[lldb-dev] Debugging a running process with lldb

[Greg Clayton]

If we launch a process and hookup a pty to its stdin/out/err, then we shouldn't get a prompt. It is probably a bug where if you launch with --no-stdio that the LLDB prompt isn't always active.

For attach, we will always have a prompt. 

So seems this is a bug that --no-stdio is still pushing a Process IOHandler and taking over the console while the process is running.

> On May 14, 2014, at 3:22 AM, Matthew Gardiner <mg11 at csr.com> wrote:
> 
> More thoughts:
> 
> I've read http://lldb.llvm.org/tutorial.html in more depth now ;-) (appreciating that the debugger and the inferior require separate stdins.)
> I see there's an option, "--no-stdin", proposing to mitigate the issue I found
> 
> "If you attach to a process, or launch a process with the "|--no-stdin|" option, the command interpreter is always available to enter commands. This might be a little disconcerting to gdb users when always have an |(lldb)| prompt. This allows you to set a breakpoint, etc without having to explicitly interrupt the program you are debugging:
> 
> |(lldb) process continue
> (lldb) breakpoint set --name stop_here |
> "
> 
> However, it seems that --no-stdin is not present as a "process launch" option anymore, but rather we have "--no-stdio". (Perhaps a typo, somewhere?). I tried this option:
> 
> (lldb) process launch -s --no-stdio
> Process 2344 launching
> Process 2344 launched: './forever' (x86_64)
> Process 2344 stopped
> * thread #1: tid = 2344, 0x0000003675a011f0, name = 'forever', stop reason = trace
>    frame #0: 0x0000003675a011f0
> -> 0x3675a011f0:  movq   %rsp, %rdi
>   0x3675a011f3:  callq  0x3675a046e0
>   0x3675a011f8:  movq   %rax, %r12
>   0x3675a011fb:  movl   0x21eb97(%rip), %eax
> (lldb) process continue
> Process 2344 resuming
> 
> The interpreter prompt still fails to appear, so I still think I'm either seeing a bug, or that the documentation is incomplete as to describing how to run lldb such that the command interpreter, is always available when the inferior is running.
> 
> thanks
> Matt
> 
> 
> 
> 
> 
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