NAME

       Test2::Harness::Util::IPC - Utilities for IPC management.

DESCRIPTION

       This package provides low-level IPC tools for Test2::Harness.

EXPORTS

       All exports are optional and must be specified at import time.

       $bool = USE_P_GROUPS()
           This is a shortcut for:

               use Config qw/%Config/;
               $Config{'d_setpgrp'};

       swap_io($from, $to)
       swap_io($from, $to, \&die)
           This will close and re-open the file handle designated by $from so that it redirects
           to the handle specified in $to. It preserves the file descriptor in the process, and
           throws an exception if it fails to do so.

               swap_io(\*STDOUT, $fh);
               # STDOUT now points to wherever $fh did, but maintains the file descriptor number '2'.

           As long as the file descriptor is greater than 0 it will open for writing. If the
           descriptor is 0 it will open for reading, allowing for a swap of "STDIN" as well.

           Extra effort is made to insure errors go to the real "STDERR", specially when trying
           to swap out "STDERR". If you have trouble with this, or do not trust it, you can
           provide a custom coderef as a third argument, this coderef will be used instead of
           "die()" to throw exceptions.

           Note that the custom die logic when you do not provide your own bypasses the exception
           catching mechanism and will exit your program. If this is not desirable then you
           should provide a custom die subref.

       $pid = run_cmd(command => [...], %params)
           This function will run the specified command and return a pid to you. When possible
           this will be done via "fork()" and "exec()". When that is not possible it uses the
           "system(1, ...)" trick to spawn a new process. Some parameters do not work in the
           second case, and are silently ignored.

           Parameters:

           command => [$command, sub { ... }, @args]
           command => sub { return ($command, @args) }
               This parameter is required. This should either be an arrayref of arguments for
               "exec()", or a coderef that returns a list of arguments for "exec()". On systems
               without fork/exec the arguments will be passed to "system(1, $command, @args)"
               instead.

               If the command arrayref has a coderef in it, the coderef will be run and its
               return value(s) will be inserted in its place. This replacement happens post-
               chroot

           run_in_parent => [sub { ... }, sub { ... }]
               An arrayref of callbacks to be run in the parent process immedietly after the
               child process is started.

           run_in_child => [sub { ... }, sub { ... }]
               An arrayref of callbacks to be run in the child process immedietly after fork.
               This parameter is silently ignored on systems without fork/exec.

           env => { ENVVAR => $VAL, ... }
               A hashref of custom environment variables to set in the child process. In the
               fork/exec model this is done post-fork, in the spawn model this is done via local
               prior to the spawn.

           no_set_pgrp => $bool,
               Normall "setpgrp(0,0)" is called on systems where it is supported. You can use
               this parameter to override the normal behavior. setpgrp() is not called in the
               spawn model, so this parameter is silently ignored there.

           chdir => 'path/to/dir'
           ch_dir => 'path/to/dir'
               chdir() to the specified directory for the new process. In the fork/exec model
               this is done post-fork in the child. In the spawn model this is done before the
               spawn, then a second chdir() puts the parent process back to its original dir
               after the spawn.

           stdout => $handle
           stderr => $handle
           stdin  => $handle
               Thise can be used to provide custom STDERR, STDOUT, and STDIN. In the fork/exec
               model these are swapped into place post-fork in the child. In the spawn model the
               swap occurs pre-spawn, then the old handles are swapped back post-spawn.

SOURCE

       The source code repository for Test2-Harness can be found at
       http://github.com/Test-More/Test2-Harness/.

MAINTAINERS

       Chad Granum <exodist@cpan.org>

AUTHORS

       Chad Granum <exodist@cpan.org>

COPYRIGHT

       Copyright 2020 Chad Granum <exodist7@gmail.com>.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       See http://dev.perl.org/licenses/