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Cstring from_raw and into_raw safety precisions #72963

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Merged
merged 2 commits into from
Jun 8, 2020
Merged

Cstring from_raw and into_raw safety precisions #72963

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00a7b56
Added the documentation about length to CString::from_raw
poliorcetics Jun 3, 2020
87abe17
Added a warning to CString::into_raw too
poliorcetics Jun 3, 2020
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11 changes: 11 additions & 0 deletions src/libstd/ffi/c_str.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -395,6 +395,12 @@ impl CString {
/// ownership of a string that was allocated by foreign code) is likely to lead
/// to undefined behavior or allocator corruption.
///
/// It should be noted that the length isn't just "recomputed," but that
/// the recomputed length must match the original length from the
/// [`into_raw`] call. This means the [`into_raw`]/`from_raw` methods
/// should not be used when passing the string to C functions that can
/// modify the string's length.
///
/// > **Note:** If you need to borrow a string that was allocated by
/// > foreign code, use [`CStr`]. If you need to take ownership of
/// > a string that was allocated by foreign code, you will need to
Expand Down Expand Up @@ -440,6 +446,11 @@ impl CString {
///
/// Failure to call [`from_raw`] will lead to a memory leak.
///
/// The C side must **not** modify the length of the string (by writing a
/// `NULL` somewhere inside the string or removing the final one) before
/// it makes it back into Rust using [`from_raw`]. See the safety section
/// in [`from_raw`].
///
/// [`from_raw`]: #method.from_raw
///
/// # Examples
Expand Down