Update the wasi crate for wasm32-wasi

This commit updates the `wasi` crate used by the standard library which
is used to implement most of the functionality of libstd on the
`wasm32-wasi` target. This update comes with a brand new crate structure
in the `wasi` crate which caused quite a few changes for the wasi target
here, but it also comes with a significant change to where the
functionality is coming from.

The WASI specification is organized into "snapshots" and a new snapshot
happened recently, so the WASI APIs themselves have changed since the
previous revision. This had only minor impact on the public facing
surface area of libstd, only changing on `u32` to a `u64` in an unstable
API. The actual source for all of these types and such, however, is now
coming from the `wasi_preview_snapshot1` module instead of the
`wasi_unstable` module like before. This means that any implementors
generating binaries will need to ensure that their embedding environment
handles the `wasi_preview_snapshot1` module.

Author: alexcrichton

Cargo.lock

@@ -1294,7 +1294,7 @@ checksum = "473a1265acc8ff1e808cd0a1af8cee3c2ee5200916058a2ca113c29f2d903571"
 dependencies = [
  "cfg-if",
  "libc",
- "wasi",
+ "wasi 0.7.0",
 ]
 
 [[package]]
@@ -4301,7 +4301,7 @@ dependencies = [
  "rustc_msan",
  "rustc_tsan",
  "unwind",
- "wasi",
+ "wasi 0.9.0+wasi-snapshot-preview1",
 ]
 
 [[package]]
@@ -5172,6 +5172,12 @@ name = "wasi"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b89c3ce4ce14bdc6fb6beaf9ec7928ca331de5df7e5ea278375642a2f478570d"
+
+[[package]]
+name = "wasi"
+version = "0.9.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-alloc",

src/libstd/Cargo.toml

@@ -54,7 +54,7 @@ fortanix-sgx-abi = { version = "0.3.2", features = ['rustc-dep-of-std'] }
 hermit-abi = { version = "0.1", features = ['rustc-dep-of-std'] }
 
 [target.wasm32-wasi.dependencies]
-wasi = { version = "0.7.0", features = ['rustc-dep-of-std', 'alloc'] }
+wasi = { version = "0.9.0", features = ['rustc-dep-of-std'], default-features = false }
 
 [features]
 default = ["std_detect_file_io", "std_detect_dlsym_getauxval"]

src/libstd/sys/wasi/args.rs

@@ -1,15 +1,11 @@
-use crate::ffi::OsString;
+use crate::ffi::{CStr, OsStr, OsString};
 use crate::marker::PhantomData;
-use crate::os::wasi::ffi::OsStringExt;
+use crate::os::wasi::ffi::OsStrExt;
 use crate::vec;
 
-use ::wasi::wasi_unstable as wasi;
+pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
 
-pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
-}
-
-pub unsafe fn cleanup() {
-}
+pub unsafe fn cleanup() {}
 
 pub struct Args {
     iter: vec::IntoIter<OsString>,
@@ -18,17 +14,24 @@ pub struct Args {
 
 /// Returns the command line arguments
 pub fn args() -> Args {
-    let buf = wasi::args_sizes_get().and_then(|args_sizes| {
-        let mut buf = Vec::with_capacity(args_sizes.get_count());
-        wasi::args_get(args_sizes, |arg| {
-            let arg = OsString::from_vec(arg.to_vec());
-            buf.push(arg);
-        })?;
-        Ok(buf)
-    }).unwrap_or(vec![]);
     Args {
-        iter: buf.into_iter(),
-        _dont_send_or_sync_me: PhantomData
+        iter: maybe_args().unwrap_or(Vec::new()).into_iter(),
+        _dont_send_or_sync_me: PhantomData,
+    }
+}
+
+fn maybe_args() -> Option<Vec<OsString>> {
+    unsafe {
+        let (argc, buf_size) = wasi::args_sizes_get().ok()?;
+        let mut argv = Vec::with_capacity(argc);
+        let mut buf = Vec::with_capacity(buf_size);
+        wasi::args_get(argv.as_mut_ptr(), buf.as_mut_ptr()).ok()?;
+        let mut ret = Vec::with_capacity(argc);
+        for ptr in argv {
+            let s = CStr::from_ptr(ptr.cast());
+            ret.push(OsStr::from_bytes(s.to_bytes()).to_owned());
+        }
+        Some(ret)
     }
 }