Builder::new()
259 /// .prefix("my-temporary-note")
260 /// .suffix(".txt")
261 /// .rand_bytes(5)
262 /// .tempfile()?;
263 ///
264 /// let name = named_tempfile
265 /// .path()
266 /// .file_name().and_then(OsStr::to_str);
267 ///
268 /// if let Some(name) = name {
269 /// assert!(name.starts_with("my-temporary-note"));
270 /// assert!(name.ends_with(".txt"));
271 /// assert_eq!(name.len(), "my-temporary-note.txt".len() + 5);
272 /// }
273 /// # Ok::<(), std::io::Error>(())
274 /// ```
275 ///
276 /// Create a temporary directory and add a file to it:
277 ///
278 /// ```
279 /// use std::io::Write;
280 /// use std::fs::File;
281 /// use std::ffi::OsStr;
282 /// use tempfile::Builder;
283 ///
284 /// let dir = Builder::new()
285 /// .prefix("my-temporary-dir")
286 /// .rand_bytes(5)
287 /// .tempdir()?;
288 ///
289 /// let file_path = dir.path().join("my-temporary-note.txt");
290 /// let mut file = File::create(file_path)?;
291 /// writeln!(file, "Brian was here. Briefly.")?;
292 ///
293 /// // By closing the `TempDir` explicitly, we can check that it has
294 /// // been deleted successfully. If we don't close it explicitly,
295 /// // the directory will still be deleted when `dir` goes out
296 /// // of scope, but we won't know whether deleting the directory
297 /// // succeeded.
298 /// drop(file);
299 /// dir.close()?;
300 /// # Ok::<(), std::io::Error>(())
301 /// ```
302 ///
303 /// Create a temporary directory with a chosen prefix under a chosen folder:
304 ///
305 /// ```no_run
306 /// use tempfile::Builder;
307 ///
308 /// let dir = Builder::new()
309 /// .prefix("my-temporary-dir")
310 /// .tempdir_in("folder-with-tempdirs")?;
311 /// # Ok::<(), std::io::Error>(())
312 /// ```
313 #[must_use]
314 pub fn new() -> Self {
315 Self::default()
316 }
317
318 /// Set a custom filename prefix.
319 ///
320 /// Path separators are legal but not advisable.
321 /// Default: `.tmp`.
322 ///
323 /// # Examples
324 ///
325 /// ```
326 /// use tempfile::Builder;
327 ///
328 /// let named_tempfile = Builder::new()
329 /// .prefix("my-temporary-note")
330 /// .tempfile()?;
331 /// # Ok::<(), std::io::Error>(())
332 /// ```
333 pub fn prefix<S: AsRef<OsStr> + ?Sized>(&mut self, prefix: &'a S) -> &mut Self {
334 self.prefix = prefix.as_ref();
335 self
336 }
337
338 /// Set a custom filename suffix.
339 ///
340 /// Path separators are legal but not advisable.
341 /// Default: empty.
342 ///
343 /// # Examples
344 ///
345 /// ```
346 /// use tempfile::Builder;
347 ///
348 /// let named_tempfile = Builder::new()
349 /// .suffix(".txt")
350 /// .tempfile()?;
351 /// # Ok::<(), std::io::Error>(())
352 /// ```
353 pub fn suffix<S: AsRef<OsStr> + ?Sized>(&mut self, suffix: &'b S) -> &mut Self {
354 self.suffix = suffix.as_ref();
355 self
356 }
357
358 /// Set the number of random bytes.
359 ///
360 /// Default: `6`.
361 ///
362 /// # Examples
363 ///
364 /// ```
365 /// use tempfile::Builder;
366 ///
367 /// let named_tempfile = Builder::new()
368 /// .rand_bytes(5)
369 /// .tempfile()?;
370 /// # Ok::<(), std::io::Error>(())
371 /// ```
372 pub fn rand_bytes(&mut self, rand: usize) -> &mut Self {
373 self.random_len = rand;
374 self
375 }
376
377 /// Set the file to be opened in append mode.
378 ///
379 /// Default: `false`.
380 ///
381 /// # Examples
382 ///
383 /// ```
384 /// use tempfile::Builder;
385 ///
386 /// let named_tempfile = Builder::new()
387 /// .append(true)
388 /// .tempfile()?;
389 /// # Ok::<(), std::io::Error>(())
390 /// ```
391 pub fn append(&mut self, append: bool) -> &mut Self {
392 self.append = append;
393 self
394 }
395
396 /// The permissions to create the tempfile or [tempdir](Self::tempdir) with.
