refactor(fspy): own Windows shared-memory mapping

Co-authored-by: GPT-5.6 <gpt-5.6@openai.com>

Author: wan9chi

Cargo.lock

@@ -168,6 +168,7 @@ wax = "0.7.0"
 which = "8.0.0"
 widestring = "1.2.0"
 winapi = "0.3.9"
+windows-sys = "0.61"
 winsafe = { version = "0.0.27", features = ["kernel"] }
 xxhash-rust = { version = "0.8.15", features = ["const_xxh3"] }
 ntest = "0.9.5"

Cargo.toml

@@ -99,8 +99,13 @@ pub const fn access_mask_to_mode(desired_access: ACCESS_MASK) -> AccessMode {
     }
 }
 
+#[link(name = "kernel32")]
 unsafe extern "system" {
     fn LocalFree(hmem: HLOCAL) -> HLOCAL;
+}
+
+#[link(name = "pathcch")]
+unsafe extern "system" {
     fn PathAllocCombine(
         pszpathin: PCWSTR,
         pszmore: PCWSTR,

crates/fspy_preload_windows/src/windows/winapi_utils.rs

@@ -7,7 +7,7 @@ license.workspace = true
 publish = false
 rust-version.workspace = true
 
-[target.'cfg(not(target_os = "linux"))'.dependencies]
+[target.'cfg(not(any(target_os = "linux", target_os = "windows")))'.dependencies]
 shared_memory = { workspace = true, features = ["logging"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
@@ -17,6 +17,16 @@ rustix = { workspace = true, features = ["fs", "net"] }
 tokio = { workspace = true, features = ["macros", "net", "rt", "time"] }
 uuid = { workspace = true, features = ["v4"] }
 
+[target.'cfg(target_os = "windows")'.dependencies]
+base64 = { workspace = true }
+uuid = { workspace = true, features = ["v4"] }
+windows-sys = { workspace = true, features = [
+  "Win32_Foundation",
+  "Win32_Security",
+  "Win32_Storage_FileSystem",
+  "Win32_System_Memory",
+] }
+
 [dev-dependencies]
 ctor = { workspace = true }
 subprocess_test = { workspace = true }

crates/fspy_shm/Cargo.toml

@@ -1,30 +1,34 @@
 //! Platform shared-memory implementation for fspy channels.
 
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 use std::io;
 #[cfg(target_os = "linux")]
 use std::{future::Future, io, pin::Pin};
 
 #[cfg(target_os = "linux")]
 mod linux;
+#[cfg(target_os = "windows")]
+mod windows;
 
 #[cfg(target_os = "linux")]
 pub use linux::{CreatedShm, Shm, create, open};
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 use shared_memory::{Shmem, ShmemConf};
+#[cfg(target_os = "windows")]
+pub use windows::{CreatedShm, Shm, create, open};
 
 /// A Linux service future that makes a shared-memory mapping available to other processes.
 #[cfg(target_os = "linux")]
 pub type ShmBroker = Pin<Box<dyn Future<Output = io::Result<()>> + Send + 'static>>;
 
 /// An owned shared-memory mapping.
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 pub struct Shm {
     inner: Shmem,
 }
 
 /// A newly created shared-memory mapping and its platform service.
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 pub struct CreatedShm {
     /// The owned shared-memory mapping.
     pub shm: Shm,
@@ -35,11 +39,9 @@ pub struct CreatedShm {
 /// # Errors
 ///
 /// Returns an error if the platform cannot create or map the region.
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 pub fn create(size: usize) -> io::Result<CreatedShm> {
     let conf = ShmemConf::new().size(size);
-    #[cfg(target_os = "windows")]
-    let conf = conf.allow_raw(true);
 
     let inner = conf.create().map_err(io::Error::other)?;
     Ok(CreatedShm { shm: Shm { inner } })
@@ -50,17 +52,15 @@ pub fn create(size: usize) -> io::Result<CreatedShm> {
 /// # Errors
 ///
 /// Returns an error if the mapping does not exist or cannot be mapped.
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 pub fn open(id: &str, size: usize) -> io::Result<Shm> {
     let conf = ShmemConf::new().size(size).os_id(id);
-    #[cfg(target_os = "windows")]
-    let conf = conf.allow_raw(true);
 
     let inner = conf.open().map_err(io::Error::other)?;
     Ok(Shm { inner })
 }
 
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "windows")))]
 #[expect(clippy::len_without_is_empty, reason = "shared-memory mappings are always non-empty")]
 impl Shm {
     /// Returns this mapping's opaque platform identifier.