Migrated first 6 gists.

kernel.c/Makefile

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+.PHONY: all
+all: kernel-1989
+	qemu-system-i386 -kernel kernel-1989 -d guest_errors
+
+kernel-1989: boot.s kmain.c
+	gcc -m32 -c boot.s -o boot.o
+	gcc -m32 -std=c99 -c kmain.c -o kmain.o
+	ld -m elf_i386 -T link.ld -o kernel-1989 boot.o kmain.o
+
+.PHONY: clean
+clean:
+	rm -f *.o kernel-1989

kernel.c/README.md

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+Hello, Kernel! - An absolutely minimal barebones x86 OS kernel, based on this tutorial https://arjunsreedharan.org/post/82710718100/kernel-101-lets-write-a-kernel
+

kernel.c/kernel.c

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+#include <stdint.h>
+#include <stdbool.h>
+
+void kmain(void) {
+  const char * str = "Hello, Kernel!";
+  const char colors[16] = { 0x00, 0x01, 0x02, 0x03,
+			    0x04, 0x05, 0x06, 0x07,
+			    0x08, 0x09, 0x0A, 0x0B,
+			    0x0C, 0x0D, 0x0E, 0x0F
+  };
+  char * vidptr = (char *)0xB8000;
+  uint32_t i = 0;
+  uint32_t j = 0;
+  uint32_t k = 0;
+  uint32_t l = 0;
+
+  while (true) {
+    while (j < 80 * 25 * 2) {
+      vidptr[j] = ' ';
+      vidptr[j + 1] = 0x00;
+      j = j + 2;
+    }
+
+    k = 0;
+    i = 0;
+    while (k < 80 * 25) {
+      j = 0;
+      while (str[j]) {
+	vidptr[i] = str[j];
+	vidptr[i + 1] = colors[l];
+	j++;
+	i += 2;
+	l = (l + 1) % 16;
+      }
+      vidptr[i] = ' ';
+      vidptr[i + 1] = colors[l];
+      i += 2;
+      k += 14;
+    }
+
+    k = 0;
+    while (k < 1500000)
+      k++;
+  }
+
+  return;
+}

kernel.c/kernel.s

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+	.section .text
+
+	// Multiboot header
+	.align 4
+	.long 0x1BADB002
+	.long 0x00
+	.long -0x1BADB002
+
+	// Entry point
+	.globl start
+
+start:
+	cli
+	mov $stack_top, %esp
+	call kmain
+	hlt
+
+	.section .bss
+	
+	.comm stack_bottom, 8192, 4
+stack_top:

kernel.c/link.ld

@@ -0,0 +1,9 @@
+OUTPUT_FORMAT(elf32-i386)
+ENTRY(start)
+SECTIONS
+ {
+    . = 0x100000;
+    .text : { *(.text) }
+    .data : { *(.data) }
+    .bss  : { *(.bss)  }
+ }

rc4.c/README.md

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+Backup of the RC4 algorithm implementation from https://web.archive.org/web/20080404222417/http://cypherpunks.venona.com/date/1994/09/msg00304.html

rc4.c/rc4.c

@@ -0,0 +1,64 @@
+/*rc4.c */
+
+#include "rc4.h"
+
+static void swap_byte(unsigned char *a, unsigned char *b);
+
+void prepare_key(unsigned char *key_data_ptr, int key_data_len, rc4_key *key)
+{
+     unsigned char swapByte;
+     unsigned char index1;
+     unsigned char index2;
+     unsigned char* state;
+     short counter;     
+     
+     state = &key->state[0];         
+     for(counter = 0; counter < 256; counter++)              
+     state[counter] = counter;               
+     key->x = 0;     
+     key->y = 0;     
+     index1 = 0;     
+     index2 = 0;             
+     for(counter = 0; counter < 256; counter++)      
+     {               
+          index2 = (key_data_ptr[index1] + state[counter] + index2) % 256;                
+          swap_byte(&state[counter], &state[index2]);
+
+          index1 = (index1 + 1) % key_data_len;
+     }       
+ }
+ 
+ void rc4(unsigned char *buffer_ptr, int buffer_len, rc4_key *key)
+ { 
+     unsigned char x;
+     unsigned char y;
+     unsigned char* state;
+     unsigned char xorIndex;
+     short counter;              
+     
+     x = key->x;     
+     y = key->y;     
+     
+     state = &key->state[0];         
+     for(counter = 0; counter < buffer_len; counter ++)      
+     {               
+          x = (x + 1) % 256;                      
+          y = (state[x] + y) % 256;               
+          swap_byte(&state[x], &state[y]);                        
+
+          xorIndex = state[x] + (state[y]) % 256;                 
+
+          buffer_ptr[counter] ^= state[xorIndex];         
+      }               
+      key->x = x;     
+      key->y = y;
+ }
+ 
+ static void swap_byte(unsigned char *a, unsigned char *b)
+ {
+     unsigned char swapByte; 
+     
+     swapByte = *a; 
+     *a = *b;      
+     *b = swapByte;
+ }

