Return error when creating FileBackedHistory with invalid capacity

examples/demo.rs

@@ -10,15 +10,15 @@ use {
         default_emacs_keybindings, default_vi_insert_keybindings, default_vi_normal_keybindings,
         ColumnarMenu, DefaultCompleter, DefaultHinter, DefaultPrompt, DefaultValidator,
         EditCommand, EditMode, Emacs, ExampleHighlighter, Keybindings, ListMenu, Reedline,
-        ReedlineEvent, ReedlineMenu, Signal, Vi,
+        ReedlineEvent, ReedlineMenu, Result, Signal, Vi,
     },
 };
 
 use reedline::CursorConfig;
 #[cfg(not(any(feature = "sqlite", feature = "sqlite-dynlib")))]
 use reedline::FileBackedHistory;
 
-fn main() -> std::io::Result<()> {
+fn main() -> Result<()> {
     println!("Ctrl-D to quit");
     // quick command like parameter handling
     let vi_mode = matches!(std::env::args().nth(1), Some(x) if x == "--vi");

src/history/file_backed.rs

@@ -37,8 +37,15 @@ impl Default for FileBackedHistory {
     /// Creates an in-memory [`History`] with a maximal capacity of [`HISTORY_SIZE`].
     ///
     /// To create a [`History`] that is synchronized with a file use [`FileBackedHistory::with_file()`]
+    ///
+    /// # Panics
+    ///
+    /// If `HISTORY_SIZE == 0` or `HISTORY_SIZE == usize::MAX`
     fn default() -> Self {
-        Self::new(HISTORY_SIZE)
+        match Self::new(HISTORY_SIZE) {
+            Ok(history) => history,
+            Err(e) => panic!("{}", e),
+        }
     }
 }
 
@@ -283,20 +290,24 @@ impl History for FileBackedHistory {
 impl FileBackedHistory {
     /// Creates a new in-memory history that remembers `n <= capacity` elements
     ///
-    /// # Panics
-    ///
-    /// If `capacity == usize::MAX`
-    pub fn new(capacity: usize) -> Self {
-        if capacity == usize::MAX {
-            panic!("History capacity too large to be addressed safely");
+    pub fn new(capacity: usize) -> Result<Self> {
+        if capacity == 0 {
+            return Err(ReedlineError(ReedlineErrorVariants::OtherHistoryError(
+                "History capacity too small to be addressed safely",
+            )));
+        } else if capacity == usize::MAX {
+            return Err(ReedlineError(ReedlineErrorVariants::OtherHistoryError(
+                "History capacity too large to be addressed safely",
+            )));
         }
-        FileBackedHistory {
+
+        Ok(FileBackedHistory {
             capacity,
             entries: VecDeque::new(),
             file: None,
             len_on_disk: 0,
             session: None,
-        }
+        })
     }
 
     /// Creates a new history with an associated history file.
@@ -307,8 +318,8 @@ impl FileBackedHistory {
     ///
     /// **Side effects:** creates all nested directories to the file
     ///
-    pub fn with_file(capacity: usize, file: PathBuf) -> std::io::Result<Self> {
-        let mut hist = Self::new(capacity);
+    pub fn with_file(capacity: usize, file: PathBuf) -> Result<Self> {
+        let mut hist = Self::new(capacity)?;
         if let Some(base_dir) = file.parent() {
             std::fs::create_dir_all(base_dir)?;
         }

src/result.rs

@@ -23,6 +23,12 @@ pub enum ReedlineErrorVariants {
 #[derive(Debug)]
 pub struct ReedlineError(pub ReedlineErrorVariants);
 
+impl From<std::io::Error> for ReedlineError {
+    fn from(err: std::io::Error) -> Self {
+        Self(ReedlineErrorVariants::IOError(err))
+    }
+}
+
 impl Display for ReedlineError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)