OSProcess 3.0
David T. Lewis, 10 March 2002
Previous released version: OSProcess 2.7
Corresponding CommandShell version: 3.0

This is the first Windows release.
Windows users please see 'Known bugs' below.

Version numbers for OSProcess, CommandShell, and all plugins have
been set to 3.0 for this release.

See the separate CommandShell change set for a Unix shell window
which uses OSProcess.

OSProcess provides access to the external operating system from Squeak.
Plugins are provided for Unix, Linux, and Windows systems. OSProcess
can be loaded on other platforms as well, and placeholder classes are
provided in the OSProcess hierarchy for other operating systems (Mac,
OS/2, RiscOS), although support for these systems is not yet implemented.

You can:
 - Open a inspector on the operating system process in which
   Squeak is running (OSProcess thisOSProcess).
 - Read or write on the stdin, stdout, and stderr streams (Unix only
   for this release).
 - Access the command line, and get or set environment variables
   (Windows: get environment only).
 - Fork and exec external programs, with control of the command
   line, environment, and stdin/stdout/stderr (Windows: run an
   external program).
 - Open an inspector on a child operating system process created
   from Squeak, with run state and exit status of the child updated
   asynchronously.
 - Run an external command:
       OSProcess command: 'xeyes' (Unix)
       OSProcess command: 'sol' (Windows)
 - Connect directly to input and outputs of external commands. See
   the separate CommandShell change set for a useful implementation,
   supporting commands like:
       (PipeableOSProcess command: 'ls -l *') output
 - Create pipes and connect them to external processes (see the
   CommandShell change set).
 - Fork an exact clone of the current running Squeak image (no
   image file) with parent and child Squeak processes proceeding
   from the same point in memory (UnixProcess forkSqueak).
 - Fork a Squeak using the disk based image (UnixProcess squeak).
 - Start a headless Squeak from the running Squeak image, giving
   it an expression to evaluate:
       (UnixProcess forkHeadlessSqueakAndDoThenQuit:
           [UnixProcess command: 'echo hello world'])
 - Tell the running image to go headless (UnixProcess decapitate), and
   reconnected the image with a window (UnixProcess recapitate).
-  Move the display to another computer on the network:
       (UnixProcess displayOnXServer: 'someOtherComputer')
 - Restart the VM on the fly (UnixProcess restartVirtualMachine).
 - Rebuild the VM, and restart Squeak with the new VM if the
   build was successful (UnixProcess makeVM).
 - Start your Swiki in a headless background process:
       (UnixProcess startSwiki: 'myswiki' onPort: 8081 loggingTo: 'log.txt')

Known bugs in 3.0:
- On Windows, OSPipe is implemented, but an OSPipe cannot yet be set
  for nonBlocking reads or writes. Reading from an OSPipe with no data
  available will block the Squeak VM (<ctl><alt><del> required!!).
- On Windows, stdin/stdout/stderr access is not yet implemented.
- On Windows, command pipelines for external commands are not yet
  implemented. CommandShell does work, and may be used for launching
  individual Windows programs as well as for the usual CommandShell
  internal commands and internal command pipelines. However, it is
  not yet possible to construct a pipeline of Windows programs.
- Forking a child Squeak, as in UnixProcess>>forkSqueak, results in two
  instances of Squeak which share a single changes file. This has no
  practical impact if one or the other of the Squeak processes exits without
  doing very much, but it would probably result in a corrupted changes
  file if both Squeak instances do a lot of changes. I am leaving this as
  is for now, since a quick fix would require one of the Squeaks to
  save itself under an different image name.
- The connectToXDisplay method is probably dangerous from a security
  perspective.
- UnixOSProcessAccessor>>primitiveEnsetEnv uses the function unsetenv(),
  which is not available on Solaris (and possibly other systems). I do not
  know the portable equivalent of unsetenv(), so for now Solaris users
  will need to comment out the call to unsetenv() and rebuild the plugin.
  Other than failing the SUnit tests, commenting the function out has
  little practical impact.

Changes in 3.0 since 2.7:
- Added support for Windows. Windows programs can be launched. Squeak
  keeps track of its external programs and updates their runState and
  exitStatus.
- Added a plugin for Windows. The plugin can run external Win32 programs,
  and provides notification to Squeak when an external process exits. It
  can create an OSPipe (but see bug notes above). Functions required for
  command pipelines and nonblocking pipes are not yet implemented.
- Refactored the plugin classes to share code between Unix and Windows
  where possible.
- Added WindowsThread to represent an OS thread of execution within an
  OS process. This may be generalized for other platforms as required (eg
  pthread support on Unix).
- Did a general refactoring and renaming of classes to incorporate Windows
  support. Most importantly, class ConnectedUnixProcess has been replaced
  by class PipeableOSProcess in the separate CommandShell change set.
  PipeableOSProcess is platform independent, and collaborates with platform
  specific instances of ExternalOSProcess to eliminate the need for separate
  'connectable' subclasses for each platform.

The classes in OSProcess are:
	OSProcess
		ExternalOSProcess
			ExternalMacOSProcess
			ExternalOS2Process
			ExternalRiscOSProcess
			ExternalUnixOSProcess
			ExternalWindowsOSProcess
		ThisOSProcess
			MacProcess
			OS2Process
			RiscOSProcess
			UnixProcess
			WindowsProcess
	WindowsThread
	OSPipe
	(StandardFileStream)
		AttachableFileStream
	OSProcessAccessor
		MacOSProcessAccessor
		OS2OSProcessAccessor
		RiscOSProcessAccessor
		UnixOSProcessAccessor
		WindowsOSProcessAccessor
	(InterpreterPlugin)
		OSProcessPlugin
			UnixOSProcessPlugin
				UnixOSProcessPluginDynamicThisSession
				UnixOSProcessPluginInterpreterGetThisSession
				UnixOSProcessPluginNoThisSessionAvailable
				UnixOSProcessPluginStaticThisSession
			Win32OSProcessPlugin
				Win32OSProcessPluginDynamicThisSession
				Win32OSProcessPluginInterpreterGetThisSession
				Win32OSProcessPluginNoThisSessionAvailable
				Win32OSProcessPluginStaticThisSession

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