Use a RefCell to provide interior mutability for VolumeManager.

README.md

@@ -17,16 +17,16 @@ let sdcard = embedded_sdmmc::SdCard::new(sdmmc_spi, delay);
 println!("Card size is {} bytes", sdcard.num_bytes()?);
 // Now let's look for volumes (also known as partitions) on our block device.
 // To do this we need a Volume Manager. It will take ownership of the block device.
-let mut volume_mgr = embedded_sdmmc::VolumeManager::new(sdcard, time_source);
+let volume_mgr = embedded_sdmmc::VolumeManager::new(sdcard, time_source);
 // Try and access Volume 0 (i.e. the first partition).
 // The volume object holds information about the filesystem on that volume.
-let mut volume0 = volume_mgr.open_volume(embedded_sdmmc::VolumeIdx(0))?;
+let volume0 = volume_mgr.open_volume(embedded_sdmmc::VolumeIdx(0))?;
 println!("Volume 0: {:?}", volume0);
 // Open the root directory (mutably borrows from the volume).
-let mut root_dir = volume0.open_root_dir()?;
+let root_dir = volume0.open_root_dir()?;
 // Open a file called "MY_FILE.TXT" in the root directory
 // This mutably borrows the directory.
-let mut my_file = root_dir.open_file_in_dir("MY_FILE.TXT", embedded_sdmmc::Mode::ReadOnly)?;
+let my_file = root_dir.open_file_in_dir("MY_FILE.TXT", embedded_sdmmc::Mode::ReadOnly)?;
 // Print the contents of the file, assuming it's in ISO-8859-1 encoding
 while !my_file.is_eof() {
     let mut buffer = [0u8; 32];
@@ -43,7 +43,7 @@ By default the `VolumeManager` will initialize with a maximum number of `4` open
 
 ```rust
 // Create a volume manager with a maximum of 6 open directories, 12 open files, and 4 volumes (or partitions)
-let mut cont: VolumeManager<_, _, 6, 12, 4> = VolumeManager::new_with_limits(block, time_source);
+let cont: VolumeManager<_, _, 6, 12, 4> = VolumeManager::new_with_limits(block, time_source);
 ```
 
 ## Supported features

examples/append_file.rs

@@ -30,12 +30,12 @@ fn main() -> Result<(), embedded_sdmmc::Error<std::io::Error>> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr.open_volume(VolumeIdx(0))?;
-    let mut root_dir = volume.open_root_dir()?;
+    let volume = volume_mgr.open_volume(VolumeIdx(0))?;
+    let root_dir = volume.open_root_dir()?;
     println!("\nCreating file {}...", FILE_TO_APPEND);
-    let mut f = root_dir.open_file_in_dir(FILE_TO_APPEND, Mode::ReadWriteAppend)?;
+    let f = root_dir.open_file_in_dir(FILE_TO_APPEND, Mode::ReadWriteAppend)?;
     f.write(b"\r\n\r\nThis has been added to your file.\r\n")?;
     Ok(())
 }

examples/big_dir.rs

@@ -11,20 +11,20 @@ fn main() -> Result<(), embedded_sdmmc::Error<std::io::Error>> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr
+    let volume = volume_mgr
         .open_volume(embedded_sdmmc::VolumeIdx(1))
         .unwrap();
     println!("Volume: {:?}", volume);
-    let mut root_dir = volume.open_root_dir().unwrap();
+    let root_dir = volume.open_root_dir().unwrap();
 
     let mut file_num = 0;
     loop {
         file_num += 1;
         let file_name = format!("{}.da", file_num);
         println!("opening file {file_name} for writing");
-        let mut file = root_dir
+        let file = root_dir
             .open_file_in_dir(
                 file_name.as_str(),
                 embedded_sdmmc::Mode::ReadWriteCreateOrTruncate,

examples/create_file.rs

@@ -30,15 +30,15 @@ fn main() -> Result<(), embedded_sdmmc::Error<std::io::Error>> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr.open_volume(VolumeIdx(0))?;
-    let mut root_dir = volume.open_root_dir()?;
+    let volume = volume_mgr.open_volume(VolumeIdx(0))?;
+    let root_dir = volume.open_root_dir()?;
     println!("\nCreating file {}...", FILE_TO_CREATE);
     // This will panic if the file already exists: use ReadWriteCreateOrAppend
     // or ReadWriteCreateOrTruncate instead if you want to modify an existing
     // file.
-    let mut f = root_dir.open_file_in_dir(FILE_TO_CREATE, Mode::ReadWriteCreate)?;
+    let f = root_dir.open_file_in_dir(FILE_TO_CREATE, Mode::ReadWriteCreate)?;
     f.write(b"Hello, this is a new file on disk\r\n")?;
     Ok(())
 }

