Support no_std without alloc

Cargo.toml

@@ -18,15 +18,19 @@ exclude = [
 travis-ci = { repository = "rafalh/rust-fatfs" }
 
 [features]
+# Use Rust std library
 std = []
-default = ["chrono", "std"]
+# Use dynamic allocation - required for LFN support
+alloc = ["core_io/collections"]
+# Default features
+default = ["chrono", "std", "alloc"]
 
 [dependencies]
 byteorder = "1"
 bitflags = "1.0"
 log = "0.4"
 chrono = { version = "0.4", optional = true }
-core_io = { version = "0.1", features = ["collections"], optional = true }
+core_io = { version = "0.1", optional = true }
 
 [dev-dependencies]
 env_logger = "0.5"

README.md

@@ -47,7 +47,11 @@ Put this in your `Cargo.toml`:
     [dependencies]
     fatfs = { version = "0.2", features = ["core_io"], default-features = false }
 
-Note: alloc crate is required at the moment so when std is disabled, custom allocator has to be provided.
+Note: LFN support requires `alloc` feature and makes use of `alloc` crate.
+You may have to provide a memory allocator implementation.
+
+For building in `no_std` mode nightly Rust version compatible with current `core_io` crate is required.
+See date string in `core_io` dependency version.
 
 License
 -------

build-nostd.sh

@@ -1,2 +1,4 @@
 #!/bin/sh
+set -e
 cargo build --no-default-features --features core_io
+cargo build --no-default-features --features core_io,alloc

src/dir.rs

@@ -1,5 +1,5 @@
-use core::slice;
+#[cfg(feature = "alloc")]
-use core::iter;
+use core::{slice, iter};
 
 use io::prelude::*;
 use io;
@@ -7,10 +7,12 @@ use io::{ErrorKind, SeekFrom};
 
 use fs::{FileSystemRef, DiskSlice};
 use file::File;
-use dir_entry::{DirEntry, DirEntryData, DirFileEntryData, DirLfnEntryData, FileAttributes,
+use dir_entry::{DirEntry, DirEntryData, DirFileEntryData, DirLfnEntryData, FileAttributes, ShortName, DIR_ENTRY_SIZE};
-    DIR_ENTRY_SIZE, LFN_PART_LEN, LFN_ENTRY_LAST_FLAG};
 
-#[cfg(not(feature = "std"))]
+#[cfg(feature = "alloc")]
+use dir_entry::{LFN_PART_LEN, LFN_ENTRY_LAST_FLAG};
+
+#[cfg(all(not(feature = "std"), feature = "alloc"))]
 use alloc::Vec;
 
 #[derive(Clone)]
@@ -254,13 +256,11 @@ impl <'a, 'b> Dir<'a, 'b> {
         }
     }
 
-    fn create_entry(&mut self, name: &str, attrs: FileAttributes, first_cluster: Option<u32>) -> io::Result<DirEntry<'a, 'b>> {
+    #[cfg(feature = "alloc")]
-        trace!("create_entry {}", name);
+    fn create_lfn_entries(&mut self, name: &str, short_name: &[u8]) -> io::Result<(DirRawStream<'a, 'b>, u64)> {
-        // check if name doesn't contain unsupported characters
+        // get short name checksum
-        validate_long_name(name)?;
-        // generate short name and long entries
-        let short_name = generate_short_name(name);
         let lfn_chsum = lfn_checksum(&short_name);
+        // convert long name to UTF-16
         let lfn_utf16 = name.encode_utf16().collect::<Vec<u16>>();
         let lfn_iter = LfnEntriesGenerator::new(&lfn_utf16, lfn_chsum);
         // find space for new entries
@@ -271,6 +271,23 @@ impl <'a, 'b> Dir<'a, 'b> {
         for lfn_entry in lfn_iter {
             lfn_entry.serialize(&mut stream)?;
         }
+        Ok((stream, start_pos))
+    }
+    #[cfg(not(feature = "alloc"))]
+    fn create_lfn_entries(&mut self, _name: &str, _short_name: &[u8]) -> io::Result<(DirRawStream<'a, 'b>, u64)> {
+        let mut stream = self.find_free_entries(1)?;
+        let start_pos = stream.seek(io::SeekFrom::Current(0))?;
+        Ok((stream, start_pos))
+    }
+
+    fn create_entry(&mut self, name: &str, attrs: FileAttributes, first_cluster: Option<u32>) -> io::Result<DirEntry<'a, 'b>> {
+        trace!("create_entry {}", name);
+        // check if name doesn't contain unsupported characters
+        validate_long_name(name)?;
+        // generate short name
+        let short_name = generate_short_name(name);
+        // generate long entries
+        let (mut stream, start_pos) = self.create_lfn_entries(&name, &short_name)?;
         // create and write short name entry
         let mut raw_entry = DirFileEntryData::new(short_name, attrs);
         raw_entry.set_first_cluster(first_cluster, self.fs.fat_type());
@@ -281,8 +298,11 @@ impl <'a, 'b> Dir<'a, 'b> {
         let end_pos = stream.seek(io::SeekFrom::Current(0))?;
         let abs_pos = stream.abs_pos().map(|p| p - DIR_ENTRY_SIZE);
         // return new logical entry descriptor
+        let short_name = ShortName::new(raw_entry.name());
         return Ok(DirEntry {
             data: raw_entry,
+            short_name,
+            #[cfg(feature = "alloc")]
             lfn: Vec::new(),
             fs: self.fs,
             entry_pos: abs_pos.unwrap(), // SAFE: abs_pos is absent only for empty file
@@ -301,6 +321,7 @@ pub struct DirIter<'a, 'b: 'a> {
 
