[PATCH] osprocess: Introduce a simple sub-process package

From: Holger Hans Peter Freyther <[hidden email]>

The >>#popen: code does not return the pid which makes shutting down
the forked process quite difficult. Introduce a sub-process package
that can be used to fork, kill and read from the stdout/stdin.

This package should be more deeply integrated with the sysdep layer,
e.g. it assumes that SIGCHLD, SIGFPE is handled by sysdep (e.g. a
popen was previously used). It would be nice if one could have a Sempahore
for the SIGCHLD like one has with the fileOp: operations.

2012-12-28  Holger Freyther  <[hidden email]>

        * configure.ac: Add a OSProcess package.
---
 ChangeLog                            |    4 +
 configure.ac                         |    1 +
 packages/osprocess/ChangeLog         |    6 ++
 packages/osprocess/Makefile.am       |   10 +++
 packages/osprocess/Makefile.frag     |    5 ++
 packages/osprocess/OSProcess.st      |  156 ++++++++++++++++++++++++++++++++++
 packages/osprocess/OSProcessTests.st |    7 ++
 packages/osprocess/gst_osprocess.c   |  153 +++++++++++++++++++++++++++++++++
 packages/osprocess/package.xml       |   14 +++
 9 files changed, 356 insertions(+)
 create mode 100644 packages/osprocess/ChangeLog
 create mode 100644 packages/osprocess/Makefile.am
 create mode 100644 packages/osprocess/Makefile.frag
 create mode 100644 packages/osprocess/OSProcess.st
 create mode 100644 packages/osprocess/OSProcessTests.st
 create mode 100644 packages/osprocess/gst_osprocess.c
 create mode 100644 packages/osprocess/package.xml

diff --git a/ChangeLog b/ChangeLog
index ec896ef..f129065 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2012-12-28  Holger Freyther  <[hidden email]>
+
+ * configure.ac: Add a OSProcess package.
+
 2013-03-30  Holger Hans Peter Freyther  <[hidden email]>
 
