> Le 4 sept. 2025 à 10:27, Patrick Steinhardt <ps@xxxxxx> a écrit :
>
> Implement a trivial test balloon for our Rust build infrastructure by
> reimplementing the "varint.c" subsystem in Rust. This subsystem is
> chosen because it is trivial to convert and because it doesn't have any
> dependencies to other components of Git.
>
> If support for Rust is enabled, we stop compiling "varint.c" and instead
> compile and use "src/varint.rs".
>
> Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
> ---
> meson.build | 5 +++-
> src/lib.rs | 1 +
> src/meson.build | 1 +
> src/varint.rs | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 98 insertions(+), 1 deletion(-)
>
> diff --git a/src/varint.rs b/src/varint.rs
> new file mode 100644
> index 00000000000..3d41760a555
> --- /dev/null
> +++ b/src/varint.rs
> @@ -0,0 +1,92 @@
> +use std::os::raw::c_int;
> +use std::os::raw::c_uchar;
> +
> +#[no_mangle]
> +pub unsafe extern "C" fn decode_varint(bufp: *mut *const c_uchar) -> usize {
> + let mut buf = *bufp;
> + let mut c = *buf;
> + let mut val = usize::from(c & 127);
> +
> + buf = buf.add(1);
> +
> + while (c & 128) != 0 {
> + val += 1;
> + if val == 0 || val.leading_zeros() < 7 {
> + return 0; // overflow
Hm. I thought overflows panic in debug builds, in which case checking afterwards is too late? Does unsafe change that?