 impl <'a, 'b> DirIter<'a, 'b> {
     fn read_dir_entry(&mut self) -> io::Result<Option<DirEntry<'a, 'b>>> {
+        #[cfg(feature = "alloc")]
         let mut lfn_buf = LongNameBuilder::new();
         let mut offset = self.stream.seek(SeekFrom::Current(0))?;
         let mut begin_offset = offset;
@@ -315,6 +336,7 @@ impl <'a, 'b> DirIter<'a, 'b> {
                     }
                     // Check if this is deleted or volume ID entry
                     if data.is_free() || data.is_volume() {
+                        #[cfg(feature = "alloc")]
                         lfn_buf.clear();
                         begin_offset = offset;
                         continue;
@@ -322,9 +344,14 @@ impl <'a, 'b> DirIter<'a, 'b> {
                     // Get entry position on volume
                     let abs_pos = self.stream.abs_pos().map(|p| p - DIR_ENTRY_SIZE);
                     // Check if LFN checksum is valid
+                    #[cfg(feature = "alloc")]
                     lfn_buf.validate_chksum(data.name());
+                    // Return directory entry
+                    let short_name = ShortName::new(data.name());
                     return Ok(Some(DirEntry {
                         data,
+                        short_name,
+                        #[cfg(feature = "alloc")]
                         lfn: lfn_buf.to_vec(),
                         fs: self.fs,
                         entry_pos: abs_pos.unwrap(), // SAFE: abs_pos is empty only for empty file
@@ -334,11 +361,13 @@ impl <'a, 'b> DirIter<'a, 'b> {
                 DirEntryData::Lfn(data) => {
                     // Check if this is deleted entry
                     if data.is_free() {
+                        #[cfg(feature = "alloc")]
                         lfn_buf.clear();
                         begin_offset = offset;
                         continue;
                     }
                     // Append to LFN buffer
+                    #[cfg(feature = "alloc")]
                     lfn_buf.process(&data);
                 }
             }
@@ -420,6 +449,7 @@ fn validate_long_name(name: &str) -> io::Result<()> {
     Ok(())
 }
 
+#[cfg(feature = "alloc")]
 fn lfn_checksum(short_name: &[u8]) -> u8 {
     let mut chksum = 0u8;
     for i in 0..11 {
@@ -428,12 +458,14 @@ fn lfn_checksum(short_name: &[u8]) -> u8 {
     chksum
 }
 
+#[cfg(feature = "alloc")]
 struct LongNameBuilder {
     buf: Vec<u16>,
     chksum: u8,
     index: u8,
 }
 
+#[cfg(feature = "alloc")]
 impl LongNameBuilder {
     fn new() -> LongNameBuilder {
         LongNameBuilder {
@@ -510,6 +542,7 @@ impl LongNameBuilder {
     }
 }
 
+#[cfg(feature = "alloc")]
 struct LfnEntriesGenerator<'a> {
     name_parts_iter: iter::Rev<slice::Chunks<'a, u16>>,
     checksum: u8,
@@ -518,6 +551,7 @@ struct LfnEntriesGenerator<'a> {
     ended: bool,
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> LfnEntriesGenerator<'a> {
     fn new(name_utf16: &'a [u16], checksum: u8) -> Self {
         let num_entries = (name_utf16.len() + LFN_PART_LEN - 1) / LFN_PART_LEN;
@@ -532,6 +566,7 @@ impl<'a> LfnEntriesGenerator<'a> {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> Iterator for LfnEntriesGenerator<'a> {
     type Item = DirLfnEntryData;
 