  * configure.ac: Introduce the Tooling package.
diff --git a/configure.ac b/configure.ac
index d58028a..fbf1ce9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -576,6 +576,7 @@ GST_PACKAGE_ENABLE([Compiler], [stinst/compiler])
 GST_PACKAGE_ENABLE([Parser], [stinst/parser])
 GST_PACKAGE_ENABLE([ClassPublisher], [stinst/doc])
 GST_PACKAGE_ENABLE([ProfileTools], [profile])
+GST_PACKAGE_ENABLE([OSProcess], [osprocess], [], [], [Makefile], [gst-osprocess.la])
 GST_PACKAGE_ENABLE([ROE], [roe])
 GST_PACKAGE_ENABLE([SandstoneDb], [sandstonedb])
 GST_PACKAGE_ENABLE([Seaside-Core], [seaside/core])
diff --git a/packages/osprocess/ChangeLog b/packages/osprocess/ChangeLog
new file mode 100644
index 0000000..ce36962
--- /dev/null
+++ b/packages/osprocess/ChangeLog
@@ -0,0 +1,6 @@
+2012-12-27  Holger Hans Peter Freyther  <[hidden email]>
+
+ * Makefile.am: Add.
+ * package.xml: Likewise.
+ * OSProcess.st: Likewise.
+ * gst_osprocess.c: Likewise.
diff --git a/packages/osprocess/Makefile.am b/packages/osprocess/Makefile.am
new file mode 100644
index 0000000..dfd78ce
--- /dev/null
+++ b/packages/osprocess/Makefile.am
@@ -0,0 +1,10 @@
+moduleexec_LTLIBRARIES = gst-osprocess.la
+
+AM_CPPFLAGS = -I$(top_srcdir)/libgst -I$(top_srcdir)/lib-src
+
+gst_module_ldflags = -rpath $(moduleexecdir) -release $(VERSION) -module \
+        -no-undefined -export-symbols-regex gst_initModule
+
+gst_osprocess_la_SOURCES = gst_osprocess.c
+gst_osprocess_la_LDFLAGS = $(gst_module_ldflags)
+
diff --git a/packages/osprocess/Makefile.frag b/packages/osprocess/Makefile.frag
new file mode 100644
index 0000000..94a75cf
--- /dev/null
+++ b/packages/osprocess/Makefile.frag
@@ -0,0 +1,5 @@
+OSProcess_FILES = \
+packages/osprocess/OSProcess.st packages/osprocess/ChangeLog packages/osprocess/OSProcessTests.st
+$(OSProcess_FILES):
+$(srcdir)/packages/osprocess/stamp-classes: $(OSProcess_FILES)
+ touch $(srcdir)/packages/osprocess/stamp-classes
diff --git a/packages/osprocess/OSProcess.st b/packages/osprocess/OSProcess.st
new file mode 100644
index 0000000..c440e0c
--- /dev/null
+++ b/packages/osprocess/OSProcess.st
@@ -0,0 +1,156 @@
+"=====================================================================
+|
+|   External OSProcess handling
+|
+|
+ ======================================================================"
+
+"======================================================================
+|
+| Copyright 2012 Free Software Foundation, Inc.
+| Written by Holger Hans Peter Freyther
+| baesed on work by Gwenael Casaccio
+|
+| This file is part of the GNU Smalltalk class library.
+|
+| The GNU Smalltalk class library is free software; you can redistribute it
+| and/or modify it under the terms of the GNU Lesser General Public License
+| as published by the Free Software Foundation; either version 2.1, or (at
+| your option) any later version.
+|
+| The GNU Smalltalk class library is distributed in the hope that it will be
+| useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
+| General Public License for more details.
+|
+| You should have received a copy of the GNU Lesser General Public License
+| along with the GNU Smalltalk class library; see the file COPYING.LIB.
+| If not, write to the Free Software Foundation, 59 Temple Place - Suite
+| 330, Boston, MA 02110-1301, USA.  
+|
+ ======================================================================"
+
+Object subclass: OSProcess [
+    | pid stdin stdout |
+    <category: 'OSProcess'>
+
+    OSProcess class >> fileDescriptorFamily [
+ <category: 'stream-family'>
+ ^ FileStream
+    ]
+
+    OSProcess class >> SIGINT [
+ <category: 'signals'>
+ ^ 2
+    ]
+
+    OSProcess class >> SIGKILL [
+ <category: 'signals'>
+ ^ 9
+    ]
+
+    OSProcess class >> kill: pid signal: asig [
+ <category: 'syscall'>
+ <cCall: 'kill' returning: #long args: #(#long #int)>
+    ]
+
+    OSProcess class >> waitpid: pid status: anIntPtr options: anInteger [
+ <category: 'syscall'>
+ <cCall: 'waitpid' returning: #long args: #(#long (#ptr #int) #int)>
+    ]
+
+    OSProcess class >> getpid [
+ <category: 'syscall'>
+ <cCall: 'getpid' returning: #long args: #()>
+    ]
+
+    OSProcess class >> getppid [
+ <category: 'syscall'>
+ <cCall: 'getppid' returning: #long args: #()>
+    ]
+
+    OSProcess class >> internalFork: command args: args stdin: outIn stdout: outOut [
+ <cCall: 'gst_osprocess_fork_and_exec' returning: #int args: #(#self #string (#ptr #string) #smalltalk #smalltalk #smalltalk)>
+    ]
+
+    OSProcess class >> forkAndExec: command args: args [
+ | argv i res pid in out|
+ <category: 'exec'>
+
+ "From ThisOSOSProcess. Make sure the last item is null terminated"
+ argv := (CStringType arrayType: args size + 2) gcNew.
+ argv at: 0 put: command.
+
+ "Add all arguments"
+ i := 1.
+ args do: [:arg |
+    argv at: i put: arg.
+    i := i + 1].
+
+ "Null terminate.. once more"
+ argv at: i put: nil.
+
+ "Fork now and get things out of the call."
+ in := self fileDescriptorFamily new.
+ out := self fileDescriptorFamily new.
+ pid := self internalFork: command args: argv
+    stdin: in stdout: out.
+ pid < 0
+    ifTrue: [^self error: 'Failed to fork the process'].
+
+ "Initialize the sockets, the fds were set inside the fork"
+ in initialize.
+ out initialize.
+
+ ^ OSProcess new
+    stdin: in;
+    stdout: out;
+    pid: pid;
+    yourself.
+    ]
+
+    stdin: aStd [
+ <category: 'creation'>
+ stdin := aStd.
+    ]
+
+    stdout: aStd [
+ <category: 'creation'>
+ stdout := aStd.
+    ]
+
+    pid: aPid [
+ <category: 'creation'>
+ pid := aPid.
+    ]
+
+    stdin [
+ <category: 'stream'>
+ ^ stdin
+    ]
+
+    stdout [
+ <category: 'stream'>
+ ^ stdout
+    ]
+
+    kill [
+ <category: 'termination'>
+ ^ self sendSignal: self class SIGKILL.
+    ]
+
+    sendSignal: aSig [
