diff --git a/library/std/src/sys/personality/dwarf/mod.rs b/library/std/src/sys/personality/dwarf/mod.rs index 652fbe95a14..281587a9732 100644 --- a/library/std/src/sys/personality/dwarf/mod.rs +++ b/library/std/src/sys/personality/dwarf/mod.rs @@ -17,32 +17,30 @@ pub struct DwarfReader { pub ptr: *const u8, } -#[repr(C, packed)] -struct Unaligned(T); - +#[deny(unsafe_op_in_unsafe_fn)] impl DwarfReader { pub fn new(ptr: *const u8) -> DwarfReader { DwarfReader { ptr } } - // DWARF streams are packed, so e.g., a u32 would not necessarily be aligned - // on a 4-byte boundary. This may cause problems on platforms with strict - // alignment requirements. By wrapping data in a "packed" struct, we are - // telling the backend to generate "misalignment-safe" code. + /// Read a type T and then bump the pointer by that amount. + /// + /// DWARF streams are "packed", so all types must be read at align 1. pub unsafe fn read(&mut self) -> T { - let Unaligned(result) = *(self.ptr as *const Unaligned); - self.ptr = self.ptr.add(mem::size_of::()); - result + unsafe { + let result = self.ptr.cast::().read_unaligned(); + self.ptr = self.ptr.byte_add(mem::size_of::()); + result + } } - // ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable - // Length Data". + /// ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable Length Data". pub unsafe fn read_uleb128(&mut self) -> u64 { let mut shift: usize = 0; let mut result: u64 = 0; let mut byte: u8; loop { - byte = self.read::(); + byte = unsafe { self.read::() }; result |= ((byte & 0x7F) as u64) << shift; shift += 7; if byte & 0x80 == 0 { @@ -57,7 +55,7 @@ pub unsafe fn read_sleb128(&mut self) -> i64 { let mut result: u64 = 0; let mut byte: u8; loop { - byte = self.read::(); + byte = unsafe { self.read::() }; result |= ((byte & 0x7F) as u64) << shift; shift += 7; if byte & 0x80 == 0 {