Do not use &mut [u8] to point to uninitialized string_buffer

src/charutils.rs

@@ -1,3 +1,5 @@
+use std::mem::MaybeUninit;
+
 use crate::safer_unchecked::GetSaferUnchecked;
 
 const STRUCTURAL_OR_WHITESPACE_NEGATED: [u32; 256] = [
@@ -83,30 +85,33 @@ pub fn hex_to_u32_nocheck(src: &[u8]) -> u32 {
 //
 #[cfg_attr(not(feature = "no-inline"), inline)]
 #[allow(clippy::cast_possible_truncation)]
-pub fn codepoint_to_utf8(cp: u32, c: &mut [u8]) -> usize {
+pub fn codepoint_to_utf8(cp: u32, c: &mut [MaybeUninit<u8>]) -> usize {
     unsafe {
         if cp <= 0x7F {
-            *c.get_kinda_unchecked_mut(0) = cp as u8;
+            c.get_kinda_unchecked_mut(0).write(cp as u8);
             1 // ascii
         } else if cp <= 0x7FF {
-            *c.get_kinda_unchecked_mut(0) = ((cp >> 6) + 192) as u8;
-            *c.get_kinda_unchecked_mut(1) = ((cp & 63) + 128) as u8;
+            c.get_kinda_unchecked_mut(0).write(((cp >> 6) + 192) as u8);
+            c.get_kinda_unchecked_mut(1).write(((cp & 63) + 128) as u8);
             2
             // universal plane
             //  Surrogates are treated elsewhere...
             //} //else if (0xd800 <= cp && cp <= 0xdfff) {
             //  return 0; // surrogates // could put assert here
         } else if cp <= 0xFFFF {
-            *c.get_kinda_unchecked_mut(0) = ((cp >> 12) + 224) as u8;
-            *c.get_kinda_unchecked_mut(1) = (((cp >> 6) & 63) + 128) as u8;
-            *c.get_kinda_unchecked_mut(2) = ((cp & 63) + 128) as u8;
+            c.get_kinda_unchecked_mut(0).write(((cp >> 12) + 224) as u8);
+            c.get_kinda_unchecked_mut(1)
+                .write((((cp >> 6) & 63) + 128) as u8);
+            c.get_kinda_unchecked_mut(2).write(((cp & 63) + 128) as u8);
             3
         } else if cp <= 0x0010_FFFF {
             // if you know you have a valid code point, this is not needed
-            *c.get_kinda_unchecked_mut(0) = ((cp >> 18) + 240) as u8;
-            *c.get_kinda_unchecked_mut(1) = (((cp >> 12) & 63) + 128) as u8;
-            *c.get_kinda_unchecked_mut(2) = (((cp >> 6) & 63) + 128) as u8;
-            *c.get_kinda_unchecked_mut(3) = ((cp & 63) + 128) as u8;
+            c.get_kinda_unchecked_mut(0).write(((cp >> 18) + 240) as u8);
+            c.get_kinda_unchecked_mut(1)
+                .write((((cp >> 12) & 63) + 128) as u8);
+            c.get_kinda_unchecked_mut(2)
+                .write((((cp >> 6) & 63) + 128) as u8);
+            c.get_kinda_unchecked_mut(3).write(((cp & 63) + 128) as u8);
             4
         } else {
             // will return 0 when the code point was too large.

src/impls/avx2/deser.rs

@@ -4,6 +4,8 @@ use std::arch::x86 as arch;
 #[cfg(target_arch = "x86_64")]
 use std::arch::x86_64 as arch;
 
+use std::mem::MaybeUninit;
+
 use arch::{
     __m256i, _mm256_cmpeq_epi8, _mm256_loadu_si256, _mm256_movemask_epi8, _mm256_set1_epi8,
     _mm256_storeu_si256,
@@ -27,7 +29,7 @@ use crate::{
 pub(crate) unsafe fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    buffer: &'invoke mut [u8],
+    buffer: &'invoke mut [MaybeUninit<u8>],
     mut idx: usize,
 ) -> Result<&'de str> {
     unsafe {
@@ -129,7 +131,7 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
                 dst_i += quote_dist as usize;
                 input
                     .add(idx + len)
-                    .copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
+                    .copy_from_nonoverlapping(buffer.as_ptr().cast::<u8>(), dst_i);
                 let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
                     input.add(idx),
                     len + dst_i,
@@ -174,7 +176,9 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
                             InvalidEscape,
                         ));
                     }
-                    *buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
+                    buffer
+                        .get_kinda_unchecked_mut(dst_i + bs_dist as usize)
+                        .write(escape_result);
                     src_i += bs_dist as usize + 2;
                     dst_i += bs_dist as usize + 1;
                 }

