#!/usr/bin/perl

$blocksize=4000;
$size     =0;

$USAGE = "
 USAGE      touch0 [OPTIONS] FILENAMES
 SYNOPSIS:  Create named file(s) of specified size(s) (or $size).
      	    Will not overwrite existing files.
 OPTIONS:   -number[KM]  Specify filesize, eg. -123 -100K -20M,
                         write blocksize=$blocksize.
            -r:number     filesize += random number;
            -R:number     file_1..file_number, max 9999 files.
            -v           verbose.
 AUTHOR:    (C)GPL, Mohsin Ahmed, http://www.cs.albany.edu/~mosh
";

while( $_ = $ARGV[0], /^-/ ){
    shift;
    m/^--$/           and last;
    m/^-v/            and ++$verbose;
    m/^-r:(\d+)/      and $randomsizes = $1;
    m/^-R:(\d{1,4})/  and (@ARGV = (1..$1));

    if(m/^-(\d+)(\w?)/){
        $size = $1;
        $size *= 1000 if m/k$/i ;
        $size *= 1e6 if  m/M$/i ;
        print "size is $size\n";
        $buffer = 'M' x $blocksize;

    }
}

die "$USAGE Need arg\n" unless @ARGV;

$timenow = time();

foreach (@ARGV) {
    if( $randomsizes ){
        $thissize = $randomsizes + int( rand( $size ) ) ;
        $_ = 'file_' . $_;
    }else{
        $thissize = $size;
    }

    if( -e $_ ){
        if( utime( $timenow, $timenow, $_) ){
            print STDERR "Touched existing file '$_'\n";
        }else{
            warn "Could not touch $_ with time=$timenow.\n";
        }
        next;
    }

    open( ONEFILE, ">$_" ) or warn "Cannot write $_\n", next;
    print STDERR "touch $thissize: $_\n";
    while( $thissize ){
        if( $thissize > $blocksize ){
            syswrite( ONEFILE, $buffer, $blocksize );
            die "syswrite error\n" if $blocksize < 0;
            $thissize -= $blocksize;
        }else{
            syswrite( ONEFILE, $buffer, $thissize );
            die "syswrite error\n" if $thissize < 0;
            $thissize = 0;
        }
    }
    close( ONEFILE ) or warn "Close '$_' failed\n";
}