Replace impl Read with Cursor<&[u8]> (#26)

* Start getting rid of Cursor

* try to make the tests pass and fail

* make the tests pass

* remove unused uses

* fix clippy warnings

* fix potential OOM exploits

* fix OOM in az-nbt

* fix nbt benchmark

* fix a test

* start replacing it with Cursor<Vec<u8>>

* wip

* fix all the issues

* fix all tests

* fix nbt benchmark

* fix warnings

6 files changed, 20 insertions, 24 deletions

diff --git a/azalea-core/src/difficulty.rs b/azalea-core/src/difficulty.rs
index 65950e8d..5cc2f9fa 100755
--- a/azalea-core/src/difficulty.rs
+++ b/azalea-core/src/difficulty.rs
@@ -1,6 +1,6 @@
 use std::{
     fmt::{Debug, Error, Formatter},
-    io::{Read, Write},
+    io::{Cursor, Write},
 };
 
 use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
@@ -67,7 +67,7 @@ impl Difficulty {
 }
 
 impl McBufReadable for Difficulty {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         Ok(Difficulty::by_id(u8::read_from(buf)?))
     }
 }
diff --git a/azalea-core/src/game_type.rs b/azalea-core/src/game_type.rs
index f3f056a4..635ee6fe 100755
--- a/azalea-core/src/game_type.rs
+++ b/azalea-core/src/game_type.rs
@@ -1,5 +1,5 @@
 use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
-use std::io::{Read, Write};
+use std::io::{Cursor, Write};
 
 #[derive(Hash, Copy, Clone, Debug)]
 pub enum GameType {
@@ -79,7 +79,7 @@ impl GameType {
 }
 
 impl McBufReadable for GameType {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let id = u8::read_from(buf)?;
         GameType::from_id(id).ok_or(BufReadError::UnexpectedEnumVariant { id: id as i32 })
     }
@@ -108,7 +108,7 @@ impl From<OptionalGameType> for Option<GameType> {
 }
 
 impl McBufReadable for OptionalGameType {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let id = i8::read_from(buf)?;
         GameType::from_optional_id(id).ok_or(BufReadError::UnexpectedEnumVariant { id: id as i32 })
     }
diff --git a/azalea-core/src/particle/mod.rs b/azalea-core/src/particle/mod.rs
index c2fa3337..8087de51 100644
--- a/azalea-core/src/particle/mod.rs
+++ b/azalea-core/src/particle/mod.rs
@@ -1,6 +1,6 @@
 use crate::{BlockPos, Slot};
 use azalea_buf::{BufReadError, McBuf, McBufReadable, McBufVarReadable, McBufWritable};
-use std::io::{Read, Write};
+use std::io::{Cursor, Write};
 
 #[derive(Debug, Clone, McBuf)]
 pub struct Particle {
@@ -153,7 +153,7 @@ pub struct VibrationParticle {
 }
 
 impl ParticleData {
-    pub fn read_from_particle_id(buf: &mut impl Read, id: u32) -> Result<Self, BufReadError> {
+    pub fn read_from_particle_id(buf: &mut Cursor<&[u8]>, id: u32) -> Result<Self, BufReadError> {
         Ok(match id {
             0 => ParticleData::AmbientEntityEffect,
             1 => ParticleData::AngryVillager,
@@ -249,7 +249,7 @@ impl ParticleData {
 }
 
 impl McBufReadable for ParticleData {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let id = u32::var_read_from(buf)?;
         ParticleData::read_from_particle_id(buf, id)
     }
diff --git a/azalea-core/src/position.rs b/azalea-core/src/position.rs
index d47072d4..d408d817 100644
--- a/azalea-core/src/position.rs
+++ b/azalea-core/src/position.rs
@@ -1,7 +1,7 @@
 use crate::ResourceLocation;
 use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
 use std::{
-    io::{Read, Write},
+    io::{Cursor, Write},
     ops::{Add, Mul, Rem},
 };
 
