Re: EPNG Chunk Registration

I.e. the following spec (I just copied the text from the link, I could
see no copyright notice, however the link was posted and this seems
fair use).  I don't think we can discuss a proposal unless it is on
the list.

John Bowler

EPNG - Executable PNG

Version: 0.1

Authors: Check Commit Log.

Rationale

Sometimes we want an image associated with a program or script.

Some operating systems, such as Windows, have an icon mechanism for
that, while others, such as Linux, don't.

The exEc Chunk

Bytes 0-3: Reserved. 00 00 00 00 as of this version.
Bytes 4-n: Executable data.
This chunk contains the bytes 00 00 00 00 followed by executable data.
Attempting to execute a PNG which has this chunk should be equivalent
to executing the 'executable data' part of this chunk.

If this chunk appears multiple times in an EPNG, each chunk should be
tried, until the first one to execute. (Doesn't have to execute
successfuly, just has to execute.)

Example

The exEc chunk containing #/usr/bin/env xdg-open should open the image
in the default image viewer, given a system with xdg-open and GNU
coreutils installed.

Security Considerations

I never heard of a system that attempts to execute PNG files. This
should be safe on any modern system.

------------------------------------------------------------------------------