src/impls/native/deser.rs

@@ -1,3 +1,5 @@
+use std::mem::MaybeUninit;
+
 use crate::{
     Deserializer, ErrorType, Result, SillyWrapper,
     safer_unchecked::GetSaferUnchecked,
@@ -8,7 +10,7 @@ use crate::{
 pub(crate) unsafe fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    _buffer: &'invoke mut [u8],
+    _buffer: &'invoke mut [MaybeUninit<u8>],
     idx: usize,
 ) -> Result<&'de str> {
     use ErrorType::{InvalidEscape, InvalidUnicodeCodepoint};
@@ -118,10 +120,15 @@ mod test {
         let mut input = input.to_vec();
         let mut input2 = input.clone();
         input2.append(vec![0; SIMDJSON_PADDING * 2].as_mut());
-        let mut buffer = vec![0; 1024];
+        let mut buffer = Vec::with_capacity(1024);
 
         let r = unsafe {
-            super::parse_str(input.as_mut_ptr().into(), &input2, buffer.as_mut_slice(), 0)?
+            super::parse_str(
+                input.as_mut_ptr().into(),
+                &input2,
+                buffer.spare_capacity_mut(),
+                0,
+            )?
         };
         Ok(String::from(r))
     }

src/impls/neon/deser.rs

@@ -10,6 +10,7 @@ use std::arch::aarch64::{
     uint8x16_t, vandq_u8, vceqq_u8, vgetq_lane_u32, vld1q_u8, vmovq_n_u8, vpaddq_u8,
     vreinterpretq_u32_u8,
 };
+use std::mem::MaybeUninit;
 
 #[cfg_attr(not(feature = "no-inline"), inline)]
 fn find_bs_bits_and_quote_bits(v0: uint8x16_t, v1: uint8x16_t) -> (u32, u32) {
@@ -45,7 +46,7 @@ fn find_bs_bits_and_quote_bits(v0: uint8x16_t, v1: uint8x16_t) -> (u32, u32) {
 pub(crate) fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    buffer: &'invoke mut [u8],
+    buffer: &'invoke mut [MaybeUninit<u8>],
     mut idx: usize,
 ) -> Result<&'de str> {
     use ErrorType::{InvalidEscape, InvalidUnicodeCodepoint};
@@ -121,9 +122,12 @@ pub(crate) fn parse_str<'invoke, 'de>(
         };
 
         unsafe {
+            // TODO: this should use `write_copy_of_slice` on Rust 1.93+
             buffer
                 .get_kinda_unchecked_mut(dst_i..dst_i + 32)
-                .copy_from_slice(src.get_kinda_unchecked(src_i..src_i + 32));
+                .as_mut_ptr()
+                .cast::<u8>()
+                .copy_from_nonoverlapping(src.get_kinda_unchecked(src_i..src_i + 32).as_ptr(), 32);
         }
 
         // store to dest unconditionally - we can overwrite the bits we don't like
@@ -147,7 +151,7 @@ pub(crate) fn parse_str<'invoke, 'de>(
             unsafe {
                 input
                     .add(idx + len)
-                    .copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
+                    .copy_from_nonoverlapping(buffer.as_ptr().cast::<u8>(), dst_i);
                 let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
                     input.add(idx),
                     len + dst_i,
@@ -196,7 +200,9 @@ pub(crate) fn parse_str<'invoke, 'de>(
                     ));
                 }
                 unsafe {
-                    *buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
+                    buffer
+                        .get_kinda_unchecked_mut(dst_i + bs_dist as usize)
+                        .write(escape_result);
                 }
                 src_i += bs_dist as usize + 2;
                 dst_i += bs_dist as usize + 1;

src/impls/portable/deser.rs

@@ -1,3 +1,4 @@
+use std::mem::MaybeUninit;
 use std::simd::{SimdPartialEq, ToBitMask, u8x32};
 
 use crate::{
@@ -10,7 +11,7 @@ use crate::{
 pub(crate) unsafe fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    buffer: &'invoke mut [u8],
+    buffer: &'invoke mut [MaybeUninit<u8>],
     mut idx: usize,
 ) -> Result<&'de str> {
     let input = input.input;
@@ -102,7 +103,7 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
             dst_i += quote_dist as usize;
             input
                 .add(idx + len)
-                .copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
+                .copy_from_nonoverlapping(buffer.as_ptr().cast::<u8>(), dst_i);
             let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
                 input.add(idx),
                 len + dst_i,
@@ -152,7 +153,9 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
                         InvalidEscape,
                     ));
                 }
-                *buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
+                buffer
+                    .get_kinda_unchecked_mut(dst_i + bs_dist as usize)
+                    .write(escape_result);
                 src_i += bs_dist as usize + 2;
                 dst_i += bs_dist as usize + 1;
             }

src/impls/simd128/deser.rs

@@ -1,4 +1,5 @@
 use std::arch::wasm32::{u8x16_bitmask, u8x16_eq, u8x16_splat, v128, v128_load, v128_store};
+use std::mem::MaybeUninit;
 