examples/delete_file.rs

@@ -33,10 +33,10 @@ fn main() -> Result<(), embedded_sdmmc::Error<std::io::Error>> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr.open_volume(VolumeIdx(0))?;
-    let mut root_dir = volume.open_root_dir()?;
+    let volume = volume_mgr.open_volume(VolumeIdx(0))?;
+    let root_dir = volume.open_root_dir()?;
     println!("Deleting file {}...", FILE_TO_DELETE);
     root_dir.delete_file_in_dir(FILE_TO_DELETE)?;
     println!("Deleted!");

examples/list_dir.rs

@@ -47,9 +47,9 @@ fn main() -> Result<(), Error> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr.open_volume(VolumeIdx(0))?;
+    let volume = volume_mgr.open_volume(VolumeIdx(0))?;
     let root_dir = volume.open_root_dir()?;
     list_dir(root_dir, "/")?;
     Ok(())
@@ -59,7 +59,7 @@ fn main() -> Result<(), Error> {
 ///
 /// The path is for display purposes only.
 fn list_dir(
-    mut directory: Directory<LinuxBlockDevice, Clock, 8, 8, 4>,
+    directory: Directory<LinuxBlockDevice, Clock, 8, 8, 4>,
     path: &str,
 ) -> Result<(), Error> {
     println!("Listing {}", path);

examples/read_file.rs

@@ -47,12 +47,15 @@ fn main() -> Result<(), embedded_sdmmc::Error<std::io::Error>> {
     let filename = args.next().unwrap_or_else(|| "/dev/mmcblk0".into());
     let print_blocks = args.find(|x| x == "-v").map(|_| true).unwrap_or(false);
     let lbd = LinuxBlockDevice::new(filename, print_blocks).map_err(Error::DeviceError)?;
-    let mut volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
+    let volume_mgr: VolumeManager<LinuxBlockDevice, Clock, 8, 8, 4> =
         VolumeManager::new_with_limits(lbd, Clock, 0xAA00_0000);
-    let mut volume = volume_mgr.open_volume(VolumeIdx(0))?;
-    let mut root_dir = volume.open_root_dir()?;
+    let volume = volume_mgr.open_volume(VolumeIdx(0))?;
+    let root_dir = volume.open_root_dir()?;
     println!("\nReading file {}...", FILE_TO_READ);
-    let mut f = root_dir.open_file_in_dir(FILE_TO_READ, Mode::ReadOnly)?;
+    let f = root_dir.open_file_in_dir(FILE_TO_READ, Mode::ReadOnly)?;
+    // Proves we can open two files at once now (or try to - this file doesn't exist)
+    let f2 = root_dir.open_file_in_dir("MISSING.DAT", Mode::ReadOnly);
+    assert!(f2.is_err());
     while !f.is_eof() {
         let mut buffer = [0u8; 16];
         let offset = f.offset();

examples/readme_test.rs

@@ -125,16 +125,16 @@ fn main() -> Result<(), Error> {
     println!("Card size is {} bytes", sdcard.num_bytes()?);
     // Now let's look for volumes (also known as partitions) on our block device.
     // To do this we need a Volume Manager. It will take ownership of the block device.
-    let mut volume_mgr = embedded_sdmmc::VolumeManager::new(sdcard, time_source);
+    let volume_mgr = embedded_sdmmc::VolumeManager::new(sdcard, time_source);
     // Try and access Volume 0 (i.e. the first partition).
     // The volume object holds information about the filesystem on that volume.
-    let mut volume0 = volume_mgr.open_volume(embedded_sdmmc::VolumeIdx(0))?;
+    let volume0 = volume_mgr.open_volume(embedded_sdmmc::VolumeIdx(0))?;
     println!("Volume 0: {:?}", volume0);
     // Open the root directory (mutably borrows from the volume).
-    let mut root_dir = volume0.open_root_dir()?;
+    let root_dir = volume0.open_root_dir()?;
     // Open a file called "MY_FILE.TXT" in the root directory
     // This mutably borrows the directory.
-    let mut my_file = root_dir.open_file_in_dir("MY_FILE.TXT", embedded_sdmmc::Mode::ReadOnly)?;
+    let my_file = root_dir.open_file_in_dir("MY_FILE.TXT", embedded_sdmmc::Mode::ReadOnly)?;
     // Print the contents of the file, assuming it's in ISO-8859-1 encoding
     while !my_file.is_eof() {
         let mut buffer = [0u8; 32];