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Improve language around ownership of OsString (#602)

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Based on discussion in #598.
This commit is contained in:
Martin Geisler
2023-04-28 01:00:07 -07:00
committed by GitHub
parent 251782aac3
commit fc68829e14
1 changed files with 4 additions and 4 deletions
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8
src/exercises/day-3/safe-ffi-wrapper.md
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@ -24,11 +24,11 @@ You will convert between all these types:
- `&str` to `CString`: you need to allocate space for a trailing `\0` character, - `&str` to `CString`: you need to allocate space for a trailing `\0` character,
- `CString` to `*const i8`: you need a pointer to call C functions, - `CString` to `*const i8`: you need a pointer to call C functions,
- `*const i8` to `&CStr`: you need something which can find the trailing `\0` character, - `*const i8` to `&CStr`: you need something which can find the trailing `\0` character,
- `&CStr` to `&[u8]`: you will ultimately return a slice of bytes, - `&CStr` to `&[u8]`: a slice of bytes is the universal interface for "some unknow data",
- `&[u8]` to `&OsStr`: you can create an `OsString` from `&[u8]`. Use - `&[u8]` to `&OsStr`: `&OsStr` is a step towards `OsString`, use
[`OsStrExt`](https://doc.rust-lang.org/std/os/unix/ffi/trait.OsStrExt.html) [`OsStrExt`](https://doc.rust-lang.org/std/os/unix/ffi/trait.OsStrExt.html)
for this. to create it,
- `&OsStr` to `OsString`: you need to take ownership of the data before you call - `&OsStr` to `OsString`: you need to clone the data in `&OsStr` to be able to return it and call
`readdir` again. `readdir` again.
The [Nomicon] also has a very useful chapter about FFI. The [Nomicon] also has a very useful chapter about FFI.