From 00993002b7c7088801c63088c48e11a97717593b Mon Sep 17 00:00:00 2001
From: geetanshjuneja <ronitjuneja2002@gmail.com>
Date: Thu, 22 May 2025 13:55:58 +0530
Subject: [PATCH 1/2] implement shim_sig macro

---
 src/helpers.rs                  | 33 +++++++++++++++++++++++++++++
 src/shims/unix/foreign_items.rs | 37 +++++++++++----------------------
 2 files changed, 45 insertions(+), 25 deletions(-)

diff --git a/src/helpers.rs b/src/helpers.rs
index ff2ec1b3e6..7db87962dc 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -1435,3 +1435,36 @@ impl ToU64 for usize {
         self.try_into().unwrap()
     }
 }
+
+#[macro_export]
+macro_rules! shim_sig {
+    ($this:ident, extern $abi:literal fn($($arg:tt),*) -> $ret:tt) => {
+        (
+            std::str::FromStr::from_str($abi).expect("incorrect abi specified"),
+            [$(layout!($this, $arg)),*],
+            layout!($this, $ret)
+        )
+    };
+
+    // default Rust abi
+    ($this:ident, extern $abi:literal fn($($arg:tt),*) -> $ret:tt) => {
+        shim_sig!($this, extern "Rust" fn($($arg),*) -> $ret)
+    };
+}
+
+#[macro_export]
+macro_rules! layout {
+    ($this:ident, ) => {};
+    ($this:ident, (*const _)) => {
+        $this.machine.layouts.const_raw_ptr.ty
+    };
+    ($this:ident, (*mut _)) => {
+        $this.machine.layouts.mut_raw_ptr.ty
+    };
+    ($this:ident, $arg:ident) => {
+        $this.tcx.types.$arg
+    };
+    ($this:ident, $arg:literal) => {
+        $this.libc_ty_layout($arg).ty
+    };
+}
\ No newline at end of file
diff --git a/src/shims/unix/foreign_items.rs b/src/shims/unix/foreign_items.rs
index 026aa1f950..6932921077 100644
--- a/src/shims/unix/foreign_items.rs
+++ b/src/shims/unix/foreign_items.rs
@@ -15,7 +15,7 @@ use self::shims::unix::solarish::foreign_items as solarish;
 use crate::concurrency::cpu_affinity::CpuAffinityMask;
 use crate::shims::alloc::EvalContextExt as _;
 use crate::shims::unix::*;
-use crate::*;
+use crate::{shim_sig, *};
 
 pub fn is_dyn_sym(name: &str, target_os: &str) -> bool {
     match name {
@@ -112,26 +112,18 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         match link_name.as_str() {
             // Environment related shims
             "getenv" => {
-                let [name] = this.check_shim_abi(
-                    link_name,
-                    abi,
-                    ExternAbi::C { unwind: false },
-                    [this.machine.layouts.const_raw_ptr.ty],
-                    this.machine.layouts.mut_raw_ptr.ty,
-                    args,
-                )?;
+                let (callee_abi, arg_types, ret_type) =
+                    shim_sig!(this, extern "C" fn((*const _)) -> (*const _));
+                let [name] =
+                    this.check_shim_abi(link_name, abi, callee_abi, arg_types, ret_type, args)?;
                 let result = this.getenv(name)?;
                 this.write_pointer(result, dest)?;
             }
             "unsetenv" => {
-                let [name] = this.check_shim_abi(
-                    link_name,
-                    abi,
-                    ExternAbi::C { unwind: false },
-                    [this.machine.layouts.const_raw_ptr.ty],
-                    this.tcx.types.i32,
-                    args,
-                )?;
+                let (callee_abi, arg_types, ret_type) =
+                    shim_sig!(this, extern "C" fn((*const _)) -> i32);
+                let [name] =
+                    this.check_shim_abi(link_name, abi, callee_abi, arg_types, ret_type, args)?;
                 let result = this.unsetenv(name)?;
                 this.write_scalar(result, dest)?;
             }
@@ -177,14 +169,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.write_scalar(result, dest)?;
             }
             "getpid" => {
-                let [] = this.check_shim_abi(
-                    link_name,
-                    abi,
-                    ExternAbi::C { unwind: false },
-                    [],
-                    this.libc_ty_layout("pid_t").ty,
-                    args,
-                )?;
+                let (callee_abi, arg_types, ret_type) = shim_sig!(this, extern "C" fn() -> "pid_t");
+                let [] =
+                    this.check_shim_abi(link_name, abi, callee_abi, arg_types, ret_type, args)?;
                 let result = this.getpid()?;
                 this.write_scalar(result, dest)?;
             }

From 21bd1b5c0a23ce2d3bd11b0d86d3b1a8fac2ddf1 Mon Sep 17 00:00:00 2001
From: geetanshjuneja <ronitjuneja2002@gmail.com>
Date: Thu, 22 May 2025 14:12:47 +0530
Subject: [PATCH 2/2] fmt

---
 src/helpers.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/helpers.rs b/src/helpers.rs
index 7db87962dc..0b1f05903e 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -1467,4 +1467,4 @@ macro_rules! layout {
     ($this:ident, $arg:literal) => {
         $this.libc_ty_layout($arg).ty
     };
-}
\ No newline at end of file
+}