RedJeep has asked for the wisdom of the Perl Monks concerning the following question:

Hello. I am trying to convert an image to Base64. My environment is Windows 10, Perl 5.24.3

Thank you all in advance!

My code is...

use MIME::Base64;
use strict;
use warnings;

my $upload_dir = 'uploaded_files';
my $file = 'image.jpg';
my $base64_a = '';

### Open the image to convert to base64
open (IMAGE, "$upload_dir/$file") or die "$!";
binmode IMAGE;
my $binary = do{ local $/ = undef; <IMAGE>; };
binmode $binary;

$base64_a = encode_base64($binary); 
my $base64 = encode_base64(pack('B*', $binary));
    
print "base64 = $base64\n";

[download]

The funny thing is that it works but also kicks off an error.

The output is below... I truncated the Base64 output but this gives you an idea.

C:\inetpub\foto_root>test_binmode.pl
binmode() on unopened filehandle at C:\inetpub\foto_root\test_binmode.
+pl line 15, <IMAGE> line 1.
base64 = oJwMowGRQNNgH8d24aQ2RsdiAAAAAAAAJLj8n+AVVkc4dN3p10iVUqqqqqqqp
+VKpVKpVVVVU3/gV
VmRYq3PyP5IelVVVVVVSqVSqVSqVSqVUZ1AAEGE3pUtAeRV1p247Xr9p2Guv7n9A9nOnOn
+ZXdA42
pdQesc/9hOpZohX2DutSt/81SZ59Hb0FIO76iahG1+vNi8zyfmjNxSejvblU86wvDLZXRm
+4ry0mW
yua0S4Q90eqW7MYcDZcP4l9PBrvn+IDVzndz7jzr6Qdtxw8229DXCkbJBku40l+WPP3LWM
+zb0n3R
1HH038+luuLCle7a0I1fbKViAAAbuACaCEXYx48/lGgW3nX3PuaVGfWYO6Hji+61TLusOy
+q4VbUB
yxV669JBpWOm9iflsw4PPuH19M39fAjGaXS9L5lTHpFLOgdiHgnWpHVBnhBcG1Ey7lUnsX
+5m6E6a
7QvIKnZ4L/a6MrbXSao8wtaijRod4XP87X2ZlXqDVetDfQoJPWW2sWnVUfMUFeIYK3RVY+
+1kUolC
ArLfmXFpHX/GYvYsydAm5e77Z9l6nO0v2Y3GjeNilVltW7uA0m1l42/tA7it9WBp2YC0RP
+w86c8+

[download]

Replies are listed 'Best First'.
Re: Error binmode() on unopened filehandle
by stevieb (Canon) on May 02, 2020 at 22:16 UTC

    $binary is not a file handle. It's a normal scalar variable that you've stuffed the entire contents of the file into.

    Side note... you're best to use the three argument form of open(), and use a lexical file handle as opposed to a bareword global one:

    open my $fh, '<', 'file.ext' or die "Can't open file: $!";

while (<$fh>) {
    ...
}

    [download]
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[d/l]
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Re: Error binmode() on unopened filehandle (Path::Tiny slurp_raw)
by Anonymous Monk on May 02, 2020 at 23:09 UTC

    make life easier for yourself use Path::Tiny 

    use Path::Tiny 'path';
my $data = path("foo.txt")->slurp_raw;

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Re: Error binmode() on unopened filehandle
by Marshall (Canon) on May 03, 2020 at 13:49 UTC
    Once you go to BINMODE on a file handle, a record separator makes no sense.
    A more typical way to read a large binary file would be statements like this: 
    binmode INBIN;
my $n_bytes = read(INBIN, $buff, $BUFSIZE);

    [download]
    That's a request to read $BUFSIZE bytes from INBIN into $buff. $n_bytes is number of bytes actually read from INBIN.
    I've never wound up reading a binary file in a single shot into a Perl variable because my bin files are not appropriate for that (so big they need to be read in chunks). However, I guess this would work (untested): 
    use MIME::Base64;
use strict;
use warnings;

my $upload_dir = 'uploaded_files';
my $file_name = 'image.jpg';

### Open the image to convert to base64
open (IMAGE, '<', "$upload_dir/$file_name") or die "$!";
binmode IMAGE;
my $binary = <IMAGE>;

my $base64 = encode_base64(pack('B*', $binary));
    
print "base64 = $base64\n";

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      Once you go to BINMODE on a file handle, a record separator makes no sense.

      Maybe you should have tested this. 

      #!/usr/bin/perl

use strict;
use warnings;

binmode DATA;
my $binary = <DATA>;

print "$binary\n";

__DATA__
first
second

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      This gives: 
      first

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      Greetings,
      -jo

      $gryYup$d0ylprbpriprrYpkJl2xyl~rzg??P~5lp2hyl0p$
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        Ok, I tested with a .jpg file I had laying around. 
        use warnings;
use strict;

open (my $fh, '<', "COVID19-Death02Apr.jpg") or die "$!";
binmode $fh;
my $binary = <$fh>; #entire binary file goes to Perl variable
print '',$binary;

        [download]
        Works just fine!

        What you are overlooking is that you must set binmode before reading from the file. The Perl DATA file handle is an open file handle to the Perl program source that is seeked to the first character on the next line after __DATA__. This is buffered character mode I/O. You can't switch modes in the midst of a file.

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