[BUG] when being attached by bpftime, bash will stuck if it spawns another bash process

[Officeyutong]

Repdocuce:

• cd examples/libbpf-tools/bashreadline && make
• Terminal 1. bpftime load ./readline
• Terminal 2. bpftime start /bin/bash --norc

Now everything works well. But if we run bash in the attached bash, it will stuck and won't handle any input, until a SIGINT (Ctrl+C) was sended

[Officeyutong]

Some initial investigations:

• This might be related with logs printed by bpftime

Why?

If we run bpftime start /bin/bash --norc, everything works well. But if we run bash in the started shell, bash will stuck for a few seconds, prints bash: /usr/bin/dirname: Argument list too long and continues to stuck. And no logs will be printed for the new bash process.

So one guess is all logs printed by bpftime has gone to stdout, and they were eaten by a certain program that invokes bash (for example bash calls itself in bashrc), but that program was unable to process such unexpected stdout contents and just stuck.

If we still spawn bash with --norc in the spawned bash, everything still works well. So the key piece must be in some calls in bashrc