Struct tempfile::NamedTempFile[][src]

pub struct NamedTempFile { /* fields omitted */ }

A named temporary file.

The default constructor, NamedTempFile::new(), creates files in the location returned by std::env::temp_dir(), but NamedTempFile can be configured to manage a temporary file in any location by constructing with NamedTempFile::new_in().

Security

Most operating systems employ temporary file cleaners to delete old temporary files. Unfortunately these temporary file cleaners don’t always reliably detect whether the temporary file is still being used.

Specifically, the following sequence of events can happen:

  1. A user creates a temporary file with NamedTempFile::new().
  2. Time passes.
  3. The temporary file cleaner deletes (unlinks) the temporary file from the filesystem.
  4. Some other program creates a new file to replace this deleted temporary file.
  5. The user tries to re-open the temporary file (in the same program or in a different program) by path. Unfortunately, they’ll end up opening the file created by the other program, not the original file.

Operating System Specific Concerns

The behavior of temporary files and temporary file cleaners differ by operating system.

Windows

On Windows, open files can’t be deleted. This removes most of the concerns around temporary file cleaners.

Furthermore, temporary files are, by default, created in per-user temporary file directories so only an application running as the same user would be able to interfere (which they could do anyways). However, an application running as the same user can still accidentally re-create deleted temporary files if the number of random bytes in the temporary file name is too small.

So, the only real concern on Windows is:

  1. Opening a named temporary file in a world-writable directory.
  2. Using the into_temp_path() and/or into_parts() APIs to close the file handle without deleting the underlying file.
  3. Continuing to use the file by path.

UNIX

Unlike on Windows, UNIX (and UNIX like) systems allow open files to be “unlinked” (deleted).

MacOS

Like on Windows, temporary files are created in per-user temporary file directories by default so calling NamedTempFile::new() should be relatively safe.

Linux

Unfortunately, most Linux distributions don’t create per-user temporary file directories. Worse, systemd’s tmpfiles daemon (a common temporary file cleaner) will happily remove open temporary files if they haven’t been modified within the last 10 days.

Resource Leaking

If the program exits before the NamedTempFile destructor is run, such as via std::process::exit(), by segfaulting, or by receiving a signal like SIGINT, then the temporary file will not be deleted.

Use the tempfile() function unless you absolutely need a named file.

Implementations

impl NamedTempFile[src]

pub fn new() -> Result<NamedTempFile>[src]

Create a new named temporary file.

See Builder for more configuration.

Security

This will create a temporary file in the default temporary file directory (platform dependent). This has security implications on many platforms so please read the security section of this type’s documentation.

Reasons to use this method:

  1. The file has a short lifetime and your temporary file cleaner is sane (doesn’t delete recently accessed files).

  2. You trust every user on your system (i.e. you are the only user).

  3. You have disabled your system’s temporary file cleaner or verified that your system doesn’t have a temporary file cleaner.

Reasons not to use this method:

  1. You’ll fix it later. No you won’t.

  2. You don’t care about the security of the temporary file. If none of the “reasons to use this method” apply, referring to a temporary file by name may allow an attacker to create/overwrite your non-temporary files. There are exceptions but if you don’t already know them, don’t use this method.

Errors

If the file can not be created, Err is returned.

Examples

Create a named temporary file and write some data to it:

use tempfile::NamedTempFile;

let mut file = NamedTempFile::new()?;

writeln!(file, "Brian was here. Briefly.")?;

pub fn new_in<P: AsRef<Path>>(dir: P) -> Result<NamedTempFile>[src]

Create a new named temporary file in the specified directory.

See NamedTempFile::new() for details.

pub fn path(&self) -> &Path[src]

Get the temporary file’s path.

Security

Referring to a temporary file’s path may not be secure in all cases. Please read the security section on the top level documentation of this type for details.

Examples

use tempfile::NamedTempFile;

let file = NamedTempFile::new()?;

println!("{:?}", file.path());

pub fn close(self) -> Result<()>[src]

Close and remove the temporary file.

Use this if you want to detect errors in deleting the file.

Errors

If the file cannot be deleted, Err is returned.

Examples

use tempfile::NamedTempFile;

let file = NamedTempFile::new()?;

// By closing the `NamedTempFile` explicitly, we can check that it has
// been deleted successfully. If we don't close it explicitly,
// the file will still be deleted when `file` goes out
// of scope, but we won't know whether deleting the file
// succeeded.
file.close()?;

pub fn persist<P: AsRef<Path>>(self, new_path: P) -> Result<File, PersistError>[src]

Persist the temporary file at the target path.

