rcl_init segfaults on non ASCII command line arguments if LANG is not set

[hidmic]

Bug report

Required Info:

• Operating System:
  • Ubuntu 18.04 Bionic Beaver
• Installation type:
  • Binaries and from source
• Version or commit hash:
  • Crystal and current ros2.repos

Steps to reproduce issue

1. Unset the LANG environment variable if set.

unset LANG

2. Start some node.

ros2 run demo_nodes_cpp talker

3. Try to set a string parameter with non-ASCII value

ros2 param set /talker value 'Ragnarök'

Expected behavior

CLI should throw UnicodeEncodeError upon message conversion and serialization (inaccurate description, see below).

Actual behavior

CLI segfaults within rcl_init:

Program received signal SIGSEGV, Segmentation fault.                                                        [9/601]
__strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:62
62      ../sysdeps/x86_64/multiarch/strlen-avx2.S: No such file or directory.
(gdb) bt  
#0  __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:62
#1  0x00007ffff5ee3daa in rcl_init (argc=2, argv=0xab36d0, options=0x7fffffff2a00, context=0x7ffff7f5ddc8)
    at /home/michel/Workspaces/ros2_base_ws/src/ros2/rcl/rcl/src/rcl/init.c:97
#2  0x00007ffff67b75e9 in rclpy_init (_unused_self=0x7ffff7e2e458, args=0x7ffff7e25dc8)
    at /home/michel/Workspaces/ros2_base_ws/src/ros2/rclpy/rclpy/src/rclpy/_rclpy.c:529
...
#1  0x00007ffff5ee3daa in rcl_init (argc=2, argv=0xab36d0, options=0x7fffffff2a00, context=0x7ffff7f5ddc8)
    at /home/michel/Workspaces/ros2_base_ws/src/ros2/rcl/rcl/src/rcl/init.c:97
97            size_t argv_i_length = strlen(argv[i]);

Additional information

Above situation only arises when system locale settings are not properly configured as specified in the installation instructions. From that perspective, this may not be a bug, and fixing it not a fix but an enhancement to better deal with such conditions.

[dirk-thomas]

CLI should throw UnicodeEncodeError upon message conversion and serialization.

The problem is not happening in message conversation / serialization. The problem already happens while passing the command line arguments.

[hidmic]

Alright, small fixes are ready!