397 ///
398 /// # Security
399 ///
400 /// By default, the permissions of tempfiles on Unix are set for it to be
401 /// readable and writable by the owner only, yielding the greatest amount
402 /// of security.
403 /// As this method allows to widen the permissions, security would be
404 /// reduced in such cases.
405 ///
406 /// # Platform Notes
407 /// ## Unix
408 ///
409 /// The actual permission bits set on the tempfile or tempdir will be affected by the `umask`
410 /// applied by the underlying syscall. The actual permission bits are calculated via
411 /// `permissions & !umask`.
412 ///
413 /// Permissions default to `0o600` for tempfiles and `0o777` for tempdirs. Note, this doesn't
414 /// include effects of the current `umask`. For example, combined with the standard umask
415 /// `0o022`, the defaults yield `0o600` for tempfiles and `0o755` for tempdirs.
416 ///
417 /// ## Windows and others
418 ///
419 /// This setting is unsupported and trying to set a file or directory read-only
420 /// will return an error.
421 ///
422 /// # Examples
423 ///
424 /// Create a named temporary file that is world-readable.
425 ///
426 /// ```
427 /// # #[cfg(unix)]
428 /// # {
429 /// use tempfile::Builder;
430 /// use std::os::unix::fs::PermissionsExt;
431 ///
432 /// let all_read_write = std::fs::Permissions::from_mode(0o666);
433 /// let tempfile = Builder::new().permissions(all_read_write).tempfile()?;
434 /// let actual_permissions = tempfile.path().metadata()?.permissions();
435 /// assert_ne!(
436 /// actual_permissions.mode() & !0o170000,
437 /// 0o600,
438 /// "we get broader permissions than the default despite umask"
439 /// );
440 /// # }
441 /// # Ok::<(), std::io::Error>(())
442 /// ```
443 ///
444 /// Create a named temporary directory that is restricted to the owner.
445 ///
446 /// ```
447 /// # #[cfg(unix)]
448 /// # {
449 /// use tempfile::Builder;
450 /// use std::os::unix::fs::PermissionsExt;
451 ///
452 /// let owner_rwx = std::fs::Permissions::from_mode(0o700);
453 /// let tempdir = Builder::new().permissions(owner_rwx).tempdir()?;
454 /// let actual_permissions = tempdir.path().metadata()?.permissions();
455 /// assert_eq!(
456 /// actual_permissions.mode() & !0o170000,
457 /// 0o700,
458 /// "we get the narrow permissions we asked for"
459 /// );
460 /// # }
461 /// # Ok::<(), std::io::Error>(())
462 /// ```
463 pub fn permissions(&mut self, permissions: std::fs::Permissions) -> &mut Self {
464 self.permissions = Some(permissions);
465 self
466 }
467
468 /// Disable cleanup of the file/folder to even when the [`NamedTempFile`]/[`TempDir`] goes out
469 /// of scope. Prefer [`NamedTempFile::keep`] and `[`TempDir::keep`] where possible,
470 /// `disable_cleanup` is provided for testing & debugging.
471 ///
472 /// By default, the file/folder is automatically cleaned up in the destructor of
473 /// [`NamedTempFile`]/[`TempDir`]. When `disable_cleanup` is set to `true`, this behavior is
474 /// suppressed. If you wish to disable cleanup after creating a temporary file/directory, call
475 /// [`NamedTempFile::disable_cleanup`] or [`TempDir::disable_cleanup`].
476 ///
477 /// # Warnings
478 ///
479 /// On some platforms (for now, only Windows), temporary files are marked with a special
480 /// "temporary file" (`FILE_ATTRIBUTE_TEMPORARY`) attribute. Disabling cleanup _will not_ unset
481 /// this attribute while calling [`NamedTempFile::keep`] will.
482 ///
483 /// # Examples
484 ///
485 /// ```
486 /// use tempfile::Builder;
487 ///
488 /// let named_tempfile = Builder::new()
489 /// .disable_cleanup(true)
490 /// .tempfile()?;
491 /// # Ok::<(), std::io::Error>(())
492 /// ```
493 pub fn disable_cleanup(&mut self, disable_cleanup: bool) -> &mut Self {
494 self.disable_cleanup = disable_cleanup;
495 self
496 }
497
498 /// Deprecated alias for [`Builder::disable_cleanup`].
