First crack at C<->Rust interaction.

Pushing elsewhere because this won't build on my laptop.

bazel/WORKSPACE

@@ -1,4 +1,4 @@
-# load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 # http_archive(
 #     name = "bazel_pkg_config",
@@ -6,6 +6,26 @@
 #     urls = ["https://github.com/cherrry/bazel_pkg_config/archive/master.zip"],
 # )
 
+# To find additional information on this release or newer ones visit:
+# https://github.com/bazelbuild/rules_rust/releases
+http_archive(
+    name = "rules_rust",
+    integrity = "sha256-Weev1uz2QztBlDA88JX6A1N72SucD1V8lBsaliM0TTg=",
+    urls = ["https://github.com/bazelbuild/rules_rust/releases/download/0.48.0/rules_rust-v0.48.0.tar.gz"],
+)
+
+load("@rules_rust//rust:repositories.bzl", "rules_rust_dependencies", "rust_register_toolchains")
+
+rules_rust_dependencies()
+rust_register_toolchains()
+
+rust_register_toolchains(
+    edition = "2021",
+    versions = [
+        "1.79.0"
+    ],
+)
+
 load("@bazel_tools//tools/build_defs/repo:local.bzl", "local_repository")
 local_repository(
     name = "bazel_pkg_config",

bazel/wrlib/BUILD.bazel

@@ -1,3 +1,12 @@
+load("@rules_rust//rust:defs.bzl", "rust_library")
+
+rust_library(
+    name = "wrlib_rs",
+    srcs = ["wrlib.rs"],
+    deps = [":wrlib"],
+    visibility = ["//visibility:public"],
+)
+
 cc_library(
     name = "wrlib",
     srcs = [

bazel/wrlib/wrlib.rs

@@ -0,0 +1,38 @@
+use std::os::raw::{c_char, c_int, c_uchar};
+
+#[repr(u8)]
+pub enum RImageFormat {
+    RGBAFormat = 0,
+    RRGBAFormat = 1,
+}
+
+#[repr(C)]
+pub struct RImage {
+    data: *mut c_uchar,
+    width: c_int,
+    height: c_int,
+    format: RImageFormat,
+    ref_count: c_int,
+}
+
+extern "C" {
+    pub fn r_destroy_conversion_tables() -> ();
+
+    pub fn RLoadPPM(file: *const c_char) -> *mut RImage;
+
+    pub fn RLoadXPM(context: *mut RContext, file: *const c_char) -> mut *RImage;
+
+    pub fn RReleaseCache() -> ();
+
+    pub fn wraster_rotate_image_180(source: *const RImage) -> *mut RImage;
+
+    pub fn wraster_change_filter(ty: RScalingFilter) -> ();
+
+    pub fn RShutdown() -> ();
+
+    #[must_use]
+    pub fn RSupportedFileFormats() -> *mut *const c_char;
+
+    #[must_use]
+    pub fn RGetImageFileFormat(file: *const c_char) -> *mut c_char;
+}