Add packet helper functions to avoid unwrapping

src/pipe.rs

@@ -6,7 +6,7 @@ use crate::{
     constants::*,
     types::packet::{
         Chain, ChainedPacket as _, Command as PacketCommand, DataBlock, Error as PacketError,
-        ExtPacket, PacketWithData as _, RawPacket, XfrBlock,
+        ExtPacket, PacketWithData as _, RawPacket, RawPacketExt as _, XfrBlock,
     },
 };
 
@@ -385,8 +385,7 @@ where
     pub fn send_wait_extension(&mut self) -> bool {
         if self.state == State::Processing {
             // Need to send a wait extension request.
-            let mut packet = RawPacket::new();
-            packet.resize_default(CCID_HEADER_LEN).ok();
+            let mut packet = RawPacket::zeroed_until(CCID_HEADER_LEN);
             packet[0] = 0x80;
             packet[6] = self.seq;
 
@@ -494,16 +493,14 @@ where
     }
 
     fn send_slot_status_ok(&mut self) {
-        let mut packet = RawPacket::new();
-        packet.resize_default(CCID_HEADER_LEN).ok();
+        let mut packet = RawPacket::zeroed_until(CCID_HEADER_LEN);
         packet[0] = 0x81;
         packet[6] = self.seq;
         self.send_packet_assuming_possible(packet);
     }
 
     fn send_slot_status_error(&mut self, error: Error) {
-        let mut packet = RawPacket::new();
-        packet.resize_default(CCID_HEADER_LEN).ok();
+        let mut packet = RawPacket::zeroed_until(CCID_HEADER_LEN);
         packet[0] = 0x6c;
         packet[6] = self.seq;
         packet[7] = 1 << 6;
@@ -512,8 +509,7 @@ where
     }
 
     fn send_parameters(&mut self) {
-        let mut packet = RawPacket::new();
-        packet.resize_default(17).ok();
+        let mut packet = RawPacket::zeroed_until(17);
         packet[0] = 0x82;
         packet[1] = 7;
         packet[6] = self.seq;

src/types/packet.rs

@@ -7,12 +7,28 @@ pub type ExtPacket = heapless::Vec<u8, MAX_MSG_LENGTH>;
 
 pub trait RawPacketExt {
     fn data_len(&self) -> usize;
+    fn zeroed() -> Self;
+    fn zeroed_until(len: usize) -> Self;
 }
 
 impl RawPacketExt for RawPacket {
     fn data_len(&self) -> usize {
         u32::from_le_bytes(self[1..5].try_into().unwrap()) as usize
     }
+
+    fn zeroed() -> Self {
+        let mut res = Self::new();
+        let cap = res.capacity();
+        res.resize_default(cap).unwrap();
+        res
+    }
+
+    fn zeroed_until(len: usize) -> Self {
+        let mut res = Self::new();
+        let cap = res.capacity();
+        res.resize_default(len.min(cap)).unwrap();
+        res
+    }
 }
 
 pub enum Error {
@@ -109,9 +125,8 @@ impl core::fmt::Debug for DataBlock<'_> {
 
 impl From<DataBlock<'_>> for RawPacket {
     fn from(block: DataBlock<'_>) -> RawPacket {
-        let mut packet = RawPacket::new();
         let len = block.data.len();
-        packet.resize_default(CCID_HEADER_LEN + len).ok();
+        let mut packet = RawPacket::zeroed_until(CCID_HEADER_LEN + len);
         packet[0] = 0x80;
         packet[1..][..4].copy_from_slice(
             &u32::try_from(len)