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authorVincent Ambo <mail@tazj.in>2018-10-09T09·20+0200
committerVincent Ambo <github@tazj.in>2018-10-09T09·38+0200
commit623a84f6f8c5d42243432be39757702f480199ae (patch)
treefcfc30945797bbc9474cbaf20ed60a175ff17ad6
parent61b2577a19715901048dd519d732caf3da90ea07 (diff)
refactor: Require directory instead of file path for cursors
The previous change, which makes journaldriver write the cursor
position in two steps, requires that journaldriver can write files
adjacent to the cursor position file itself.

Instead of simply guessing that this is possible (e.g. by changing the
file suffix), expect the user to provide a directory that
journaldriver can work with.
-rw-r--r--src/main.rs35
1 files changed, 25 insertions, 10 deletions
diff --git a/src/main.rs b/src/main.rs
index ef28ee880465..03b57517cc28 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -103,17 +103,24 @@ lazy_static! {
     /// information.
     static ref MONITORED_RESOURCE: Value = determine_monitored_resource();
 
-    /// Path to the file in which journaldriver should persist its
-    /// cursor state.
-    static ref CURSOR_FILE: PathBuf = env::var("CURSOR_POSITION_FILE")
-        .unwrap_or("/var/lib/journaldriver/cursor.pos".into())
+    /// Path to the directory in which journaldriver should persist
+    /// its cursor state.
+    static ref CURSOR_DIR: PathBuf = env::var("CURSOR_POSITION_DIR")
+        .unwrap_or("/var/lib/journaldriver".into())
         .into();
 
+    /// Path to the cursor position file itself.
+    static ref CURSOR_FILE: PathBuf = {
+        let mut path = CURSOR_DIR.clone();
+        path.push("cursor.pos");
+        path
+    };
+
     /// Path to the temporary file used for cursor position writes.
     static ref CURSOR_TMP_FILE: PathBuf = {
-        let mut tmp_path = CURSOR_FILE.clone();
-        tmp_path.set_extension("pos.tmp");
-        tmp_path
+        let mut path = CURSOR_DIR.clone();
+        path.push("cursor.tmp");
+        path
     };
 }
 
@@ -506,8 +513,11 @@ fn persist_cursor(cursor: String) -> Result<()> {
         return Ok(())
     }
 
-    let mut file = File::create(&*CURSOR_TMP_FILE)?;
+    let mut file = File::create(&*CURSOR_TMP_FILE)
+        .context("Failed to create cursor file")?;
+
     write!(file, "{}", cursor).context("Failed to write cursor file")?;
+
     rename(&*CURSOR_TMP_FILE, &*CURSOR_FILE)
         .context("Failed to move cursor file")
         .map_err(Into::into)
@@ -609,8 +619,13 @@ fn initial_cursor() -> Result<JournalSeek> {
 fn main () {
     env_logger::init();
 
-    // If the cursor file does not yet exist, the directory structure
-    // leading up to it should be created:
+    // The directory in which cursor positions are persisted should
+    // have been created:
+    if !CURSOR_DIR.exists() {
+        error!("Cursor directory at '{:?}' does not exist", *CURSOR_DIR);
+        process::exit(1);
+    }
+
     let cursor_position_dir = CURSOR_FILE.parent()
         .expect("Invalid cursor position file path");