feat: Store.get_storedir()

(cherry picked from commit 6f4ba636f1e563167e6456d42c9fb6f65c9ca504)

flake.lock

@@ -156,11 +156,11 @@
         "pre-commit-hooks": "pre-commit-hooks"
       },
       "locked": {
-        "lastModified": 1732892090,
-        "narHash": "sha256-Ka/uNdaqpTAiVL++4MPHg8fG5o1tiJeY6G2t5UiKhd8=",
+        "lastModified": 1734340930,
+        "narHash": "sha256-BeyD6r1rQWaL+K7vLRSiCcZG4czEfmBYEL3kvBS2nGw=",
         "owner": "NixOS",
         "repo": "nix",
-        "rev": "64000481168d1da9d2519f055dd1fdee22275c21",
+        "rev": "2f32cf6d90df599d620eea5c48b9469f1c251025",
         "type": "github"
       },
       "original": {

rust/Cargo.lock

@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "Inflector"
@@ -346,6 +346,7 @@ dependencies = [
  "lazy_static",
  "nix-c-raw",
  "nix-util",
+ "pkg-config",
 ]
 
 [[package]]

rust/nix-store/Cargo.toml

@@ -2,6 +2,7 @@
 name = "nix-store"
 version = "0.1.0"
 edition = "2021"
+build = "build.rs"
 
 [lib]
 path = "src/lib.rs"
@@ -11,3 +12,6 @@ anyhow = "1.0.79"
 nix-util = { path = "../nix-util" }
 nix-c-raw = { path = "../nix-c-raw" }
 lazy_static = "1.4.0"
+
+[build-dependencies]
+pkg-config = "0.3.30"

rust/nix-store/build.rs

@@ -0,0 +1,39 @@
+fn main() {
+    // Get nix version
+    let nix_version = pkg_config::probe_library("nix-store-c").unwrap().version;
+
+    // Generate version flags
+    // Unfortunately, Rust doesn't give us a "greater than" operator in conditional
+    // compilation, so we pre-evaluate the version comparisons here, making use
+    // of the multi-valued nature of Rust cfgs.
+    let relevant_versions = vec!["2.26"];
+    let versions = relevant_versions
+        .iter()
+        .map(|v| format!("\"{}\"", v))
+        .collect::<Vec<_>>()
+        .join(",");
+
+    // Declare the known versions, so that Rust can warn about unknown versions
+    // that aren't part of `relevant_versions` yet - feel free to add entries.
+    println!(
+        "cargo:rustc-check-cfg=cfg(nix_at_least,values({}))",
+        versions
+    );
+
+    let nix_version = nix_version.split('.').collect::<Vec<&str>>();
+    let nix_version = (
+        nix_version[0].parse::<u32>().unwrap(),
+        nix_version[1].parse::<u32>().unwrap(),
+    );
+
+    for version_str in relevant_versions {
+        let version = version_str.split('.').collect::<Vec<&str>>();
+        let version = (
+            version[0].parse::<u32>().unwrap(),
+            version[1].parse::<u32>().unwrap(),
+        );
+        if nix_version >= version {
+            println!("cargo:rustc-cfg=nix_at_least=\"{}\"", version_str);
+        }
+    }
+}

rust/nix-store/src/store.rs

@@ -172,6 +172,21 @@ impl Store {
         r
     }
 
+    #[cfg(nix_at_least = "2.26")]
+    #[doc(alias = "nix_store_get_storedir")]
+    pub fn get_storedir(&mut self) -> Result<String> {
+        let mut r = result_string_init!();
+        unsafe {
+            check_call!(raw::store_get_storedir(
+                &mut self.context,
+                self.inner.ptr(),
+                Some(callback_get_result_string),
+                callback_get_result_string_data(&mut r)
+            ))
+        }?;
+        r
+    }
+
     pub fn weak_ref(&self) -> StoreWeak {
         StoreWeak {
             inner: Arc::downgrade(&self.inner),