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//! Assets
//!
//! See also [the NDK docs](https://developer.android.com/ndk/reference/group/asset)
use std::ffi::{CStr, CString};
use std::io;
use std::ptr::NonNull;
/// A native `AAssetManager *`.
#[derive(Debug)]
pub struct AssetManager {
ptr: NonNull<ffi::AAssetManager>,
}
// AAssetManager is thread safe.
// See https://developer.android.com/ndk/reference/group/asset#aassetmanager
unsafe impl Send for AssetManager {}
unsafe impl Sync for AssetManager {}
impl AssetManager {
/// Create an `AssetManager` from a pointer
///
/// # Safety
/// By calling this function, you assert that the pointer is a valid pointer to a native
/// `AAssetManager`.
pub unsafe fn from_ptr(ptr: NonNull<ffi::AAssetManager>) -> Self {
Self { ptr }
}
/// Returns the pointer to the native `AAssetManager`.
pub fn ptr(&self) -> NonNull<ffi::AAssetManager> {
self.ptr
}
/// Open the asset. Returns `None` if opening the asset fails.
///
/// This currently always opens the asset in the streaming mode.
pub fn open(&self, filename: &CStr) -> Option<Asset> {
unsafe {
let ptr = ffi::AAssetManager_open(
self.ptr.as_ptr(),
filename.as_ptr(),
ffi::AASSET_MODE_STREAMING as i32,
);
Some(Asset::from_ptr(NonNull::new(ptr)?))
}
}
/// Open an asset directory. Returns `None` if opening the directory fails.
pub fn open_dir(&self, filename: &CStr) -> Option<AssetDir> {
unsafe {
let ptr = ffi::AAssetManager_openDir(self.ptr.as_ptr(), filename.as_ptr());
Some(AssetDir::from_ptr(NonNull::new(ptr)?))
}
}
}
/// A native `AAssetDir *`.
///
/// ```no_run
/// # use std::ffi::CString;
/// # use ndk::asset::AssetManager;
/// # let asset_manager: AssetManager = unimplemented!();
/// use std::io::Read;
///
/// let mut my_dir = asset_manager
/// .open_dir(&CString::new("my_dir").unwrap())
/// .expect("Could not open directory");
///
/// // Use it as an iterator
/// let all_files = my_dir.collect::<Vec<CString>>();
///
/// // Reset the iterator
/// my_dir.rewind();
///
/// // Use .with_next() to iterate without allocating `CString`s
/// while let Some(asset) = my_dir.with_next(|cstr| asset_manager.open(cstr).unwrap()) {
/// let mut text = String::new();
/// asset.read_to_string(&mut text);
/// // ...
/// }
/// ```
#[derive(Debug)]
pub struct AssetDir {
ptr: NonNull<ffi::AAssetDir>,
}
// It's unclear if AAssetDir is thread safe.
// However, AAsset is not, so there's a good chance that AAssetDir is not either.
impl Drop for AssetDir {
fn drop(&mut self) {
unsafe { ffi::AAssetDir_close(self.ptr.as_ptr()) }
}
}
impl AssetDir {
/// Construct an `AssetDir` from the native `AAssetDir *`. This gives ownership of the
/// `AAssetDir *` to the `AssetDir`, which will handle closing the asset. Avoid using
/// the pointer after calling this function.
///
/// # Safety
/// By calling this function, you assert that it points to a valid native `AAssetDir`.
pub unsafe fn from_ptr(ptr: NonNull<ffi::AAssetDir>) -> Self {
Self { ptr }
}
/// The corresponding native `AAssetDir *`
pub fn ptr(&self) -> NonNull<ffi::AAssetDir> {
self.ptr
}
/// Get the next filename, if any, and process it. Like `.next()`, but performs no additional
/// allocation.
