Crate linux_api

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Type definitions and utilities for interacting with the Linux API. Does not depend on the std crate (i.e. is no_std) nor libc.

We currently re-export C bindings. This allows normal C code, using libc headers, to work with these kernel types. Normally this can’t be done because the libc and kernel headers contain incompatible definitions.

§Type names

We provide 3 styles of types:

  • snake-cased-types prefixed with linux_. These are ABI-compatible with the corresponding kernel types. These types are re-exported in this crate’s generated C header, and are the types used in exported C function APIs.

  • snake-cased-types without the linux_ prefix. These are also ABI-compatible with the corresponding kernel types, and are intended for use in Rust code. They never require or enforce invariants beyond that bytes are initialized, so are safe to transmute from initialized bytes, or from the corresponding linux_ type if the required bytes are known to be initialized. See crate::signal::sigaction for an example of a type with such invariants.

    We do not expose these types in C interfaces, since they have the same name as types in the original Linux headers, and often with the same name in C library headers. Exported C APIs should use the linux_ types in their signatures, and convert internally to the non-prefixed types. In cases where the 2 types are not simply aliased, they usually implement bytemuck::TransparentWrapper or similar APIs that allow converting values and references in both directions.

  • camel-cased types are not necessarily bitwise-compatible with kernel types with similar names. These primarily include enums and bitflags types. Kernel constants such as O_WRONLY are typically defined as instants of such types, and are convertible to and from the original integer types.

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