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UUID4

A drop-in two files library to generate version 4 UUIDs.

⚠ The underlying PRNG is SplitMix which makes UUIDs produced by this library trivially predictable. But if you're willing to generate secure "tokens", that's not what UUIDs are made for anyway 🤷‍♂️

The statistical properties of the generated UUIDs have been tested with PractRand and TestU01 🎲

This implementation has been used in production for years without any reported defect so far 🤞

Supported platforms:

  • Windows
  • Linux
  • Mac
  • iOS
  • Android

Just drop uuid4.h and uuid4.c into your build and get started. (see also customizing compilation)

Usage

  • uuid4_seed() seeds the version 4 UUID generator.
  • uuid4_gen() generates a version 4 UUID.
  • uuid4_to_s() converts a version 4 UUID into a string.

Example usage:

#include <stdio.h>
#include <uuid4.h>

int main()
{
  UUID4_STATE_T state;
  UUID4_T uuid;

  uuid4_seed(&state);
  uuid4_gen(&state, &uuid);

  char buffer[UUID4_STR_BUFFER_SIZE];
  if (!uuid4_to_s(uuid, buffer, sizeof(buffer)))
    exit(EXIT_FAILURE);

  printf("%s\n", buffer);

  return EXIT_SUCCESS;
}

Customizing compilation

You can customize the library's behavior by defining the following macros:

  • UUID4_FUNCSPEC
  • UUID4_PREFIX
  • UUID4_ASSERT

Compiling for Windows

There is a Visual Studio 2015 solution in the _win-vs14/ folder.

Compiling for Linux or Mac

There is a GNU Make 3.81 MakeFile in the _gnu-make/ folder:

$ make -j -C _gnu-make/

Compiling for Mac

See above if you want to compile from command line. Otherwise there is an Xcode project located in the _mac-xcode/ folder.

Compiling for iOS

There is an Xcode project located in the _ios-xcode/ folder.

If you prefer compiling from command line and deploying to a jailbroken device through SSH, use:

$ make -j -C _gnu-make/ platform=ios architecture=arm64 CC="$(xcrun --sdk iphoneos --find clang) -isysroot $(xcrun --sdk iphoneos --show-sdk-path) -arch arm64" postbuild="codesign -s 'iPhone Developer'"

Compiling for Android

You will have to install the Android NDK, and point the $NDK_ROOT environment variable to the NDK path: e.g. export NDK_ROOT=/opt/android-ndk (without a trailing / character).

Next, the easy way is to make a standalone Android toolchain with the following command:

$ $NDK_ROOT/build/tools/make_standalone_toolchain.py --arch=arm64 --api 21 --install-dir=/tmp/android-toolchain

Now you can compile the example by running:

$ make -j -C _gnu-make/ platform=android architecture=arm64 CC=/tmp/android-toolchain/bin/aarch64-linux-android-gcc CXX=/tmp/android-toolchain/bin/aarch64-linux-android-g++

If you find this library useful and decide to use it in your own projects please drop me a line @gpakosz.