Re: «run_pending_traps: bad value in trap_list» when `jobs` is run a trap

[Chet Ramey]

On 7/1/24 4:45 PM, Gioele Barabucci wrote:
> Hi,
>
> the following script (reduced from <https://bugs.debian.org/417946>)
>
>      #!/bin/bash
>      childfinished () { echo "jobs: $(jobs)"; }
>      trap childfinished SIGCHLD
>      sleep 1 &
>      wait
>
> causes bash 5.2.21 to output
>
>      ./par.sh: line 2: warning: run_pending_traps:
>      bad value in trap_list[17]: 0x5625e6fa43d0
>
> Does this warning hint at something like a dangling reference that should 
> be fixed, or can it be safely ignored?

It's warning you that you're recursively calling the SIGCHLD trap handler.
It's clearer when the debugging messages are enabled:

$ ./bash x2
x2: line 2: DEBUG warning: wait_for: recursively setting old_sigint_handler 
to wait_sigint_handler: running_trap = 21
jobs: [1]+  Done                       sleep 1
x2: line 2: DEBUG warning: run_pending_traps: recursive invocation while 
running trap for signal 20
x2: line 2: warning: run_pending_traps: bad value in trap_list[20]: 0x102dc8a0c

We use the `bad value' as a sentinel to make sure the user can reset the
SIGCHLD disposition in the trap handler without run_trap_internal restoring
it to the original value.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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