Split large unsafe function slide #2406
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The old slice was doing several things at the same time: demonstrating both external functions as well as unsafe Rust functions. We now treat those two topics separately. In addition, the “Calling Unsafe Functions” heading has become its own slide with a non-crashing example that shows what can go wrong if an argument is misunderstood in a call to an unsafe function. The old example didn’t actually illustrate the danger clearly: it would produce mangled UTF-8 output, which the Playground server refuses to print.
djmitche
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Oct 28, 2024
| /// | ||
| /// # Safety | ||
| /// | ||
| /// The pointers must be valid and properly aligned. |
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oh, because these are u8 it's actually ok to overlap
| `abs` is unsafe because it is an external function (FFI). Calling external | ||
| functions is usually only a problem when those functions do things with pointers | ||
| which might violate Rust's memory model, but in general any C function might | ||
| have undefined behaviour under any arbitrary circumstances. |
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Is it worth mentioning here that there is no automatic checking of the Rust function signature against that of the target function? For example, in this case the C function might take uint64_t and this would cause UB.
Co-authored-by: Dustin J. Mitchell <[email protected]>
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The old slice was doing several things at the same time: demonstrating
both external functions as well as unsafe Rust functions.
We now treat those two topics separately. In addition, the “Calling
Unsafe Functions” heading has become its own slide with a non-crashing
example that shows what can go wrong if an argument is misunderstood
in a call to an unsafe function. The old example didn’t actually
illustrate the danger clearly: it would produce mangled UTF-8 output,
which the Playground server refuses to print.
Part of #2445.