Why does my image download with Perl's LWP give me the wrong-sized file?

Question

I am trying to get an image from an HTTP server using Perl.

I have the full URL of the file and am attempting to use

my $data = LWP::Simple::get $params{URL};
my $filename = "image.jpg";
open (FH, ">$filename");
print FH $data;
close (FH);

Now, logically, to me at least, this should work. But the files are slightly different sizes, and I can't work out why.

Help!

Is the only problem that the files are different sizes? How slight is slight? Is the image that is being sent to the user the same as the image on your server? — John Christensen, May 29 '09 at 15:06
a 20k image was off by maybe 30 bytes. Dave Hinton solved the problem. I was not running in binmode. — Xetius, May 29 '09 at 15:18

score 14 · Accepted Answer · edited May 29 '09 at 21:03

14

You need to use binmode to properly write the image data to disk.

my $data = LWP::Simple::get $params{URL};
my $filename = "image.jpg";
open (FH, ">$filename");
binmode (FH);
print FH $data;
close (FH);

Otherwise it is interpreted as text, and the newlines get munged.

edited May 29 '09 at 21:03

brian d foy

answered May 29 '09 at 15:06

dave4420

2

You don't need a global filehandle hanging around like that. Use File::Slurp's write_file or LWP::Simple::getstore. – Sinan Ünür May 29 '09 at 19:01
I found the big green checkmark right next to binmode amusing. – ysth May 31 '09 at 06:01

innaM · Answer 2 · 2010-06-16T19:12:22.450

13

Dave is right, you should/must set your file handle to binary mode. But you could do all that in one go:

LWP::Simple::getstore( $params{URL}, 'image.jpg' );

edited Jun 16 '10 at 19:12

answered May 29 '09 at 15:14

innaM

2 Answers2