How to get the size of a gunzipped file in vim

Question

When viewing (or editing) a .gz file, vim knows to locate gunzip and display the file properly.
In such cases, getfsize(expand("%")) would be the size of the gzipped file.

Is there a way to get the size of the expanded file?

[EDIT]
Another way to solve this might be getting the size of current buffer, but there seems to be no such function in vim. Am I missing something?

Answer 1

If you're on Unix/linux, try

:%!wc -c

That's in bytes. (It works on windows, if you have e.g. cygwin installed.) Then hit u to get your content back.

HTH

Answer 2

There's no easy way to get the uncompressed size of a gzipped file, short of uncompressing it and using the getfsize() function. That might not be what you want. I took at a look at RFC 1952 - GZIP File Format Specification, and the only thing that might be useful is the ISIZE field, which contains "...the size of the original (uncompressed) input data modulo 2^32".

EDIT:

I don't know if this helps, but here's some proof-of-concept C code I threw together that retrieves the value of the ISIZE field in a gzip'd file. It works for me using Linux and gcc, but your mileage may vary. If you compile the code, and then pass in a gzip'd filename as a parameter, it will tell you the uncompressed size of the original file.

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

int main(int argc, char *argv[])
{
    FILE *fp = NULL;
    int  i=0;

    if ( argc != 2 ) {
        fprintf(stderr, "Must specify file to process.\n" );
        return -1;
    }

    // Open the file for reading
    if (( fp = fopen( argv[1], "r" )) == NULL ) {
        fprintf( stderr, "Unable to open %s for reading:  %s\n", argv[1], strerror(errno));
        return -1;
    }

    // Look at the first two bytes and make sure it's a gzip file
    int c1 = fgetc(fp);
    int c2 = fgetc(fp);
    if ( c1 != 0x1f || c2 != 0x8b ) {
        fprintf( stderr, "File is not a gzipped file.\n" );
        return -1;
    }


    // Seek to four bytes from the end of the file
    fseek(fp, -4L, SEEK_END);

    // Array containing the last four bytes
    unsigned char read[4];

    for (i=0; i<4; ++i ) {
        int charRead = 0;
        if ((charRead = fgetc(fp)) == EOF ) {
            // This shouldn't happen
            fprintf( stderr, "Read end-of-file" );
            exit(1);
        }
        else
            read[i] = (unsigned char)charRead;
    }

    // Copy the last four bytes into an int.  This could also be done
    // using a union.
    int intval = 0;
    memcpy( &intval, &read, 4 );

    printf( "The uncompressed filesize was %d bytes (0x%02x hex)\n", intval, intval );

    fclose(fp);

    return 0;
}

Answer 3

This appears to work for getting the byte count of a buffer

(line2byte(line("$")+1)-1)

Answer 4

From within vim editor, try this:

<Esc>:!wc -c my_zip_file.gz

That will display you the number of bytes the file is having.