miri/shims/wasi/
foreign_items.rs

1use rustc_abi::CanonAbi;
2use rustc_middle::ty::Ty;
3use rustc_span::Symbol;
4use rustc_target::callconv::FnAbi;
5
6use crate::shims::alloc::EvalContextExt as _;
7use crate::*;
8
9pub fn is_dyn_sym(_name: &str) -> bool {
10    false
11}
12
13impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
14pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
15    fn emulate_foreign_item_inner(
16        &mut self,
17        link_name: Symbol,
18        abi: &FnAbi<'tcx, Ty<'tcx>>,
19        args: &[OpTy<'tcx>],
20        dest: &MPlaceTy<'tcx>,
21    ) -> InterpResult<'tcx, EmulateItemResult> {
22        let this = self.eval_context_mut();
23        match link_name.as_str() {
24            // Allocation
25            "posix_memalign" => {
26                let [memptr, align, size] =
27                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
28                let result = this.posix_memalign(memptr, align, size)?;
29                this.write_scalar(result, dest)?;
30            }
31            "aligned_alloc" => {
32                let [align, size] =
33                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
34                let res = this.aligned_alloc(align, size)?;
35                this.write_pointer(res, dest)?;
36            }
37
38            // Standard input/output
39            // FIXME: These shims are hacks that just get basic stdout/stderr working. We can't
40            // constrain them to "std" since std itself uses the wasi crate for this.
41            "get-stdout" => {
42                let [] =
43                    this.check_shim_sig(shim_sig!(extern "C" fn() -> i32), link_name, abi, args)?;
44                this.write_scalar(Scalar::from_i32(1), dest)?; // POSIX FD number for stdout
45            }
46            "get-stderr" => {
47                let [] =
48                    this.check_shim_sig(shim_sig!(extern "C" fn() -> i32), link_name, abi, args)?;
49                this.write_scalar(Scalar::from_i32(2), dest)?; // POSIX FD number for stderr
50            }
51            "[resource-drop]output-stream" => {
52                let [handle] =
53                    this.check_shim_sig(shim_sig!(extern "C" fn(i32) -> ()), link_name, abi, args)?;
54                let handle = this.read_scalar(handle)?.to_i32()?;
55
56                if !(handle == 1 || handle == 2) {
57                    throw_unsup_format!("wasm output-stream: unsupported handle");
58                }
59                // We don't actually close these FDs, so this is a NOP.
60            }
61            "[method]output-stream.blocking-write-and-flush" => {
62                let [handle, buf, len, ret_area] = this.check_shim_sig(
63                    shim_sig!(extern "C" fn(i32, *mut _, usize, *mut _) -> ()),
64                    link_name,
65                    abi,
66                    args,
67                )?;
68                let handle = this.read_scalar(handle)?.to_i32()?;
69                let buf = this.read_pointer(buf)?;
70                let len = this.read_target_usize(len)?;
71                let ret_area = this.read_pointer(ret_area)?;
72
73                if len > 4096 {
74                    throw_unsup_format!(
75                        "wasm output-stream.blocking-write-and-flush: buffer too big"
76                    );
77                }
78                let len = usize::try_from(len).unwrap();
79                let Some(fd) = this.machine.fds.get(handle) else {
80                    throw_unsup_format!(
81                        "wasm output-stream.blocking-write-and-flush: unsupported handle"
82                    );
83                };
84                fd.write(
85                    this.machine.communicate(),
86                    buf,
87                    len,
88                    this,
89                    callback!(
90                        @capture<'tcx> {
91                            len: usize,
92                            ret_area: Pointer,
93                        }
94                        |this, result: Result<usize, IoError>| {
95                            if !matches!(result, Ok(l) if l == len) {
96                                throw_unsup_format!("wasm output-stream.blocking-write-and-flush: returning errors is not supported");
97                            }
98                            // 0 in the first byte of the ret_area indicates success.
99                            let ret = this.ptr_to_mplace(ret_area, this.machine.layouts.u8);
100                            this.write_null(&ret)?;
101                            interp_ok(())
102                    }),
103                )?;
104            }
105
106            _ => return interp_ok(EmulateItemResult::NotSupported),
107        }
108        interp_ok(EmulateItemResult::NeedsReturn)
109    }
110}
miri/shims/wasi/foreign_items.rs

miri/shims/wasi/
foreign_items.rs
