dongjiuzhu1 1946bc4e44 drivers/serial: fix crash when buffer is full and only recvbuf is implemented
When the receive buffer is full and the driver only implements recvbuf
operation without receive operation, the code would crash due to calling
a NULL function pointer. This patch fixes the issue by:

1. Check if recvbuf is available before calling it
2. When buffer is full, use a temporary buffer to drain hardware FIFO
   to prevent data accumulation in hardware
3. Add proper NULL check for receive operation to avoid crash
4. Initialize pbuf to NULL to prevent uninitialized variable usage

This ensures the serial driver works correctly even when only recvbuf
is implemented and the receive buffer is full.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
2026-01-28 22:19:21 +08:00

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Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).

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