Feature: defmt support

CHANGELOG.md

@@ -9,6 +9,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 -
 
+## [v0.8.1](https://github.com/trussed-dev/littlefs2/releases/tag/0.8.1) - 2026-08-08
+
+### Added
+
+- Added optional support for `defmt`.
+
 ## [v0.8.0](https://github.com/trussed-dev/littlefs2/releases/tag/0.8.0) - 2026-06-23
 
 ### Added

Cargo.toml

@@ -9,7 +9,7 @@ repository = "https://github.com/trussed-dev/littlefs2"
 [package]
 name = "littlefs2"
 description = "Idiomatic Rust API for littlefs"
-version = "0.8.0"
+version = "0.8.1"
 authors = ["Nicolas Stalder <n@stalder.io>", "Brandon Edens <brandonedens@gmail.com>", "The Trussed developers"]
 readme = "README.md"
 categories = ["embedded", "filesystem", "no-std"]
@@ -30,6 +30,7 @@ generic-array = "0.14"
 heapless = "0.9"
 littlefs2-core = { version = "0.1", path = "core" }
 littlefs2-sys = { version = "0.4", features = ["multiversion"] }
+defmt = { version = "1", optional = true }
 
 [dev-dependencies]
 ssmarshal = "1"
@@ -54,6 +55,8 @@ log-debug = []
 log-warn = []
 log-error = []
 
+defmt = ["dep:defmt", "littlefs2-core/defmt"]
+
 # unstable features -- enabling one of the following features may break semantic versioning guarantees
 
 # Use a patched version of littlefs, see littlefs2-sys.

core/CHANGELOG.md

@@ -7,9 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
-### Changed
+-
 
-- Documented the MSRV 1.74
+## [v0.1.3](https://github.com/trussed-dev/littlefs2/releases/tag/core-0.1.3) - 2026-08-08
+
+- Add optional support for `defmt`
+- Document the MSRV 1.74
 
 ## [v0.1.2](https://github.com/trussed-dev/littlefs2/releases/tag/core-0.1.2) - 2025-10-16
 

core/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "littlefs2-core"
-version = "0.1.2"
+version = "0.1.3"
 authors = ["The Trussed developers"]
 description = "Core types for the littlefs2 crate"
 rust-version = "1.74"
@@ -18,6 +18,7 @@ heapless07 = { package = "heapless", version = "0.7", optional = true }
 heapless08 = { package = "heapless", version = "0.8", optional = true }
 heapless09 = { package = "heapless", version = "0.9", optional = true }
 serde = { version = "1", default-features = false, features = ["derive"], optional = true }
+defmt = { version = "1", optional = true }
 
 [features]
 heapless-bytes03 = ["dep:heapless-bytes03"]
@@ -28,3 +29,4 @@ heapless08 = ["dep:heapless08"]
 heapless09 = ["dep:heapless09"]
 serde = ["dep:serde"]
 debug-error = []
+defmt = ["dep:defmt"]

core/src/fs.rs

@@ -30,6 +30,7 @@ bitflags! {
 /// Regular file vs directory
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum FileType {
     File,
     Dir,
@@ -48,6 +49,7 @@ impl FileType {
 /// File type (regular vs directory) and size of a file.
 #[derive(Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Metadata {
     file_type: FileType,
     size: usize,

