How can I convert a ZipWriter to Bytes in Rust?

help
1

I want to create a zip from a certain file, then i convert this zip (A buffer, not a file in the disk) to bytes, then to send it by a post body to an api.

Thats the code (simplifyed) just with the essencial, and from now to the next step, how can i convert it into bytes?

pub fn to_zip() {
    let buf: &mut [u8] = &mut [0u8; 65536];
    let w = std::io::Cursor::new(buf);
    let mut zip = zip::ZipWriter::new(w);

    // * Convert the buffer to bytes

    zip.finish().unwrap();
}

Sorry for a maybe confuse code first time with Rust beeing loving it so far!

2

The buf you have in your code is for the output, not the input. So, once you have called zip.start_file() on the relevant files and you have called zip.finish(), the buffer should have the zipped content. You can then send it over.

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3

The zip.finish() method will return a result containing your original writer, w (a std::io::Cursor<&mut [u8]>). You can use this to find out how many bytes were written, and from there we can access the original buffer and get the compressed bytes.

use std::io::Cursor;
use zip::ZipWriter;

pub fn to_zip() {
    let mut buf = [0u8; 65536];
    let cursor = Cursor::new(&mut buf[..]);
    let mut zip = ZipWriter::new(cursor);

    // TODO: write stuff to the zip writer

    // Finish writing and get the original cursor back
    let cursor = zip.finish().unwrap();

    // Ask the cursor how many bytes were written
    let bytes_written = cursor.position();
    // And get a reference to the original [u8] slice
    let buf = cursor.get_ref();
    // These are the bytes we want
    let compressed_bytes = &buf[..bytes_written as usize];
}

This could be written differently using scoping/helper functions to avoid the .get_ref() awkwardness, but the result would be the same.

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4

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