@@ -301,7 +301,7 @@ const Z_OFFSET: u64 = PACKED_Y_LENGTH;
 const X_OFFSET: u64 = PACKED_Y_LENGTH + PACKED_Z_LENGTH;
 
 impl McBufReadable for BlockPos {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let val = i64::read_from(buf)?;
         let x = (val << (64 - X_OFFSET - PACKED_X_LENGTH) >> (64 - PACKED_X_LENGTH)) as i32;
         let y = (val << (64 - PACKED_Y_LENGTH) >> (64 - PACKED_Y_LENGTH)) as i32;
@@ -311,7 +311,7 @@ impl McBufReadable for BlockPos {
 }
 
 impl McBufReadable for GlobalPos {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         Ok(GlobalPos {
             dimension: ResourceLocation::read_from(buf)?,
             pos: BlockPos::read_from(buf)?,
@@ -320,7 +320,7 @@ impl McBufReadable for GlobalPos {
 }
 
 impl McBufReadable for ChunkSectionPos {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let long = i64::read_from(buf)?;
         Ok(ChunkSectionPos {
             x: (long >> 42) as i32,
@@ -361,8 +361,6 @@ impl McBufWritable for ChunkSectionPos {
 
 #[cfg(test)]
 mod tests {
-    use std::io::Cursor;
-
     use super::*;
 
     #[test]
@@ -403,10 +401,10 @@ mod tests {
 
     #[test]
     fn test_read_blockpos_from() {
-        let mut buf = Cursor::new(Vec::new());
+        let mut buf = Vec::new();
         13743895338965u64.write_into(&mut buf).unwrap();
-        buf.set_position(0);
-        let block_pos = BlockPos::read_from(&mut buf).unwrap();
+        let buf = &mut &buf[..];
+        let block_pos = BlockPos::read_from(buf).unwrap();
         assert_eq!(block_pos, BlockPos::new(49, -43, -3));
     }
 }
diff --git a/azalea-core/src/resource_location.rs b/azalea-core/src/resource_location.rs
index 4c0764e5..5f8dcea1 100755
--- a/azalea-core/src/resource_location.rs
+++ b/azalea-core/src/resource_location.rs
@@ -1,7 +1,7 @@
 //! A resource, like minecraft:stone
 
 use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
-use std::io::{Read, Write};
+use std::io::{Cursor, Write};
 
 #[derive(Hash, Clone, PartialEq, Eq)]
 pub struct ResourceLocation {
@@ -46,7 +46,7 @@ impl std::fmt::Debug for ResourceLocation {
 }
 
 impl McBufReadable for ResourceLocation {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let location_string = String::read_from(buf)?;
         ResourceLocation::new(&location_string)
     }
@@ -59,8 +59,6 @@ impl McBufWritable for ResourceLocation {
 
 #[cfg(test)]
 mod tests {
-    use std::io::Cursor;
-
     use super::*;
 
     #[test]
@@ -96,7 +94,7 @@ mod tests {
             .write_into(&mut buf)
             .unwrap();
 
-        let mut buf = Cursor::new(buf);
+        let mut buf = &mut &buf[..];
 
         assert_eq!(
             ResourceLocation::read_from(&mut buf).unwrap(),
diff --git a/azalea-core/src/slot.rs b/azalea-core/src/slot.rs
index 38abcf61..d60c7390 100644
--- a/azalea-core/src/slot.rs
+++ b/azalea-core/src/slot.rs
@@ -1,7 +1,7 @@
 // TODO: have an azalea-inventory or azalea-container crate and put this there
 
 use azalea_buf::{BufReadError, McBuf, McBufReadable, McBufWritable};
-use std::io::{Read, Write};
+use std::io::{Cursor, Write};
 
 #[derive(Debug, Clone)]
 pub enum Slot {
@@ -18,7 +18,7 @@ pub struct SlotData {
 }
 
 impl McBufReadable for Slot {
-    fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
         let present = bool::read_from(buf)?;
         if !present {
             return Ok(Slot::Empty);