rust: uaccess: add UserSliceReader::read_slice_partial()

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The existing read_slice() method is a wrapper around copy_from_user()
and expects the user buffer to be larger than the destination buffer.

However, userspace may split up writes in multiple partial operations
providing an offset into the destination buffer and a smaller user
buffer.

In order to support this common case, provide a helper for partial
reads.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Matthew Maurer <mmaurer@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
[ Replace map_or() with let-else; use saturating_add(). - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

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Danilo Krummrich 2025-10-22 16:30:36 +02:00

parent db7bd1affa

commit f2af7b01b0

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rust/kernel/uaccess.rs

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