From 346dc37aee60f995e6c1548ce7f406d5500f8570 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Tue, 5 Feb 2019 20:07:45 +0100 Subject: [PATCH] fix str mutating through a ptr derived from &self --- src/libcore/str/mod.rs | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs index 3cb3936038093..b01cb688ee5c6 100644 --- a/src/libcore/str/mod.rs +++ b/src/libcore/str/mod.rs @@ -1757,7 +1757,7 @@ mod traits { } #[inline] unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { - let ptr = slice.as_ptr().add(self.start); + let ptr = slice.as_mut_ptr().add(self.start); let len = self.end - self.start; super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr as *mut u8, len)) } @@ -1821,7 +1821,7 @@ mod traits { } #[inline] unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { - let ptr = slice.as_ptr(); + let ptr = slice.as_mut_ptr(); super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr as *mut u8, self.end)) } #[inline] @@ -1883,7 +1883,7 @@ mod traits { } #[inline] unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { - let ptr = slice.as_ptr().add(self.start); + let ptr = slice.as_mut_ptr().add(self.start); let len = slice.len() - self.start; super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr as *mut u8, len)) } @@ -2213,6 +2213,22 @@ impl str { self as *const str as *const u8 } + /// Converts a mutable string slice to a raw pointer. + /// + /// As string slices are a slice of bytes, the raw pointer points to a + /// [`u8`]. This pointer will be pointing to the first byte of the string + /// slice. + /// + /// It is your responsibility to make sure that the string slice only gets + /// modified in a way that it remains valid UTF-8. + /// + /// [`u8`]: primitive.u8.html + #[unstable(feature = "str_as_mut_ptr", issue = "0")] + #[inline] + pub fn as_mut_ptr(&mut self) -> *mut u8 { + self as *mut str as *mut u8 + } + /// Returns a subslice of `str`. /// /// This is the non-panicking alternative to indexing the `str`. Returns