@@ -577,4 +612,5 @@ impl<'a> Iterator for LfnEntriesGenerator<'a> {
 }
 
 // name_parts_iter is ExactSizeIterator so size_hint returns one limit
+#[cfg(feature = "alloc")]
 impl<'a> ExactSizeIterator for LfnEntriesGenerator<'a> {}

src/dir_entry.rs

@@ -1,4 +1,4 @@
-use core::fmt;
+use core::{fmt, str};
 use io::prelude::*;
 use io;
 use io::Cursor;
@@ -10,7 +10,7 @@ use chrono::{TimeZone, Local, Datelike, Timelike};
 #[cfg(feature = "chrono")]
 use chrono;
 
-#[cfg(not(feature = "std"))]
+#[cfg(all(not(feature = "std"), feature = "alloc"))]
 use alloc::{Vec, String, string::ToString};
 
 use fs::{FileSystemRef, FatType};
@@ -37,6 +37,45 @@ pub(crate) const DIR_ENTRY_SIZE: u64 = 32;
 pub(crate) const DIR_ENTRY_FREE_FLAG: u8 = 0xE5;
 pub(crate) const LFN_ENTRY_LAST_FLAG: u8 = 0x40;
 
+/// Decoded file short name
+#[derive(Clone, Debug, Default)]
+pub(crate) struct ShortName {
+    name: [u8; 12],
+    len: u8,
+}
+
+impl ShortName {
+    pub(crate) fn new(raw_name: &[u8; 11]) -> Self {
+        // get name components length by looking for space character
+        const SPACE: u8 = ' ' as u8;
+        let name_len = raw_name[0..8].iter().position(|x| *x == SPACE).unwrap_or(8);
+        let ext_len = raw_name[8..11].iter().position(|x| *x == SPACE).unwrap_or(3);
+        let mut name = [SPACE; 12];
+        name[..name_len].copy_from_slice(&raw_name[..name_len]);
+        let total_len = if ext_len > 0 {
+            name[name_len] = '.' as u8;
+            name[name_len+1..name_len+1+ext_len].copy_from_slice(&raw_name[8..8+ext_len]);
+            // Return total name length
+            name_len+1+ext_len
+        } else {
+            // No extension - return length of name part
+            name_len
+        };
+        // Short names in FAT filesystem are encoded in OEM code-page. Rust operates on UTF-8 strings
+        // and there is no built-in conversion so strip non-ascii characters in the name.
+        use strip_non_ascii;
+        strip_non_ascii(&mut name);
+        ShortName {
+            name,
+            len: total_len as u8,
+        }
+    }
+
+    fn to_str(&self) -> &str {
+        str::from_utf8(&self.name[..self.len as usize]).unwrap() // SAFE: all characters outside of ASCII table has been removed
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Clone, Debug, Default)]
 pub(crate) struct DirFileEntryData {
@@ -251,10 +290,12 @@ impl DirLfnEntryData {
         Ok(())
     }
 
+    #[cfg(feature = "alloc")]
     pub(crate) fn order(&self) -> u8 {
         self.order
     }
 
+    #[cfg(feature = "alloc")]
     pub(crate) fn checksum(&self) -> u8 {
         self.checksum
     }
@@ -539,6 +580,8 @@ impl DirEntryEditor {
 #[derive(Clone)]
 pub struct DirEntry<'a, 'b: 'a> {
     pub(crate) data: DirFileEntryData,
+    pub(crate) short_name: ShortName,
+    #[cfg(feature = "alloc")]
     pub(crate) lfn: Vec<u16>,
     pub(crate) entry_pos: u64,
     pub(crate) offset_range: (u64, u64),
@@ -547,19 +590,17 @@ pub struct DirEntry<'a, 'b: 'a> {
 
 impl <'a, 'b> DirEntry<'a, 'b> {
     /// Returns short file name
+    #[cfg(feature = "alloc")]
     pub fn short_file_name(&self) -> String {
-        let name_str = String::from_utf8_lossy(&self.data.name[0..8]);
+        self.short_name.to_str().to_string()
-        let ext_str = String::from_utf8_lossy(&self.data.name[8..11]);
-        let name_trimmed = name_str.trim_right();
-        let ext_trimmed = ext_str.trim_right();
-        if ext_trimmed.is_empty() {
-            name_trimmed.to_string()
-        } else {
-            format!("{}.{}", name_trimmed, ext_trimmed)
     }
+    #[cfg(not(feature = "alloc"))]
+    pub fn short_file_name(&self) -> &str {
+        self.short_name.to_str()
     }
 