///
/// The filenames are in the correct format to be passed to `AssetManager::open`
pub fn with_next<T>(&mut self, f: impl for<'a> FnOnce(&'a CStr) -> T) -> Option<T> {
unsafe {
let next_name = ffi::AAssetDir_getNextFileName(self.ptr.as_ptr());
if next_name.is_null() {
None
} else {
Some(f(CStr::from_ptr(next_name)))
}
}
}
/// Reset the iteration state
pub fn rewind(&mut self) {
unsafe {
ffi::AAssetDir_rewind(self.ptr.as_ptr());
}
}
}
impl Iterator for AssetDir {
type Item = CString;
fn next(&mut self) -> Option<CString> {
self.with_next(|cstr| cstr.to_owned())
}
}
/// A native `AAsset *`, open in the streaming mode
///
/// ```no_run
/// # use std::ffi::CString;
/// # use ndk::asset::AssetManager;
/// # let asset_manager: AssetManager = unimplemented!();
/// use std::io::Read;
///
/// let asset = asset_manager
/// .open(&CString::new("path/to/asset").unwrap())
/// .expect("Could not open asset");
///
/// let mut data = vec![];
/// asset.read_to_end(&mut data);
/// // ... use data ...
/// ```
#[derive(Debug)]
pub struct Asset {
ptr: NonNull<ffi::AAsset>,
}
// AAsset is *not* thread safe.
// See https://developer.android.com/ndk/reference/group/asset#aasset
impl Drop for Asset {
fn drop(&mut self) {
unsafe { ffi::AAsset_close(self.ptr.as_ptr()) }
}
}
impl Asset {
/// Construct an `Asset` from the native `AAsset *`. This gives ownership of the `AAsset *` to
/// the `Asset`, which will handle closing the asset. Avoid using the pointer after calling
/// this function.
///
/// # Safety
/// By calling this function, you assert that it points to a valid native `AAsset`, open
/// in the streaming mode.
pub unsafe fn from_ptr(ptr: NonNull<ffi::AAsset>) -> Self {
Self { ptr }
}
/// The corresponding native `AAsset *`
pub fn ptr(&self) -> NonNull<ffi::AAsset> {
self.ptr
}
/// Returns the total length of the asset, in bytes
pub fn get_length(&self) -> usize {
unsafe { ffi::AAsset_getLength64(self.ptr.as_ptr()) as usize }
}
/// Returns the remaining length of the asset, in bytes
pub fn get_remaining_length(&self) -> usize {
unsafe { ffi::AAsset_getRemainingLength64(self.ptr.as_ptr()) as usize }
}
/// Reads all data into a buffer and returns it
pub fn get_buffer(&mut self) -> io::Result<&[u8]> {
unsafe {
let buf_ptr = ffi::AAsset_getBuffer(self.ptr.as_ptr());
if buf_ptr.is_null() {
Err(io::Error::new(
io::ErrorKind::Other,
"Android Asset error creating buffer",
))
} else {
Ok(std::slice::from_raw_parts(
buf_ptr as *const u8,
self.get_remaining_length(),
))
}
}
}
//pub fn open_file_descriptor(&self) -> TODO
}
impl io::Read for Asset {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
unsafe {
let res = ffi::AAsset_read(
self.ptr.as_ptr(),
buf.as_mut_ptr() as *mut _,
buf.len() as ffi::size_t,
);
if res >= 0 {
Ok(res as usize)
} else {
Err(io::Error::new(
io::ErrorKind::Other,
"Android Asset read error",
))
}
}
}
}
impl io::Seek for Asset {
fn seek(&mut self, seek: io::SeekFrom) -> io::Result<u64> {
unsafe {
let res = match seek {
io::SeekFrom::Start(x) => {
ffi::AAsset_seek64(self.ptr.as_ptr(), x as i64, ffi::SEEK_SET as i32)
}
io::SeekFrom::Current(x) => {
ffi::AAsset_seek64(self.ptr.as_ptr(), x, ffi::SEEK_CUR as i32)
}
io::SeekFrom::End(x) => {
ffi::AAsset_seek64(self.ptr.as_ptr(), x, ffi::SEEK_END as i32)
}
};
if res < 0 {
Err(io::Error::new(
io::ErrorKind::Other,
"Android Asset seek error",
))
} else {
Ok(res as u64)
}
}
}
}