able/ext2-rs
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use &Buffer<u8> instead of &[u8] on Superblock::find

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This commit is contained in:
Szymon Walter 2018-03-19 08:39:23 +01:00
parent 6b34d3325a
commit bae7f23b3e
1 changed files with 13 additions and 14 deletions
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27
src/sys/superblock.rs
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@ -1,6 +1,7 @@
use core::mem; use core::mem;
use error::Error; use error::Error;
use buffer::Buffer;
/// Ext2 signature (0xef53), used to help confirm the presence of Ext2 on a /// Ext2 signature (0xef53), used to help confirm the presence of Ext2 on a
/// volume /// volume
@ -38,6 +39,7 @@ pub const OS_LITE: u32 = 4;
/// 512 byte sectors, the Superblock will begin at LBA 2 and will occupy all of /// 512 byte sectors, the Superblock will begin at LBA 2 and will occupy all of
/// sector 2 and 3. /// sector 2 and 3.
#[repr(C, packed)] #[repr(C, packed)]
#[derive(Clone, Copy)]
pub struct Superblock { pub struct Superblock {
// taken from https://wiki.osdev.org/Ext2 // taken from https://wiki.osdev.org/Ext2
/// Total number of inodes in file system /// Total number of inodes in file system
@ -143,24 +145,23 @@ pub struct Superblock {
} }
impl Superblock { impl Superblock {
pub unsafe fn find<'a>( pub fn find<'a>(
haystack: &'a mut [u8], haystack: &'a Buffer<u8>,
offset: isize, ) -> Result<(Superblock, usize), Error> {
) -> Result<&'a mut Superblock, Error> { let offset = 1024;
let offset = (1024 + offset) as usize;
let end = offset + mem::size_of::<Superblock>(); let end = offset + mem::size_of::<Superblock>();
if haystack.len() < end { if haystack.len() < end {
return Err(Error::OutOfBounds(end)); return Err(Error::OutOfBounds(end));
} }
let superblock: &mut Superblock = { let superblock = unsafe {
let ptr = haystack.as_mut_ptr().offset(offset as isize) haystack
as *mut Superblock; .slice_unchecked(offset..end)
ptr.as_mut().unwrap() .dynamic_cast::<Superblock>()
}; };
if superblock.magic != EXT2_MAGIC { if superblock.0.magic != EXT2_MAGIC {
Err(Error::BadMagic(superblock.magic)) Err(Error::BadMagic(superblock.0.magic))
} else { } else {
Ok(superblock) Ok(superblock)
} }
@ -243,16 +244,14 @@ mod tests {
#[test] #[test]
fn find() { fn find() {
let mut buffer = vec![0_u8; 4096]; let mut buffer = vec![0_u8; 4096];
let addr = &buffer[1024] as *const _ as usize;
// magic // magic
buffer[1024 + 56] = EXT2_MAGIC as u8; buffer[1024 + 56] = EXT2_MAGIC as u8;
buffer[1024 + 57] = (EXT2_MAGIC >> 8) as u8; buffer[1024 + 57] = (EXT2_MAGIC >> 8) as u8;
let superblock = unsafe { Superblock::find(&mut buffer, 0) }; let superblock = Superblock::find(&buffer);
assert!( assert!(
superblock.is_ok(), superblock.is_ok(),
"Err({:?})", "Err({:?})",
superblock.err().unwrap_or_else(|| unreachable!()), superblock.err().unwrap_or_else(|| unreachable!()),
); );
assert_eq!(superblock.unwrap() as *const _ as usize, addr);
} }
} }