Add Rust progress task wrapper

The manual `std::mem::drop()` bits are ugly; while we can do
function pointers from Rust to C++, let's just add the obvious
high level wrapper in Rust that accepts a `FnOnce()`.

Note in one instance we directly pass a function pointer which
is quite clean.

rust/src/lib.rs

@@ -433,6 +433,7 @@ mod passwd;
 use passwd::*;
 mod console_progress;
 pub(crate) use self::console_progress::*;
+mod progress;
 mod scripts;
 pub(crate) use self::scripts::*;
 mod rpmutils;

rust/src/live.rs

@@ -9,6 +9,7 @@
 
 use crate::ffi::LiveApplyState;
 use crate::isolation;
+use crate::progress::progress_task;
 use crate::{cxxrsutil::*, variant_utils};
 use anyhow::{anyhow, Context, Result};
 use fn_error_context::context;
@@ -468,34 +469,30 @@ pub(crate) fn transaction_apply_live(
 
     // Gather the current diff of /etc - we need to avoid changing
     // any files which are locally modified.
-    let task = crate::ffi::progress_begin_task("Computing /etc diff to preserve");
-    let config_diff = {
+    let config_diff = progress_task("Computing /etc diff to preserve", || -> Result<_> {
         let usretc = &rootfs_dfd.sub_dir("usr/etc")?;
         let etc = &rootfs_dfd.sub_dir("etc")?;
-        crate::dirdiff::diff(usretc, etc)?
-    };
+        crate::dirdiff::diff(usretc, etc)
+    })?;
     println!("Computed /etc diff: {}", &config_diff);
-    std::mem::drop(task);
 
     // The heart of things: updating the overlayfs on /usr
-    let task = crate::ffi::progress_begin_task("Updating /usr");
-    apply_diff(repo, &diff, &target_commit, &openat::Dir::open("/usr")?)?;
-    std::mem::drop(task);
+    progress_task("Updating /usr", || -> Result<_> {
+        apply_diff(repo, &diff, &target_commit, &openat::Dir::open("/usr")?)
+    })?;
 
     // The other important bits are /etc and /var
-    let task = crate::ffi::progress_begin_task("Updating /etc");
-    update_etc(
-        repo,
-        &diff,
-        &config_diff,
-        &sepolicy,
-        &target_commit,
-        &openat::Dir::open("/etc")?,
-    )?;
-    std::mem::drop(task);
-    let task = crate::ffi::progress_begin_task("Running systemd-tmpfiles for /run and /var");
-    rerun_tmpfiles()?;
-    std::mem::drop(task);
+    progress_task("Updating /etc", || -> Result<_> {
+        update_etc(
+            repo,
+            &diff,
+            &config_diff,
+            &sepolicy,
+            &target_commit,
+            &openat::Dir::open("/etc")?,
+        )
+    })?;
+    progress_task("Running systemd-tmpfiles for /run and /var", rerun_tmpfiles)?;
 
     // Success! Update the recorded state.
     state.commit = target_commit.to_string();

rust/src/progress.rs

@@ -0,0 +1,15 @@
+//! Rust convenience APIs over our rpmostree-output.h
+//! progress/output APIs.
+
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Call the provided function, while displaying a "task progress"
+/// message.
+pub(crate) fn progress_task<F, T>(msg: &str, f: F) -> T
+where
+    F: FnOnce() -> T,
+{
+    // Drop will end the task
+    let _task = crate::ffi::progress_begin_task(msg);
+    f()
+}