UUID Generator — Zig source

// RFC 4122 v4 UUID generator (cryptographically secure).
//
// Language: Zig (0.13+)
// CosmoDev polyglot showcase port of the `uuid` tool.
// Ported from src/lib/uuid.ts — display source, part of CosmoDev's
// polyglot tool pages.
//
// Produces a random (v4) UUID: 36 characters, lowercase, hyphenated as
// 8-4-4-4-12 hex digits, with the RFC version (4) and variant (10xx)
// bits set. std.crypto.random is Zig's bridge to the host CSPRNG, so
// output is unpredictable and collision-safe.

const std = @import("std");

/// Write a fresh RFC 4122 version-4 UUID into `buf` (36 bytes).
fn uuidV4(buf: *[36]u8) void {
    var b: [16]u8 = undefined;
    std.crypto.random.bytes(&b);

    b[6] = (b[6] & 0x0f) | 0x40; // version 4: high nibble of byte 6
    b[8] = (b[8] & 0x3f) | 0x80; // variant  : high bits of byte 8

    // Lowercase hex, hyphens at the 8-4-4-4-12 boundaries.
    const hex = "0123456789abcdef";
    var p: usize = 0;
    for (b, 0..) |byte, i| {
        if (i == 4 or i == 6 or i == 8 or i == 10) {
            buf[p] = '-';
            p += 1;
        }
        buf[p] = hex[byte >> 4];
        buf[p + 1] = hex[byte & 0x0f];
        p += 2;
    }
}

pub fn main() !void {
    var id: [36]u8 = undefined;
    uuidV4(&id);
    const stdout = std.io.getStdOut().writer();
    try stdout.print("{s}\n", .{id});
}