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make windows compat_fn (crudely) work on Miri #95775

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merged 2 commits into from
Apr 8, 2022
Merged

make windows compat_fn (crudely) work on Miri #95775

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fe85591
make windows compat_fn (crudely) work on Miri
RalfJung Apr 7, 2022
c599a4c
do not round-trip function pointer through integer
RalfJung Apr 7, 2022
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25 changes: 17 additions & 8 deletions library/std/src/sys/windows/compat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,10 @@ macro_rules! compat_fn {
static INIT_TABLE_ENTRY: unsafe extern "C" fn() = init;

unsafe extern "C" fn init() {
PTR = get_f();
}

unsafe extern "C" fn get_f() -> Option<F> {
// There is no locking here. This code is executed before main() is entered, and
// is guaranteed to be single-threaded.
//
Expand All @@ -88,13 +92,13 @@ macro_rules! compat_fn {
let symbol_name: *const u8 = concat!(stringify!($symbol), "\0").as_ptr();
let module_handle = $crate::sys::c::GetModuleHandleA(module_name as *const i8);
if !module_handle.is_null() {
match $crate::sys::c::GetProcAddress(module_handle, symbol_name as *const i8).addr() {
0 => {}
n => {
PTR = Some(mem::transmute::<usize, F>(n));
}
let ptr = $crate::sys::c::GetProcAddress(module_handle, symbol_name as *const i8);
if !ptr.is_null() {
// Transmute to the right function pointer type.
return Some(mem::transmute(ptr));
}
}
return None;
}

#[allow(dead_code)]
Expand All @@ -105,10 +109,15 @@ macro_rules! compat_fn {
#[allow(dead_code)]
pub unsafe fn call($($argname: $argtype),*) -> $rettype {
if let Some(ptr) = PTR {
ptr($($argname),*)
} else {
$fallback_body
return ptr($($argname),*);
}
if cfg!(miri) {
// Miri does not run `init`, so we just call `get_f` each time.
if let Some(ptr) = get_f() {
return ptr($($argname),*);
}
}
$fallback_body
}
}

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