rc4.c/rc4.h

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+/* rc4.h */
+
+typedef struct rc4_key
+{      
+     unsigned char state[256];       
+     unsigned char x;        
+     unsigned char y;
+} rc4_key;
+
+void prepare_key(unsigned char *key_data_ptr,int key_data_len, rc4_key *key);
+
+void rc4(unsigned char *buffer_ptr,int buffer_len,rc4_key * key);

rip2iso.sh/README.md

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+Rips raw data from a CD using the /dev/sr1 device (USB cd writer) to an iso image file.

rip2iso.sh/rip2iso.sh

@@ -0,0 +1,17 @@
+#! /bin/bash
+
+# Usage: ./rip2iso.sh ISO_FILE_NAME
+# Output: a file named "ISO_FILE_NAME01.iso"
+
+cdrdao read-cd \
+       --datafile $1.bin \
+       --driver generic-mmc:0x20000 \
+       --device /dev/sr1 \
+       --read-raw \
+       $1.toc
+
+toc2cue $1.toc $1.cue
+
+bchunk $1.bin $1.cue $1
+
+rm -i $i.bin $i.toc $i.cue

rmfen.l/README.md

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+Flex lexer for rithmomachia boards represented in reduced modified FEN notation.

rmfen.l/rmfen.l

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+%{
+#include <stdio.h>
+%}
+
+%option outfile="rmfen.c"
+%option always-interactive
+%option nounput noinput
+
+space      [1-7]
+piece      (c|s|t|C|S|T)([1-9][0-9]{0,2})"."
+pyramid    (p|P){piece}+"."
+boardpiece ({pyramid}|{piece})
+row        (({space}|{boardpiece}){0,7}{boardpiece})?
+board      ({row}"/"){15}{row}
+
+%%
+
+{board} { printf("Valid board: %s\n", yytext); }
+
+. { printf("Unknown text %s\n", yytext); }

unknytt.py/README.md

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+File extractor for Knytt Stories story files updated for Python 3. Originally from here: https://nifflas.lp1.nl/index.php?topic=2685.0

unknytt.py/unknytt.py

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+#!/usr/bin/python
+
+import struct
+import os
+import sys
+
+def readheader(f):
+    magic = f.read(2)
+    if magic == b'':
+        raise EOFError
+    if magic != b'NF':
+        raise ValueError("Bad header")
+    nextchar = f.read(1)
+    name = []
+    while nextchar != b'\0':
+        name.append(nextchar.decode())
+        nextchar = f.read(1)
+    name = ''.join(name)
+    sizedata = f.read(4)
+    (size,) = struct.unpack('<L', sizedata)
+    return name, size
+
+def extractfile(f, destdir='.'):
+    try:
+        name, size = readheader(f)
+    except EOFError:
+        return False
+    
+    outfilename = os.path.join(destdir, *name.split('\\'))
+    
+    print("Extracting %s (%s bytes).." % (name, size))
+    
+    outdir, dummy = os.path.split(outfilename)
+    try:
+        os.makedirs(outdir)
+    except OSError:
+        pass
+    
+    outfile = open(outfilename, 'wb')
+    bytestowrite = size
+    while bytestowrite > 0:
+        data = f.read(min(bytestowrite, 4096))
+        if data == '':
+            raise EOFError("file ended prematurely")
+        outfile.write(data)
+        bytestowrite -= len(data)
+    
+    return True
+
+def unknytt(f, worlddir='.'):
+    try:
+        name, dummy = readheader(f)
+    except EOFError:
+        raise ValueError("not a valid knytt stories file")
+    
+    print("Creating %s\\" % name)
+    destdir = os.path.join(worlddir, name)
+    os.mkdir(destdir)
+    
+    while extractfile(f, destdir):
+        pass
+    
+    print("Everything is ok.")
+
+if __name__ == '__main__':
+    f = open(sys.argv[1], 'rb')
+    unknytt(f)

whoami.php/README.md

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+Testing things...

whoami.php/whoami.php

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+<?php
+echo '<pre>';
+
+// Outputs all the result of shellcommand "ls", and returns
+// the last output line into $last_line. Stores the return value
+// of the shell command in $retval.
+$last_line = system('whoami', $retval);
+
+// Printing additional info
+echo '
+</pre>
+<hr />Last line of the output: ' . $last_line . '
+<hr />Return value: ' . $retval;
+?>