Implement os.waitpid() for Windows, in a way that's compatible with Linux
where their capabilities intersect. Would be nice if people using non-
MSVC compilers (Borland etc) took a whack at doing something similar for
them (this code relies on the MS _cwait function).
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index 51f0027..5739485 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -96,7 +96,7 @@
the mapping is modified.
If \function{putenv()} is not provided, this mapping may be passed to
-the appropriate process-creation functions to cause child processes to
+the appropriate process-creation functions to cause child processes to
use a modified environment.
\end{datadesc}
@@ -184,7 +184,7 @@
supported, assignments to items in \code{os.environ} are automatically
translated into corresponding calls to \function{putenv()}; however,
calls to \function{putenv()} don't update \code{os.environ}, so it is
-actually preferable to assign to items of \code{os.environ}.
+actually preferable to assign to items of \code{os.environ}.
\end{funcdesc}
\begin{funcdesc}{setegid}{egid}
@@ -413,7 +413,7 @@
\end{funcdesc}
\begin{funcdesc}{ftruncate}{fd, length}
-Truncate the file corresponding to file descriptor \var{fd},
+Truncate the file corresponding to file descriptor \var{fd},
so that it is at most \var{length} bytes in size.
Availability: \UNIX.
\end{funcdesc}
@@ -909,7 +909,7 @@
\begin{funcdesc}{abort}{}
Generate a \constant{SIGABRT} signal to the current process. On
-\UNIX, the default behavior is to produce a core dump; on Windows, the
+\UNIX, the default behavior is to produce a core dump; on Windows, the
process immediately returns an exit code of \code{3}. Be aware that
programs which use \function{signal.signal()} to register a handler
for \constant{SIGABRT} will behave differently.
@@ -1166,12 +1166,14 @@
\end{funcdesc}
\begin{funcdesc}{waitpid}{pid, options}
+The details of this function differ on \UNIX and Windows.
+
+On \UNIX:
Wait for completion of a child process given by process id \var{pid},
and return a tuple containing its process id and exit status
indication (encoded as for \function{wait()}). The semantics of the
call are affected by the value of the integer \var{options}, which
should be \code{0} for normal operation.
-Availability: \UNIX.
If \var{pid} is greater than \code{0}, \function{waitpid()} requests
status information for that specific process. If \var{pid} is
@@ -1180,6 +1182,19 @@
pertains to any child of the current process. If \var{pid} is less
than \code{-1}, status is requested for any process in the process
group \code{-\var{pid}} (the absolute value of \var{pid}).
+
+On Windows:
+Wait for completion of a process given by process id \var{pid},
+and return a tuple containing \var{pid},
+and its exit status shifted left by 8 bits (shifting makes cross-platform
+use of the function easier).
+A \var{pid} less than or equal to \code{0} has no special meaning on
+Windows, and raises an exception.
+The value of integer \var{options} has no effect.
+\var{pid} can refer to any process whose id is known, not necessarily a
+child process.
+The \function{spawn()} functions called with \constant{P_NOWAIT}
+return suitable process ids.
\end{funcdesc}
\begin{datadesc}{WNOHANG}
@@ -1211,7 +1226,7 @@
\begin{funcdesc}{WEXITSTATUS}{status}
If \code{WIFEXITED(\var{status})} is true, return the integer
-parameter to the \manpage{exit}{2} system call. Otherwise, the return
+parameter to the \manpage{exit}{2} system call. Otherwise, the return
value is meaningless.
Availability: \UNIX.
\end{funcdesc}
diff --git a/Misc/NEWS b/Misc/NEWS
index ee9df99..c151067 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -59,6 +59,13 @@
Windows
+- os.waitpid() is now implemented for Windows, and can be used to block
+ until a specified process exits. This is similar to, but not exactly
+ the same as, os.waitpid() on POSIX systems. If you're waiting for
+ a specific process whose pid was obtained from one of the spawn()
+ functions, the same Python os.waitpid() code works across platforms.
+ See the docs for details.
+
- New tempfile.TemporaryFile implementation for Windows: this doesn't
need a TemproraryFileWrapper wrapper anymore, and should be immune
to a nasty problem: before 2.3, if you got a temp file on Windows, it
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 77b0d66..40cf5a7 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -78,6 +78,7 @@
#define HAVE_PIPE 1
#define HAVE_POPEN 1
#define HAVE_SYSTEM 1
+#define HAVE_CWAIT 1
#else /* 16-bit Windows */
#endif /* !MS_WIN32 */
#else /* all other compilers */
@@ -3333,8 +3334,33 @@
else
return Py_BuildValue("ii", pid, status_i);
}
-#endif /* HAVE_WAITPID */
+#elif defined(HAVE_CWAIT)
+
+/* MS C has a variant of waitpid() that's usable for most purposes. */
+static char posix_waitpid__doc__[] =
+"waitpid(pid, options) -> (pid, status << 8)\n"
+"Wait for completion of a given process. options is ignored on Windows.";
+
+static PyObject *
+posix_waitpid(PyObject *self, PyObject *args)
+{
+ int pid, options;
+ int status;
+
+ if (!PyArg_ParseTuple(args, "ii:waitpid", &pid, &options))
+ return NULL;
+ Py_BEGIN_ALLOW_THREADS
+ pid = _cwait(&status, pid, options);
+ Py_END_ALLOW_THREADS
+ if (pid == -1)
+ return posix_error();
+ else
+ /* shift the status left a byte so this is more like the
+ POSIX waitpid */
+ return Py_BuildValue("ii", pid, status << 8);
+}
+#endif /* HAVE_WAITPID || HAVE_CWAIT */
#ifdef HAVE_WAIT
static char posix_wait__doc__[] =
@@ -5678,7 +5704,7 @@
#ifdef HAVE_WAIT
{"wait", posix_wait, METH_VARARGS, posix_wait__doc__},
#endif /* HAVE_WAIT */
-#ifdef HAVE_WAITPID
+#if defined(HAVE_WAITPID) || defined(HAVE_CWAIT)
{"waitpid", posix_waitpid, METH_VARARGS, posix_waitpid__doc__},
#endif /* HAVE_WAITPID */
#ifdef HAVE_SETSID