+ <category: 'termination'>
+ ^ self class kill: pid signal: aSig.
+    ]
+
+    close [
+ stdin close.
+ stdout close.
+    ]
+]
+
+Eval [
+    "Install SIGCHLD handler..."
+    (FileStream popen: '/bin/true' dir: FileDescriptor read) close.
+]
diff --git a/packages/osprocess/OSProcessTests.st b/packages/osprocess/OSProcessTests.st
new file mode 100644
index 0000000..d858552
--- /dev/null
+++ b/packages/osprocess/OSProcessTests.st
@@ -0,0 +1,7 @@
+Eval [
+PackageLoader fileInPackage: #OSProcess.
+[
+ (OSProcess.OSProcess forkAndExec: 'ls' args: #('/')) inspect; close.
+ stdin next.
+] repeat.
+]
diff --git a/packages/osprocess/gst_osprocess.c b/packages/osprocess/gst_osprocess.c
new file mode 100644
index 0000000..b3f7316
--- /dev/null
+++ b/packages/osprocess/gst_osprocess.c
@@ -0,0 +1,153 @@
+/******************************* -*- C -*- ****************************
+ *
+ *      Subprocess handling
+ *
+ *
+ ***********************************************************************/
+/***********************************************************************
+ *
+ * Copyright 2012 Free Software Foundation, Inc.
+ * Written by Holger Hans Peter Freyther.
+ *
+ * Forking code from libgst/sysdep/posix/files.c:
+ * Copyright 1988,89,90,91,92,94,95,99,2000,2001,2002,2003,2006,2007,2008,2009
+ *
+ * This file is part of GNU Smalltalk.
+ *
+ * GNU Smalltalk is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2, or (at your option) any later
+ * version.
+ *
+ * Linking GNU Smalltalk statically or dynamically with other modules is
+ * making a combined work based on GNU Smalltalk.  Thus, the terms and
+ * conditions of the GNU General Public License cover the whole
+ * combination.
+ *
+ * In addition, as a special exception, the Free Software Foundation
+ * give you permission to combine GNU Smalltalk with free software
+ * programs or libraries that are released under the GNU LGPL and with
+ * independent programs running under the GNU Smalltalk virtual machine.
+ *
+ * You may copy and distribute such a system following the terms of the
+ * GNU GPL for GNU Smalltalk and the licenses of the other code
+ * concerned, provided that you include the source code of that other
+ * code when and as the GNU GPL requires distribution of source code.
+ *
+ * Note that people who make modified versions of GNU Smalltalk are not
+ * obligated to grant this special exception for their modified
+ * versions; it is their choice whether to do so.  The GNU General
+ * Public License gives permission to release a modified version without
+ * this exception; this exception also makes it possible to release a
+ * modified version which carries forward this exception.
+ *
+ * GNU Smalltalk is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Smalltalk; see the file COPYING.  If not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ ***********************************************************************/
+
+#include "gstpub.h"
+
+#include <sys/types.h>          /* See NOTES */
+#include <sys/socket.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+static VMProxy *vmProxy;
+
+typedef struct st_OSProcess {
+  OBJ_HEADER;
+  OOP pid;
+  OOP _stdin;
+  OOP _stdout;
+} *OSProcess;
+
+static pid_t
+gst_fork_and_exec (OOP self, const char *cmd, char * const argv[], OOP in, OOP out)
+{
+  /*
+   * TODO: The SIGCHLD handler needs to be installed by gst! It is depending
+   * on various usages!
+   *
+   * The whole code should be moved into the sysdeps and use waitpid with a
+   * queue like done for file-io to raise a semaphore once a process has
+   * entered.
+   * The forking code is taken from sysdep/posix/files.c
+   */
+
+  int stdin_pipe[2];
+  int stdout_pipe[2];
+
+  int result;
+
+  result = socketpair (AF_UNIX, SOCK_STREAM, 0, stdin_pipe);
+  if (result == -1)
+    return -1;
+  result = socketpair (AF_UNIX, SOCK_STREAM, 0, stdout_pipe);
+  if (result == -1) {
+    close(stdin_pipe[0]);
+    close(stdin_pipe[1]);
+    return -1;
+  }
+
+  /* TODO: create a pipe with close on exec to check if the process runs? */
+
+  /* We suppose it is a system that has fork.  */
+  result = fork ();
+  if (result == 0)
+    {
+      /* Child process */
+      close (stdin_pipe[0]);
+      close (stdout_pipe[0]);
+
+      /* Setup file descriptor */
+      dup2 (stdin_pipe[1], STDIN_FILENO);
+      dup2 (stdout_pipe[1], STDOUT_FILENO);
+      close (stdin_pipe[1]);
+      close (stdout_pipe[1]);
+
+      /* stderr is still going to the main stream */
+      /* close other fds? */
+
+      execvp(cmd, argv);
+
+      _exit (-1);
+      /*NOTREACHED*/
+    }
+
+  /* now close the client side of the socket.. */
+  close (stdin_pipe[1]);
+  close (stdout_pipe[1]);
+
+  if (result == -1)
+    {
+      int save_errno;
+      save_errno = errno;
+      /* forking failed */
+      close (stdin_pipe[0]);
+      close (stdout_pipe[0]);
+      errno = save_errno;
+      return (-1);
+    }
+
+
+    /* trying to return information */
+    vmProxy->strMsgSend(in, "setFD:", vmProxy->intToOOP(stdin_pipe[0]), NULL);
+    vmProxy->strMsgSend(out, "setFD:", vmProxy->intToOOP(stdout_pipe[0]), NULL);
+    return result;
+}
+
+void
+gst_initModule (VMProxy * proxy)
+
+{
+  vmProxy = proxy;
+  vmProxy->defineCFunc ("gst_osprocess_fork_and_exec", gst_fork_and_exec);
+}
diff --git a/packages/osprocess/package.xml b/packages/osprocess/package.xml
new file mode 100644
index 0000000..2c85f93
--- /dev/null
+++ b/packages/osprocess/package.xml
@@ -0,0 +1,14 @@
+<package>
+  <name>OSProcess</name>
+  <namespace>OSProcess</namespace>
+  <module>gst-osprocess</module>
+
+  <test>
+    <sunit>OSProcess.ProcessTest</sunit>
+    <filein>OSProcessTests.st</filein>
+  </test>
+
+  <filein>OSProcess.st</filein>
+
+  <file>ChangeLog</file>
+</package>
--
1.7.10.4


