imager::expr::assem(3pm) [debian man page]

Imager::Expr::Assem(3pm)				User Contributed Perl Documentation				  Imager::Expr::Assem(3pm)

NAME

	 Imager::Expr::Assem - an assembler for producing code for the Imager
	 register machine

SYNOPSIS

	 use Imager::Expr::Assem;
	 my $expr = Imager::Expr->new(assem=>'...', ...)

DESCRIPTION

       This module is a simple Imager::Expr compiler that compiles a low-level language that has a nearly 1-to-1 relationship to the internal
       representation used for compiled register machine code.

   Syntax
       Each line can contain multiple statements separated by semi-colons.

       Anything after '#' in a line is ignored.

       Types of statements:

       variable definition
	       "var" name:type

	   defines variable name to have type, which can be any of "n" or "num" for a numeric type or "pixel", "p" or "c" for a pixel or color
	   type.

	   Variable names cannot include white-space.

       operators
	   Operators can be split into 3 basic types, those that have a result value, those that don't and the null operator, eg. jump has no
	   value.

	   The format for operators that return a value is typically:

	       result = operator operand ...

	   and for those that don't return a value:

	       operator operand

	   where operator is any valid register machine operator, result is any variable defined with "var", and operands are variables, constants
	   or literals, or for jump operators, labels.

	   The set operator can be simplified to:

	       result = operator

	   All operators maybe preceded by a label, which is any non-white-space text immediately followed by a colon (':').

BUGS

       Note that the current optimizer may produce incorrect optimization for your code, fortunately the optimizer will disable itself if you
       include any jump operator in your code.	A single jump to anywhere after your final "ret" operator can be used to disable the optimizer
       without slowing down your code.

       There's currently no high-level code generation that can generate code with loops or real conditions.

SEE ALSO

       Imager(3), transform.perl, regmach.c

AUTHOR

       Tony Cook <tony@develop-help.com>

perl v5.14.2							    2011-06-06						  Imager::Expr::Assem(3pm)

Check Out this Related Man Page

Imager::Security(3pm)					User Contributed Perl Documentation				     Imager::Security(3pm)

NAME

       Imager::Security - brief notes on security and image processing

SYNOPSIS

	 # keep abreast of security updates
	 apt-get update && apt-get upgrade
	 yum upgrade
	 pkgin update && pkgin upgrade
	 # or local equivalent

	 # limit memory use
	 use Imager;
	 # only images that use up to 10MB
	 Imager->set_file_limits(bytes => 10_000_000);

DESCRIPTION

       There's two basic security considerations when dealing with images from an unknown source:

       o   keeping your libraries up to date

       o   limiting the amount of memory used to store images

   Keeping libraries up to date
       Image file format libraries such as "libpng" or "libtiff" have relatively frequent security updates, keeping your libraries up to date is
       basic security.

       If you're using user supplied fonts, you will need to keep your font libraries up to date too.

   Limiting memory used
       With compression, and especially with pointer formats like TIFF, it's possible to store very large images in a relatively small file.

       If you're receiving image data from an untrusted source you should limit the amount of memory that Imager can allocate for a read in image
       file using the "set_file_limits()" method.

	 Imager->set_file_limits(bytes => 10_000_000);

       You may also want to limit the maximum width and height of images read from files:

	 Imager->set_file_limits(width => 10_000, height => 10_000,
				 bytes => 10_000_000);

       This has no effect on images created without a file:

	 # succeeds
	 my $image = Imager->new(xsize => 10_001, ysize => 10_001);

       You can reset to the defaults with:

	 Imager->set_file_limits(reset => 1);

AUTHOR

       Tony Cook <tonyc@cpan.org>

perl v5.14.2							    2012-06-04						     Imager::Security(3pm)

Linux and UNIX Man Pages

imager::expr::assem(3pm) [debian man page]

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