CMake: Rust bindgen w/ C libs outside std include path

In order to generate Rust bindings for C code, Rust's bindgen module
needs to know where to find all headers included by the API.
If they're all inside the project or inside the standard include path
(e.g. /usr/include and /usr/local/include) that's fine. But for third-
party C library headers from outside the standard include path, that's
a problem.
We didn't really notice this problem when generating on Unix systems
until we switched to use OpenSSL 3.1 and tested on systems that have
the OpenSSL 1.1.1 dev package installed.

The ability to find headers outside the project path is also needed to
generate bindings on Windows, if desired.

This commit solves the problem by passing include directories for the
ClamAV::libclamav CMake build target to the Rust build via the
CARGO_INCLUDE_DIRECTORIES environment variable.
Then, in the `libclamav_rust/build.rs` script, where we run bindgen,
we split that `;` separated string into invididual paths and add each
to the bindgen builder.

cmake/FindRust.cmake

@@ -236,7 +236,7 @@ function(add_rust_executable)
     # Build the executable.
     add_custom_command(
         OUTPUT "${OUTPUT}"
-        COMMAND ${CMAKE_COMMAND} -E env "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS}
+        COMMAND ${CMAKE_COMMAND} -E env "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS}
         WORKING_DIRECTORY "${ARGS_SOURCE_DIRECTORY}"
         DEPENDS ${EXE_SOURCES}
         COMMENT "Building ${ARGS_TARGET} in ${ARGS_BINARY_DIRECTORY} with:\n\t ${cargo_EXECUTABLE} ${MY_CARGO_ARGS_STRING}")
@@ -265,7 +265,7 @@ endfunction()
 
 function(add_rust_library)
     set(options)
-    set(oneValueArgs TARGET SOURCE_DIRECTORY BINARY_DIRECTORY PRECOMPILE_TESTS)
+    set(oneValueArgs TARGET SOURCE_DIRECTORY BINARY_DIRECTORY PRECOMPILE_TESTS INCLUDE_DIRECTORIES)
     cmake_parse_arguments(ARGS "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
     if(WIN32)
@@ -287,8 +287,8 @@ function(add_rust_library)
     if("${CMAKE_OSX_ARCHITECTURES}" MATCHES "^(arm64;x86_64|x86_64;arm64)$")
         add_custom_command(
             OUTPUT "${OUTPUT}"
-            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=x86_64-apple-darwin
-            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=aarch64-apple-darwin
+            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=x86_64-apple-darwin
+            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=aarch64-apple-darwin
             COMMAND ${CMAKE_COMMAND} -E make_directory "${ARGS_BINARY_DIRECTORY}/${RUST_COMPILER_TARGET}/${CARGO_BUILD_TYPE}"
             COMMAND lipo -create ${ARGS_BINARY_DIRECTORY}/x86_64-apple-darwin/${CARGO_BUILD_TYPE}/lib${ARGS_TARGET}.a ${ARGS_BINARY_DIRECTORY}/aarch64-apple-darwin/${CARGO_BUILD_TYPE}/lib${ARGS_TARGET}.a -output "${OUTPUT}"
             WORKING_DIRECTORY "${ARGS_SOURCE_DIRECTORY}"
@@ -297,22 +297,22 @@ function(add_rust_library)
     elseif("${CMAKE_OSX_ARCHITECTURES}" MATCHES "^(arm64)$")
         add_custom_command(
             OUTPUT "${OUTPUT}"
-            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=aarch64-apple-darwin
+            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=aarch64-apple-darwin
             WORKING_DIRECTORY "${ARGS_SOURCE_DIRECTORY}"
             DEPENDS ${LIB_SOURCES}
             COMMENT "Building ${ARGS_TARGET} in ${ARGS_BINARY_DIRECTORY} with:  ${cargo_EXECUTABLE} ${MY_CARGO_ARGS_STRING}")
     elseif("${CMAKE_OSX_ARCHITECTURES}" MATCHES "^(x86_64)$")
         add_custom_command(
             OUTPUT "${OUTPUT}"
-            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=x86_64-apple-darwin
+            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS} --target=x86_64-apple-darwin
             COMMAND ${CMAKE_COMMAND} -E make_directory "${ARGS_BINARY_DIRECTORY}/${RUST_COMPILER_TARGET}/${CARGO_BUILD_TYPE}"
             WORKING_DIRECTORY "${ARGS_SOURCE_DIRECTORY}"
             DEPENDS ${LIB_SOURCES}
             COMMENT "Building ${ARGS_TARGET} in ${ARGS_BINARY_DIRECTORY} with:  ${cargo_EXECUTABLE} ${MY_CARGO_ARGS_STRING}")
     else()
         add_custom_command(
             OUTPUT "${OUTPUT}"
-            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS}
+            COMMAND ${CMAKE_COMMAND} -E env "CARGO_CMD=build" "CARGO_TARGET_DIR=${ARGS_BINARY_DIRECTORY}" "MAINTAINER_MODE=${MAINTAINER_MODE}" "CARGO_INCLUDE_DIRECTORIES=${ARGS_INCLUDE_DIRECTORIES}" "RUSTFLAGS=${RUSTFLAGS}" ${cargo_EXECUTABLE} ${MY_CARGO_ARGS}
             WORKING_DIRECTORY "${ARGS_SOURCE_DIRECTORY}"
             DEPENDS ${LIB_SOURCES}
             COMMENT "Building ${ARGS_TARGET} in ${ARGS_BINARY_DIRECTORY} with:  ${cargo_EXECUTABLE} ${MY_CARGO_ARGS_STRING}")

libclamav_rust/CMakeLists.txt

@@ -8,6 +8,7 @@
 add_rust_library(TARGET clamav_rust
     SOURCE_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
     BINARY_DIRECTORY "${CMAKE_BINARY_DIR}"
+    INCLUDE_DIRECTORIES "$<LIST:TRANSFORM,$<TARGET_PROPERTY:ClamAV::libclamav,INCLUDE_DIRECTORIES>,PREPEND,-I>"
     # Tests cannot be pre-compiled here, because there are circular dependencies
     # between libclamav_rust and libclamav to include calls like `cli_getdsig()`
     # as well as the logging functions.

libclamav_rust/build.rs

@@ -133,6 +133,7 @@ fn main() -> Result<(), &'static str> {
 fn execute_bindgen() -> Result<(), &'static str> {
     let build_dir = PathBuf::from(env::var("CARGO_TARGET_DIR").unwrap_or_else(|_| ".".into()));
     let build_include_path = format!("-I{}", build_dir.join(".").to_str().unwrap());
+    let has_include_directories = env::var("CARGO_INCLUDE_DIRECTORIES").ok();
 
     // Configure and generate bindings.
     let mut builder = builder()
@@ -147,6 +148,15 @@ fn execute_bindgen() -> Result<(), &'static str> {
         // Enable bindgen to find generated headers in the build directory, too.
         .clang_arg(build_include_path);
 
+    // If include directories were specified, add them to the builder.
+    if let Some(include_directories) = has_include_directories {
+        for include_directory in include_directories.split(';') {
+            eprintln!("Including {include_directory}");
+            // Enable bindgen to find dependencies headers.
+            builder = builder.clang_arg(include_directory);
+        }
+    }
+
     for &include_path in BINDGEN_INCLUDE_PATHS {
         builder = builder.clang_arg(include_path);
     }