Windows no std shim

website/docs/windows.md

@@ -69,11 +69,11 @@ of this documentation.
 
 ### DotSlash Windows Shim
 
-**This is the preferred method.** The _DotSlash Windows Shim_ is a tiny `.exe`
-executable that is placed next to the DotSlash file that performs the same
-function as the [batch script](#sibling-batch-script) above, but is a native
-executable rather than a batch script. This is the _ideal_ method that allows
-for easy execution without any of the drawbacks of batch scripts. But this
+**This is the preferred method.** The _DotSlash Windows Shim_ is a tiny 4KB
+`.exe` executable that is placed next to the DotSlash file that performs the
+same function as the [batch script](#sibling-batch-script) above, but is a
+native executable rather than a batch script. This is the _ideal_ method that
+allows for easy execution without any of the drawbacks of batch scripts. But this
 method requires compiling a small executable and keeping it next to the DotSlash
 file.
 
@@ -82,6 +82,9 @@ The _DotSlash Windows Shim_ is available under the
 folder in the
 [DotSlash GitHub repository](https://github.com/facebook/dotslash).
 
+A pre-built version can also be downloaded from there:
+[`dotslash_windows_shim-x86_64.exe`](https://github.com/facebook/dotslash/raw/main/windows_shim/dotslash_windows_shim-x86_64.exe)
+
 ## `MAX_PATH` limits
 
 DotSlash stores fetched artifacts in a cache directory and they're executed from

windows_shim/Cargo.toml

@@ -14,6 +14,27 @@ name = "dotslash_windows_shim"
 path = "dotslash_windows_shim.rs"
 test = false
 
+[dependencies]
+cfg-if = "0.1.10"
+compiler_builtins = { version = "0.1.146", features = ["mem"], optional = true }
+windows-sys = { version = "0.59.0", features = [
+    "Win32_Foundation",
+    "Win32_Globalization",
+    "Win32_Security",
+    "Win32_Storage_FileSystem",
+    "Win32_System_Console",
+    "Win32_System_Environment",
+    "Win32_System_IO",
+    "Win32_System_LibraryLoader",
+    "Win32_System_Memory",
+    "Win32_System_Threading",
+    "Win32_UI_Shell",
+] }
+
+[features]
+default = ["no_std"]
+no_std = ["compiler_builtins"]
+
 [profile.release]
 opt-level = "z"
 lto = true

windows_shim/README.md

@@ -24,5 +24,29 @@ The _DotSlash Windows Shim_ does this:
 
 ## Binary size
 
-The current "reference implementation" is rather large. A no_std version that
-uses only Windows APIs will be added soon. Stay tuned!
+_DotSlash Windows Shim_ builds without a standard library and only uses Windows
+APIs. Release binaries are around ~5KB.
+
+## Release
+
+A nightly toolchain is required:
+
+```shell
+cargo +nightly build --release
+```
+
+Alternatively, though not recommended:
+
+```shell
+RUSTC_BOOTSTRAP=1 cargo build --release
+```
+
+## Debugging
+
+It may be useful to have the standard library (e.g. `dbg!`) when debugging.
+Build with `--no-default-features` (avoids the default `no_std` feature) to have
+access to the standard library.
+
+```shell
+cargo build --no-default-features
+```