`cbindgen`

This project can be used to generate C bindings for Rust code. It is currently being developed to support creating bindings for WebRender, but has been designed to support any project.

Features

Builds bindings for a crate, its mods, its dependent crates, and their mods
Only the necessary types for exposed functions are given bindings
Can specify annotations for controlling some aspects of binding
Support for generic structs and unions
Support for exporting constants and statics
Customizable formatting, can be used in C or C++ projects
Support for generating #ifdef's for #[cfg] attributes

Use

Command line

cbindgen crate/ -o crate/bindings.h

See cbindgen --help for more options.

`build.rs`

cbindgen can also be used in build scripts. How this fits into compiling the native code depends on your project.

Here's an example build.rs script:

extern crate cbindgen;

use std::env;

fn main() {
    let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();

    cbindgen::Builder::new()
      .with_crate(crate_dir)
      .generate()
      .expect("Unable to generate bindings")
      .write_to_file("bindings.h");
}

Configuration

There are some options that can be used to configure the binding generation.

For the command line, they can be specified by creating a cbindgen.toml with the options. This can be placed in the binding crate root or at a path manually specified.

For build scripts, options can be specified on the builder or by writing a cbindgen.toml and using the helper function cbindgen::generate.

Here is a description of the options available in a config.

# An optional string of text to output at the beginning of the generated file
header = "/* Text to put at the beginning of the generated file. Probably a license. */"
# An optional string of text to output at the end of the generated file
trailer = "/* Text to put at the end of the generated file */"
# An optional name to use as an include guard
include_guard = "mozilla_wr_bindings_h"
# An optional string of text to output between major sections of the generated
# file as a warning against manual editing
autogen_warning = "/* Warning, this file is autogenerated by cbindgen. Don't modify this manually. */"
# Whether to include a comment with the version of cbindgen used to generate the
# file
include_version = true
# An optional namespace to output around the generated bindings
namespace = "ffi"
# An optional list of namespaces to output around the generated bindings
namespaces = ["mozilla", "wr"]
# The style to use for curly braces
braces = "[SameLine|NextLine]"
# The desired length of a line to use when formatting lines
line_length = 80
# The amount of spaces in a tab
tab_width = 2
# The language to output bindings in
language = "[C|C++]"

[parse]
# Whether to parse dependent crates and include their types in the generated
# bindings
parse_deps = true
# A white list of crate names that are allowed to be parsed
include = ["webrender", "webrender_traits"]
# A black list of crate names that are not allowed to be parsed
exclude = ["libc"]
# A list of crate names that should be run through `cargo expand` before
# parsing to expand any macros
expand = ["euclid"]

[fn]
# An optional prefix to put before every function declaration
prefix = "string"
# An optional postfix to put after any function declaration
postfix = "string"
# How to format function arguments
args = "[Auto|Vertical|Horizontal]"
# A rule to use to rename function argument names
rename_args = "[None|GeckoCase|LowerCase|UpperCase|PascalCase|CamelCase|SnakeCase|ScreamingSnakeCase|QualifiedScreamingSnakeCase]"

[struct]
# A rule to use to rename field names
rename_fields = "[None|GeckoCase|LowerCase|UpperCase|PascalCase|CamelCase|SnakeCase|ScreamingSnakeCase|QualifiedScreamingSnakeCase]"
# Whether to derive an operator== for all structs
derive_eq = false
# Whether to derive an operator!= for all structs
derive_neq = false
# Whether to derive an operator< for all structs
derive_lt = false
# Whether to derive an operator<= for all structs
derive_lte = false
# Whether to derive an operator> for all structs
derive_gt = false
# Whether to derive an operator>= for all structs
derive_gte = false

[enum]
# A rule to use to rename enum variants
rename_variants = "[None|GeckoCase|LowerCase|UpperCase|PascalCase|CamelCase|SnakeCase|ScreamingSnakeCase|QualifiedScreamingSnakeCase]"

Examples

See tests/rust/ for some examples of rust source that can be handled.

Major differences between `cbindgen` and `rusty-cheddar`

cbindgen supports generics
cbindgen supports C++ output using enum class and template specialization
cbindgen supports generating bindings including multiple modules and crates

There may be other differences, but those are the ones that I know of. Please correct me if I misrepresented anything.

Prominent users

If you're using cbindgen and would like to be added to this list, please open a pull request!

cbindgen 0.3.0

cbindgen