CMake: fetch and build dependencies
Using cmake to fetch and build instead of using git submodule.
WebRTC: Compile Native WebRTC Android SDK
The very first step of modifying native WebRTC SDK for Android is cloning source code from WebRTC repository and compiling it into jar.
mbedTLS: MBEDTLS_ERR_SSL_INVALID_RECORD
Using some RTOS built-in mbedTLS to connect to AWS IoT Core might fail due to MBEDTLS_ERR_SSL_INVALID_RECORD(-0x7200 or -29184) during ssl handshake. There are several possible causes:
- The task stack set for mbedTLS running is not enough. Increase task stack and try again.
MBEDTLS_SSL_MAX_CONTENT_LENis not enough. IncreaseMBEDTLS_SSL_MAX_CONTENT_LENto 16384 and try again.
CMake: Toolchain File
When we have a build system like Yocto or Buildroot, cross compiling a CMake project is a simple task - We just need to create a simple CMake inherited recipe. If the SoC vendor only provides toolchain for you to cross compile a single CMake project, CMake toolchain file is a good approach.
printf not working?
Sometimes we noticed that printf will only flush after there is a newline in the print string, this behavior is caused by stdout stream buffer, which is line buffered by default. This behavior has been mentioned in ISO C99 standard:
There are few options to make it to print immediately once you called it.
SSH: Keep Connection Alive
SSH connection will automatically drop due to timeout if there is no operation for a period. To keep connection alive, we can config ssh client to send a keepalive periodically. In ~/.ssh/config, there is a parameter for this:
1 | ServerAliveInterval 60 |
If we set this value to 60, SSH client will send a keepalive every 60 seconds.
Algorithm Puzzles: Symmetric Tree
Algorithm Puzzles everyday every week sometimes: Symmetric Tree
Algorithm Puzzles: Number of Islands
Algorithm Puzzles everyday every week sometimes: Number of Islands
Run tshark/wireshark In Docker
Last week when I was trying to run tshark in a Docker container to capture http packets, tshark reported following error even with root user:
1 | tshark: Couldn't run /usr/bin/dumpcap in child process: Operation not permitted |
After searching, to access dumcap, we need to add --cap-add options when start container, then add user into wireshark group:
1 | docker run --cap-add=NET_RAW --cap-add=NET_ADMIN $IMAGE |