225 lines
8.8 KiB
CMake
225 lines
8.8 KiB
CMake
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# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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# SPDX-License-Identifier: Apache-2.0 OR ISC
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# Module for generating Rust bindings using bindgen-cli
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#
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# Background: Symbol Prefix Mechanism
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# ------------------------------------
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# AWS-LC supports building with a symbol prefix (via BORINGSSL_PREFIX) to avoid
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# symbol collisions when multiple copies of the library are linked into one binary.
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# The C build achieves this by generating a boringssl_prefix_symbols.h header that
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# #define-renames every public symbol (e.g., #define SSL_new AWSLC_SSL_new), then
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# force-including it during compilation.
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#
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# For Rust bindings, we must NOT include that prefix header when invoking bindgen.
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# Instead, we use bindgen's --prefix-link-name option, which adds the prefix to
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# #[link_name] attributes (for the linker) while keeping the Rust function names
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# unprefixed. If we included the prefix header, bindgen would see already-prefixed
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# names and --prefix-link-name would double-prefix them, producing broken bindings.
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#
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# This produces bindings like:
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# extern "C" {
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# #[link_name = "AWSLC_SSL_new"] // Prefixed for linker
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# pub fn SSL_new(...) -> ...; // Unprefixed for Rust API
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# }
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# Headers to exclude from Rust bindings generation.
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# Each exclusion should have a comment explaining why.
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set(RUST_WRAPPER_EXCLUDED_HEADERS
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# Template files (not actual headers, used by configure_file)
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"base.h.in"
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"opensslv.h.in"
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# Prefix symbol headers must not be included. See module-level comment above.
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"boringssl_prefix_symbols.h"
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"boringssl_prefix_symbols_asm.h"
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"boringssl_prefix_symbols_nasm.inc"
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# Platform/architecture-specific internal headers (not part of public API)
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"arm_arch.h"
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"asm_base.h"
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"target.h"
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# SSL headers (conditionally included via AWS_LC_RUST_INCLUDE_SSL define)
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"ssl.h"
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"ssl3.h"
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"tls1.h"
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"dtls1.h"
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)
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# Discover all OpenSSL headers for dependency tracking
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# Uses CONFIGURE_DEPENDS on CMake 3.12+ for automatic reconfiguration
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function(discover_openssl_headers OUT_VAR OUT_EXPERIMENTAL_VAR)
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if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.12")
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file(GLOB _all_headers
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CONFIGURE_DEPENDS
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"${AWSLC_SOURCE_DIR}/include/openssl/*.h")
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file(GLOB _experimental_headers
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CONFIGURE_DEPENDS
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"${AWSLC_SOURCE_DIR}/include/openssl/experimental/*.h")
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else()
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file(GLOB _all_headers "${AWSLC_SOURCE_DIR}/include/openssl/*.h")
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file(GLOB _experimental_headers "${AWSLC_SOURCE_DIR}/include/openssl/experimental/*.h")
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endif()
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set(${OUT_VAR} "${_all_headers}" PARENT_SCOPE)
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set(${OUT_EXPERIMENTAL_VAR} "${_experimental_headers}" PARENT_SCOPE)
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endfunction()
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# Generate rust_wrapper.h from template by discovering headers
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function(generate_rust_wrapper_header)
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discover_openssl_headers(_all_headers _experimental_headers)
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# Build the include list, filtering out excluded headers
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set(_includes "")
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foreach(_header ${_all_headers})
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get_filename_component(_header_name "${_header}" NAME)
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list(FIND RUST_WRAPPER_EXCLUDED_HEADERS "${_header_name}" _excluded_idx)
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if(_excluded_idx EQUAL -1)
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string(APPEND _includes "#include <openssl/${_header_name}>\n")
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endif()
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endforeach()
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# Build the experimental include list
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set(_experimental_includes "")
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foreach(_header ${_experimental_headers})
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get_filename_component(_header_name "${_header}" NAME)
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string(APPEND _experimental_includes "#include <openssl/experimental/${_header_name}>\n")
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endforeach()
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# Set variables for configure_file substitution
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set(RUST_WRAPPER_INCLUDES "${_includes}")
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set(RUST_WRAPPER_EXPERIMENTAL_INCLUDES "${_experimental_includes}")
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# Generate the header from template
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configure_file(
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"${AWSLC_SOURCE_DIR}/cmake/rust_wrapper.h.in"
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"${AWSLC_BINARY_DIR}/include/rust_wrapper.h"
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@ONLY
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)
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message(STATUS "Generated rust_wrapper.h with discovered headers")
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endfunction()
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# Determine the symbol prefix format based on target platform
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#
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# Different platforms have different symbol naming conventions:
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# - Apple platforms (macOS, iOS): Symbols have a leading underscore (_SSL_new)
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# - 32-bit Windows: Symbols have a leading underscore (_SSL_new)
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# - Other platforms (Linux, 64-bit Windows): No leading underscore (SSL_new)
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#
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# When we add our prefix, we need to account for this:
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# - Apple/Win32: _AWSLC_SSL_new (prefix goes after the leading underscore)
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# - Others: AWSLC_SSL_new
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#
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# The --prefix-link-name option prepends the given string to link names,
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# so we format it appropriately for each platform.
