mkext4 0.0.3

Deterministic, streaming, pure-Rust ext4 image builder with a verification-grade reader
Documentation 
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//! Little-endian field access over byte slices.
//!
//! All on-disk structures are decoded/encoded through these helpers so
//! that field offsets stay explicit and greppable.
//! Callers validate slice length once per structure; these panic on
//! out-of-bounds, which indicates a bug, not bad input.

pub(crate) fn u16(b: &[u8], off: usize) -> u16 {
    u16::from_le_bytes(b[off..off + 2].try_into().unwrap())
}

pub(crate) fn u32(b: &[u8], off: usize) -> u32 {
    u32::from_le_bytes(b[off..off + 4].try_into().unwrap())
}

pub(crate) fn u64(b: &[u8], off: usize) -> u64 {
    u64::from_le_bytes(b[off..off + 8].try_into().unwrap())
}

pub(crate) fn put_u16(b: &mut [u8], off: usize, v: u16) {
    b[off..off + 2].copy_from_slice(&v.to_le_bytes());
}

pub(crate) fn put_u32(b: &mut [u8], off: usize, v: u32) {
    b[off..off + 4].copy_from_slice(&v.to_le_bytes());
}

pub(crate) fn put_u64(b: &mut [u8], off: usize, v: u64) {
    b[off..off + 8].copy_from_slice(&v.to_le_bytes());
}

/// Big-endian accessors (jbd2 journal structures only).
pub(crate) mod be {
    pub(crate) fn u32(b: &[u8], off: usize) -> u32 {
        u32::from_be_bytes(b[off..off + 4].try_into().unwrap())
    }

    pub(crate) fn put_u32(b: &mut [u8], off: usize, v: u32) {
        b[off..off + 4].copy_from_slice(&v.to_be_bytes());
    }
}