Re: zsh testcase hangs in AIX

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Tue, Jul 30, 2019 at 7:47 AM Ayappan P2 <ayappap2@xxxxxxxxxx> wrote:
>
> We are porting zsh 5.5.1 in AIX.

Why not 5.7.1, the more recent release?

> Any help would be great.

This is testing the coprocess, which uses pipe() and then dups the
resulting descriptors before forking a child process.  This means
there is a situation where you have two-way communication between the
parent and child, so if there is either insufficient buffer space [so
write() blocks] or the buffers are not flushed [so read() blocks] then
the exchange can deadlock.  The test is assuming that pipes have more
than 12 bytes of buffering but are flushed at least on a line-by-line
basis.