How to get the size of a gunzipped file in vim

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?

From stackoverflow

• 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

  Zsolt Botykai : Someone should explain why it was downvoted, as it works?

• 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;
  }
  

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

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

• 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.