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function(get_symbol_prefix_format PREFIX OUT_VAR)
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# Use CMAKE_SYSTEM_NAME for cross-compilation support
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# (WIN32/APPLE variables reflect the HOST, not the TARGET)
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if(CMAKE_SYSTEM_NAME STREQUAL "Darwin" OR CMAKE_SYSTEM_NAME STREQUAL "iOS")
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set(${OUT_VAR} "_${PREFIX}_" PARENT_SCOPE)
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elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows" AND CMAKE_SIZEOF_VOID_P EQUAL 4)
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set(${OUT_VAR} "_${PREFIX}_" PARENT_SCOPE)
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else()
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set(${OUT_VAR} "${PREFIX}_" PARENT_SCOPE)
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endif()
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endfunction()
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# Generate Rust bindings using bindgen-cli
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#
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# Arguments:
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# OUTPUT_FILE - Path where the generated .rs file will be written
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# INCLUDE_DIRS - List of include directories for clang
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# PREFIX - (Optional) Symbol prefix (e.g., "AWSLC")
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# INCLUDE_SSL - (Optional) Flag to include SSL headers
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function(generate_rust_bindings)
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set(options INCLUDE_SSL)
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set(oneValueArgs OUTPUT_FILE PREFIX)
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set(multiValueArgs INCLUDE_DIRS)
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cmake_parse_arguments(ARG "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
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# Discover headers for dependency tracking
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discover_openssl_headers(_all_openssl_headers _experimental_headers)
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# Build include path arguments for clang
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set(_clang_include_args "")
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foreach(_dir ${ARG_INCLUDE_DIRS})
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list(APPEND _clang_include_args "-I${_dir}")
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endforeach()
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# Build bindgen arguments (based on aws-lc-rs/aws-lc-sys configuration)
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#
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# Note on regex escaping for --allowlist-file:
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# - CMake requires \\ to represent a single backslash in strings
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# - The regex itself needs \\ to match a literal backslash (for Windows paths)
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# - Combined: \\\\ in CMake -> \\ passed to bindgen -> \\ in regex -> matches one backslash
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# - The pattern matches paths like: .../openssl/ssl.h or ...\openssl\ssl.h
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set(_bindgen_args
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"--allowlist-file" ".*(/|\\\\)openssl((/|\\\\)[^/\\\\]+)+\\.h"
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"--allowlist-file" ".*(/|\\\\)rust_wrapper\\.h"
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"--rustified-enum" "point_conversion_form_t"
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"--default-macro-constant-type" "signed"
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"--with-derive-default"
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"--with-derive-partialeq"
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"--with-derive-eq"
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"--generate" "functions,types,vars,methods,constructors,destructors"
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"--rust-target" "${RUST_BINDINGS_TARGET_VERSION}"
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"--formatter" "rustfmt"
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)
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# Add symbol prefix if specified. See module-level comment for why we use
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# --prefix-link-name instead of including the prefix symbols header.
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if(ARG_PREFIX AND NOT ARG_PREFIX STREQUAL "")
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get_symbol_prefix_format("${ARG_PREFIX}" _sym_prefix)
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list(APPEND _bindgen_args "--prefix-link-name" "${_sym_prefix}")
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message(STATUS "Rust bindings will use symbol prefix: ${_sym_prefix}")
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endif()
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# Build clang arguments (prefix symbols header is intentionally excluded)
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set(_clang_args "")
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# Add SSL support if requested
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if(ARG_INCLUDE_SSL)
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list(APPEND _clang_args "-DAWS_LC_RUST_INCLUDE_SSL")
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message(STATUS "Rust bindings: SSL support enabled (INCLUDE_SSL=ON)")
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else()
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message(STATUS "Rust bindings: SSL support disabled (INCLUDE_SSL not set)")
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endif()
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# Add include paths (unprefixed headers only)
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list(APPEND _clang_args ${_clang_include_args})
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# Ensure output directory exists
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get_filename_component(_output_dir "${ARG_OUTPUT_FILE}" DIRECTORY)
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message(STATUS "Rust bindings clang args: ${_clang_args}")
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message(STATUS "Rust bindings bindgen args: ${_bindgen_args}")
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# Create custom command for generating bindings
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# Dependencies include all OpenSSL headers to ensure regeneration when headers change
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#
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# Note: VERBATIM is used to ensure proper argument escaping across platforms,
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# especially important for the regex patterns on Windows. If debugging command-line
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# issues, be aware that VERBATIM affects how CMake quotes arguments.
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add_custom_command(
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OUTPUT "${ARG_OUTPUT_FILE}"
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COMMAND ${CMAKE_COMMAND} -E make_directory "${_output_dir}"
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COMMAND ${BINDGEN_EXECUTABLE}
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${_bindgen_args}
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"${AWSLC_BINARY_DIR}/include/rust_wrapper.h"
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"--output" "${ARG_OUTPUT_FILE}"
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"--"
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${_clang_args}
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DEPENDS
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"${AWSLC_BINARY_DIR}/include/rust_wrapper.h"
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"${AWSLC_SOURCE_DIR}/cmake/rust_wrapper.h.in"
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${_all_openssl_headers}
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${_experimental_headers}
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COMMENT "Generating Rust bindings with bindgen-cli"
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VERBATIM
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)
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# Create target for bindings generation (not part of ALL; built on-demand or via install)
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add_custom_target(rust_bindings DEPENDS "${ARG_OUTPUT_FILE}")
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endfunction()
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