If a file exists at the target path, persist will atomically replace it. If this method fails, it will return self in the resulting PersistError.

Note: Temporary files cannot be persisted across filesystems. Also neither the file contents nor the containing directory are synchronized, so the update may not yet have reached the disk when persist returns.

Security

This method persists the temporary file using its path and may not be secure in the in all cases. Please read the security section on the top level documentation of this type for details.

Errors

If the file cannot be moved to the new location, Err is returned.

Examples

use tempfile::NamedTempFile;

let file = NamedTempFile::new()?;

let mut persisted_file = file.persist("./saved_file.txt")?;
writeln!(persisted_file, "Brian was here. Briefly.")?;

pub fn persist_noclobber<P: AsRef<Path>>(
    self,
    new_path: P
) -> Result<File, PersistError>
[src]

Persist the temporary file at the target path if and only if no file exists there.

If a file exists at the target path, fail. If this method fails, it will return self in the resulting PersistError.

Note: Temporary files cannot be persisted across filesystems. Also Note: This method is not atomic. It can leave the original link to the temporary file behind.

Security

This method persists the temporary file using its path and may not be secure in the in all cases. Please read the security section on the top level documentation of this type for details.

Errors

If the file cannot be moved to the new location or a file already exists there, Err is returned.

Examples

use tempfile::NamedTempFile;

let file = NamedTempFile::new()?;

let mut persisted_file = file.persist_noclobber("./saved_file.txt")?;
writeln!(persisted_file, "Brian was here. Briefly.")?;

pub fn keep(self) -> Result<(File, PathBuf), PersistError>[src]

Keep the temporary file from being deleted. This function will turn the temporary file into a non-temporary file without moving it.

Errors

On some platforms (e.g., Windows), we need to mark the file as non-temporary. This operation could fail.

Examples

use tempfile::NamedTempFile;

let mut file = NamedTempFile::new()?;
writeln!(file, "Brian was here. Briefly.")?;

let (file, path) = file.keep()?;

pub fn reopen(&self) -> Result<File>[src]

Securely reopen the temporary file.

This function is useful when you need multiple independent handles to the same file. It’s perfectly fine to drop the original NamedTempFile while holding on to Files returned by this function; the Files will remain usable. However, they may not be nameable.

Errors

If the file cannot be reopened, Err is returned.

Security

Unlike File::open(my_temp_file.path()), NamedTempFile::reopen() guarantees that the re-opened file is the same file, even in the presence of pathological temporary file cleaners.

Examples

use tempfile::NamedTempFile;

let file = NamedTempFile::new()?;

let another_handle = file.reopen()?;

pub fn as_file(&self) -> &File[src]

Get a reference to the underlying file.

pub fn as_file_mut(&mut self) -> &mut File[src]

Get a mutable reference to the underlying file.

pub fn into_file(self) -> File[src]

Convert the temporary file into a std::fs::File.

The inner file will be deleted.

pub fn into_temp_path(self) -> TempPath[src]

Closes the file, leaving only the temporary file path.

This is useful when another process must be able to open the temporary file.

pub fn into_parts(self) -> (File, TempPath)[src]

Converts the named temporary file into its constituent parts.

Note: When the path is dropped, the file is deleted but the file handle is still usable.

Trait Implementations

impl AsRawFd for NamedTempFile[src]

impl AsRef<Path> for NamedTempFile[src]

impl Debug for NamedTempFile[src]

impl From<PersistError> for NamedTempFile[src]

impl Read for NamedTempFile[src]

impl<'a> Read for &'a NamedTempFile[src]

impl Seek for NamedTempFile[src]

impl<'a> Seek for &'a NamedTempFile[src]

impl Write for NamedTempFile[src]

impl<'a> Write for &'a NamedTempFile[src]

Auto Trait Implementations

impl RefUnwindSafe for NamedTempFile

impl Send for NamedTempFile

impl Sync for NamedTempFile

impl Unpin for NamedTempFile

impl UnwindSafe for NamedTempFile

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
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impl<T> Borrow<T> for T where
    T: ?Sized
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impl<T> BorrowMut<T> for T where
    T: ?Sized
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impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
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impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
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type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<V, T> VZip<V> for T where
    V: MultiLane<T>, 
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