Re: [BUG] Solaris-specific program flow corruption after subshell error exit

[Bart Schaefer <schaefer@brasslantern.com>]

On Feb 26,  6:36am, Martijn Dekker wrote:
}
} In the course of that testing I've come across a zsh bug that *only*
} manifests on Solaris, at least version 11.3. (A free VirtualBox VM for
} evaluation purposes is available from Oracle.)
} 
} If a subshell exits due to an error in a special builtin or redirection,
} execution flow is corrupted in such a manner that, when end of file is
} reached without an explicit 'return' or 'exit' being encountered,
} execution of the file does not end but restarts at the point exactly
} after the subshell was exited. The second time around, if program
} specifics allow it, execution ends normally.

Given that this is specific to Solaris and has to do with execution of
script files, I'm going to guess that it's related to file descriptor
management and buffering within STREAMS modules.

In particular I'm guessing that the POSIX-compatible behavior referenced
at the "fatal:" label in exec.c near line 4000 is leaving some kind of
shared stdin state between the parent and the subshell, because "set"
is a special builtin so will invoke the exit at that point.  Without
actually running the code, I'd expect we're going through the _exit()
branch rather than the exit() branch which under normal circumstances is
deliberately to avoid having such shared state mess up the parent file
descriptor positions, but maybe that's not sufficient.

Whether this is revealing a bug in zsh or a bug in Solaris 11.3 I can't
say.