From acb1274c089c60488ee0060bd84f537faff54bc8 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Mon, 8 Apr 2024 16:25:37 +0200
Subject: [PATCH] refact: Add callback_get_vec_u8_data

Make it easier to correctly use the string callbacks.

(cherry picked from commit 32db5dfc020053c36b7a4776313ee72d7bc961dd)
---
 rust/nix-store/src/store.rs        | 4 ++--
 rust/nix-util/src/string_return.rs | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/rust/nix-store/src/store.rs b/rust/nix-store/src/store.rs
index ba1b4bc..3aeaa48 100644
--- a/rust/nix-store/src/store.rs
+++ b/rust/nix-store/src/store.rs
@@ -2,7 +2,7 @@ use anyhow::{bail, Result};
 use lazy_static::lazy_static;
 use nix_c_raw as raw;
 use nix_util::context::Context;
-use nix_util::string_return::callback_get_vec_u8;
+use nix_util::string_return::{callback_get_vec_u8, callback_get_vec_u8_data};
 use std::ffi::CString;
 use std::ptr::null_mut;
 use std::ptr::NonNull;
@@ -84,7 +84,7 @@ impl Store {
                 self.context.ptr(),
                 self.inner.ptr(),
                 Some(callback_get_vec_u8),
-                &mut raw_buffer as *mut Vec<u8> as *mut std::ffi::c_void,
+                callback_get_vec_u8_data(&mut raw_buffer),
             )
         };
         self.context.check_err()?;
diff --git a/rust/nix-util/src/string_return.rs b/rust/nix-util/src/string_return.rs
index 9fe5a8f..cfead12 100644
--- a/rust/nix-util/src/string_return.rs
+++ b/rust/nix-util/src/string_return.rs
@@ -16,6 +16,10 @@ pub unsafe extern "C" fn callback_get_vec_u8(
     (*ret).extend_from_slice(slice);
 }
 
+pub fn callback_get_vec_u8_data(vec: &mut Vec<u8>) -> *mut std::os::raw::c_void {
+    vec as *mut Vec<u8> as *mut std::os::raw::c_void
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;