499 #[deprecated = "Use Builder::disable_cleanup"]
500 pub fn keep(&mut self, keep: bool) -> &mut Self {
501 self.disable_cleanup(keep)
502 }
503
504 /// Create the named temporary file.
505 ///
506 /// # Security
507 ///
508 /// See [the security][security] docs on `NamedTempFile`.
509 ///
510 /// # Resource leaking
511 ///
512 /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`.
513 ///
514 /// # Errors
515 ///
516 /// If the file cannot be created, `Err` is returned.
517 ///
518 /// # Examples
519 ///
520 /// ```
521 /// use tempfile::Builder;
522 ///
523 /// let tempfile = Builder::new().tempfile()?;
524 /// # Ok::<(), std::io::Error>(())
525 /// ```
526 ///
527 /// [security]: struct.NamedTempFile.html#security
528 /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking
529 pub fn tempfile(&self) -> io::Result<NamedTempFile> {
530 self.tempfile_in(env::temp_dir())
531 }
532
533 /// Create the named temporary file in the specified directory.
534 ///
535 /// # Security
536 ///
537 /// See [the security][security] docs on `NamedTempFile`.
538 ///
539 /// # Resource leaking
540 ///
541 /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`.
542 ///
543 /// # Errors
544 ///
545 /// If the file cannot be created, `Err` is returned.
546 ///
547 /// # Examples
548 ///
549 /// ```
550 /// use tempfile::Builder;
551 ///
552 /// let tempfile = Builder::new().tempfile_in("./")?;
553 /// # Ok::<(), std::io::Error>(())
554 /// ```
555 ///
556 /// [security]: struct.NamedTempFile.html#security
557 /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking
558 pub fn tempfile_in<P: AsRef<Path>>(&self, dir: P) -> io::Result<NamedTempFile> {
559 util::create_helper(
560 dir.as_ref(),
561 self.prefix,
562 self.suffix,
563 self.random_len,
564 |path| {
565 file::create_named(
566 path,
567 OpenOptions::new().append(self.append),
568 self.permissions.as_ref(),
569 self.disable_cleanup,
570 )
571 },
572 )
573 }
574
575 /// Attempts to make a temporary directory inside of [`env::temp_dir()`] whose
576 /// name will have the prefix, `prefix`. The directory and
577 /// everything inside it will be automatically deleted once the
578 /// returned `TempDir` is destroyed.
579 ///
580 /// # Resource leaking
581 ///
582 /// See [the resource leaking][resource-leaking] docs on `TempDir`.
583 ///
584 /// # Errors
585 ///
586 /// If the directory can not be created, `Err` is returned.
587 ///
588 /// # Examples
589 ///
590 /// ```
591 /// use tempfile::Builder;
592 ///
593 /// let tmp_dir = Builder::new().tempdir()?;
594 /// # Ok::<(), std::io::Error>(())
595 /// ```
596 ///
597 /// [resource-leaking]: struct.TempDir.html#resource-leaking
598 pub fn tempdir(&self) -> io::Result<TempDir> {
599 self.tempdir_in(env::temp_dir())
600 }
601
602 /// Attempts to make a temporary directory inside of `dir`.
603 /// The directory and everything inside it will be automatically
604 /// deleted once the returned `TempDir` is destroyed.
605 ///
606 /// # Resource leaking
607 ///
608 /// See [the resource leaking][resource-leaking] docs on `TempDir`.
609 ///
610 /// # Errors
611 ///
612 /// If the directory can not be created, `Err` is returned.
613 ///
614 /// # Examples
615 ///
616 /// ```
617 /// use tempfile::Builder;
618 ///
619 /// let tmp_dir = Builder::new().tempdir_in("./")?;
620 /// # Ok::<(), std::io::Error>(())
621 /// ```
622 ///
623 /// [resource-leaking]: struct.TempDir.html#resource-leaking
624 pub fn tempdir_in<P: AsRef<Path>>(&self, dir: P) -> io::Result<TempDir> {
625 util::create_helper(
626 dir.as_ref(),
627 self.prefix,
628 self.suffix,
629 self.random_len,
630 |path| dir::create(path, self.permissions.as_ref(), self.disable_cleanup),
631 )
632 }
633
634 /// Attempts to create a temporary file (or file-like object) using the
635 /// provided closure. The closure is passed a temporary file path and
636 /// returns an [`std::io::Result`]. The path provided to the closure will be
637 /// inside of [`env::temp_dir()`]. Use [`Builder::make_in`] to provide
638 /// a custom temporary directory. If the closure returns one of the
639 /// following errors, then another randomized file path is tried:
640 /// - [`std::io::ErrorKind::AlreadyExists`]
641 /// - [`std::io::ErrorKind::AddrInUse`]
642 ///
643 /// This can be helpful for taking full control over the file creation, but
644 /// leaving the temporary file path construction up to the library. This
645 /// also enables creating a temporary UNIX domain socket, since it is not
646 /// possible to bind to a socket that already exists.
