Klaus Brunner klausbrunner

## unsigned-java.md

      
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                klausbrunner
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              March 11, 2023 09:29
            
              
                Dealing with unsigned integers in Java
              
          
      View unsigned-java.md
  
      
    Since version 1.0, Java's type system has remained pretty much the same when it comes to primitive types: we have signed short (16 bits), int (32 bits), and long (64 bits), but no unsigned counterparts to these.
This is rarely a problem, but sometimes it might seem to be: especially when reading and writing binary data formats that use unsigned values.
ByteBuffer buf = ...
int unsignedIntValue = buf.getInt(); 
Whenever the unsigned value is greater than Integer.MAX_VALUE, our variable unsignedIntValue will look like a negative number - since Java uses the common approach of representing signed values in two's complement encoding. But as long as we don't have to know the actual value, we don't have to care. Java doesn't change the bits if we don't ask it to, and writing out the number again will result in the exact same bytes as our previous input (if we make sure to use the same byte order, of course):

  
## create-test-zips.sh
# quickly create large/very populated zip files for testing purposes, without taking up lots of disk space

dd if=/dev/zero bs=1m count=10k | zip -9 single-10g-file.zip -

dd if=/dev/urandom bs=1 count=20000 | split -b 1 -a 4 - test_ && zip -q -m 20k-tiny-files.zip test_*

# this ensures CD entries with the LFH offset in the ZIP64 EIEF:
dd if=/dev/zero bs=1g count=6 | split -b 2g - test_ && zip -0 -m few-huge-files.zip test_*

## usno-sunrise-table-parser.py
#!/usr/bin/env python3
"""Parse sunrise/sunset tables as provided by the USNO website at https://aa.usno.navy.mil/data/RS_OneYear"""

import re
import argparse


def parse_table(filename: str):
    def to_decimal_deg(latlon_tup) -> float:
        assert len(latlon_tup) == 3 and re.match("[NESW]", latlon_tup[0])

## markdown_to_pdf_sans.sh
pandoc -t pdf -F mermaid-filter -o README.pdf README.md --pdf-engine=xelatex -V mainfont="PT Sans" -V monofont="PT Mono" -V papersize:a4

## rspamd-podman.md

      
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                klausbrunner
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              May 19, 2022 07:10
            
              
                Running Rspamd with redis and unbound in Podman
              
          
      View rspamd-podman.md
  
      
    Quick notes on running Rspamd in a Podman pod
This includes three containers:

Rspamd itself, for use as a Postfix milter
redis
unbound (because rspamd's DNSBL lookups will likely fail when using public or your provider's DNS, see https://www.rspamd.com/doc/faq.html#resolver-setup).

Ideally, all of this should work in both rootless and rootful mode.

  
## proc.py
from typing import Sequence

def mark_bidirectionals(pairs: Sequence) -> list:
    """Given a sequence of pairs (A, B), return a list of 3-tuples (A, B, T) where T is a boolean that
    marks whether the sequence contains the inverted pair (B, A) as well. Order is preserved, but all
    identical and inverted pairs to the right of (i.e. on higher indexes than) the original pair are removed.
    Implementation note: pairs must be immutable (usable as dict keys)."""
    marks = dict()
    for a, b in pairs:
        if (b, a) in marks:

## hexdump.java
    static String hexDump(byte[] bytes) {
        Formatter format = new Formatter(new StringBuilder());
        for (int j = 0; j < bytes.length; j++) {
            if (j % 16 == 0) {
                format.format((j > 0 ? "\n" : "") + "%08X  ", j);
            }
            format.format("%02X ", bytes[j]);
        }
        return format.toString();
    }

## sshd_config
# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

HostKey /etc/ssh/ssh_host_ed25519_key
HostKey /etc/ssh/ssh_host_rsa_key

ChallengeResponseAuthentication no
UsePAM yes

# Allow client to pass locale environment variables

## parent-from-existing.py
#!/usr/bin/env python3

import os
import argparse

parser = argparse.ArgumentParser(description='Generate a Maven parent pom for existing Maven projects in a folder.')
parser.add_argument('root', default='.', nargs='?',
                    help='root (parent) folder')
parser.add_argument('--group', default='localhost',
                    help='groupId for parent POM')

## hls-distances.html
<!DOCTYPE html>

<html>

<head>
  <meta charset="utf-8" />
  <script src="http://js.api.here.com/v3/3.0/mapsjs-core.js" type="text/javascript" charset="utf-8"></script>
  <script src="http://js.api.here.com/v3/3.0/mapsjs-service.js" type="text/javascript" charset="utf-8"></script>
</head>
	# quickly create large/very populated zip files for testing purposes, without taking up lots of disk space

	dd if=/dev/zero bs=1m count=10k \| zip -9 single-10g-file.zip -

	dd if=/dev/urandom bs=1 count=20000 \| split -b 1 -a 4 - test_ && zip -q -m 20k-tiny-files.zip test_*

	# this ensures CD entries with the LFH offset in the ZIP64 EIEF:
	dd if=/dev/zero bs=1g count=6 \| split -b 2g - test_ && zip -0 -m few-huge-files.zip test_*
	#!/usr/bin/env python3
	"""Parse sunrise/sunset tables as provided by the USNO website at https://aa.usno.navy.mil/data/RS_OneYear"""

	import re
	import argparse


	def parse_table(filename: str):
	def to_decimal_deg(latlon_tup) -> float:
	assert len(latlon_tup) == 3 and re.match("[NESW]", latlon_tup[0])
	from typing import Sequence

	def mark_bidirectionals(pairs: Sequence) -> list:
	"""Given a sequence of pairs (A, B), return a list of 3-tuples (A, B, T) where T is a boolean that
	marks whether the sequence contains the inverted pair (B, A) as well. Order is preserved, but all
	identical and inverted pairs to the right of (i.e. on higher indexes than) the original pair are removed.
	Implementation note: pairs must be immutable (usable as dict keys)."""
	marks = dict()
	for a, b in pairs:
	if (b, a) in marks:
	static String hexDump(byte[] bytes) {
	Formatter format = new Formatter(new StringBuilder());
	for (int j = 0; j < bytes.length; j++) {
	if (j % 16 == 0) {
	format.format((j > 0 ? "\n" : "") + "%08X ", j);
	}
	format.format("%02X ", bytes[j]);
	}
	return format.toString();
	}
	# This is the sshd server system-wide configuration file. See
	# sshd_config(5) for more information.

	HostKey /etc/ssh/ssh_host_ed25519_key
	HostKey /etc/ssh/ssh_host_rsa_key

	ChallengeResponseAuthentication no
	UsePAM yes

	# Allow client to pass locale environment variables
	#!/usr/bin/env python3

	import os
	import argparse

	parser = argparse.ArgumentParser(description='Generate a Maven parent pom for existing Maven projects in a folder.')
	parser.add_argument('root', default='.', nargs='?',
	help='root (parent) folder')
	parser.add_argument('--group', default='localhost',
	help='groupId for parent POM')
	<!DOCTYPE html>

	<html>

	<head>
	<meta charset="utf-8" />
	<script src="http://js.api.here.com/v3/3.0/mapsjs-core.js" type="text/javascript" charset="utf-8"></script>
	<script src="http://js.api.here.com/v3/3.0/mapsjs-service.js" type="text/javascript" charset="utf-8"></script>
	</head>