Move getentropy handling to a shared location for foreign item implementation

Author: BlackHoleFox

src/shims/mod.rs

@@ -13,6 +13,7 @@ pub mod dlsym;
 pub mod env;
 pub mod os_str;
 pub mod panic;
+pub mod rand;
 pub mod time;
 pub mod tls;
 

src/shims/rand.rs

@@ -0,0 +1,19 @@
+use crate::*;
+
+impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
+pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
+    fn getentropy(
+        &mut self,
+        buffer_op: &OpTy<'tcx, Provenance>,
+        length_op: &OpTy<'tcx, Provenance>,
+    ) -> InterpResult<'tcx, Scalar<Provenance>> {
+        let this = self.eval_context_mut();
+        this.assert_target_os("macos", "getentropy");
+
+        let ptr = this.read_pointer(buffer_op)?;
+        let len = this.read_target_usize(length_op)?;
+        this.gen_random(ptr, len)?;
+
+        Ok(Scalar::from_i32(0)) // KERN_SUCCESS
+    }
+}

src/shims/unix/macos/dlsym.rs

@@ -2,7 +2,7 @@ use rustc_middle::mir;
 
 use log::trace;
 
-use crate::*;
+use crate::{shims::rand::EvalContextExt as _, *};
 use helpers::check_arg_count;
 
 #[derive(Debug, Copy, Clone)]
@@ -38,10 +38,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         match dlsym {
             Dlsym::getentropy => {
                 let [ptr, len] = check_arg_count(args)?;
-                let ptr = this.read_pointer(ptr)?;
-                let len = this.read_target_usize(len)?;
-                this.gen_random(ptr, len)?;
-                this.write_null(dest)?;
+                let result = this.getentropy(ptr, len)?;
+                this.write_scalar(result, dest)?;
             }
         }
 

src/shims/unix/macos/foreign_items.rs

@@ -3,6 +3,7 @@ use rustc_target::spec::abi::Abi;
 
 use crate::*;
 use shims::foreign_items::EmulateByNameResult;
+use shims::rand::EvalContextExt as _;
 use shims::unix::fs::EvalContextExt as _;
 use shims::unix::thread::EvalContextExt as _;
 
@@ -109,6 +110,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 this.write_scalar(result, dest)?;
             }
 
+            // Random generation related shims
+            "getentropy" => {
+                let [buf, bufsize] =
+                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+                let result = this.getentropy(buf, bufsize)?;
+                this.write_scalar(result, dest)?;
+            }
+
             // Access to command-line arguments
             "_NSGetArgc" => {
                 let [] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;