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On Sun, May 05, 2013 at 11:25:31AM +0200, Holger Hans Peter Freyther wrote:
> e.g. it assumes that SIGCHLD, SIGFPE is handled by sysdep (e.g. a

probably SIGPIPE. :)


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Il 05/05/2013 11:25, Holger Hans Peter Freyther ha scritto:
Perhaps the user interface should just be

    OSProcess new
          ... ;
          exec: command args: args;
          yourself

You could have methods like

    FileDescriptor class>>#twoPipes (returns an array of two pipes)
    OSProcess>>#stdin: (accepts a readable FileDescriptor)
    OSProcess>>#stdout: (accepts a writeable FileDescriptor)
    OSProcess>>#stderr: (accepts a writeable FileDescriptor)
    OSProcess>>#stdin
    OSProcess>>#stdout
    OSProcess>>#stderr
    OSProcess>>#stdinPipe (returns the write side)
    OSProcess>>#stdoutPipe (returns the read side)
    OSProcess>>#stderrPipe (returns the read side)

Thanks for doing this.  It's been on my todo list forever.


Doesn't need to be a socketpair, it can be just a pipe.

Paolo


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On Sat, May 11, 2013 at 08:15:45PM +0200, Paolo Bonzini wrote:

Any opinion on SIGCHLD/wait handling? Should there be a semaphore
in OSProcess to indicate the termination of the process or should
we hope that the termination will lead to the socket being closed
and this is something that leads to EndOfStream notification?

holger


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