Improve install_blake3.sh script error handling and OS detection

Installation script for BLAKE3 has been refactored for better error handling and OS detection. Functions were introduced to handle common tasks such as error exit, detecting OS, checking root access, getting the number of processors, cloning the repository, and building & installing BLAKE3. This enhancement increases the robustness of the script and eases its usage on different Unix-like systems.

install_blake3.sh

@@ -1,29 +1,63 @@
-#!/bin/env bash
+#!/usr/bin/env bash
 
 # This script is used to build and install BLAKE3 on Unix-like systems.
 # Requires CMake, Ninja, and GCC (or a compatible C compiler) to be installed.
 
-C_COMPILER=gcc
-
-if [ "$1" ]; then
-    C_COMPILER="$1"
-fi
+# Function to display error message and exit
+error_exit() {
+    echo "$1" 1>&2
+    exit 1
+}
+
+# Function to Detect OS and set variables
+detect_os() {
+    case "$OSTYPE" in
+    "linux-gnu"*) CURRENT_OS="linux" ;;
+    "darwin"*) CURRENT_OS="macos" ;;
+    esac
+}
+
+# Function to check root access
+check_root() {
+    [[ "$CURRENT_OS" != "macos" && "$EUID" -ne 0 ]] && error_exit "This script must be run as root."
+}
+
+get_number_of_processors() {
+    case "$CURRENT_OS" in
+    "linux") NUMBER_OF_PROCESSORS=$(nproc) ;;
+    "macos") NUMBER_OF_PROCESSORS=$(sysctl -n hw.ncpu) ;;
+    *) NUMBER_OF_PROCESSORS=4 ;;
+    esac
+}
+
+# Function to clone repository
+clone_repo() {
+    git clone https://github.com/BLAKE3-team/BLAKE3.git || error_exit "Failed to clone BLAKE3 repository."
+}
+
+# Function to build and install BLAKE3
+build_install() {
+    cd BLAKE3/c || error_exit "Failed to navigate to BLAKE3/c directory."
+    cmake -B build -DCMAKE_C_COMPILER="$C_COMPILER" -G Ninja || error_exit "Failed to run cmake."
+    get_number_of_processors
+
+    cmake --build build --config Release --target install -j "$NUMBER_OF_PROCESSORS" || error_exit "Failed to build and install."
+
+    # Cleanup
+    cd ../..
+    rm -rf BLAKE3
+}
+
+# Set C compiler
+C_COMPILER=${1:-gcc}
+
+detect_os
+check_root
+
+cd "${0%/*}" || error_exit "Failed to change directory to script location."
 
 echo "Compiling BLAKE3 with $C_COMPILER compiler.."
 
-# Root access is required to install BLAKE3 to the system.
-if [ "$EUID" -ne 0 ]; then
-    echo "Please run as root."
-    exit
-fi
-
-# Run from this directory
-cd "${0%/*}" || exit 1
-
-# Clone the repository
-git clone https://github.com/BLAKE3-team/BLAKE3.git
-
-# Build and install BLAKE3
-cd BLAKE3/c || echo "Failed to find BLAKE3/c directory" && exit 1
-cmake -B build -DCMAKE_C_COMPILER="$C_COMPILER" -G Ninja
-cmake --build build --config Release --target install -j 4
+# Call functions
+clone_repo
+build_install