11 unstable releases (3 breaking)

Uses new Rust 2021

new 0.4.1 Jan 28, 2023
0.4.0 Dec 22, 2022
0.3.3 Nov 27, 2022
0.2.0 Sep 29, 2022
0.1.2 Aug 30, 2022

#174 in Embedded development

MIT license

4.5K SLoC


A cross-platform, fast, and safe general purpose C library written in Rust.

The library is organized as a series of modules. The top level module nstd encompasses the entire crate. Each module can have their own submodules (eg. nstd.io.stdout or nstd::io::stdout with Rust syntax).

Example using C

// Build nstd with features set to "clib nstd_core nstd_io".
#include <nstd.h>

/// Main entry point of the program.
int main()
    const NSTDStr output = nstd_core_str_from_raw_cstr("Hello, 🌎!");
    return 0;

Library modules

  • nstd - A cross-platform, fast, and safe general purpose C library written in Rust.
    • alloc - Low level memory allocation.
    • core - Provides core functionality for nstd.
      • cstr - Unowned C string slices.
        • raw - Raw C string processing.
      • cty - Provides functions for examining and operating on character types.
      • def - Contains common types used throughout nstd.
      • fty - Provides functions for examining and operating on floating point types.
      • ity - Provides functions for examining and operating on integral types.
      • math - Low level math operations.
      • mem - Contains mostly unsafe functions for interacting with raw memory.
      • ops - Operator overloading for types and operators that may cause overflow.
      • optional - Represents an optional (possibly uninitialized) value.
      • ptr - A sized pointer to some arbitrary type.
        • raw - Provides useful utilities for working with raw pointers.
      • range - A numerical range.
      • result - Defines a "result" type with success and error variants.
      • slice - A view into a sequence of values in memory.
      • str - An unowned view into a UTF-8 encoded byte string.
    • cstring - A dynamically sized, null terminated, C string.
    • env - Process environment management.
    • fs - Provides access to the file system.
      • file - A handle to an opened file.
    • heap_ptr - A pointer type for single value heap allocation.
    • io - Provides functionality for interacting with the standard I/O streams.
      • stderr - A handle to the standard error stream.
      • stdin - A handle to the standard input stream.
      • stdout - A handle to the standard output stream.
    • math - High level math operations.
    • os - Operating system specific functionality.
      • unix - Low level Unix-like operating system support.
        • alloc - Memory allocation for Unix-like systems.
        • shared_lib - Provides shared library access for Unix-like systems.
      • windows - OS support for Windows.
        • alloc - Low level memory allocation for Windows.
          • heap - Process heap management for Windows.
        • shared_lib - Shared library/module access for Windows.
    • proc - Calling/Child process management.
    • shared_lib - Access symbols from loaded shared libraries.
    • shared_ptr - A reference counting smart pointer.
    • string - Dynamically sized UTF-8 encoded byte string.
    • thread - Thread spawning, joining, and detaching.
    • vec - A dynamically sized contiguous sequence of values.

Platform support

nstd.core should support anything that rustc supports.

nstd.os's child modules will only work on the operating system they target. For example, nstd.os.windows will only work on Windows and nstd.os.unix will only work on Unix-like systems.

Other modules will work on most platforms, primarily targeting Windows, macOS, Linux, Android, and iOS.

Language support

This library can be accessed from any language that supports calling C code. As of now this will need to be done manually as there are no official wrappers for the API, however somewhere around version 0.11, the plan is to start adding official wrappers so developers from other languages can easily use the API.


Please note that these safety notes (as well as the framework as a whole) are a work in progress.

User safety notes

  • Raw pointers are unsafe to access.

  • References are assumed to be valid (aligned, non-null, and non-dangling), and are safe to access. Users can refer to the docs to see which APIs expect or return valid references.

  • Reference data is assumed to remain unaltered by other code/threads.

  • When a mutable reference is in use, the underlying data must not be accessed by other code.

  • Private (non-pub) structure members must not be directly accessed by the user.

  • The panic behavior is set to abort by default, as it is undefined behavior to unwind from Rust code into foreign code (though this is subject to change).

Contributor safety notes

  • Any operation that may cause undefined behavior must be marked unsafe.

  • Any operation that may cause data races must be marked unsafe.

  • All C function pointers taken as input by the API must be marked unsafe.

How to build

Building nstd as a C library requires you to specify the "crate-type" manually. To do this you must pass a --crate-type of either cdylib or staticlib to rustc. Rust allows you to use this flag multiple times in case you need both.

nstd lets you decide what features you want to use.

Any module that falls under the top level module has a dedicated feature flag, for example nstd.core has the feature flag nstd_core and nstd.alloc has the feature flag nstd_alloc.

Each module may have additional features, for example nstd.os has the additional nstd_os_windows_alloc feature for memory allocation on Windows, this allows other modules to use the low level memory allocation API for Windows without enabling memory allocation for other operating systems.

The clib feature flag is used to build nstd as a C library.

The std feature flag links the Rust standard library into the binary.

The asm feature permits the library to use assembly to optimize certain build configurations.

std and nstd_core are enabled by default.


cargo rustc --release --crate-type cdylib --crate-type staticlib --features "clib nstd_alloc"

To build with all features:

cargo rustc --release --crate-type cdylib --crate-type staticlib --all-features


nstd versions follow the Semantic Versioning rules. Each release is given a major, minor, and patch number that makes up that version of the library (major.minor.patch).

There have not yet been any major releases for the framework as it is not yet stable.

A new minor version is released every 6 weeks, exactly 1 week after a new minor Rust release.

Patch releases are released every so often with bug fixes.

See semver.org to learn more about Semantic Versioning.


~88K SLoC