Look for stub handshake

Co-authored-by: Timothy Mertz <mertzt89@gmail.com>

Author: ryankurte

espflash/src/error.rs

@@ -152,6 +152,8 @@ pub enum ConnectionError {
         help("Try hard-resetting the device and try again, if the error persists your rom might be corrupted")
     )]
     OverSizedPacket,
+    #[error("Invalid stub handshake response received")]
+    InvalidStubHandshake,
 }
 
 #[derive(Debug, Default, Clone)]

espflash/src/flash_target/ram.rs

@@ -67,13 +67,12 @@ impl FlashTarget for RamTarget {
         if reboot {
             let entry = self.entry.unwrap_or_default();
             connection.with_timeout(CommandType::MemEnd.timeout(), |connection| {
-                connection.write_command(Command::MemEnd {
+                connection.command(Command::MemEnd {
                     no_entry: entry == 0,
                     entry,
                 })
-            })
-        } else {
-            Ok(())
+            })?;
         }
+        Ok(())
     }
 }

espflash/src/flasher.rs

@@ -26,6 +26,8 @@ const FLASH_SECTORS_PER_BLOCK: usize = FLASH_SECTOR_SIZE / FLASH_BLOCK_SIZE;
 // register used for chip detect
 const CHIP_DETECT_MAGIC_REG_ADDR: u32 = 0x40001000;
 
+const EXPECTED_STUB_HANDSHAKE: &str = "OHAI";
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq, Display, EnumVariantNames)]
 #[repr(u8)]
 pub enum FlashSize {
@@ -289,8 +291,10 @@ impl Flasher {
 
         debug!("Stub written...");
 
-        // Re-sync connection
-        self.connection.sync()?;
+        match self.connection.read(EXPECTED_STUB_HANDSHAKE.len())? {
+            Some(resp) if resp == EXPECTED_STUB_HANDSHAKE.as_bytes() => Ok(()),
+            _ => Err(Error::Connection(ConnectionError::InvalidStubHandshake)),
+        }?;
 
         // Re-detect chip to check stub is up
         let magic = self.connection.read_reg(CHIP_DETECT_MAGIC_REG_ADDR)?;