Auto merge of rust-lang#2226 - InfRandomness:unix-helpers, r=RalfJung

Add unix helpers

This creates unix helper(s)

src/helpers.rs

@@ -493,6 +493,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         )
     }
 
+    /// Helper function used inside the shims of foreign functions to assert that the target OS
+    /// is part of the UNIX family. It panics showing a message with the `name` of the foreign function
+    /// if this is not the case.
+    fn assert_target_os_is_unix(&self, name: &str) {
+        assert!(
+            target_os_is_unix(self.eval_context_ref().tcx.sess.target.os.as_ref()),
+            "`{}` is only available for supported UNIX family targets",
+            name,
+        );
+    }
+
     /// Get last error variable as a place, lazily allocating thread-local storage for it if
     /// necessary.
     fn last_error_place(&mut self) -> InterpResult<'tcx, MPlaceTy<'tcx, Tag>> {
@@ -895,3 +906,9 @@ impl std::fmt::Display for HexRange {
         write!(f, "[{:#x}..{:#x}]", self.0.start.bytes(), self.0.end().bytes())
     }
 }
+
+/// Helper function used inside the shims of foreign functions to check that
+/// `target_os` is a supported UNIX OS.
+pub fn target_os_is_unix(target_os: &str) -> bool {
+    matches!(target_os, "linux" | "macos")
+}

src/shims/dlsym.rs

@@ -1,6 +1,7 @@
 use rustc_middle::mir;
 use rustc_target::spec::abi::Abi;
 
+use crate::helpers::target_os_is_unix;
 use crate::*;
 use shims::unix::dlsym as unix;
 use shims::windows::dlsym as windows;
@@ -18,7 +19,8 @@ impl Dlsym {
     pub fn from_str<'tcx>(name: &[u8], target_os: &str) -> InterpResult<'tcx, Option<Dlsym>> {
         let name = &*String::from_utf8_lossy(name);
         Ok(match target_os {
-            "linux" | "macos" => unix::Dlsym::from_str(name, target_os)?.map(Dlsym::Posix),
+            target if target_os_is_unix(target) =>
+                unix::Dlsym::from_str(name, target)?.map(Dlsym::Posix),
             "windows" => windows::Dlsym::from_str(name)?.map(Dlsym::Windows),
             os => bug!("dlsym not implemented for target_os {}", os),
         })

src/shims/env.rs

@@ -8,6 +8,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_target::abi::Size;
 
+use crate::helpers::target_os_is_unix;
 use crate::*;
 
 /// Check whether an operation that writes to a target buffer was successful.
@@ -55,7 +56,7 @@ impl<'tcx> EnvVars<'tcx> {
                 };
                 if forward {
                     let var_ptr = match target_os {
-                        "linux" | "macos" =>
+                        target if target_os_is_unix(target) =>
                             alloc_env_var_as_c_str(name.as_ref(), value.as_ref(), ecx)?,
                         "windows" => alloc_env_var_as_wide_str(name.as_ref(), value.as_ref(), ecx)?,
                         unsupported =>
@@ -113,11 +114,7 @@ impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mi
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
     fn getenv(&mut self, name_op: &OpTy<'tcx, Tag>) -> InterpResult<'tcx, Pointer<Option<Tag>>> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`getenv` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("getenv");
 
         let name_ptr = this.read_pointer(name_op)?;
         let name = this.read_os_str_from_c_str(name_ptr)?;
@@ -211,11 +208,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         value_op: &OpTy<'tcx, Tag>,
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`setenv` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("setenv");
 
         let name_ptr = this.read_pointer(name_op)?;
         let value_ptr = this.read_pointer(value_op)?;
@@ -285,11 +278,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
     fn unsetenv(&mut self, name_op: &OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`unsetenv` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("unsetenv");
 
         let name_ptr = this.read_pointer(name_op)?;
         let mut success = None;
@@ -319,11 +308,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         size_op: &OpTy<'tcx, Tag>,
     ) -> InterpResult<'tcx, Pointer<Option<Tag>>> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`getcwd` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("getcwd");
 
         let buf = this.read_pointer(buf_op)?;
         let size = this.read_scalar(size_op)?.to_machine_usize(&*this.tcx)?;
@@ -378,11 +363,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
     fn chdir(&mut self, path_op: &OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`chdir` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("chdir");
 
         let path = this.read_path_from_c_str(this.read_pointer(path_op)?)?;
 
@@ -468,11 +449,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
     fn getpid(&mut self) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
-        let target_os = &this.tcx.sess.target.os;
-        assert!(
-            target_os == "linux" || target_os == "macos",
-            "`getpid` is only available for the UNIX target family"
-        );
+        this.assert_target_os_is_unix("getpid");
 
         this.check_no_isolation("`getpid`")?;
 

src/shims/foreign_items.rs

@@ -22,7 +22,7 @@ use rustc_target::{
 };
 
 use super::backtrace::EvalContextExt as _;
-use crate::helpers::convert::Truncate;
+use crate::helpers::{convert::Truncate, target_os_is_unix};
 use crate::*;
 
 /// Returned by `emulate_foreign_item_by_name`.
@@ -702,7 +702,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
             // Platform-specific shims
             _ => match this.tcx.sess.target.os.as_ref() {
-                "linux" | "macos" => return shims::unix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
+                target if target_os_is_unix(target) => return shims::unix::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
                 "windows" => return shims::windows::foreign_items::EvalContextExt::emulate_foreign_item_by_name(this, link_name, abi, args, dest, ret),
                 target => throw_unsup_format!("the target `{}` is not supported", target),
             }