     /// Returns long file name or if it doesn't exist fallbacks to short file name.
+    #[cfg(feature = "alloc")]
     pub fn file_name(&self) -> String {
         if self.lfn.len() > 0 {
             String::from_utf16_lossy(&self.lfn)
@@ -567,6 +608,10 @@ impl <'a, 'b> DirEntry<'a, 'b> {
             self.short_file_name()
         }
     }
+    #[cfg(not(feature = "alloc"))]
+    pub fn file_name(&self) -> &str {
+        self.short_file_name()
+    }
 
     /// Returns file attributes
     pub fn attributes(&self) -> FileAttributes {

src/fs.rs

@@ -11,8 +11,10 @@ use dir::{DirRawStream, Dir};
 use dir_entry::DIR_ENTRY_SIZE;
 use table::{ClusterIterator, alloc_cluster, read_fat_flags};
 
-#[cfg(not(feature = "std"))]
+#[cfg(all(not(feature = "std"), feature = "alloc"))]
 use alloc::{String, string::ToString};
+#[cfg(all(not(feature = "std"), not(feature = "alloc")))]
+use core::str;
 
 // FAT implementation based on:
 //   http://wiki.osdev.org/FAT
@@ -46,6 +48,14 @@ impl<T> ReadSeek for T where T: Read + Seek {}
 pub trait ReadWriteSeek: Read + Write + Seek {}
 impl<T> ReadWriteSeek for T where T: Read + Write + Seek {}
 
+pub(crate) fn strip_non_ascii(slice: &mut [u8]) {
+    for c in slice {
+        if *c < 0x20 || *c >= 0x80 {
+            *c = '_' as u8;
+        }
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Default, Debug, Clone)]
 struct BiosParameterBlock {
@@ -130,6 +140,8 @@ impl BiosParameterBlock {
             rdr.read_exact(&mut bpb.volume_label)?;
             rdr.read_exact(&mut bpb.fs_type_label)?;
         }
+        // Strip non-ascii characters from volume label
+        strip_non_ascii(&mut bpb.volume_label);
         if bpb.ext_sig != 0x29 {
             // fields after ext_sig are not used - clean them
             bpb.volume_id = 0;
@@ -284,9 +296,14 @@ impl <'a> FileSystem<'a> {
     ///
     /// Note: File with VOLUME_ID attribute in root directory is ignored by this library.
     /// Only label from BPB is used.
+    #[cfg(feature = "alloc")]
     pub fn volume_label(&self) -> String {
         String::from_utf8_lossy(&self.bpb.volume_label).trim_right().to_string()
     }
+    #[cfg(not(feature = "alloc"))]
+    pub fn volume_label(&self) -> &str {
+        str::from_utf8(&self.bpb.volume_label).unwrap_or("").trim_right()
+    }
 
     /// Returns root directory object allowing futher penetration of filesystem structure.
     pub fn root_dir<'b>(&'b self) -> Dir<'b, 'a> {

src/lib.rs

@@ -4,6 +4,9 @@
 #![cfg_attr(not(feature="std"), no_std)]
 #![cfg_attr(not(feature="std"), feature(alloc))]
 
+// Disable warnings to not clutter code with cfg too much
+#![cfg_attr(not(feature="alloc"), allow(dead_code, unused_imports))]
+
 extern crate byteorder;
 
 #[macro_use]
@@ -18,7 +21,7 @@ extern crate chrono;
 #[cfg(not(feature = "std"))]
 extern crate core_io;
 
-#[cfg(not(feature = "std"))]
+#[cfg(all(not(feature = "std"), feature = "alloc"))]
 #[macro_use]
 extern crate alloc;
 
@@ -27,6 +30,8 @@ mod dir;
 mod dir_entry;
 mod file;
 mod table;
+
+#[cfg(feature = "alloc")]
 mod utils;
 
 #[cfg(not(feature = "std"))]
@@ -48,4 +53,6 @@ pub use fs::*;
 pub use dir::*;
 pub use dir_entry::*;
 pub use file::*;
+
+#[cfg(feature = "alloc")]
 pub use utils::*;