openfirmware VS qpdf

OpenFirmware has some code for paging! ;)

purpose: Set up page tables and turn on paging

https://github.com/openbios/openfirmware/blob/master/cpu/x86...

NeWS didn't use FORTH. But HyperTIES used both FORTH and NeWS because there were a lot of things that FORTH could do that NeWS couldn't, like link and call C code. The FORTH I used was Mitch Bradley's "Sun Forth", which evolved into OpenFirmware, and which was once defined by an IEEE standard, "IEEE 1275-1994", but it was withdrawn because the standard was not reaffirmed:

https://en.wikipedia.org/wiki/Open_Firmware

>Open Firmware is described by IEEE standard IEEE 1275-1994, which was not reaffirmed by the Open Firmware Working Group (OFWG) since 1998 and has therefore been officially withdrawn by IEEE.

It's still alive and maintained and used for many things. Here's the source code, called OpenBIOS:

https://github.com/openbios

https://github.com/openbios/openfirmware

https://openfirmware.info

https://openfirmware.info/Welcome_to_OpenBIOS

Some Forth systems even have a "metacompiler" that lets one FORTH system compile another FORTH system for the same or different CPU, word size, byte order, threading model, etc, from the same source code!

OpenFirmware (the FORTH burnt into boot roms of SPARC, PowerPC, OLPC, and other systems) is a great example:

openfirmware/forth/kernel/metacompile.fth

https://github.com/openbios/openfirmware/blob/d5cc657ce81c0f...

QPDF is a CLI tool that performs content-preserving transformations on PDF files. We have another tool for managing files!

Given how well Preview.app and Safari work for viewing >99% of PDFs I actually encounter in the wild, this article makes Apple's engineering decisions look good.

It also confirms many suspicions I've had over the years that have led me to, e.g., running all PDFs from questionable sources through VirusTotal before viewing on platforms where I wouldn't normally run antivirus software.

The original article also confirms my suspicions that this step is inadequate:

Because the Launch action can be considered as a danger- ous feature, we conducted a large-scale evaluation of 294,586 PDF documents downloaded from the Internet, in order to research if there are any legitimate use cases at all. Of those documents, only 532 files (0.18%) contained a Launch action. While none of the files was classified as malicious according to the VirusTotal database, we conclude that the Launch action is rarely used in the wild and its support should be removed by PDF implementations as well as the standard.

Incidentally, the Launch action is still present in the most recent version of the PDF standard[1], with only OS-specific launch parameters deprecated (which include passing arguments to the launched executable, so eliminating the deprecated feature is still a significant security gain).

Finally, I'm both personally and professionally curious about how the non-DoS examples in this articles may apply to non-viewer PDF tools and libraries like qpdf[2] and Ghostscript's original and recently reimplemented PDF interpreters[3].

[1] https://pdfa.org/resource/iso-32000-pdf/

(registration required, but at least the base standard is available at no cost; sadly, important incorporated standards like ISO 21757-1:2020 [ECMAScript for PDF] are not)

[2] https://qpdf.sourceforge.io

[3] https://ghostscript.com/blog/pdfi.html

I know you're talking about GUI editing, but I've found libqpdf[1] incredibly useful for making programmatic PDF edits with minimal (typically no) structural disturbance.

[1] https://qpdf.sourceforge.io

Solved this. So the string which we were concerned about depends on the time, which is why it changes everytime a new document is generated with the same source PDF. it is a meaningless string really. from the documentation, it gives this explanatin. To be sure, i raised an issue with the guys at QPDF and they were quick to answer the question too. The explanation theyve given is even more clearer.

Hi, this is my first Emacs package! It provides a transient wrapper for the qpdf command-line tool aimed especially at users of pdf-tools or at least DocView. With it one can, for example, remove/reorder/split/rotate pages of a pdf file, merge pdf files, remove annotations, and apply a range of transformations to a pdf file. See the qpdf documentation.

There are some here, as test files in the qpdf library: https://github.com/qpdf/qpdf/tree/main/qpdf/qtest/qpdf

(I wrote a low-level PDF parser and ran it over the PDF files that happened to be present on my laptop—just regular ones—and ran into some files that (some) PDF viewers open but even qpdf doesn't. I say "even" because qpdf is really good IMO.)

If you're comfortable handling the (typo)graphical aspects of the PDF yourself and have the ability to consume a C++ library, I've had good experiences using the Apache-licensed qpdf[1] library to handle the low-level structural aspects of the PDF standard. It's particularly convenient when your application requires structure-preserving integration of existing PDF content.

Simple example applications, each completed in 2–3 days, both in C#, using C++/CLI to integrate libqpdf:

1. Overlaying fixed-format text on pre-existing blank PDF form pages, ensuring the content of each distinct form page is embedded exactly once, and that all necessary assets (fonts, images, etc.) from the blank form PDF pages are included in the output PDF.

2. Losslessly combining a sequence of PDF, TIFF, and JPEG images into a single PDF with bookmarks pointing to the first page of each source file and existing image compression maintained where possible. In this application, only the source TIFFs were anything other than arbitrary (i.e., the TIFFs were more-or-less baseline images coming from a small number of scanning systems, but the JPEGs and PDFs came from all sorts of different applications).

[1] https://github.com/qpdf/qpdf

Use qpdf https://github.com/qpdf/qpdf

I was looking for a way on macOS to batch remove the user password from a bunch of PDF files that had the same password. I found the easiest way was to use qpdf with the following command: