feat: nix-fetchers crate

(cherry picked from commit 27d572403ac98d83d652481da6c22ad50bb00168)

rust/Cargo.lock

@@ -323,6 +323,19 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "nix-fetchers"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "cstr",
+ "ctor",
+ "nix-c-raw",
+ "nix-store",
+ "nix-util",
+ "tempfile",
+]
+
 [[package]]
 name = "nix-flake"
 version = "0.1.0"
@@ -333,6 +346,7 @@ dependencies = [
  "lazy_static",
  "nix-c-raw",
  "nix-expr",
+ "nix-fetchers",
  "nix-store",
  "nix-util",
  "tempfile",

rust/Cargo.toml

@@ -1,9 +1,10 @@
 [workspace]
 members = [
     "nix-c-raw",
-    "nix-flake",
     "nix-expr",
-    "nix-util",
+    "nix-fetchers",
+    "nix-flake",
     "nix-store",
+    "nix-util",
 ]
 resolver = "2"

rust/nix-fetchers/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "nix-fetchers"
+version = "0.1.0"
+edition = "2021"
+license = "LGPL-2.1"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+anyhow = "1.0.79"
+nix-store = { path = "../nix-store" }
+nix-util = { path = "../nix-util" }
+nix-c-raw = { path = "../nix-c-raw" }
+ctor = "0.2.7"
+tempfile = "3.10.1"
+cstr = "0.2.12"

rust/nix-fetchers/src/lib.rs

@@ -0,0 +1,38 @@
+use anyhow::{Context as _, Result};
+use nix_c_raw as raw;
+use nix_util::context::{self, Context};
+use std::ptr::NonNull;
+
+pub struct FetchersSettings {
+    pub(crate) ptr: NonNull<raw::fetchers_settings>,
+}
+impl Drop for FetchersSettings {
+    fn drop(&mut self) {
+        unsafe {
+            raw::fetchers_settings_free(self.ptr.as_ptr());
+        }
+    }
+}
+impl FetchersSettings {
+    pub fn new() -> Result<Self> {
+        let mut ctx = Context::new();
+        let ptr = unsafe { context::check_call!(raw::fetchers_settings_new(&mut ctx))? };
+        Ok(FetchersSettings {
+            ptr: NonNull::new(ptr).context("fetchers_settings_new unexpectedly returned null")?,
+        })
+    }
+
+    pub fn raw_ptr(&self) -> *mut raw::fetchers_settings {
+        self.ptr.as_ptr()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fetchers_settings_new() {
+        let _ = FetchersSettings::new().unwrap();
+    }
+}

rust/nix-flake/Cargo.toml

@@ -10,6 +10,7 @@ path = "src/lib.rs"
 [dependencies]
 anyhow = "1.0.79"
 nix-expr = { path = "../nix-expr" }
+nix-fetchers = { path = "../nix-fetchers" }
 nix-store = { path = "../nix-store" }
 nix-util = { path = "../nix-util" }
 nix-c-raw = { path = "../nix-c-raw" }