Panda: refactor get_firmware_version, return std::optional<std::vector> (#19896)

Co-authored-by: Willem Melching <willem.melching@gmail.com>

selfdrive/boardd/boardd.cc

@@ -133,12 +133,12 @@ bool usb_connect() {
     panda->set_loopback(true);
   }
 
-  const char *fw_sig_buf = panda->get_firmware_version();
-  if (fw_sig_buf){
-    params.write_db_value("PandaFirmware", fw_sig_buf, 128);
+  if (auto fw_sig = panda->get_firmware_version(); fw_sig) {
+    params.write_db_value("PandaFirmware", (const char *)fw_sig->data(), fw_sig->size());
 
     // Convert to hex for offroad
     char fw_sig_hex_buf[16] = {0};
+    const uint8_t *fw_sig_buf = fw_sig->data();
     for (size_t i = 0; i < 8; i++){
       fw_sig_hex_buf[2*i] = NIBBLE_TO_HEX((uint8_t)fw_sig_buf[i] >> 4);
       fw_sig_hex_buf[2*i+1] = NIBBLE_TO_HEX((uint8_t)fw_sig_buf[i] & 0xF);
@@ -146,8 +146,6 @@ bool usb_connect() {
 
     params.write_db_value("PandaFirmwareHex", fw_sig_hex_buf, 16);
     LOGW("fw signature: %.*s", 16, fw_sig_hex_buf);
-
-    delete[] fw_sig_buf;
   } else { return false; }
 
   // get panda serial

selfdrive/boardd/panda.cc

@@ -252,18 +252,11 @@ void Panda::set_loopback(bool loopback){
   usb_write(0xe5, loopback, 0);
 }
 
-const char* Panda::get_firmware_version(){
-  const char* fw_sig_buf = new char[128]();
-
-  int read_1 = usb_read(0xd3, 0, 0, (unsigned char*)fw_sig_buf, 64);
-  int read_2 = usb_read(0xd4, 0, 0, (unsigned char*)fw_sig_buf + 64, 64);
-
-  if ((read_1 == 64) && (read_2 == 64)) {
-    return fw_sig_buf;
-  }
-
-  delete[] fw_sig_buf;
-  return NULL;
+std::optional<std::vector<uint8_t>> Panda::get_firmware_version(){
+  std::vector<uint8_t> fw_sig_buf(128);
+  int read_1 = usb_read(0xd3, 0, 0, &fw_sig_buf[0], 64);
+  int read_2 = usb_read(0xd4, 0, 0, &fw_sig_buf[64], 64);
+  return ((read_1 == 64) && (read_2 == 64)) ? std::make_optional(fw_sig_buf) : std::nullopt;
 }
 
 std::optional<std::string> Panda::get_serial() {

selfdrive/boardd/panda.h

@@ -4,6 +4,7 @@
 #include <cstdint>
 #include <pthread.h>
 #include <mutex>
+#include <vector>
 #include <optional>
 
 #include <libusb-1.0/libusb.h>
@@ -73,7 +74,7 @@ class Panda {
   void set_ir_pwr(uint16_t ir_pwr);
   health_t get_health();
   void set_loopback(bool loopback);
-  const char* get_firmware_version();
+  std::optional<std::vector<uint8_t>> get_firmware_version();
   std::optional<std::string> get_serial();
   void set_power_saving(bool power_saving);
   void set_usb_power_mode(cereal::HealthData::UsbPowerMode power_mode);