Struct FileResolver 

pub struct FileResolver { /* private fields */ }

Manages /etc/resolver/<domain> files.

Lifecycle

1. register writes a resolver file.
2. macOS picks it up immediately (no restart needed).
3. unregister removes the file on shutdown.

Crash recovery

If the process exits without calling unregister, the file persists. On next startup, call cleanup_orphaned to remove files whose creating PID is no longer running.

Permissions

/etc/resolver/ requires root. The caller must handle elevation.

Example

use macos_resolver::{FileResolver, ResolverConfig};

let resolver = FileResolver::new("myapp");
resolver.register(&ResolverConfig::new("myapp.local", "127.0.0.1", 5553))?;
// ...
resolver.unregister("myapp.local")?;

Implementations

impl FileResolver

pub fn new(prefix: &str) -> Self

Creates a resolver targeting the default /etc/resolver directory.

prefix is used for two purposes:

1. Marker comment — files are tagged with # managed by <prefix>.
2. Environment variable namespace — {PREFIX}_RESOLVER_DIR overrides the default /etc/resolver directory (prefix is uppercased, - → _).

pub fn with_marker(marker: impl Into<String>) -> Self

Creates a resolver with an exact marker string (written as-is).

Use this when you need full control over the marker comment.

pub fn dir(self, resolver_dir: impl Into<PathBuf>) -> Self

Overrides the resolver directory (useful for testing).

pub fn resolver_dir(&self) -> &Path

Returns the resolver directory path.

pub fn marker(&self) -> &str

Returns the marker string used to identify managed files.

pub fn register(&self, config: &ResolverConfig) -> Result<()>

Writes /etc/resolver/<domain> with the given configuration.

The file contains a marker with the current PID for orphan detection. Calling this again for the same domain overwrites the previous file.

Errors

Returns ResolverError::Io if the directory cannot be created or the file cannot be written.

pub fn register_permanent(&self, config: &ResolverConfig) -> Result<()>

Writes /etc/resolver/<domain> as a permanent (static) entry.

Unlike register, this does not embed a PID in the marker comment. The file is therefore immune to cleanup_orphaned (which skips files without a PID) and survives daemon restarts.

Intended for one-time installation commands (e.g. sudo myapp dns install).

Errors

Returns ResolverError::Io if the directory cannot be created or the file cannot be written.

pub fn unregister(&self, domain: &str) -> Result<()>

Removes /etc/resolver/<domain>.

Only removes files that contain the ownership marker. Files created by other tools are left untouched and a ResolverError::NotManaged error is returned.

If the file does not exist, this is a no-op.

Errors

Returns ResolverError::Io on I/O failure, or ResolverError::NotManaged if the file belongs to another tool.

pub fn list(&self) -> Result<Vec<String>>

Lists all domains with a managed resolver file.

Returns an empty vec if the directory does not exist.

Errors

Returns ResolverError::Io if the directory cannot be read.

pub fn is_registered(&self, domain: &str) -> bool

Returns true if domain has a managed resolver file on disk.

pub fn cleanup_orphaned(&self) -> Result<usize>

Removes resolver files whose creating PID is no longer running.

Returns the number of files removed. Non-managed files and files belonging to still-alive processes are left untouched. Permanent files (no PID) are also left untouched.

Errors

Returns ResolverError::Io if the directory cannot be read.