647 ///
648 /// Note that [`Builder::append`] is ignored when using [`Builder::make`].
649 ///
650 /// # Security
651 ///
652 /// This has the same [security implications][security] as
653 /// [`NamedTempFile`], but with additional caveats. Specifically, it is up
654 /// to the closure to ensure that the file does not exist and that such a
655 /// check is *atomic*. Otherwise, a [time-of-check to time-of-use
656 /// bug][TOCTOU] could be introduced.
657 ///
658 /// For example, the following is **not** secure:
659 ///
660 /// ```
661 /// use std::fs::File;
662 /// use tempfile::Builder;
663 ///
664 /// // This is NOT secure!
665 /// let tempfile = Builder::new().make(|path| {
666 /// if path.is_file() {
667 /// return Err(std::io::ErrorKind::AlreadyExists.into());
668 /// }
669 ///
670 /// // Between the check above and the usage below, an attacker could
671 /// // have replaced `path` with another file, which would get truncated
672 /// // by `File::create`.
673 ///
674 /// File::create(path)
675 /// })?;
676 /// # Ok::<(), std::io::Error>(())
677 /// ```
678 ///
679 /// Note that simply using [`std::fs::File::create`] alone is not correct
680 /// because it does not fail if the file already exists:
681 ///
682 /// ```
683 /// use tempfile::Builder;
684 /// use std::fs::File;
685 ///
686 /// // This could overwrite an existing file!
687 /// let tempfile = Builder::new().make(|path| File::create(path))?;
688 /// # Ok::<(), std::io::Error>(())
689 /// ```
690 /// For creating regular temporary files, use [`Builder::tempfile`] instead
691 /// to avoid these problems. This function is meant to enable more exotic
692 /// use-cases.
693 ///
694 /// # Resource leaking
695 ///
696 /// See [the resource leaking][resource-leaking] docs on `NamedTempFile`.
697 ///
698 /// # Errors
699 ///
700 /// If the closure returns any error besides
701 /// [`std::io::ErrorKind::AlreadyExists`] or
702 /// [`std::io::ErrorKind::AddrInUse`], then `Err` is returned.
703 ///
704 /// # Examples
705 /// ```
706 /// # #[cfg(unix)]
707 /// # {
708 /// use std::os::unix::net::UnixListener;
709 /// use tempfile::Builder;
710 ///
711 /// let tempsock = Builder::new().make(|path| UnixListener::bind(path))?;
712 /// # }
713 /// # Ok::<(), std::io::Error>(())
714 /// ```
715 ///
716 /// [TOCTOU]: https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use
717 /// [security]: struct.NamedTempFile.html#security
718 /// [resource-leaking]: struct.NamedTempFile.html#resource-leaking
719 pub fn make<F, R>(&self, f: F) -> io::Result<NamedTempFile<R>>
720 where
721 F: FnMut(&Path) -> io::Result<R>,
722 {
723 self.make_in(env::temp_dir(), f)
724 }
725
726 /// This is the same as [`Builder::make`], except `dir` is used as the base
727 /// directory for the temporary file path.
728 ///
729 /// See [`Builder::make`] for more details and security implications.
730 ///
731 /// # Examples
732 /// ```
733 /// # #[cfg(unix)]
734 /// # {
735 /// use tempfile::Builder;
736 /// use std::os::unix::net::UnixListener;
737 ///
738 /// let tempsock = Builder::new().make_in("./", |path| UnixListener::bind(path))?;
739 /// # }
740 /// # Ok::<(), std::io::Error>(())
741 /// ```
742 pub fn make_in<F, R, P>(&self, dir: P, mut f: F) -> io::Result<NamedTempFile<R>>
743 where
744 F: FnMut(&Path) -> io::Result<R>,
745 P: AsRef<Path>,
746 {
747 util::create_helper(
748 dir.as_ref(),
749 self.prefix,
750 self.suffix,
751 self.random_len,
752 move |path| {
753 Ok(NamedTempFile::from_parts(
754 f(&path)?,
755 TempPath::new(path, self.disable_cleanup),
756 ))
757 },
758 )
759 }
760}