lashman
e36646f7d1
build.rs swaps the dynamic import library with the static archive from webview2-com-sys, so the WebView2 loader code is baked into the exe. msvc_compat.rs provides the MSVC CRT symbols (security cookie, thread-safe init, C++ operators) that the MSVC-compiled static library expects.
99 lines
3.9 KiB
Rust
99 lines
3.9 KiB
Rust
//! Compatibility shims for MSVC CRT symbols required by WebView2LoaderStatic.lib.
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//!
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//! When statically linking the WebView2 loader on GNU/MinGW, the MSVC-compiled
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//! object code references these symbols. We provide minimal implementations so
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//! the linker can resolve them.
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use std::sync::atomic::{AtomicI32, Ordering};
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// ── MSVC Buffer Security Check (/GS) ────────────────────────────────────────
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//
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// MSVC's /GS flag instruments functions with stack canaries. These two symbols
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// implement the canary check. The cookie value is arbitrary — real MSVC CRT
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// randomises it at startup, but for a statically-linked helper library this
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// fixed sentinel is sufficient.
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#[no_mangle]
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pub static __security_cookie: u64 = 0x00002B992DDFA232;
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#[no_mangle]
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pub unsafe extern "C" fn __security_check_cookie(cookie: u64) {
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if cookie != __security_cookie {
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std::process::abort();
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}
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}
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// ── MSVC Thread-Safe Static Initialisation ───────────────────────────────────
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//
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// C++11 guarantees that function-local statics are initialised exactly once,
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// even under concurrent access. MSVC implements this with an epoch counter and
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// a set of helper functions. The WebView2 loader uses a few statics internally.
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//
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// Simplified implementation: uses an atomic spin for the guard. This is safe
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// because WebView2 initialisation runs on the main thread in practice.
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#[no_mangle]
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pub static _Init_thread_epoch: AtomicI32 = AtomicI32::new(0);
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#[no_mangle]
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pub unsafe extern "C" fn _Init_thread_header(guard: *mut i32) {
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if guard.is_null() {
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return;
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}
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// Spin until we can claim the guard (-1 = uninitialized, 0 = done, 1 = in progress)
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loop {
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let val = guard.read_volatile();
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if val == 0 {
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// Already initialised — tell caller to skip
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return;
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}
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if val == -1 {
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// Not yet initialised — try to claim it
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guard.write_volatile(1);
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return;
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}
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// val == 1: another thread is initialising — yield and retry
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std::thread::yield_now();
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}
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}
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#[no_mangle]
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pub unsafe extern "C" fn _Init_thread_footer(guard: *mut i32) {
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if !guard.is_null() {
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guard.write_volatile(0); // Mark initialisation complete
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_Init_thread_epoch.fetch_add(1, Ordering::Release);
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}
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}
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// ── MSVC C++ Runtime Operators (mangled names) ───────────────────────────────
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//
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// The static library is compiled with MSVC, which uses its own C++ name mangling.
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// MinGW's libstdc++ exports the same operators but with GCC/Itanium mangling,
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// so the linker can't match them. We provide the MSVC-mangled versions here.
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/// `std::nothrow` — MSVC-mangled `?nothrow@std@@3Unothrow_t@1@B`
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/// An empty struct constant used as a tag for nothrow `new`.
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#[export_name = "?nothrow@std@@3Unothrow_t@1@B"]
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pub static MSVC_STD_NOTHROW: u8 = 0;
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/// `operator new(size_t, const std::nothrow_t&)` — nothrow allocation
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/// MSVC-mangled: `??2@YAPEAX_KAEBUnothrow_t@std@@@Z`
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#[export_name = "??2@YAPEAX_KAEBUnothrow_t@std@@@Z"]
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pub unsafe extern "C" fn msvc_operator_new_nothrow(size: usize, _nothrow: *const u8) -> *mut u8 {
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let size = if size == 0 { 1 } else { size };
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let layout = std::alloc::Layout::from_size_align_unchecked(size, 8);
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let ptr = std::alloc::alloc(layout);
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ptr // null on failure — nothrow semantics
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}
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/// `operator delete(void*, size_t)` — sized deallocation
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/// MSVC-mangled: `??3@YAXPEAX_K@Z`
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#[export_name = "??3@YAXPEAX_K@Z"]
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pub unsafe extern "C" fn msvc_operator_delete_sized(ptr: *mut u8, size: usize) {
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if !ptr.is_null() {
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let size = if size == 0 { 1 } else { size };
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let layout = std::alloc::Layout::from_size_align_unchecked(size, 8);
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std::alloc::dealloc(ptr, layout);
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}
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}
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