Introduce FsOptions struct for providing options for library.

Old read_only flag in FileSystem::new was misleading.

README.md

@@ -31,8 +31,8 @@ Put this in your crate root:
 You can start using library now:
 
     let img_file = File::open("fat.img").unwrap();
-    let mut buf_stream = BufStream::new(img_file);
-    let fs = fatfs::FileSystem::new(&mut buf_stream, true).unwrap();
+    let mut buf_stream = fatfs::BufStream::new(img_file);
+    let fs = fatfs::FileSystem::new(&mut buf_stream, fatfs::FsOptions::new()).unwrap();
     let mut root_dir = fs.root_dir();
     let mut file = root_dir.create_file("hello.txt").unwrap();
     file.write_all(b"Hello World!").unwrap();

examples/cat.rs

@@ -5,12 +5,12 @@ use std::fs::File;
 use std::io::prelude::*;
 use std::str;
 
-use fatfs::{FileSystem, BufStream};
+use fatfs::{FileSystem, FsOptions, BufStream};
 
 fn main() {
     let file = File::open("resources/fat32.img").unwrap();
     let mut buf_rdr = BufStream::new(file);
-    let fs = FileSystem::new(&mut buf_rdr, true).unwrap();
+    let fs = FileSystem::new(&mut buf_rdr, FsOptions::new()).unwrap();
     let mut root_dir = fs.root_dir();
     let mut file = root_dir.open_file(&env::args().nth(1).unwrap()).unwrap();
     let mut buf = vec![];

examples/ls.rs

@@ -5,7 +5,7 @@ use std::env;
 use std::fs::File;
 use chrono::{DateTime, Local};
 
-use fatfs::{FileSystem, BufStream};
+use fatfs::{FileSystem, FsOptions, BufStream};
 
 fn format_file_size(size: u64) -> String {
     const KB: u64 = 1024;
@@ -25,7 +25,7 @@ fn format_file_size(size: u64) -> String {
 fn main() {
     let file = File::open("resources/fat32.img").unwrap();
     let mut buf_rdr = BufStream::new(file);
-    let fs = FileSystem::new(&mut buf_rdr, true).unwrap();
+    let fs = FileSystem::new(&mut buf_rdr, FsOptions::new()).unwrap();
     let mut root_dir = fs.root_dir();
     let dir = match env::args().nth(1) {
         None => root_dir,

src/file.rs

@@ -194,7 +194,7 @@ impl<'a, 'b> Read for File<'a, 'b> {
         self.current_cluster = Some(current_cluster);
 
         match self.entry {
-            Some(ref mut e) if !self.fs.read_only => e.reset_accessed(),
+            Some(ref mut e) if self.fs.options.update_accessed_date => e.reset_accessed(),
             _ => {},
         }
         Ok(read_bytes)

src/fs.rs

@@ -129,6 +129,14 @@ impl BiosParameterBlock {
         }
         Ok(bpb)
     }
+
+    fn mirroring_enabled(&self) -> bool {
+        self.extended_flags & 0x80 == 0
+    }
+
+    fn active_fat(&self) -> u16 {
+        self.extended_flags & 0x0F
+    }
 }
 
 #[allow(dead_code)]
@@ -169,12 +177,32 @@ impl Default for BootRecord {
     }
 }
 
+/// FAT filesystem options.
+#[derive(Debug, Clone, Copy)]
+pub struct FsOptions {
+    pub(crate) update_accessed_date: bool,
+}
+
+impl FsOptions {
+    pub fn new() -> Self {
+        FsOptions {
+            update_accessed_date: false,
+        }
+    }
+
+    /// If enabled library updates accessed date field in directory entry when reading
+    pub fn update_accessed_date(mut self, enabled: bool) -> Self {
+        self.update_accessed_date = enabled;
+        self
+    }
+}
+
 pub(crate) type FileSystemRef<'a, 'b: 'a> = &'a FileSystem<'b>;
 
