Standalone MIRI - memrchr and better null checking

2 files changed, 25 insertions, 0 deletions

diff --git a/tools/standalone_miri/main.cpp b/tools/standalone_miri/main.cpp
index 16cfd972..4ee503d3 100644
--- a/tools/standalone_miri/main.cpp
+++ b/tools/standalone_miri/main.cpp
@@ -1857,6 +1857,28 @@ Value MIRI_Invoke_Extern(ModuleTree& modtree, ThreadState& thread, const ::std::
         }
         return rv;
     }
+    else if( link_name == "memrchr" )
+    {
+        auto ptr_alloc = args.at(0).get_relocation(0);
+        auto c = args.at(1).read_i32(0);
+        auto n = args.at(2).read_usize(0);
+        const void* ptr = args.at(0).read_pointer_const(0, n);
+
+        const void* ret = memrchr(ptr, c, n);
+
+        auto rv = Value(::HIR::TypeRef(RawType::USize));
+        rv.create_allocation();
+        if( ret )
+        {
+            rv.write_usize(0, args.at(0).read_usize(0) + ( static_cast<const uint8_t*>(ret) - static_cast<const uint8_t*>(ptr) ));
+            rv.allocation.alloc().relocations.push_back({ 0, ptr_alloc });
+        }
+        else
+        {
+            rv.write_usize(0, 0);
+        }
+        return rv;
+    }
     // Allocators!
     else
     {
diff --git a/tools/standalone_miri/value.cpp b/tools/standalone_miri/value.cpp
index 468425e9..db352019 100644
--- a/tools/standalone_miri/value.cpp
+++ b/tools/standalone_miri/value.cpp
@@ -169,6 +169,9 @@ void* ValueCommon::read_pointer_unsafe(size_t rd_ofs, size_t req_valid, size_t&
         if( ofs != 0 ) {
             LOG_FATAL("Read a non-zero offset with no relocation");
         }
+        if( req_valid > 0 ) {
+            LOG_ERROR("Attempting to read a null pointer");
+        }
         out_is_mut = false;
         out_size = 0;
         return nullptr;