 use crate::{
     Deserializer, Result, SillyWrapper,
@@ -17,7 +18,7 @@ use crate::{
 pub(crate) fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    buffer: &'invoke mut [u8],
+    buffer: &'invoke mut [MaybeUninit<u8>],
     mut idx: usize,
 ) -> Result<&'de str> {
     use ErrorType::{InvalidEscape, InvalidUnicodeCodepoint};
@@ -115,7 +116,7 @@ pub(crate) fn parse_str<'invoke, 'de>(
             unsafe {
                 input
                     .add(idx + len)
-                    .copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
+                    .copy_from_nonoverlapping(buffer.as_ptr().cast::<u8>(), dst_i);
                 let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
                     input.add(idx),
                     len + dst_i,
@@ -164,7 +165,9 @@ pub(crate) fn parse_str<'invoke, 'de>(
                     ));
                 }
                 unsafe {
-                    *buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
+                    buffer
+                        .get_kinda_unchecked_mut(dst_i + bs_dist as usize)
+                        .write(escape_result);
                 }
                 src_i += bs_dist as usize + 2;
                 dst_i += bs_dist as usize + 1;

src/impls/sse42/deser.rs

@@ -4,6 +4,8 @@ use std::arch::x86 as arch;
 #[cfg(target_arch = "x86_64")]
 use std::arch::x86_64 as arch;
 
+use std::mem::MaybeUninit;
+
 use crate::{
     Deserializer, Result, SillyWrapper,
     error::ErrorType,
@@ -20,7 +22,7 @@ use arch::{
 pub(crate) unsafe fn parse_str<'invoke, 'de>(
     input: SillyWrapper<'de>,
     data: &'invoke [u8],
-    buffer: &'invoke mut [u8],
+    buffer: &'invoke mut [MaybeUninit<u8>],
     mut idx: usize,
 ) -> Result<&'de str> {
     unsafe {
@@ -120,7 +122,7 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
                 dst_i += quote_dist as usize;
                 input
                     .add(idx + len)
-                    .copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
+                    .copy_from_nonoverlapping(buffer.as_ptr().cast::<u8>(), dst_i);
                 let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
                     input.add(idx),
                     len + dst_i,
@@ -165,7 +167,9 @@ pub(crate) unsafe fn parse_str<'invoke, 'de>(
                             InvalidEscape,
                         ));
                     }
-                    *buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
+                    buffer
+                        .get_kinda_unchecked_mut(dst_i + bs_dist as usize)
+                        .write(escape_result);
                     src_i += bs_dist as usize + 2;
                     dst_i += bs_dist as usize + 1;
                 }

src/lib.rs

@@ -68,6 +68,7 @@ mod stage2;
 /// simd-json JSON-DOM value
 pub mod value;
 
+use std::mem::MaybeUninit;
 use std::{alloc::dealloc, mem};
 pub use value_trait::StaticNode;
 
@@ -357,7 +358,7 @@ type FnRaw = *mut ();
 type ParseStrFn = for<'invoke, 'de> unsafe fn(
     SillyWrapper<'de>,
     &'invoke [u8],
-    &'invoke mut [u8],
+    &'invoke mut [MaybeUninit<u8>],
     usize,
 ) -> std::result::Result<&'de str, error::Error>;
 #[cfg(all(
@@ -514,7 +515,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str>
     where
@@ -538,7 +539,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str>
     where
@@ -552,7 +553,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str>
     where
@@ -571,7 +572,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str> {
         let input: SillyWrapper<'de> = SillyWrapper::from(input);
@@ -588,7 +589,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str> {
         let input: SillyWrapper<'de> = SillyWrapper::from(input);
@@ -600,7 +601,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str> {
         let input: SillyWrapper = SillyWrapper::from(input);
@@ -611,7 +612,7 @@ impl<'de> Deserializer<'de> {
     pub(crate) unsafe fn parse_str_<'invoke>(
         input: *mut u8,
         data: &'invoke [u8],
-        buffer: &'invoke mut [u8],
+        buffer: &'invoke mut [MaybeUninit<u8>],
         idx: usize,
     ) -> Result<&'de str> {
         let input: SillyWrapper<'de> = SillyWrapper::from(input);
@@ -876,10 +877,6 @@ impl<'de> Deserializer<'de> {
         buffer.string_buffer.clear();
         buffer.string_buffer.reserve(len + SIMDJSON_PADDING);
 
-        unsafe {
-            buffer.string_buffer.set_len(len + SIMDJSON_PADDING);
-        };
-
         let input_buffer = &mut buffer.input_buffer;
         if input_buffer.capacity() < simd_safe_len {
             *input_buffer = AlignedBuf::with_capacity(simd_safe_len);
@@ -907,7 +904,7 @@ impl<'de> Deserializer<'de> {
         Self::build_tape(
             input,
             input_buffer,
-            &mut buffer.string_buffer,
+            buffer.string_buffer.spare_capacity_mut(),
             &buffer.structural_indexes,
             &mut buffer.stage2_stack,
             buffer.max_depth,