Re: gawk 5.2.2 fatal crash when closing a two-way pipe for a process that does not have a pid anymore

[Andrew J. Schorr]

Hi,

Thanks for the bug report. Can you please provide a simple recipe
for how to reproduce this problem?

Thanks,
Andy

On Thu, Aug 24, 2023 at 09:56:54AM +0000, Finn Magnusson via Bug reports only 
for gawk. wrote:
>  Dear gawk developers
> I noticed the below issue in gawk 5.2.2 which was not present in previous 
> gawk version I was using (5.1.1): when using the close() function to close a 
> two-way pipe to a process that does not have a PID anymore (e.g. due to the 
> process got closed by an external command), then I got the below fatal crash: 
> gawk.lin64: /app/moshell/23.2h/moshell/prog.awk:19919: fatal: flush to 
> "/app/moshell/23.2h/moshell/commonjars/ssh.lin64 -p 2022 -z 
> '/proj/wcdma-userarea/users/eanzmagn/moshell_logfiles/logs_moshell/tempfiles/20230824-114538_6552/sshz6592'
>  -l expert -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o 
> HostKeyAlgorithms="ssh-dss,ssh-rsa,rsa-sha2-512,rsa-sha2-256" -o 
> NumberOfPasswordPrompts=1 -o ConnectTimeout=10 -o ServerAliveInterval=300 -o 
> ConnectionAttempts=1 -o ServerAliveCountMax=0 -o TCPKeepAlive=no -o 
> PreferredAuthentications=publickey,password 10.136.72.120 -s netconf 2>&1" 
> failed: reason unknown
> 
> I was able to solve it by commenting out the below efflush statement in 
> gawk-5.2.2/io.c :  /* flush before closing to leverage special error handling 
> */ efflush(rp->output.fp, "flush", rp);
> Is it possible to make a fix for this in a coming gawk release?
> Many thanks.BRFinn