core/src/io.rs

@@ -229,6 +229,31 @@ impl Debug for Error {
     }
 }
 
+// Keep it separate implementation from `Debug`
+// see: https://github.com/trussed-dev/littlefs2/pull/137#issuecomment-5201666242
+#[cfg(feature = "defmt")]
+impl defmt::Format for Error {
+    fn format(&self, fmt: defmt::Formatter) {
+        match self {
+            &Self::IO => defmt::write!(fmt, "IO"),
+            &Self::CORRUPTION => defmt::write!(fmt, "CORRUPTION"),
+            &Self::NO_SUCH_ENTRY => defmt::write!(fmt, "NO_SUCH_ENTRY"),
+            &Self::ENTRY_ALREADY_EXISTED => defmt::write!(fmt, "ENTRY_ALREADY_EXISTED"),
+            &Self::PATH_NOT_DIR => defmt::write!(fmt, "PATH_NOT_DIR"),
+            &Self::PATH_IS_DIR => defmt::write!(fmt, "PATH_IS_DIR"),
+            &Self::DIR_NOT_EMPTY => defmt::write!(fmt, "DIR_NOT_EMPTY"),
+            &Self::BAD_FILE_DESCRIPTOR => defmt::write!(fmt, "BAD_FILE_DESCRIPTOR"),
+            &Self::FILE_TOO_BIG => defmt::write!(fmt, "FILE_TOO_BIG"),
+            &Self::INVALID => defmt::write!(fmt, "INVALID"),
+            &Self::NO_SPACE => defmt::write!(fmt, "NO_SPACE"),
+            &Self::NO_MEMORY => defmt::write!(fmt, "NO_MEMORY"),
+            &Self::NO_ATTRIBUTE => defmt::write!(fmt, "NO_ATTRIBUTE"),
+            &Self::FILENAME_TOO_LONG => defmt::write!(fmt, "FILENAME_TOO_LONG"),
+            other => defmt::write!(fmt, "Error({})", &other.code),
+        }
+    }
+}
+
 impl From<Error> for c_int {
     fn from(error: Error) -> Self {
         error.code

core/src/path.rs

@@ -370,6 +370,13 @@ impl fmt::Debug for Path {
     }
 }
 
+#[cfg(feature = "defmt")]
+impl defmt::Format for Path {
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "p{:?}", self.as_str_ref_with_trailing_nul())
+    }
+}
+
 impl fmt::Display for Path {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(self.as_ref())
@@ -725,6 +732,7 @@ impl core::cmp::Eq for PathBuf {}
 
 /// Errors that arise from converting byte buffers into paths
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PathError {
     /// Byte buffer contains non-ASCII characters
     NotAscii,

src/fs.rs

@@ -357,45 +357,45 @@ impl<Storage: driver::Storage> Filesystem<'_, Storage> {
         use crate::path;
 
         if !self.exists(path) {
-            debug_now!("no such directory {}, early return", path);
+            debug_lib!("no such directory {}, early return", path);
             return Ok(RemoveDirAllProgress {
                 files_removed: 0,
                 skipped_any: false,
             });
         }
         let mut skipped_any = false;
         let mut files_removed = 0;
-        debug_now!("starting to remove_dir_all_where in {}", path);
+        debug_lib!("starting to remove_dir_all_where in {}", path);
         self.read_dir_and_then(path, |read_dir| {
             // skip "." and ".."
             for entry in read_dir.skip(2) {
                 let entry = entry?;
 
                 if entry.file_type().is_file() {
                     if predicate(&entry) {
-                        debug_now!("removing file {}", &entry.path());
+                        debug_lib!("removing file {}", &entry.path());
                         self.remove(entry.path())?;
-                        debug_now!("...done");
+                        debug_lib!("...done");
                         files_removed += 1;
                     } else {
-                        debug_now!("skipping file {}", &entry.path());
+                        debug_lib!("skipping file {}", &entry.path());
                         skipped_any = true;
                     }
                 }
                 if entry.file_type().is_dir() {
-                    debug_now!("recursing into directory {}", &entry.path());
+                    debug_lib!("recursing into directory {}", &entry.path());
                     let progress = self.remove_dir_all_where_inner(entry.path(), predicate)?;
                     files_removed += progress.files_removed;
                     skipped_any |= progress.skipped_any;
-                    debug_now!("...back");
+                    debug_lib!("...back");
                 }
             }
             Ok(())
         })?;
         if !skipped_any && path != path!("") && path != path!("/") {
-            debug_now!("removing directory {} too", &path);
+            debug_lib!("removing directory {} too", &path);
             self.remove_dir(path)?;
-            debug_now!("..worked");
+            debug_lib!("..worked");
         }
         Ok(RemoveDirAllProgress {
             files_removed,

src/lib.rs

@@ -156,6 +156,18 @@ pub mod path {
 extern crate delog;
 generate_macros!();
 
+#[collapse_debuginfo(yes)]
+macro_rules! debug_lib {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            debug_now!($s $(, $x)*);
+
+            #[cfg(feature = "defmt")]
+            ::defmt::debug!($s $(, $x)*);
+        }
+    };
+}
+
 /// cf. Macros documentation
 #[macro_use]
 pub mod macros;
@@ -180,6 +192,7 @@ pub const DISK_VERSION: Version = Version(0x0002_0000);
 
 /// A littlefs version number.
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Version(u32);
 
 impl Version {