Cargo C-ABI helpers
cargo applet to build and install C-ABI compatible dynamic and static libraries.
It produces and installs a correct pkg-config file, a static library and a dynamic library, and a C header to be used by any C (and C-compatible) software.
Installation
cargo-c may be installed from crates.io.
cargo install cargo-c
The rustc
version supported is the same as the one supported by the cargo
version embedded in the package version, or as set in the
rust-version field.
You must have the cargo build requirements satisfied in order to build cargo-c:
git
pkg-config
(on Unix, used to figure out the host-provided headers/libraries)curl
(on Unix)- OpenSSL headers (only for Unix, this is the
libssl-dev
package on deb-based distributions)
You may pass --features=vendored-openssl
if you have problems building openssl-sys using the host-provided OpenSSL.
cargo install cargo-c --features=vendored-openssl
Usage
# build the library, create the .h header, create the .pc file
$ cargo cbuild --destdir=${D} --prefix=/usr --libdir=/usr/lib64
# build the library, create the .h header, create the .pc file, build and run the tests
$ cargo ctest
# build the library, create the .h header, create the .pc file and install all of it
$ cargo cinstall --destdir=${D} --prefix=/usr --libdir=/usr/lib64
For a more in-depth explanation of how cargo-c
works and how to use it for
your crates, read Building Crates so they Look Like C ABI Libraries.
The TL;DR:
- Create a
capi.rs
with the C-API you want to expose and use#[cfg(cargo_c)]
#[cfg(feature="capi")]
to hide it when you build a normal rust library. - Make sure you have a lib target and if you are using a workspace the first member is the crate you want to export, that means that you might have to add a "." member at the start of the list.
Since Rust 1.38, also add "staticlib" to the "lib"Do not specify thecrate-type
.crate-type
, cargo-c will add the correct library target by itself.- You may use the feature
capi
to add C-API-specific optional dependencies.NOTE: It must be always present in
Cargo.toml
- Remember to add a
cbindgen.toml
and fill it with at least the include guard and probably you want to set the language to C (it defaults to C++) - Once you are happy with the result update your documentation to tell the user
to install
cargo-c
and docargo cinstall --prefix=/usr --destdir=/tmp/some-place
or something along those lines.
Advanced
You may override various aspects of cargo-c
via settings in Cargo.toml
under the package.metadata.capi
key
[package.metadata.capi]
# Configures the minimum required cargo-c version. Trying to run with an
# older version causes an error.
min_version = "0.6.10"
Header Generation
[package.metadata.capi.header]
# Used as header file name. By default this is equal to the crate name.
# The name can be with or without the header filename extension `.h`
name = "new_name"
# Install the header into a subdirectory with the name of the crate. This
# is enabled by default, pass `false` or "" to disable it.
subdirectory = "libfoo-2.0/foo"
# Generate the header file with `cbindgen`, or copy a pre-generated header
# from the `assets` subdirectory. By default a header is generated.
generation = true
# Can be use to disable header generation completely.
# This can be used when generating dynamic modules instead of an actual library.
enabled = true
pkg-config
File Generation
[package.metadata.capi.pkg_config]
# Used as the package name in the pkg-config file and defaults to the crate name.
name = "libfoo"
# Used as the pkg-config file name and defaults to the crate name.
filename = "libfoo-2.0"
# Used as the package description in the pkg-config file and defaults to the crate description.
description = "some description"
# Used as the package version in the pkg-config file and defaults to the crate version.
version = "1.2.3"
# Used as the Requires field in the pkg-config file, if defined
requires = "gstreamer-1.0, gstreamer-base-1.0"
# Used as the Requires.private field in the pkg-config file, if defined
requires_private = "gobject-2.0, glib-2.0 >= 2.56.0, gmodule-2.0"
# Strip the include search path from the last n components, useful to support installing in a
# subdirectory but then include with the path. By default it is 0.
strip_include_path_components = 1
Library Generation
[package.metadata.capi.library]
# Used as the library name and defaults to the crate name. This might get
# prefixed with `lib` depending on the target platform.
name = "new_name"
# Used as library version and defaults to the crate version. How this is used
# depends on the target platform.
version = "1.2.3"
# Used to install the library to a subdirectory of `libdir`.
install_subdir = "gstreamer-1.0"
# Used to disable versioning links when installing the dynamic library
versioning = false
# Add `-Cpanic=abort` to the RUSTFLAGS automatically, it may be useful in case
# something might panic in the crates used by the library.
rustflags = "-Cpanic=abort"
# Used to disable the generation of additional import library file in platforms
# that have the concept such as Windows
import_library = false
Custom data install
[package.metadata.capi.install.data]
# Used to install the data to a subdirectory of `datadir`. By default it is the same as `name`
subdirectory = "foodata"
# Copy the pre-generated data files found in {root_dir}/{from} to {datadir}/{to}/{matched subdirs}
# If {from} is a single path instead of a glob, the destination is {datapath}/{to}.
# datapath is {datadir}/{subdirectory}
asset = [{from="pattern/with/or/without/**/*", to="destination"}]
# Copy the pre-generated data files found in {OUT_DIR}/{from} to {includedir}/{to}/{matched subdirs}
# If {from} is a single path instead of a glob, the destination is {datapath}/{to}.
# datapath is {datadir}/{subdirectory}
generated = [{from="pattern/with/or/without/**/*", to="destination"}]
[package.metadata.capi.install.include]
# Copy the pre-generated includes found in {root_dir}/{from} to {includedir}/{to}/{matched subdirs}
# If {from} is a single path instead of a glob, the destination is {includepath}/{to}.
# includepath is {includedir}/{header.subdirectory}
asset = [{from="pattern/with/or/without/**/*", to="destination"}]
# Copy the pre-generated includes found in {OUT_DIR}/{from} to {includedir}/{to}/{matched subdirs}
# If {from} is a single path instead of a glob, the destination is {includedpath}/{to}.
# includepath is {includedir}/{header.subdirectory}
generated = [{from="pattern/with/or/without/**/*", to="destination"}]
Notes
Do not pass RUSTFLAGS
that are managed by cargo through other means, (e.g. the flags driven by [profiles]
or the flags driven by [target.<>]
), cargo-c effectively builds as if the target is always explicitly passed.
Users
Status
- cli
- build command
- install command
- test command
- cargo applet support
- build targets
- pkg-config generation
- header generation (cbindgen integration)
-
staticlib
support -
cdylib
support - Generate version information in the header
- Make it tunable
- Extra Cargo.toml keys
- Better status reporting
Acknowledgements
This software has been partially developed in the scope of the H2020 project SIFIS-Home with GA n. 952652.