perl - 为什么我的图像在使用此 Perl CGI 脚本时会被剪裁？

Question

当我尝试在 Perl CGI 脚本中将图像打印到 STDOUT 时，在浏览器中查看时图像被剪裁。

下面是代码:

if ($path =~ m/\.jpe?g$/i)
{    
  my $length = (stat($path))[7];
  $| = 1;
  print "Content-type: image/jpg\r\n";
  print "Content-length: $length\r\n\r\n";
  open(IMAGE,"<$path");
  binmode(IMAGE);
  binmode(STDOUT);
  my ($image, $buff);
  read IMAGE, $buff, $length;
  syswrite STDOUT, $buff, $length;
  close IMAGE;
}

Answer 1

如果你真的想在服务前将整个文件读入内存，使用File::Slurp :

#!/usr/bin/perl

use strict; use warnings;

use CGI::Simple;
use File::Slurp;
use File::stat;

local $| = 1;

my $cgi = CGI::Simple->new;

my $st = stat($path) or die "Cannot stat '$path'";

print $cgi->header(
    -type => 'image/jpeg',
    -length => $st->size,
);

write_file(\*STDOUT, {binmode => ':raw'}, 
    \ read_file( $path, binmode => ':raw' )
);

但是对于大图，读取整个文件会消耗大量内存。因此，参见 How can I serve an image with a Perl CGI script? .