fix: Ensure timeout_ms is non-negative in serial read and write functions

- Added a check to set timeout_ms to 0 if it is negative in both serial_read.cpp and serial_write.cpp to prevent potential issues with negative timeout values.

Author: Katze719

src/serial_read.cpp

@@ -24,6 +24,11 @@ extern "C"
                                                             "Invalid handle");
         }
 
+        if (timeout_ms < 0)
+        {
+            timeout_ms = 0;
+        }
+
         const int fd = static_cast<int>(handle);
         auto *buf = static_cast<unsigned char *>(buffer);
 

src/serial_write.cpp

@@ -27,6 +27,11 @@ extern "C"
                                                             "Invalid handle");
         }
 
+        if (timeout_ms < 0)
+        {
+            timeout_ms = 0;
+        }
+
         const int fd = static_cast<int>(handle);
 
         ssize_t bytes_written = ::write(fd, buffer, buffer_size);