Struct tempfile::NamedTempFile

pub struct NamedTempFile(_);

A named temporary file.

This variant is NOT secure/reliable in the presence of a pathological temporary file cleaner.

NamedTempFiles are deleted on drop. As rust doesn't guarantee that a struct will ever be dropped, these temporary files will not be deleted on abort, resource leak, early exit, etc.

Please use TempFile unless you absolutely need a named file.

Methods

impl NamedTempFile

pub fn new() -> Result<NamedTempFile>

Create a new temporary file.

SECURITY WARNING: This will create a temporary file in the default temporary file directory (platform dependent). These directories are often patrolled by temporary file cleaners so only use this method if you're positive that the temporary file cleaner won't delete your file.

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.

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

Create a new temporary file in the specified directory.

pub fn path(&self) -> &Path

Get the temporary file's path.

SECURITY WARNING: Only use this method if you're positive that a temporary file cleaner won't have deleted your file. Otherwise, the path returned by this method may refer to an attacker controlled file.

pub fn close(self) -> Result<()>

Close and remove the temporary file.

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

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

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.

SECURITY WARNING: Only use this method if you're positive that a temporary file cleaner won't have deleted your file. Otherwise, you might end up persisting an attacker controlled file.

Methods from Deref<Target = File>

pub fn sync_all(&self) -> Result<(), Error>

Attempts to sync all OS-internal metadata to disk.

This function will attempt to ensure that all in-core data reaches the filesystem before returning.

Examples

use std::fs::File;
use std::io::prelude::*;

fn main() -> std::io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello, world!")?;

    f.sync_all()?;
    Ok(())
}

pub fn sync_data(&self) -> Result<(), Error>

This function is similar to sync_all, except that it may not synchronize file metadata to the filesystem.

This is intended for use cases that must synchronize content, but don't need the metadata on disk. The goal of this method is to reduce disk operations.

Note that some platforms may simply implement this in terms of sync_all.

Examples

use std::fs::File;
use std::io::prelude::*;

fn main() -> std::io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello, world!")?;

    f.sync_data()?;
    Ok(())
}

pub fn set_len(&self, size: u64) -> Result<(), Error>

Truncates or extends the underlying file, updating the size of this file to become size.

If the size is less than the current file's size, then the file will be shrunk. If it is greater than the current file's size, then the file will be extended to size and have all of the intermediate data filled in with 0s.

The file's cursor isn't changed. In particular, if the cursor was at the end and the file is shrunk using this operation, the cursor will now be past the end.

Errors

This function will return an error if the file is not opened for writing.

Examples

use std::fs::File;

fn main() -> std::io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.set_len(10)?;
    Ok(())
}

Note that this method alters the content of the underlying file, even though it takes &self rather than &mut self.

pub fn metadata(&self) -> Result<Metadata, Error>

Queries metadata about the underlying file.

Examples

use std::fs::File;

fn main() -> std::io::Result<()> {
    let mut f = File::open("foo.txt")?;
    let metadata = f.metadata()?;
    Ok(())
}

pub fn try_clone(&self) -> Result<File, Error>

Create a new File instance that shares the same underlying file handle as the existing File instance. Reads, writes, and seeks will affect both File instances simultaneously.

Examples

Create two handles for a file named foo.txt:

use std::fs::File;

fn main() -> std::io::Result<()> {
    let mut file = File::open("foo.txt")?;
    let file_copy = file.try_clone()?;
    Ok(())
}

Assuming there’s a file named foo.txt with contents abcdef\n, create two handles, seek one of them, and read the remaining bytes from the other handle:

use std::fs::File;
use std::io::SeekFrom;
use std::io::prelude::*;

fn main() -> std::io::Result<()> {
    let mut file = File::open("foo.txt")?;
    let mut file_copy = file.try_clone()?;

    file.seek(SeekFrom::Start(3))?;

    let mut contents = vec![];
    file_copy.read_to_end(&mut contents)?;
    assert_eq!(contents, b"def\n");
    Ok(())
}

pub fn set_permissions(&self, perm: Permissions) -> Result<(), Error>

Changes the permissions on the underlying file.

Platform-specific behavior

This function currently corresponds to the fchmod function on Unix and the SetFileInformationByHandle function on Windows. Note that, this may change in the future.

Errors

This function will return an error if the user lacks permission change attributes on the underlying file. It may also return an error in other os-specific unspecified cases.

Examples

fn main() -> std::io::Result<()> {
    use std::fs::File;

    let file = File::open("foo.txt")?;
    let mut perms = file.metadata()?.permissions();
    perms.set_readonly(true);
    file.set_permissions(perms)?;
    Ok(())
}

Note that this method alters the permissions of the underlying file, even though it takes &self rather than &mut self.

Trait Implementations

impl Debug for NamedTempFile

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Deref for NamedTempFile

type Target = File

The resulting type after dereferencing.

Important traits for &'a File

impl<'a> Read for &'a Fileimpl Read for Fileimpl<'a> Write for &'a Fileimpl Write for File

fn deref(&self) -> &File

Dereferences the value.

impl DerefMut for NamedTempFile

Important traits for &'a File

impl<'a> Read for &'a Fileimpl Read for Fileimpl<'a> Write for &'a Fileimpl Write for File

fn deref_mut(&mut self) -> &mut File

Mutably dereferences the value.

impl Drop for NamedTempFile

fn drop(&mut self)

Executes the destructor for this type.

impl Read for NamedTempFile

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

Important traits for &'a mut R

impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Read.

Important traits for Bytes<R>

impl<R> Iterator for Bytes<R> where
    R: Read,  type Item = Result<u8, Error>;

fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an [Iterator] over its bytes.

Important traits for Chars<R>

impl<R> Iterator for Chars<R> where
    R: Read,  type Item = Result<char, CharsError>;

fn chars(self) -> Chars<Self>

🔬 This is a nightly-only experimental API. (io)

the semantics of a partial read/write of where errors happen is currently unclear and may change

Transforms this Read instance to an [Iterator] over [char]s.

Important traits for Chain<T, U>

impl<T, U> Read for Chain<T, U> where
    T: Read,
    U: Read, 

fn chain<R>(self, next: R) -> Chain<Self, R> where     R: Read,

Creates an adaptor which will chain this stream with another.

Important traits for Take<T>

impl<T> Read for Take<T> where
    T: Read, 

fn take(self, limit: u64) -> Take<Self>

Creates an adaptor which will read at most limit bytes from it.

impl Write for NamedTempFile

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this object, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this write.

fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

Important traits for &'a mut R

impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Write.

impl Seek for NamedTempFile

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

impl AsRawFd for NamedTempFile

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.