Generate C preprocessor code to hide things not on Windows

Author: Mark McCaskey

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## **[Unreleased]**
 
+- [#952](https://github.com/wasmerio/wasmer/pull/952) Use C preprocessor to properly hide trampoline functions on Windowns and non-x86_64 targets.
+
 ## 0.10.0 - 2019-11-11
 
 Special thanks to [@newpavlov](https://github.com/newpavlov) and [@Maxgy](https://github.com/Maxgy) for their contributions!

lib/runtime-c-api/build.rs

@@ -12,12 +12,31 @@ fn main() {
     let mut out_wasmer_header_file = PathBuf::from(&out_dir);
     out_wasmer_header_file.push("wasmer");
 
+    const WASMER_PRE_HEADER: &str = r#"
+#ifndef WASMER_H_MACROS
+#define WASMER_H_MACROS
+#if MSVC
+#ifdef _M_AMD64
+#define ARCH_X86_64
+#endif
+#endif
+
+#if GCC
+#ifdef __x86_64__
+#define ARCH_X86_64
+#endif
+#endif
+#endif // WASMER_H_MACROS
+"#;
     // Generate the C bindings in the `OUT_DIR`.
     out_wasmer_header_file.set_extension("h");
     Builder::new()
         .with_crate(crate_dir.clone())
         .with_language(Language::C)
         .with_include_guard("WASMER_H")
+        .with_header(WASMER_PRE_HEADER)
+        .with_define("target_family", "windows", "_WIN32")
+        .with_define("target_arch", "x86_64", "ARCH_X86_64")
         .generate()
         .expect("Unable to generate C bindings")
         .write_to_file(out_wasmer_header_file.as_path());
@@ -28,6 +47,9 @@ fn main() {
         .with_crate(crate_dir)
         .with_language(Language::Cxx)
         .with_include_guard("WASMER_H")
+        .with_header(WASMER_PRE_HEADER)
+        .with_define("target_family", "windows", "_WIN32")
+        .with_define("target_arch", "x86_64", "ARCH_X86_64")
         .generate()
         .expect("Unable to generate C++ bindings")
         .write_to_file(out_wasmer_header_file.as_path());

lib/runtime-c-api/src/lib.rs

@@ -101,7 +101,9 @@ pub mod instance;
 pub mod memory;
 pub mod module;
 pub mod table;
-#[cfg(all(unix, target_arch = "x86_64"))]
+// `not(target_family = "windows")` is simpler than `unix`.  See build.rs
+// if you want to change the meaning of these `cfg`s in the header file.
+#[cfg(all(not(target_family = "windows"), target_arch = "x86_64"))]
 pub mod trampoline;
 pub mod value;
 

lib/runtime-c-api/wasmer.h

@@ -1,3 +1,20 @@
+
+#ifndef WASMER_H_MACROS
+#define WASMER_H_MACROS
+#if MSVC
+#ifdef _M_AMD64
+#define ARCH_X86_64
+#endif
+#endif
+
+#if GCC
+#ifdef __x86_64__
+#define ARCH_X86_64
+#endif
+#endif
+#endif // WASMER_H_MACROS
+
+
 #ifndef WASMER_H
 #define WASMER_H
 
@@ -162,17 +179,23 @@ typedef struct {
 
 } wasmer_serialized_module_t;
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 typedef struct {
 
 } wasmer_trampoline_buffer_builder_t;
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 typedef struct {
 
 } wasmer_trampoline_callable_t;
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 typedef struct {
 
