lerc-reader 0.5.0

Pure-Rust decoder for the LERC raster compression format
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

use std::mem;

use lerc_core::{Error, Result};

const MAX_DECODED_ALLOCATION_BYTES: usize = 512 * 1024 * 1024;

pub(crate) fn checked_mul(a: usize, b: usize, label: &'static str) -> Result<usize> {
    a.checked_mul(b).ok_or(Error::SizeOverflow(label))
}

pub(crate) fn check_allocation<T>(len: usize, label: &'static str) -> Result<()> {
    let bytes = checked_mul(len, mem::size_of::<T>(), label)?;
    if bytes > MAX_DECODED_ALLOCATION_BYTES {
        return Err(Error::invalid_blob(format!(
            "{label} allocation request of {bytes} bytes exceeds decoder limit of {MAX_DECODED_ALLOCATION_BYTES} bytes"
        )));
    }
    Ok(())
}

pub(crate) fn default_vec<T: Default + Clone>(len: usize, label: &'static str) -> Result<Vec<T>> {
    check_allocation::<T>(len, label)?;
    let mut values = Vec::new();
    values
        .try_reserve_exact(len)
        .map_err(|_| Error::AllocationFailed(label))?;
    values.resize(len, T::default());
    Ok(values)
}

pub(crate) fn vec_with_capacity<T>(len: usize, label: &'static str) -> Result<Vec<T>> {
    check_allocation::<T>(len, label)?;
    let mut values = Vec::new();
    values
        .try_reserve_exact(len)
        .map_err(|_| Error::AllocationFailed(label))?;
    Ok(values)
}