resolve half of the integer_arithmetic lints, couple misc changes

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/database/key_value/rooms/pdu_metadata.rs

@@ -23,10 +23,10 @@ impl service::rooms::pdu_metadata::Data for KeyValueDatabase {
 		let mut current = prefix.clone();
 
 		let count_raw = match until {
-			PduCount::Normal(x) => x - 1,
+			PduCount::Normal(x) => x.saturating_sub(1),
 			PduCount::Backfilled(x) => {
 				current.extend_from_slice(&0_u64.to_be_bytes());
-				u64::MAX - x - 1
+				u64::MAX.saturating_sub(x).saturating_sub(1)
 			},
 		};
 		current.extend_from_slice(&count_raw.to_be_bytes());

src/database/key_value/rooms/read_receipt.rs

@@ -48,7 +48,7 @@ impl service::rooms::read_receipt::Data for KeyValueDatabase {
 		let prefix2 = prefix.clone();
 
 		let mut first_possible_edu = prefix.clone();
-		first_possible_edu.extend_from_slice(&(since + 1).to_be_bytes()); // +1 so we don't send the event at since
+		first_possible_edu.extend_from_slice(&(since.saturating_add(1)).to_be_bytes()); // +1 so we don't send the event at since
 
 		Box::new(
 			self.readreceiptid_readreceipt

src/database/key_value/rooms/state_accessor.rs

@@ -17,7 +17,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
 			.expect("there is always one layer")
 			.1;
 		let mut result = HashMap::new();
-		let mut i = 0;
+		let mut i: u8 = 0;
 		for compressed in full_state.iter() {
 			let parsed = services()
 				.rooms
@@ -25,7 +25,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
 				.parse_compressed_state_event(compressed)?;
 			result.insert(parsed.0, parsed.1);
 
-			i += 1;
+			i = i.saturating_add(1);
 			if i % 100 == 0 {
 				tokio::task::yield_now().await;
 			}
@@ -44,7 +44,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
 			.1;
 
 		let mut result = HashMap::new();
-		let mut i = 0;
+		let mut i: u8 = 0;
 		for compressed in full_state.iter() {
 			let (_, eventid) = services()
 				.rooms
@@ -63,7 +63,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
 				);
 			}
 
-			i += 1;
+			i = i.saturating_add(1);
 			if i % 100 == 0 {
 				tokio::task::yield_now().await;
 			}

src/database/key_value/rooms/state_cache.rs

@@ -154,11 +154,11 @@ impl service::rooms::state_cache::Data for KeyValueDatabase {
 			if user_is_local(&joined) && !services().users.is_deactivated(&joined).unwrap_or(true) {
 				real_users.insert(joined);
 			}
-			joinedcount += 1;
+			joinedcount = joinedcount.saturating_add(1);
 		}
 
 		for _invited in self.room_members_invited(room_id).filter_map(Result::ok) {
-			invitedcount += 1;
+			invitedcount = invitedcount.saturating_add(1);
 		}
 
 		self.roomid_joinedcount

src/database/key_value/rooms/threads.rs

@@ -19,7 +19,7 @@ impl service::rooms::threads::Data for KeyValueDatabase {
 			.to_vec();
 
 		let mut current = prefix.clone();
-		current.extend_from_slice(&(until - 1).to_be_bytes());
+		current.extend_from_slice(&(until.saturating_sub(1)).to_be_bytes());
 
 		Ok(Box::new(
 			self.threadid_userids

src/database/key_value/rooms/timeline.rs

@@ -256,7 +256,7 @@ fn pdu_count(pdu_id: &[u8]) -> Result<PduCount> {
 		utils::u64_from_bytes(&pdu_id[pdu_id.len() - 2 * size_of::<u64>()..pdu_id.len() - size_of::<u64>()]);
 
 	if matches!(second_last_u64, Ok(0)) {
-		Ok(PduCount::Backfilled(u64::MAX - last_u64))
+		Ok(PduCount::Backfilled(u64::MAX.saturating_sub(last_u64)))
 	} else {
 		Ok(PduCount::Normal(last_u64))
 	}
@@ -275,22 +275,22 @@ fn count_to_id(room_id: &RoomId, count: PduCount, offset: u64, subtract: bool) -
 	let count_raw = match count {
 		PduCount::Normal(x) => {
 			if subtract {
-				x - offset
+				x.saturating_sub(offset)
 			} else {
-				x + offset
+				x.saturating_add(offset)
 			}
 		},
 		PduCount::Backfilled(x) => {
 			pdu_id.extend_from_slice(&0_u64.to_be_bytes());
-			let num = u64::MAX - x;
+			let num = u64::MAX.saturating_sub(x);
 			if subtract {
 				if num > 0 {
-					num - offset
+					num.saturating_sub(offset)
 				} else {
 					num
 				}
 			} else {
-				num + offset
+				num.saturating_add(offset)
 			}
 		},
 	};

src/database/key_value/rooms/user.rs

@@ -110,7 +110,8 @@ impl service::rooms::user::Data for KeyValueDatabase {
 						.enumerate()
 						.find(|(_, &b)| b == 0xFF)
 						.ok_or_else(|| Error::bad_database("Invalid userroomid_joined in db."))?
-						.0 + 1; // +1 because the room id starts AFTER the separator
+						.0
+						.saturating_add(1); // +1 because the room id starts AFTER the separator
 
 					let room_id = key[roomid_index..].to_vec();