package JpegTester;
use strict;
use re 'taint';
use vars qw($buf $buf_l $buf_ofs);
sub makeTwo($) { my($fh) = @_;
$buf_l>=0 or die "jpeg: Panic, program error1, pos=$buf_ofs";
if ($buf_l<2) {
my($len) = sysread($fh,$buf,2048,$buf_l); defined $len or die "jpeg: Can't read: $!\n";
$buf_l += $len;
}
}
sub takeN($$) { my($fh,$n) = @_; my($err) = undef;
for ($buf_l>=2||makeTwo($fh); $n>0; ) {
if ($buf_l<=0) { $err = "Truncated by $n bytes or more"; last }
if ($n >= $buf_l) { $n -= $buf_l; $buf_ofs += $buf_l; $buf = '' }
else { $buf = substr($buf,$n); $buf_ofs += $n; $n = 0 }
$buf_l = length($buf); $buf_l>=2 || makeTwo($fh);
}
$err;
}
sub takeECS($) { my($fh) = @_;
for ($buf_l>=2||makeTwo($fh); $buf_l>0; ) {
if ($buf =~ s/^([^\xff]+)//) { $buf_ofs += length($1) }
elsif ($buf =~ s/^(\xff\x00)+//) { $buf_ofs += length($1) }
else { last }
$buf_l = length($buf); $buf_l>=2 || makeTwo($fh);
}
}
sub takeFill($) { my($fh) = @_;
for (makeTwo($fh); $buf_l>0; $buf_l=length($buf),makeTwo($fh)) {
if ($buf =~ s/^ \xff+ (?= \xff )//x) { $buf_ofs += length($1) }
else { last }
}
}
sub takeTail($) { my($fh) = @_;
for (makeTwo($fh); $buf_l>0; $buf_l=length($buf),makeTwo($fh)) {
if ($buf =~ s/^[\x00\xff]+//) { $buf_ofs += length($1) }
else { last }
}
}
sub test_jpeg($;@) {
my($fn) = @_; local(*F); my($fh) = \*F;
open($fh,"<$fn") or die "jpeg: Can't open file $fn for reading: $!";
binmode($fh) or die "jpeg: Can't set binmode on $fn: $!";
$buf = ''; $buf_l = 0; $buf_ofs = 0; makeTwo($fh); my(@r) = (0,"jpeg ok");
if ($buf !~ /^\xff\xd8/) { @r = (0,"not jpeg") }
else { takeN($fh,2); if ($buf !~ /^\xff/) { @r = (0,"not jpeg") } }
if ($r[1] eq "jpeg ok") {
my($ecs_ok) = 0; local($1);
for (;;) { if ($buf_l<=0 || $buf eq "\xff") {
@r = (2,"Truncated, no EOI, pos=$buf_ofs") if !$r[0];
last;
} elsif ($buf =~ /^( [^\xff] | \xff \x00 )/x) { @r = (2,"Unexpected entropy-coded data segment, pos=$buf_ofs")
if !$ecs_ok && !$r[0];
takeECS($fh); $ecs_ok = 0;
} elsif ($buf =~ /^ \xff+ (?= \xff ) /x) { takeFill($fh); $ecs_ok = 0;
} elsif ($buf =~ /^ \xff ([^\x00\xff]) /x) { my($m) = $1; takeN($fh,2);
if ($m =~ /[\xd0-\xd7]/) { $ecs_ok = 1;
} elsif ($m =~ /[\x01\xd8]/) { $ecs_ok = 0;
}
elsif ($m eq "\xd9") { takeFill($fh); $ecs_ok = 0;
@r = (2,"Trailing garbage, pos=$buf_ofs") if $buf_l>0 && !$r[0];
last;
} else { $ecs_ok = $m eq "\xda"; my($len) = unpack("n",substr($buf,0,2));
@r = (1,sprintf("Invalid marker segm len %d, pos=%d, marker=0x%02X",
$len,$buf_ofs,ord($m)) ) if $len<2;
my($err) = takeN($fh,$len);
@r = (2,"$err, pos=$buf_ofs") if defined $err && !$r[0];
}
} else { die "jpeg: Panic, program error2, pos=$buf_ofs" }
$buf_l>=2 || makeTwo($fh);
}
}
close($fh) or die "jpeg: Can't close $fn: $!";
$r[1] = "bad jpeg: ".$r[1] if $r[0];
@r;
}
1;