 /// FAT filesystem main struct.
 pub struct FileSystem<'a> {
     pub(crate) disk: RefCell<&'a mut ReadWriteSeek>,
-    pub(crate) read_only: bool,
+    pub(crate) options: FsOptions,
     fat_type: FatType,
     bpb: BiosParameterBlock,
     first_data_sector: u32,
@@ -184,12 +212,9 @@ pub struct FileSystem<'a> {
 impl <'a> FileSystem<'a> {
     /// Creates new filesystem object instance.
     ///
-    /// read_only argument is a hint for library. It doesnt prevent user from writing to file.
-    /// For now it prevents accessed date field automatic update in dir entry.
-    ///
     /// Note: creating multiple filesystem objects with one underlying device/disk image can
     /// cause filesystem corruption.
-    pub fn new<T: ReadWriteSeek>(disk: &'a mut T, read_only: bool) -> io::Result<FileSystem<'a>> {
+    pub fn new<T: ReadWriteSeek>(disk: &'a mut T, options: FsOptions) -> io::Result<FileSystem<'a>> {
         let bpb = {
             let boot = BootRecord::deserialize(disk)?;
             if boot.boot_sig != [0x55, 0xAA] {
@@ -214,7 +239,7 @@ impl <'a> FileSystem<'a> {
 
         Ok(FileSystem {
             disk: RefCell::new(disk),
-            read_only,
+            options,
             fat_type,
             bpb: bpb,
             first_data_sector,
@@ -272,11 +297,11 @@ impl <'a> FileSystem<'a> {
         let sectors_per_fat =
             if self.bpb.sectors_per_fat_16 == 0 { self.bpb.sectors_per_fat_32 }
             else { self.bpb.sectors_per_fat_16 as u32 };
-        let mirroring_enabled = self.bpb.extended_flags & 0x80 == 0;
+        let mirroring_enabled = self.bpb.mirroring_enabled();
         let (fat_first_sector, mirrors) = if mirroring_enabled {
             (self.bpb.reserved_sectors as u32, self.bpb.fats)
         } else {
-            let active_fat = (self.bpb.extended_flags & 0x0F) as u32;
+            let active_fat = self.bpb.active_fat() as u32;
             let fat_first_sector = (self.bpb.reserved_sectors as u32) + active_fat * sectors_per_fat;
             (fat_first_sector, 1)
         };

tests/read.rs

@@ -6,7 +6,7 @@ use std::io::SeekFrom;
 use std::io::prelude::*;
 use std::str;
 
-use fatfs::{FileSystem, FatType, DirEntry, BufStream};
+use fatfs::{FileSystem, FsOptions, FatType, DirEntry, BufStream};
 
 const TEST_TEXT: &str = "Rust is cool!\n";
 const FAT12_IMG: &str = "resources/fat12.img";
@@ -17,7 +17,7 @@ fn call_with_fs(f: &Fn(FileSystem) -> (), filename: &str) {
     let _ = env_logger::init();
     let file = fs::File::open(filename).unwrap();
     let mut buf_file = BufStream::new(file);
-    let fs = FileSystem::new(&mut buf_file, true).unwrap();
+    let fs = FileSystem::new(&mut buf_file, FsOptions::new()).unwrap();
     f(fs);
 }
 

tests/write.rs

@@ -6,8 +6,7 @@ use std::io::prelude::*;
 use std::io;
 use std::str;
 
-use fatfs::FileSystem;
-use fatfs::BufStream;
+use fatfs::{FileSystem, FsOptions, BufStream};
 
 const FAT12_IMG: &str = "fat12.img";
 const FAT16_IMG: &str = "fat16.img";
@@ -25,7 +24,8 @@ fn call_with_fs(f: &Fn(FileSystem) -> (), filename: &str, test_seq: u32) {
     {
         let file = fs::OpenOptions::new().read(true).write(true).open(&tmp_path).unwrap();
         let mut buf_file = BufStream::new(file);
-        let fs = FileSystem::new(&mut buf_file, false).unwrap();
+        let options = FsOptions::new().update_accessed_date(true);
+        let fs = FileSystem::new(&mut buf_file, options).unwrap();
         f(fs);
     }
     fs::remove_file(tmp_path).unwrap();