From a7e10be881740b13e894d9ce29b0fe0675b47ee9 Mon Sep 17 00:00:00 2001
From: Stephan Renatus <srenatus@chef.io>
Date: Fri, 20 Dec 2019 16:29:44 +0100
Subject: [PATCH] Add function to get NULL-terminated strings from memory

Fixes #1086.

Signed-off-by: Stephan Renatus <srenatus@chef.io>
---
 lib/runtime-core/src/memory/ptr.rs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/runtime-core/src/memory/ptr.rs b/lib/runtime-core/src/memory/ptr.rs
index 5e31627c20f..502a419f121 100644
--- a/lib/runtime-core/src/memory/ptr.rs
+++ b/lib/runtime-core/src/memory/ptr.rs
@@ -10,7 +10,7 @@ use crate::{
     memory::Memory,
     types::{ValueType, WasmExternType},
 };
-use std::{cell::Cell, fmt, marker::PhantomData, mem};
+use std::{cell::Cell, ffi::CStr, fmt, marker::PhantomData, mem};
 
 /// Array.
 pub struct Array;
@@ -137,6 +137,17 @@ impl<T: Copy + ValueType> WasmPtr<T, Array> {
         let slice: &[u8] = unsafe { std::slice::from_raw_parts(ptr, str_len as usize) };
         std::str::from_utf8(slice).ok()
     }
+
+    /// Get a UTF-8 string representation of this `WasmPtr`, where the string is NULL-terminated.
+    /// Note that this does not account for UTF-8 strings that _contain_ NULL themselves,
+    /// [`get_utf8_string`] has to be used for those.
+    pub fn get_utf8_string_null_terminated<'a>(self, memory: &'a Memory) -> Option<&'a str> {
+        unsafe {
+            CStr::from_ptr(memory.view::<u8>().as_ptr().add(self.offset as usize) as *const i8)
+                .to_str()
+                .ok()
+        }
+    }
 }
 
 unsafe impl<T: Copy, Ty> WasmExternType for WasmPtr<T, Ty> {