Re: [pbs-devel] [PATCH v2 proxmox-backup 1/2] datastore: check for null pointer when allocating DynamicIndexHeader

[Christian Ebner <c.ebner@proxmox.com>]

Please provide a short commit message on why this is done.

As far as I see this now panics in handle_alloc_error() if either memory 
is exhausted or the layout does not fit the allocator constraints, while 
previously this failed on Box::from_raw() for the null pointer?

So maybe better to propagate the allocation error to the call site of 
zeroed() in DynamicIndexWriter::create() and return it there as well?

On 12/30/25 1:42 PM, Robert Obkircher wrote:
> Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
> ---
>   pbs-datastore/src/dynamic_index.rs | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/pbs-datastore/src/dynamic_index.rs b/pbs-datastore/src/dynamic_index.rs
> index ad49cdf3..12df78b1 100644
> --- a/pbs-datastore/src/dynamic_index.rs
> +++ b/pbs-datastore/src/dynamic_index.rs
> @@ -41,13 +41,20 @@ proxmox_lang::static_assert_size!(DynamicIndexHeader, 4096);
>   impl DynamicIndexHeader {
>       /// Convenience method to allocate a zero-initialized header struct.
>       pub fn zeroed() -> Box<Self> {
> +        let layout = std::alloc::Layout::new::<Self>();
>           unsafe {
> -            Box::from_raw(std::alloc::alloc_zeroed(std::alloc::Layout::new::<Self>()) as *mut Self)
> +            let ptr = std::alloc::alloc_zeroed(layout) as *mut Self;
> +            if ptr.is_null() {
> +                std::alloc::handle_alloc_error(layout);
> +            }
> +            Box::from_raw(ptr)
>           }
>       }
>   
>       pub fn as_bytes(&self) -> &[u8] {
>           unsafe {
> +            // There can't be any uninitialized padding, because the fields
> +            // take up all of the statically asserted total size.
>               std::slice::from_raw_parts(
>                   self as *const Self as *const u8,
>                   std::mem::size_of::<Self>(),



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