Add process.get_module_path (#73)

src/runtime/process.rs

@@ -194,6 +194,42 @@ impl Process {
         }
     }
 
+    /// Gets the path of a module in the file system. The path is a path that is
+    /// accessible through the WASI file system, so a Windows path of
+    /// `C:\foo\bar.dll` would be returned as `/mnt/c/foo/bar.dll`.
+    #[cfg(feature = "alloc")]
+    #[inline]
+    pub fn get_module_path(&self, name: &str) -> Result<alloc::string::String, Error> {
+        // SAFETY: Calling `process_get_module_path` with a null pointer and 0
+        // length will return the required length. We then allocate a buffer
+        // with the required length and call it again with the buffer. We then
+        // convert the buffer into a string, which is guaranteed to be valid
+        // UTF-8.
+        unsafe {
+            let mut len = 0;
+            sys::process_get_module_path(
+                self.0,
+                name.as_ptr(),
+                name.len(),
+                core::ptr::null_mut(),
+                &mut len,
+            );
+            let mut buf = alloc::vec::Vec::with_capacity(len);
+            let success = sys::process_get_module_path(
+                self.0,
+                name.as_ptr(),
+                name.len(),
+                buf.as_mut_ptr(),
+                &mut len,
+            );
+            if !success {
+                return Err(Error {});
+            }
+            buf.set_len(len);
+            Ok(alloc::string::String::from_utf8_unchecked(buf))
+        }
+    }
+
     /// Gets the address and size of a module in the process.
     #[inline]
     pub fn get_module_range(&self, name: &str) -> Result<(Address, u64), Error> {

src/runtime/sys.rs

@@ -125,6 +125,24 @@ extern "C" {
         name_ptr: *const u8,
         name_len: usize,
     ) -> Option<NonZeroU64>;
+    /// Stores the file system path of a module in a process in the buffer
+    /// given. The pointer to the module name needs to point to valid UTF-8
+    /// encoded text with the given length. The path is a path that is
+    /// accessible through the WASI file system, so a Windows path of
+    /// `C:\foo\bar.exe` would be returned as `/mnt/c/foo/bar.exe`. Returns
+    /// `false` if the buffer is too small. After this call, no matter whether
+    /// it was successful or not, the `buf_len_ptr` will be set to the required
+    /// buffer size. If `false` is returned and the `buf_len_ptr` got set to 0,
+    /// the path or the module does not exist or it failed to get read. The path
+    /// is guaranteed to be valid UTF-8 and is not nul-terminated.
+    #[cfg(feature = "alloc")]
+    pub fn process_get_module_path(
+        process: Process,
+        name_ptr: *const u8,
+        name_len: usize,
+        buf_ptr: *mut u8,
+        buf_len_ptr: *mut usize,
+    ) -> bool;
     /// Stores the file system path of the executable in the buffer given. The
     /// path is a path that is accessible through the WASI file system, so a
     /// Windows path of `C:\foo\bar.exe` would be returned as