[PATCH 2/4] tools/mount-flatpak: Create utility function to open a subdirectory

[Demi Marie Obenour <demiobenour@gmail.com>]

This rejects non-directories where a directory is expected.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---
 tools/mount-flatpak/src/main.rs | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/tools/mount-flatpak/src/main.rs b/tools/mount-flatpak/src/main.rs
index dca42e5007e52b24c9a4b6940d5667f770a64bd0..68a1f6ea308387a9471682c927d3a71439ab69e4 100644
--- a/tools/mount-flatpak/src/main.rs
+++ b/tools/mount-flatpak/src/main.rs
@@ -49,8 +49,8 @@ use std::os::unix::prelude::*;
 use std::path::{Path, PathBuf};
 use std::process::exit;
 
-use pathrs::Root;
 use pathrs::flags::{OpenFlags, ResolverFlags};
+use pathrs::{Root, error::Error};
 use rustix::fs::{CWD, FileType, fstat};
 use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree};
 
@@ -61,6 +61,11 @@ fn ex_usage() -> ! {
     exit(1);
 }
 
+fn open_subdir(root: &Root, path: &Path) -> Result<Root, Error> {
+    root.open_subpath(path, OpenFlags::O_PATH | OpenFlags::O_DIRECTORY)
+        .map(|f| Root::from_fd(f).with_resolver_flags(ResolverFlags::NO_SYMLINKS))
+}
+
 fn mount_commit(
     source_commit: &dyn AsFd,
     target_installation: &Root,
@@ -106,11 +111,8 @@ fn run(mut args: ArgsOs) -> Result<(), String> {
         .map_err(|e| format!("opening user data partition: {e}"))?
         .with_resolver_flags(ResolverFlags::NO_SYMLINKS);
 
-    let source_installation_dir = user_data
-        .open_subpath(&installation_path, OpenFlags::O_PATH)
-        .map(Root::from_fd)
-        .map_err(|e| format!("opening source flatpak installation: {e}"))?
-        .with_resolver_flags(ResolverFlags::NO_SYMLINKS);
+    let source_installation_dir = open_subdir(&user_data, &installation_path)
+        .map_err(|e| format!("opening source flatpak installation: {e}"))?;
 
     std::fs::create_dir("flatpak")
         .map_err(|e| format!("creating target flatpak installation: {e}"))?;
@@ -150,12 +152,11 @@ fn run(mut args: ArgsOs) -> Result<(), String> {
 
     full_app_path.pop();
     full_app_path.push(&commit);
-    let source_app_dir = source_installation_dir
-        .resolve(&full_app_path)
+    let source_app_dir = open_subdir(&source_installation_dir, &full_app_path)
         .map_err(|e| format!("opening source app directory: {e}"))?;
 
     let metadata = source_installation_dir
-        .resolve(full_app_path.join("metadata"))
+        .resolve(&full_app_path.join("metadata"))
         .map_err(|e| format!("resolving app metadata: {e}"))?;
 
     let metadata_stat =
@@ -182,8 +183,7 @@ fn run(mut args: ArgsOs) -> Result<(), String> {
 
     full_runtime_path.pop();
     full_runtime_path.push(&runtime_commit);
-    let source_runtime_dir = source_installation_dir
-        .resolve(&full_runtime_path)
+    let source_runtime_dir = open_subdir(&source_installation_dir, &full_runtime_path)
         .map_err(|e| format!("opening source runtime directory: {e}"))?;
 
     mount_commit(&source_app_dir, &target_installation_dir, &full_app_path)?;

-- 
2.52.0