line-endings detection

Question

I would like to detect which is the line-endings type of a file. I wrote this function:

 open my $fh, '<afile.txt';
 seteol($fh);

Here the eol detection subroutine:

 sub seteol {
 my $fh = shift;
 my $byte;
 my $i = 0;
 while (sysread($fh, $byte, 1)) { 
 if($byte eq "\n") {
 $/ = "\n"; 
 return 0;
 }
 elsif($byte eq "\r") {
 sysread($fh, $byte, 1);
 if($byte eq "\n") {
 $/ = "\r\n";
 return 0;
 } else {
 $/ = "\r";
 return 0;
 }
 }
 last if $i++ > 65535;
 }
 return -1;
 seek($fh,0,0); 
}

I am wondering if I can do a better job with only core-modules.

Answer 1

It reads file by 4096 chars in hope to find EOL,

local $/ = seteol($fh) // $/;
sub seteol {
 my $fh = shift;
 local $/ = 4096円;
 my $line = "";
 while (my $b = <$fh>) { 
 $line .= $b;
 last if $line =~ /(\R)/;
 }
 seek($fh,0,0);
 return 1ドル if 1ドル;
 warn "Unknown EOL";
 return;
}

• mpapec: @coin check update
• nowox: Why did you chose 4096?
• mpapec: @coin for no particular reason, it is 4kb in a hope that it would be enough to find EOL with first read.