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Linux Signal Handling — TL;DR

Remember: signals come from the OS. The kernel decides a signal is pending for your process or thread, and when your code gets CPU time again, delivery happens according to the handling rules you previously told the OS to use.
Almost every signal-related function is a variation of: “kernel, for signal X, do Y.”

Core setup / registration

• sigaction()
  Register with the OS that you want a specific way of handling a signal, such as running your handler function, ignoring it, or restoring default behavior.
• sigemptyset(): Clear set

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Python unittest Assertions

Equality and Identity

self.assertEqual(a, b)          # a == b
self.assertNotEqual(a, b)       # a != b
self.assertIs(a, b)            # a is b
self.assertIsNot(a, b)         # a is not b

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self.assertEqual(a, b)          # a == b
self.assertNotEqual(a, b)       # a != b
self.assertTrue(x)             # bool(x) is True
self.assertFalse(x)            # bool(x) is False
self.assertIs(a, b)            # a is b
self.assertIsNot(a, b)         # a is not b
self.assertIsNone(x)           # x is None
self.assertIsNotNone(x)        # x is not None
self.assertIn(a, b)            # a in b
self.assertNotIn(a, b)         # a not in b

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Unity Test Framework Asserts Cheat Sheet 📋

Language: C
Testing framwork: Unity

This cheat sheet provides an overview of key assertions in the Unity Test Framework, commonly used for unit testing in C. Each assertion includes a description, syntax, and practical examples to help you write effective tests. 🚀

Basic Assertions 🧪

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🔴 Most Expensive Operations (High Cost) Memory Allocations (malloc, calloc, realloc, free)

These involve system calls or interactions with the heap manager.

Slow because they may require searching free lists, splitting blocks, or coalescing memory.

Disk or I/O Operations (fread, fwrite, etc.)

Extremely slow compared to CPU-bound code.

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

// Structure to hold all parsed options
typedef struct {
    int verbose;
    int debug;
    int quiet;

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static char **
create_matrix (int rows, int columns)
{
    if (!rows || !columns)
    {
        return NULL;
    }

    char **pp_matrix = malloc(rows * sizeof(char *));
    if (!pp_matrix)

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// swaps bytes to change endianess
// void pointer to be used for any data type to swap bytes

void reverse_bytes(const void *src, void *dest, size_t size)
{
    const uint8_t *s = src;
    uint8_t *d = dest;

    for (size_t i = 0; i < size; i++)
    {

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// able to be used both ways, to go little to big or big to little.

double swap_double_endian(const uint8_t *in)
{
    uint8_t reversed_bytes[8];

    for (int i = 0; i < 8; i++)
    {
        reversed_bytes[i] = in[7 - i];
    }

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.PHONY: debug clean all tidy tsan asan

BIN := TEST

OBJ_DIR := obj

SRC_DIR := src
INC_DIR := include

STANDARD := -std=c99