 } wasmer_trampoline_buffer_t;
+#endif
 
 /**
  * Opens a directory that's visible to the WASI module as `alias` but
@@ -780,46 +803,60 @@ uint32_t wasmer_table_length(wasmer_table_t *table);
  */
 wasmer_result_t wasmer_table_new(wasmer_table_t **table, wasmer_limits_t limits);
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Adds a callinfo trampoline to the builder.
  */
 uintptr_t wasmer_trampoline_buffer_builder_add_callinfo_trampoline(wasmer_trampoline_buffer_builder_t *builder,
                                                                    const wasmer_trampoline_callable_t *func,
                                                                    const void *ctx,
                                                                    uint32_t num_params);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Adds a context trampoline to the builder.
  */
 uintptr_t wasmer_trampoline_buffer_builder_add_context_trampoline(wasmer_trampoline_buffer_builder_t *builder,
                                                                   const wasmer_trampoline_callable_t *func,
                                                                   const void *ctx);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Finalizes the trampoline builder into an executable buffer.
  */
 wasmer_trampoline_buffer_t *wasmer_trampoline_buffer_builder_build(wasmer_trampoline_buffer_builder_t *builder);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Creates a new trampoline builder.
  */
 wasmer_trampoline_buffer_builder_t *wasmer_trampoline_buffer_builder_new(void);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Destroys the trampoline buffer if not null.
  */
 void wasmer_trampoline_buffer_destroy(wasmer_trampoline_buffer_t *buffer);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Returns the callable pointer for the trampoline with index `idx`.
  */
 const wasmer_trampoline_callable_t *wasmer_trampoline_buffer_get_trampoline(const wasmer_trampoline_buffer_t *buffer,
                                                                             uintptr_t idx);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /**
  * Returns the context added by `add_context_trampoline`, from within the callee function.
  */
 void *wasmer_trampoline_get_context(void);
+#endif
 
 /**
  * Returns true for valid wasm bytes and false for invalid bytes

lib/runtime-c-api/wasmer.hh

@@ -1,3 +1,20 @@
+
+#ifndef WASMER_H_MACROS
+#define WASMER_H_MACROS
+#if MSVC
+#ifdef _M_AMD64
+#define ARCH_X86_64
+#endif
+#endif
+
+#if GCC
+#ifdef __x86_64__
+#define ARCH_X86_64
+#endif
+#endif
+#endif // WASMER_H_MACROS
+
+
 #ifndef WASMER_H
 #define WASMER_H
 
@@ -146,17 +163,23 @@ struct wasmer_serialized_module_t {
 
 };
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 struct wasmer_trampoline_buffer_builder_t {
 
 };
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 struct wasmer_trampoline_callable_t {
 
 };
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 struct wasmer_trampoline_buffer_t {
 
 };
+#endif
 
 /// Opens a directory that's visible to the WASI module as `alias` but
 /// is backed by the host file at `host_file_path`
@@ -612,32 +635,46 @@ uint32_t wasmer_table_length(wasmer_table_t *table);
 /// and `wasmer_last_error_message` to get an error message.
 wasmer_result_t wasmer_table_new(wasmer_table_t **table, wasmer_limits_t limits);
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Adds a callinfo trampoline to the builder.
 uintptr_t wasmer_trampoline_buffer_builder_add_callinfo_trampoline(wasmer_trampoline_buffer_builder_t *builder,
                                                                    const wasmer_trampoline_callable_t *func,
                                                                    const void *ctx,
                                                                    uint32_t num_params);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Adds a context trampoline to the builder.
 uintptr_t wasmer_trampoline_buffer_builder_add_context_trampoline(wasmer_trampoline_buffer_builder_t *builder,
                                                                   const wasmer_trampoline_callable_t *func,
                                                                   const void *ctx);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Finalizes the trampoline builder into an executable buffer.
 wasmer_trampoline_buffer_t *wasmer_trampoline_buffer_builder_build(wasmer_trampoline_buffer_builder_t *builder);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Creates a new trampoline builder.
 wasmer_trampoline_buffer_builder_t *wasmer_trampoline_buffer_builder_new();
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Destroys the trampoline buffer if not null.
 void wasmer_trampoline_buffer_destroy(wasmer_trampoline_buffer_t *buffer);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Returns the callable pointer for the trampoline with index `idx`.
 const wasmer_trampoline_callable_t *wasmer_trampoline_buffer_get_trampoline(const wasmer_trampoline_buffer_t *buffer,
                                                                             uintptr_t idx);
+#endif
 
+#if (!defined(_WIN32) && defined(ARCH_X86_64))
 /// Returns the context added by `add_context_trampoline`, from within the callee function.
 void *wasmer_trampoline_get_context();
+#endif
 
 /// Returns true for valid wasm bytes and false for invalid bytes
 bool wasmer_validate(const uint8_t *wasm_bytes, uint32_t wasm_bytes_len);