Struct GzDecoder

pub struct GzDecoder<W: Write> { /* private fields */ }

A decoder for a single member of a gzip file.

This structure exposes a Write interface, receiving compressed data and writing uncompressed data to the underlying writer.

After decoding a single member of the gzip data this writer will return the number of bytes up to to the end of the gzip member and subsequent writes will return Ok(0) allowing the caller to handle any data following the gzip member.

To handle gzip files that may have multiple members, see MultiGzDecoder or read more in the introduction.

Examples

use std::io::prelude::*;
use std::io;
use flate2::Compression;
use flate2::write::{GzEncoder, GzDecoder};

// Uncompresses a gzip encoded vector of bytes and returns a string or error
// Here Vec<u8> implements Write
fn decode_writer(bytes: Vec<u8>) -> io::Result<String> {
   let mut writer = Vec::new();
   let mut decoder = GzDecoder::new(writer);
   decoder.write_all(&bytes[..])?;
   writer = decoder.finish()?;
   let return_string = String::from_utf8(writer).expect("String parsing error");
   Ok(return_string)
}

Implementations

impl<W: Write> GzDecoder<W>

pub fn new(w: W) -> GzDecoder<W>

Creates a new decoder which will write uncompressed data to the stream.

When this encoder is dropped or unwrapped the final pieces of data will be flushed.

pub fn header(&self) -> Option<&GzHeader>

Returns the header associated with this stream.

pub fn get_ref(&self) -> &W

Acquires a reference to the underlying writer.

pub fn get_mut(&mut self) -> &mut W

Acquires a mutable reference to the underlying writer.

Note that mutating the output/input state of the stream may corrupt this object, so care must be taken when using this method.

pub fn try_finish(&mut self) -> Result<()>

Attempt to finish this output stream, writing out final chunks of data.

Note that this function can only be used once data has finished being written to the output stream. After this function is called then further calls to write may result in a panic.

Panics

Attempts to write data to this stream may result in a panic after this function is called.

Errors

This function will perform I/O to finish the stream, returning any errors which happen.

pub fn finish(self) -> Result<W>

Consumes this decoder, flushing the output stream.

This will flush the underlying data stream and then return the contained writer if the flush succeeded.

Note that this function may not be suitable to call in a situation where the underlying stream is an asynchronous I/O stream. To finish a stream the try_finish (or shutdown) method should be used instead. To re-acquire ownership of a stream it is safe to call this method after try_finish or shutdown has returned Ok.

Errors

This function will perform I/O to complete this stream, and any I/O errors which occur will be returned from this function.

Trait Implementations

impl<W: Debug + Write> Debug for GzDecoder<W>

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

Formats the value using the given formatter.

impl<W: Read + Write> Read for GzDecoder<W>

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.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

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

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

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

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

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

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Reads the exact number of bytes required to fill cursor.

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

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

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

where Self: Sized,

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

impl<W: Write> Write for GzDecoder<W>

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

Writes a buffer into this writer, returning how many bytes were written.

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

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

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

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

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

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

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

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

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.